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This forum is provided to promote discussion amongst students enrolled in Computer Networks (CITS3002).
 
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UWA week 29 - mid-year break

photo Re: csmark: project mark not available (all 6)
Mon 13th Jul, 3:44pm, Christopher M.
It may be a break for you, but not for me. Sorry for the delay, but I'm working towards this (while doing many other things). (posting anonymously, here, is not really the correct approach, and/as I have your email)

UWA week 28 - mid-year break

photo Re: csmark: project mark not available (all 6)
Wed 8th Jul, 7:17pm, Christopher M.
ANONYMOUS wrote: I have received your email(s), and will reply to them. I've asked the Faculty why students are now presenting plain-text SC emails, addressed just to 'Dear Student' and previously not sent to me, rather than the expected ones on UWA letterhead....

UWA week 27 - mid-year break

photo Re: project feedback (all 3)
Sun 5th Jul, 11:37am, Christopher M.
ANONYMOUS wrote: Please read the Announcement just posted. I may not have received a copy of your project extension information, so you'll have to email me about it (provide a copy if you still have it).
photo Project marks finally available
Sun 5th Jul, 11:35am, Christopher M.
Your project marks are now available for the CITS3002 project. The project marks include any penalties for late submission of your work (the standard UAP rate of 5%, or 2/40 marks, per day for up to 7 days), and have accounted for all Special Considerations...

UWA week 24 - 1st semester, 1st exam week

photo Re: Pseudo Code Marking Guide (all 13)
Mon 8th Jun, 6:36pm, Christopher M.
ANONYMOUS wrote: There are many types of simulation - they do not all just involve time slots and packet collisions. Although you won't be asked to produce any answers using the cnet code/API, that was a form of simulation that didn't require you to set...
photo Re: Pseudo Code Marking Guide (all 13)
Mon 8th Jun, 6:16pm, Christopher M.
ANONYMOUS wrote: Hi, It depends how the question is worded. If it just asks for pseudo-code, that's all it's asking for, and you're answering the question through the use of well chosen identifiers, variables/data structures, and control flow. And you...
photo Re: Mid Sem Q's (both)
Mon 8th Jun, 4:43pm, Christopher M.
ANONYMOUS wrote: Hello; We had no mid-semester test this semester, but the sample questions (though no answers released) appear at the bottom of: https://teaching.csse.uwa.edu.au/units/CITS3002/examinations.php
photo Re: Exam Marking Rubric (both)
Mon 8th Jun, 4:40pm, Christopher M.
ANONYMOUS wrote: There's no single answer, as it depends on the question type - for example, some questions may ask for, say, '2 advantages and 2 disadvantages...' (which may not be equal in 'size' or difficulty in knowing', others may just ask you 'to...
photo Re: Pseudo Code Marking Guide (all 13)
Mon 8th Jun, 4:34pm, Christopher M.
ANONYMOUS wrote: About 7or8 / 10 on the generous scale. Important things to consider/add: - it's based on Ethernet, so you need binary-exponential backoff, not just a random backoff. - nodes can detect collisions that even they are not involved in (they did...
photo Re: Network utilisation formula (both)
Mon 8th Jun, 4:23pm, Christopher M.
ANONYMOUS wrote: (well worded question; thank you). If asked about slotted Aloha, they're effectively the same, as the nodes only transmit, or not, at the beginning of each slot, and defer until the beginning of following slots. For pure Aloha, the formula...
photo Re: Exam password? (both)
Mon 8th Jun, 9:10am, Christopher M.
ANONYMOUS wrote: I have no idea; I have not been involved with setting up Examplify. I only know it will be available via LMS, and presume it's described here: https://www.uwa.edu.au/students/Study-success/Student-support-for-online-exams
photo Re: Formatting Examplify answers (both)
Mon 8th Jun, 5:05am, Christopher M.
ANONYMOUS wrote: I believe it is, but only by manually adding spaces or tabs to beginning of your lines (nothing automatic). Yes, though we have to mark them by looking at an Examplify screen because, when the answers are exported to any other format, it...
photo Re: 2018 Q2b (all 3)
Mon 8th Jun, 5:02am, Christopher M.
ANONYMOUS wrote: You're correct (that question would have been from our Week-12). Thanks; I've added it to the list on the https://teaching.csse.uwa.edu.au/units/CITS3002/examinations.php page.
photo Re: Two Contending Network Layer Schemes (both)
Mon 8th Jun, 4:58am, Christopher M.
ANONYMOUS wrote: Not specifically about that page. But the question is asking about two approaches to fragmentation, one which fragments and re- assembles at the ends, and the other which fragments and re-assembles at each node it passes through. You may...
photo Re: Exam Suggestions (all 4)
😴Mon 8th Jun, 4:44am, Christopher M.
ANONYMOUS wrote: Released Friday 24th April, in the week that it was always due to come out: https://secure.csse.uwa.edu.au/run/help3002?p=np&a=168 with the first student seeking clarification on Sun 26th April, over the long weekend: https://secure.csse.uwa.edu.au/run/help3002?p=np&a=173&all=y2...

UWA week 23 - 1st semester, study break

photo Re: Pg.14 Lecture 11 - broken link (both)
Sun 7th Jun, 7:52am, Christopher M.
Hi Laura, I can't find that original article anywhere. I suspect the author has left the Univ of Washington, and they've removed his account. This article: https://medium.com/swlh/20-years-of-ddos-7d2d4223f303 provides a very similar summary and (not coincidently)...
photo Re: Exam Suggestions (all 4)
😴Sun 7th Jun, 7:36am, Christopher M.
ANONYMOUS wrote: What you want me to say, and what is the truth, and likely quite different. Are you now revising, or studying it for the first time? It's clear that many pushed out their project submission, perhaps, without keeping an eye on their exam...
photo Re: 2017 Exam - Q3a) (both)
Sun 7th Jun, 7:22am, Christopher M.
ANONYMOUS wrote: Protocols at multiple levels are required for this answer, so when you say 'the address', 'the response', and 'the information' you'll need to specify what kind of addresses, for which protocol, you're meaning, and what the responses involve....
photo Re: Network Layer Lecture Slides (both)
Sun 7th Jun, 7:15am, Christopher M.
ANONYMOUS wrote: Good reasoning, but in the case of token bucket, there's still a maximum limit on the tokens that may be accumulated, so there's till a limit how long a burst of traffic can be. Much like rolling-over your remaining mobile phone data each...
photo Re: Small error in slide footer (both)
Sun 7th Jun, 7:06am, Christopher M.
ANONYMOUS wrote: Fixed; thanks. (hope no-one applies for an extension, for that :-)
photo Re: 2018 Q3a (both)
Sun 7th Jun, 7:05am, Christopher M.
ANONYMOUS wrote: Certainly identify (highlight) the above things, as they provide all the important things for addressing (the connectivity between src and dest). Show the embedding of the protocols, that 'higher' protocols sit within the payloads of lower...
photo Re: When is the file descriptors in Select() 'ready'? (all 5)
Sat 6th Jun, 8:38am, Christopher M.
No surprises there ^^. A NULL pointer indicates to select() that you're not interested in writable descriptors, etc. Providing a non-NULL pointer says "the array or file descriptors I AM interested in starts here...."
photo Re: Lecture 3 - Protocols (all 3)
Sat 6th Jun, 8:36am, Christopher M.
The first reply, above, is good one. You could write your pseudo-code with a C syntax, and even use nested functions, if it helps you present/explain your answer.
photo Re: ipv4/6 (both)
Fri 5th Jun, 10:57am, Christopher M.
ANONYMOUS wrote: Discussion about IPv4 is in Week-7; there is nothing mentioned about IPv6.
photo Re: pthread in c (all 3)
Fri 5th Jun, 10:54am, Christopher M.
ANONYMOUS wrote: If you have been solving this, yourself, by manually entering the function's prototype (declaration), it suggests that you are not including the <pthread.h> header file. However, your question suggests that you've found this "solution"...
photo Re: Past paper (all 5)
Thu 4th Jun, 6:01pm, Christopher M.
My guess: https://secure.csse.uwa.edu.au/run/help3002?search=discord
photo Re: When is the file descriptors in Select() 'ready'? (all 5)
Thu 4th Jun, 5:58pm, Christopher M.
No changes to the code, and it starts working? I guess you're starting to believe in good fairies about now :-)
photo Re: Response format (all 3)
Thu 4th Jun, 5:56pm, Christopher M.
ANONYMOUS wrote: It would (have been) really, really good if, as requested, produced a very simple HTML output. It makes the marking process easier, often because it doesn't have to be performed using a web- browser. I appreciate that developing more detailed...
photo Re: PDF Lecture 11 (both)
Wed 3rd Jun, 7:20pm, Christopher M.
Thanks; it's back (no idea where it went!)
photo Re: last minute question (all 4)
Tue 2nd Jun, 7:12pm, Christopher M.
If the problem is your Content-length header, then this should help: https://secure.csse.uwa.edu.au/run/help3002?p=np&a=384&all=y5
photo Re: udp stuff (both)
Tue 2nd Jun, 1:33pm, Christopher M.
ANONYMOUS wrote: Each of your servers will have open two descriptors: - one to receive new requests from a browser via TCP - one to communicate with neighbours, using udp. New, original, requests will only arrive via your TCP descriptor. Communication with...
photo Re: Location of Timetable Files (both)
Tue 2nd Jun, 1:27pm, Christopher M.
You can safely assume that all timetable files will be in the same directory as your station-server executable files (all in the same directory). (though not usually described as 'next to')
photo Re: Marking for invalid route (all 5)
Tue 2nd Jun, 1:16pm, Christopher M.
ANONYMOUS wrote: That first part off your reply sounds good. However, I'm unsure of the part you describe as 'layers of looping' - do you mean UDP packets stuck in a cycle, that you see multiple times? I'd probably not think of them as layers, but more...
photo Re: Yet another weeks 10-12 lecture recordings question (all 5)
Tue 2nd Jun, 1:08pm, Christopher M.
Hello Laura, That is not what I said. The Zoom video recordings for lectures 10 and 11 will be completed and uploaded today, as I said. The lecture slides for that material has been available via our Schedule page for 2-3 weeks. As you will see from the Schedule...
photo [Final Exam] - Week-12 material not examinable
Tue 2nd Jun, 1:07pm, Christopher M.
As you will see from the Schedule page, I have indicated that the material from Week-12 WILL NOT be examinable in the final exam. This material was added to the Schedule part way through the semester, to fill the 'gap' created when UWA extended the semester,...
photo Re: select (all 3)
Mon 1st Jun, 3:58pm, Christopher M.
ANONYMOUS wrote: Difficult to answer your question because we have no idea what your variable accept_fd is used for - is it the descriptor passed to accept(), or the descriptor returned from a successful call to accept() ? If the latter, it probably shouldn't...
photo Re: Submission (both)
Mon 1st Jun, 11:13am, Christopher M.
ANONYMOUS wrote: So far, I have only manually entered a few of the (standard, non-CV19) '3002 extensions into cssubmit. To date, we have 118 extension, and clearly a number of students have exploited the opportunity; unsure how many we'll receive by the...
photo Re: Yet another weeks 10-12 lecture recordings question (all 5)
Mon 1st Jun, 5:09am, Christopher M.
Hello Macallister, The lecture recordings will all be complete by the end of Tuesday. (Like many students) I'm working through this long weekend to catch up.
photo Re: Ports remain bound for a little while after closing (all 7)
Mon 1st Jun, 5:08am, Christopher M.
ANONYMOUS wrote: Still through cssubmit.

UWA week 22 - 1st semester, week 12

photo Re: java equals (all 9)
Sun 31st May, 11:22am, Christopher M.
ANONYMOUS wrote: How are you testing for equality: - with object equality (s1 == s2), or - with value equality ( s1.equals(s2) ) ??
photo Re: Ports remain bound for a little while after closing (all 7)
Sun 31st May, 11:21am, Christopher M.
If you've applied for an extension, they should have all been moved to 2nd June; so still time to resubmit if you have any energy left.
photo Re: Marking for invalid route (all 5)
Sun 31st May, 11:19am, Christopher M.
ANONYMOUS wrote: Probably only checked for a couple of 'no route' cases, and in each language. If your approach doesn't work for, say, 5 nodes, then it's unlikely to work for 20 nodes. And if it works for 20 nodes, then it's likely to work for 5 nodes.
photo Re: Could you please upload the lecture recording from week-10 to week-12 on LMS? (all 3)
Fri 29th May, 1:41pm, Christopher M.
ANONYMOUS wrote: I cannot upload the lectures until they have been recorded; that's why they say "to be recorded". Thanks - the first time that anyone has mentioned this problem.
photo Re: Using switch cases vs if-else conditionals (both)
Fri 29th May, 1:24pm, Christopher M.
ANONYMOUS wrote: When asking a question about programming languages, you need to indicate which language you're discussing. But on the chance you're asking about C, you could declare local variables with: {{{ switch (expression) { case 1 : { int local1;...
photo Re: Ports remain bound for a little while after closing (all 7)
Fri 29th May, 10:07am, Christopher M.
Are you implementing socket (address) reuse, with setsockopt ?
photo Re: Language choice for project (all 3)
Fri 29th May, 10:06am, Christopher M.
ANONYMOUS wrote: Yes. Was clarified on 28th April: https://teaching.csse.uwa.edu.au/units/CITS3002/project2020/clarifications.php
photo Re: Global Constants (all 4)
Wed 27th May, 5:44pm, Christopher M.
ANONYMOUS wrote: That just sounds like a function (not a global constant) receiving a parameter providing "the blanks". Nothing out of the usual, there. I have, for example (in C): extern void write_http_header(FILE *fp, const char *response); declared in...
photo Re: Global Constants (all 4)
Wed 27th May, 5:34pm, Christopher M.
ANONYMOUS wrote: Not quite sure what type of thing you're asking about, but: - being global means that all functions in all source files will have read+write access to it if they can name it, and - you'd only generally define something with global scope...
photo Re: Are non-blocking sockets needed if select is being used? (all 3)
Wed 27th May, 12:59pm, Christopher M.
One thing to ask yourself, when considering non-blocking I/O, is "what will my application be doing when it's not testing for any pending I/O?" In the case of our project, it really has nothing else to do.
photo Final examination information - PLEASE RE-READ IT
Wed 27th May, 12:57pm, Christopher M.
Our final examination information is available from: https://teaching.csse.uwa.edu.au/units/CITS3002/examinations.php Please re-read the instructions. Good luck,
photo Re: Lecture recordings (all 7)
Tue 26th May, 5:49pm, Christopher M.
ANONYMOUS wrote: I'd hope so, being the last week of the semester; just struggling with exams, marking, extensions, my other unit, research projects, and designing new degrees commencing next year...
photo Re: Read in all station files to get station metadata (all 6)
Tue 26th May, 2:19pm, Christopher M.
ANONYMOUS wrote: Somewhere; there's no real client required for this project (other than what I've provided). Ok, as long as the actual result can be clearly read as English text (and doesn't require a JS interpret to disenshroud any encoding).
photo Re: Can we use HTTP POST? (all 4)
Tue 26th May, 2:15pm, Christopher M.
ANONYMOUS wrote: Yes, but please keep in mind that there's no extra marks on the marking rubric for doing anything beyond what's on the rubric - nothing for a more polished interface, or a better algorithm. So unless you already have all this extra interface...
photo Re: Can we use HTTP POST? (all 4)
Tue 26th May, 6:48am, Christopher M.
ANONYMOUS wrote: If you want to support POST, please support *both* POST and GET (but why do you wish to use POST?). - Supporting GET is far easier (requires just parsing a single input line), - 'all the work' is provided for you with the makeform.sh script,...
photo Re: Read in all station files to get station metadata (all 6)
Tue 26th May, 6:41am, Christopher M.
ANONYMOUS wrote: Please read the main page, Getting Started page, the Clarifications page for the project, and scan project-related posts on this forum (commencing week-8 of semester).
photo Re: Read in all station files to get station metadata (all 6)
Tue 26th May, 6:37am, Christopher M.
ANONYMOUS wrote: That webpage is automatically generated by the makeform.sh shellscript. See the Clarifications Page from about 2 weeks ago. The webpage just provides a simple interface to pass requests to your station-servers. It is not an assessed part...
photo Re: Chrome sending a second non receivable TCP request suspected Favicon (all 12)
Tue 26th May, 6:31am, Christopher M.
ANONYMOUS wrote: Do you know if this is the case (have you tested it)? The problem is that Chrome opens a second TCP connection, but doesn't send anything on it. How do you differentiate between a GET not being sent, and a POST not being sent?
photo Re: How to check if the timetable has changed after the server has already started? (all 11)
Mon 25th May, 1:28pm, Christopher M.
ANONYMOUS wrote: The stat structure stores the time a file was last modified, which has nothing to do with when (even if) you last opened it.
photo Re: Why is 1970 the reference point for time in C (and everything)? (all 3)
Mon 25th May, 12:28pm, Christopher M.
Sorry, too short a reply. At the time of Unix's development, there were many disparate proprietary operating systems, each with their own representations of operating system values, influenced by their own architecture's byte- and word-sizes. The Unix designers...
photo Additional laboratory sessions in Week-12
Mon 25th May, 8:53am, Christopher M.
As we have so many students have approved projects extensions (more than half the unit - unprecedented!) Daniel and I will be running Zoom laboratories at the regular times this week - - Monday 11am-3pm and - Friday 10am-2pm.

UWA week 21 - 1st semester, week 11

photo Re: Why is 1970 the reference point for time in C (and everything)? (all 3)
Sun 24th May, 8:32pm, Christopher M.
https://www.levenez.com/unix/ ... and signed, not unsigned, 32-bit integers.
photo Re: Only complete the project in 1 language (all 4)
Sun 24th May, 4:48pm, Christopher M.
ANONYMOUS wrote: Yes. The requirements listed on the rubric were to be implemented in two languages. If strictly following a marking rubric, you do not lose marks for not doing something - you only gain marks for doing things. Many students have indicated...
photo Re: Chrome sending a second non receivable TCP request suspected Favicon (all 12)
Sun 24th May, 8:19am, Christopher M.
ANONYMOUS wrote: Do you mean this setting? Settings > Privacy and security > More > disable 'Preload pages for faster browsing and searching' which I testing on v83.0.4103.61, which Chrome states is their latest version (macOS).
photo Re: Only complete the project in 1 language (all 4)
Sun 24th May, 6:07am, Christopher M.
ANONYMOUS wrote: No, I'm afraid not. The project has always required implementation in two languages. That first part of the rubric requires two implementations, both of which have used their language's standard networking features, and not used other inter-process...
photo Re: Chrome sending a second non receivable TCP request suspected Favicon (all 12)
Sun 24th May, 5:54am, Christopher M.
ANONYMOUS wrote: Not encouraging you to undertake any changes or more work that you don't want to, but you can still apply for an extension, without providing a reason, up until Wednesday: https://www.uwa.edu.au/students/need-help/special-consideration...
photo Re: Chrome sending a second non receivable TCP request suspected Favicon (all 12)
Sat 23rd May, 7:45am, Christopher M.
ANONYMOUS wrote: Certainly an annoying Chrome 'feature', which doesn't violate the HTTP standards, but does give the suggestion that Chrome (Google) is wanting to 'dictate' how servers must be written. The practice can be addressed by having a multithreaded...
photo Re: Response to client (all 4)
Fri 22nd May, 4:06pm, Christopher M.
ANONYMOUS wrote: No, don't explicitly ignore the 'favicon' requests, ignore EVERYTHING that is not a '/?to=xxxx' request. And, by ignore, we mean send back a reply indicating that you're ignoring it.
photo Re: Chrome sending a second non receivable TCP request suspected Favicon (all 12)
Fri 22nd May, 4:04pm, Christopher M.
ANONYMOUS wrote: OK, if it's bigger than the both of us, can you download Firefox and use that instead?
photo Re: Chrome sending a second non receivable TCP request suspected Favicon (all 12)
Fri 22nd May, 2:17pm, Christopher M.
ANONYMOUS wrote: It's unclear what you mean by (or how you know) that there's something there, but that you can't read it. Do you try to read it? What value does your read function return, such as a number of bytes, or an error indication? Unsure what you...
photo Re: Response to client (all 4)
Fri 22nd May, 1:35pm, Christopher M.
ANONYMOUS wrote: Could this be related to the discussed 'favicon' requests, sent my some browsers? https://secure.csse.uwa.edu.au/run/help3002?p=np&a=316&all=y7 Have you seen a favicon request and, if so, do you deal with it? Otherwise you might be processing...
photo Update on project extensions
Fri 22nd May, 7:15am, Christopher M.
The Eng. Faculty Office has confirmed the discrepancies in the dates given for extension requests under UWA's blanket COVID19 policy (partially caused because the extensions also came from other Faculties, not just EMS). So, if you've previously received...
photo Re: storing timetable in C (both)
Fri 22nd May, 5:26am, Christopher M.
ANONYMOUS wrote: Every line of the timetable file can be stored in a structure, and the whole file in an array of such structures. Every line of the timetable file needs to be split into fields (at the commas) and each field of the line stored in a field...
photo Re: buildrandomtimetables station name capitalization (all 3)
🍺Fri 22nd May, 5:21am, Christopher M.
ANONYMOUS wrote: Glad you found your error (and glad that it wasn't mine). The only places where capitalisation needs to, and will, match are the station names given on the command-line, and the station names at the end of each timetable line. There is no...
photo Re: Determining if a route is not valid in a given day? (all 10)
Thu 21st May, 5:40pm, Christopher M.
ANONYMOUS wrote: That's correct - they both mean 'no route today'.
photo Re: Determining if a route is not valid in a given day? (all 10)
Thu 21st May, 5:10pm, Christopher M.
ANONYMOUS wrote: Eddie's reply is a good one. You'll be asking each station "what's the earliest time you can get to X". If each station examines its own timetable data, it'll find no possible trip leaving (today). So have it reply with an 'impossible', large...
photo Re: Just wondering the facicon problem and the structure of the response (all 4)
Thu 21st May, 5:01pm, Christopher M.
ANONYMOUS wrote: Yes, that's all the information required. I made mine a bit prettier (not required), but it also just provides the answer. Your project doesn't recognise the favicon request, so it can 'ignore' it. However, the browser will still be waiting...
photo Re: How to check if the timetable has changed after the server has already started? (all 11)
Thu 21st May, 4:56pm, Christopher M.
ANONYMOUS wrote: It's a trivial addition to your code to do it the right way! In C: {{{ struct stat sbuf; // ENSURE THAT WE CAN stat() THE TIMETABLE FILE if(stat(timetable_filename &sbuf) != 0) { ...... } // NOTHING TO DO IF THE TIMETABLE...
photo Re: Submitted Project File Structure (all 4)
Thu 21st May, 11:58am, Christopher M.
That's fine; you're more of a Java expert than me (so is that spider crawling up my wall); I think jar believes that the first file on its command-line provides main (even if it doesn't), and just uses that filename. But don't change what you have; we'll...
photo Re: How to check if the timetable has changed after the server has already started? (all 11)
Thu 21st May, 11:56am, Christopher M.
ANONYMOUS wrote: Yes, but you wouldn't want to re-read the timetable file if it hasn't changed. The operating-system provides the system call stat(), well discussed in CITS2002, to provide attributes of a file.
photo Re: Request for extension of Project due date (Write a comment if you would like to request as well) (all 4)
Thu 21st May, 11:53am, Christopher M.
ANONYMOUS wrote: Firstly, it's not an adversarial process. No coding framework was ever released, just a small number of optional shellscripts designed to ease the task of converting a text specification of a transport-network into a script to start off...
photo Re: Request for extension of Project due date (Write a comment if you would like to request as well) (all 4)
Thu 21st May, 10:54am, Christopher M.
ANONYMOUS wrote: I'm sorry, but I'm not going to do this (and not through a lack of understanding). When the university paused during week-7, all units were given an opportunity to change assessments and deadline, and the requests had to be approved by...
photo Re: Knowledge of Neighbor's Station Name (all 3)
Thu 21st May, 10:44am, Christopher M.
ANONYMOUS wrote: While it's true that you don't *need* your neighbours' names, it will help to know them (and to prevent you from 'annoying' your other neighbours). No, there's no guaranteed relationship between names and port numbers. The station-servers...
photo Re: TCP suddenly stopped working (no longer receiving requests from client) (all 8)
Thu 21st May, 10:41am, Christopher M.
ANONYMOUS wrote: There's probably a lot of different things you're observing: - as you're likely using my shellscripts, you'll be requesting port numbers around 4000+ - much larger port numbers, say the 40,000+ ones you've mentioned, are ones allocated by...
photo Re: Submitted Project File Structure (all 4)
Thu 21st May, 7:37am, Christopher M.
Cannot think of additional. The maven specification will probably not be used as it may not be installed on the markers' machines. Does it include anything specific, or can your Java just be compiled 'by hand'?
photo Re: Multiple files (both)
Thu 21st May, 7:23am, Christopher M.
ANONYMOUS wrote: If your chosen programming language supports hiding of data and function/methods using separate files, then its certainly a good, preferred practice. Cannot answer to "expected", but certainly "anticipated".
photo Re: TCP suddenly stopped working (no longer receiving requests from client) (all 8)
Thu 21st May, 7:20am, Christopher M.
ANONYMOUS wrote: Your operating system will certainly have a limit on how many ports can simultaneously be in use, but it will be in the thousands. Does the provided portsinuse script list a huge number of ports?
photo Re: Station transit time (all 4)
Thu 21st May, 7:16am, Christopher M.
ANONYMOUS wrote: Clearly a time of zero would not be possible, unless you're staying on the same bus (you can see that in the Transperth data because most buses arrive and then depart at the same time). Though don't bother testing for the same bus-numbers,...
photo Re: FInal test network (both)
Thu 21st May, 7:11am, Christopher M.
ANONYMOUS wrote: Not on the whole network, as there's missing information, but a consistent subset could be possible. But the names and trip times of any transport-network should have no affect on your approach to finding a valid route. It's the *shape*...
photo Re: Directed vs Undirected adjacency graph (all 4)
Thu 21st May, 7:06am, Christopher M.
Yes, and/or remove those stations from your network's adjacency file and timetables (grep -v will help). There's information we don't have, such as buses changing the number (and hence route) at particular stops, and buses finishing at a stop and going...
photo Re: Extension of project (all 11)
Thu 21st May, 7:03am, Christopher M.
Sorry, won't be changing the time of the deadline. It's been set for weeks to allow students to plan their time, and the same time is used for approved extensions. Sorry.
photo Re: python udp communication (both)
Wed 20th May, 7:51am, Christopher M.
ANONYMOUS wrote: Yeehah! Can I suggest that you search for the function name 'select', or similar, discussed many times in this forum, with many examples provided in the tutorials linked on our Getting Started page? It will enable your station-server to...
photo Re: Extension of project (all 11)
Wed 20th May, 7:47am, Christopher M.
ANONYMOUS wrote: Even more importantly, tell your friends to read the email that UWA has sent several times, and the centrally-provided FAQ webpages.
photo Re: file name naming convention (all 5)
Wed 20th May, 7:44am, Christopher M.
ANONYMOUS wrote: No. As others have stated, the format is just tt-StationName with no filename extension. ... There does seem to be am ongoing confusion/misunderstanding about filename extensions, raised by many students in different units.
photo Project marking rubric is available
Wed 20th May, 7:43am, Christopher M.
The project's marking rubric has been added to the bottom of the project's main webpage. It should contain no surprises, and all of its points have been discussed on this help forum (so please search through the topics). Good luck.
photo Re: Marking Rubric (both)
Wed 20th May, 7:41am, Christopher M.
Hello Isabelle, It is now at the bottom of the project's main webpage; I don't believe that it contains any surprises, and all of its points have been discussed on this help forum.
photo Re: Extension of project (all 11)
Tue 19th May, 6:39pm, Christopher M.
Hi, I'm aware of these discrepancies and inequities, and have asked the Faculty Office about them a few days ago. I've not been involved in setting any deadlines, other that to state my (now naive) hope of keeping the project deadlines away from the final...
photo Re: buildtimetables.sh (all 5)
Tue 19th May, 6:07pm, Christopher M.
Did you resolve this problem?
photo Re: time information (both)
Tue 19th May, 5:46pm, Christopher M.
ANONYMOUS wrote: Stations can only communicate with their neighbours. So, if your final calculated result/arrival-time is determined from a station not a neighbour of the one your web-browser first contacted (A), the the result will (likely) need to traverse...
photo Re: Java NIO library (all 10)
Tue 19th May, 5:43pm, Christopher M.
ANONYMOUS wrote: Hi, yes, I believe that that's the best approach. Other approaches may work, but are not as elegant, nor as efficient (for a systems' point of view).
photo Re: Transperth network adjacency (all 3)
Tue 19th May, 2:42pm, Christopher M.
ANONYMOUS wrote: Here you go; save it as a shellscript and run ./buildadjacency.sh adjacencyfile tt-* {{{ #!/bin/bash # written by [email protected] if [[ "$#" < "4" ]]; then echo "Usage: $0 adjacencyfile timetable1 timetable2 [timetable3...]"...
photo Re: java station call (both)
Tue 19th May, 2:33pm, Christopher M.
ANONYMOUS wrote: Aren't there a variety of ways to do it, such as - java station (so, yes) and - java -cp . station.Main (depending on how you've built your program?) ... https://docs.oracle.com/javase/tutorial/getStarted/cupojava/unix.html
photo Re: Java NIO library (all 10)
Tue 19th May, 2:26pm, Christopher M.
ANONYMOUS wrote: I think we're talking about different meanings of blocking or non-blocking here. Yes, select() and its abstractions, do block - until something is ready-to-read. Knowing that a socket is ready-to-read means that, when you try to read it,...
photo Re: Does the order of arguments correspond to the order on the timetable? (all 3)
😴Tue 19th May, 2:21pm, Christopher M.
ANONYMOUS wrote: Agreed, there is no relationship. There is no real 'order of stations on the timetable'. If using my buildrandomtimetable programs, the timetables lines are just generated in time order.
photo Re: Station Knowledge (all 7)
Tue 19th May, 2:19pm, Christopher M.
Hi Macdara, It's a possible solution and, if completed quickly enough, would find the optimal solution. But it will likely result in far more communication than necessary - if you know that one of your neighbours is the final destination, and you have a...
photo Re: Project query string parameters (all 7)
Tue 19th May, 2:15pm, Christopher M.
ANONYMOUS wrote: Yes.
photo Re: Project query string parameters (all 7)
Tue 19th May, 2:15pm, Christopher M.
ANONYMOUS wrote: There's all sorts of problem scenarios that we could invent - what if the browser, or users', notion of time is ahead of the servers' time - you may miss the train that's just about to leave. (Politely), just keep it simple.
photo Re: Getting incorrect port number from recvfrom (all 5)
Tue 19th May, 2:12pm, Christopher M.
ANONYMOUS wrote: That's great news; sockets (used for both TCP connections and UDP datagrams) are bidirectional by default, so you can/should use the same for both reading and writing (you can make a socket unidirectional, by using shutdown(), but we don't...
photo Re: Java NIO library (all 10)
Tue 19th May, 7:48am, Christopher M.
I do not believe that an approach using threading or non-blocking I/O is the best approach for our (honestly) quite simple requirements. Any approach involving select(), even it wraps it in some other abstraction that enables you to iterate over the ready...
photo Re: Getting incorrect port number from recvfrom (all 5)
Tue 19th May, 7:37am, Christopher M.
ANONYMOUS wrote: This sounds like a good suggestion. Unless you specifically bind a known address to a socket (such as 4???), the operating system will assign you a 'random' port number, often a large value 'away' from the smaller numbers that humans tend...
photo Re: Project query string parameters (all 7)
Tue 19th May, 7:34am, Christopher M.
ANONYMOUS wrote: Strongly preferred that you just send/receive/support /?to=Perth_Stn What do you need the other part of the request for? Please read https://secure.csse.uwa.edu.au/run/help3002?hl=operating%20system%20time&a=257
photo Re: buildtimetables.sh (all 5)
Tue 19th May, 7:32am, Christopher M.
ANONYMOUS wrote: That message is confusing. I suggest that the executable program ./buildrandomtimetables is trying to use/compile a C program. What command and files did you use to get that error?
photo Re: HTTP request (both)
Tue 19th May, 7:27am, Christopher M.
ANONYMOUS wrote: You are simply requiring functions to perform simple I/O, the same functions that you would use to read/write data to files on disk. We're using integer socket descriptors, which can be used the same way that we use integer file descriptors....
photo Re: Station Knowledge (all 7)
Tue 19th May, 7:22am, Christopher M.
ANONYMOUS wrote: Both of those algorithms require that every node (or every node needing to perform the algorithms) have the full network knowledge, including the connectivity of/between all nodes. That work must be performed before, and then regularly,...
photo Re: Station Knowledge (all 7)
Mon 18th May, 5:47pm, Christopher M.
ANONYMOUS wrote: No, not permitted. And the information would become stale, if any of the stations' timetable files changed. Yes, since about 3.30pm; it has been reported. Seems to be many websites, too - Library, Timetable, Faculty... I'm sure that they're...
photo Re: Java NIO library (all 10)
Mon 18th May, 5:41pm, Christopher M.
ANONYMOUS wrote: The important question is - if your application becomes reliant on non-blocking I/O, what will your application be doing the rest of the time? If there's nothing else to do, other than read a small piece of information from the network,...
photo Re: Worst case scenarios in project (all 4)
Mon 18th May, 3:59pm, Christopher M.
ANONYMOUS wrote: None of the problems you've describe will occur (we've stated that the programs and their data files exist, and will be called correctly). You can assume that the shellscripts I've provided all work as advertised, and if they don't I'll...
photo Re: Project - Neighbouring (both)
Mon 18th May, 12:17pm, Christopher M.
Please stop looking for loopholes in the wording. - Stations know the port numbers of their neighbours (given on the command-line). - Stations read their own timetable files, and no other files. - Stations only communicate with the browser (using TCP) and...
photo Re: Basic Layout (all 3)
💡Mon 18th May, 11:07am, Christopher M.
ANONYMOUS wrote: It's unclear if there's some confusion, here, or if the words you've used are just confusing me. Each server-station (program) can be invoked from the command-line, or from within a shellscript that does it for you. Servers don't specifically...
photo Re: The out put format (both)
Mon 18th May, 10:54am, Christopher M.
ANONYMOUS wrote: No instructions have changed since the project has been released, and there's been no mention of any compulsory output format, only this suggestion: https://secure.csse.uwa.edu.au/run/help3002?hl=catch&a=440 The unchanged project sheet,...
photo Re: writing back http in java (all 5)
Mon 18th May, 10:49am, Christopher M.
ANONYMOUS wrote: I suspect that the problems you are seeing are related to a module or class that you are using that is hiding the basics of using sockets from you. ?? The use of "Content-length...." is entirely optional in an HTTP reply, so there should...

UWA week 20 - 1st semester, week 10

photo Re: writing back http in java (all 5)
Sun 17th May, 8:47am, Christopher M.
ANONYMOUS wrote: The browser will not be listening for connections. It will only be waiting for some response on the same TCP connection that it sent its request. There's also no need to send "Content-Length: 60", and it suggests that you know the length...
photo Re: Project - Final Returned Result to Browser (all 4)
Sun 17th May, 8:44am, Christopher M.
ANONYMOUS wrote: (Answered somewhere) there is no need to report the full route to be taken. Just report, for example: "At 09:15, catch busA_B, from stopA. You will arrive at your final destination at 09:34"
photo Re: Worst case scenarios in project (all 4)
Sun 17th May, 8:41am, Christopher M.
ANONYMOUS wrote: These and similar questions would better be thought of, not as "what are we allowed to do?", but "what is the correct thing to do?". The correct thing to do is to read everything sent by the browser. If only part of it is meaningful, find...
photo Re: Can destination send directly back to origin? (all 6)
Sun 17th May, 8:30am, Christopher M.
ANONYMOUS wrote: You can place anything you like in your datagram payload (you're not placing a port in it, just an integer/string representing that port). The constraint is that servers may only communicate with their neighbours (and the browser making...
photo Re: Project - Server and Client (all 3)
Sun 17th May, 8:27am, Christopher M.
ANONYMOUS wrote: This is correct; the project does not require two different programs, that might be named 'client' and 'server'. We are developing one program, our station-servers. They act as traditional servers when awaiting new queries from a web-browser....
photo Re: Can destination send directly back to origin? (all 6)
Sat 16th May, 11:45am, Christopher M.
ANONYMOUS wrote: My same answer as above. Stations may only communicate with their neighbours, and they already know their neighbours' ports. There's no need to place any port number in datagram payloads, as recvfrom() provides the sender's (src) port.
photo Re: Directed vs Undirected adjacency graph (all 4)
Sat 16th May, 3:47am, Christopher M.
Yes, (I think it's written somewhere that all links are bidirectional). In terms of connectivity, the (computer) networks is the same as the transport network. If two bus/train stations are physically adjacent, then they'll know each other's UDP ports via...
photo Re: Java LocalDateTime and Timetable Files (all 3)
Fri 15th May, 5:30pm, Christopher M.
ANONYMOUS wrote: You could remove all past-midnight trips with a few lines: {{{ for tt in tt-* do grep -v ",2[45]" < $tt > tmp mv tmp $tt done }}} though, obviously, that will make more routes no longer possible.
photo Re: Test Cases (both)
Fri 15th May, 5:25pm, Christopher M.
ANONYMOUS wrote: Have you tried using the buildrandomtimetables program? (though when the networks get larger, it's obviously much harder to trace calculate things by hand, to verify them). There's two aspects to testing: - does all the networking code...
photo Re: Can destination send directly back to origin? (all 6)
Fri 15th May, 5:23pm, Christopher M.
ANONYMOUS wrote: Stations may only communicate with their neighbouring stations. (you must be passing UDP ports in your datagram payloads, or assuming everyone can read a specific file :-) Any valid time is valid; anything better is just for pride.
photo Re: Hint request: Getting the fastest path (all 12)
Fri 15th May, 1:28pm, Christopher M.
There's no perfect answer in all cases; the problem with having a time-limit is that you don't always know the correct limit (either too short, or too long), and the problem with counting replies, is that you may already have the best information and just...
photo Re: Fastest or most direct route (both)
Fri 15th May, 1:11pm, Christopher M.
ANONYMOUS wrote: If striving for the 'fastest' journey, it's the one that gets us to the destination the earliest. From the project: "Ideally, the returned result will be the fastest journey - even if it leaves later or includes more segments (hops) than...
photo Re: Hint request: Getting the fastest path (all 12)
Fri 15th May, 12:55pm, Christopher M.
Hi Jai, I think you're confusing the two meanings of 'being reliable'. Yes, because we're on a single machine, your UDP datagrams will not be lost. So we can assume that if we send it, it will arrive, there is no need to acknowledge the arrival of the datagram...
photo Re: Adjacent Stations - Edge Case (all 4)
Thu 14th May, 5:40pm, Christopher M.
Yep, great. A famous quote, from an even more famous Computer Scientist, Donald Knuth, is: "Premature optimization is the root of all evil (or at least most of it) in programming" https://en.wikiquote.org/wiki/Donald_Knuth
photo Re: Adjacent Stations - Edge Case (all 4)
Thu 14th May, 5:11pm, Christopher M.
Hi Lemar, The example you've given, where a journey of more hops may be quicker, is certainly a possible case, but obtaining the absolute fastest journey is not a requirement of the project. A few lines further down, after the part you've quoted, the project...
photo Re: Hint request: Getting the fastest path (all 12)
Thu 14th May, 3:57pm, Christopher M.
But if you've already seen the query, coming from the same port (neighbour), before and you've replied to it correctly the first time, how is that affecting correctness? And why did they send it to you, again, anyway?
photo Re: Hint request: Getting the fastest path (all 12)
Thu 14th May, 3:50pm, Christopher M.
Then why do you describe it as 'dropping' the packet, if you're responding to it in a reasonable way? No information will be lost, and for every datagram sent out, a reply is still received.
photo Re: Hint request: Getting the fastest path (all 12)
Thu 14th May, 3:45pm, Christopher M.
Don't drop them; reply to them indicating that you've already answered their query.
photo Re: HTTP GET Request Problems (all 7)
Thu 14th May, 2:52pm, Christopher M.
Depends. Are you a teapot?
photo Re: Python UDP ports not decoding message (all 8)
Thu 14th May, 2:32pm, Christopher M.
ANONYMOUS wrote: Has your call to recvfrom() *ever* returned? If not, your problem is probably not related to encoding or endianness (what made you suspicious of the encoding?), but to your waiting for a datagram using the wrong port, or that it was sent...
photo Re: Project - Forking in C (all 6)
Thu 14th May, 1:53pm, Christopher M.
ANONYMOUS wrote: Each station server needs to check if its timetable file has changed, dispose/deallocate its old one, read in the new one. All done while the 'network' is already running. Yes, use a shellscript, use a variant of mine if it helps. But the...
photo Re: Python UDP ports not decoding message (all 8)
Thu 14th May, 1:15pm, Christopher M.
ANONYMOUS wrote: It's great that everyone's asking about my health, but anonymously :-) It's not clear what needs to be decoded when it arrives, because it's not clear what has encoded before you sent it. Are you sending simply Python strings, or sending...
photo Re: HTTP GET Request Problems (all 7)
Thu 14th May, 1:10pm, Christopher M.
But first .... don't just send them a "200 All's fine here mate", send them a "400 Bad Request". Then close the socket.
photo Re: Project - Forking in C (all 6)
Thu 14th May, 1:08pm, Christopher M.
ANONYMOUS wrote: That's a very unusual way to get the workflow achieved, and I'm unsurprised that you're having difficulties. There's no need for any C code, no forks. Here's my single shellscript to build and start everything (from within a testing subdirectory):...
photo Re: Station's knowledge of network (all 3)
Thu 14th May, 1:01pm, Christopher M.
Hi Macdara, The answer to this very much depends on how you're doing/thinking about it. Yes, your UDP queries do need to Short answer is 'yes'. Server software often runs for days or months, and shouldn't terminate or hang through a lack of memory, because...
photo Re: How do avoid buffer space error in Python? (all 10)
Wed 13th May, 3:50pm, Christopher M.
ANONYMOUS wrote: No, don't add the 's' and 'r' in the datagrams, have all processes append them to a file-on-disk, then eventually run sort thatfilename | uniq -c to see the number of 's' and number of 'r' lines. Varying sizes, 2, 4, 6, 10, 20 - the...
photo Re: How do avoid buffer space error in Python? (all 10)
Wed 13th May, 6:52am, Christopher M.
ANONYMOUS wrote: Yes, it certainly sounds like you've hit some limit in the number of pending (unreceived) datagrams that your machine can support, and nothing to do with recvfrom(). Do you know how many datagrams have been sent but not received (each...
photo Re: java servelt (both)
Wed 13th May, 6:47am, Christopher M.
That's seems like a lot of overhead to meet the 'requirements' demonstrated in the Getting Started page: - read a number of lines from an open connection, until blank line is reached. - from the line beginning with 'GET', extract the required destination...
photo Re: How do avoid buffer space error in Python? (all 10)
Tue 12th May, 5:20pm, Christopher M.
ANONYMOUS wrote: Do you know what method call is throwing this error? Is it just the recvfrom() call - have you wrapped them in a try/except clause to be sure? Each single datagram is limited to 64KB; if your transport network is running with up to 20 stations...
photo Re: Clarification (all 5)
Tue 12th May, 2:24pm, Christopher M.
We'll be testing with (much simpler) timetables built by my buildtimetables program, or built manually (nothing past 10pm), so that we know the anticipated result (no specific formatting required), and maybe determine how different results were attained....
photo Re: Can we assume that there will always be a route to a given station? (all 3)
Tue 12th May, 12:12pm, Christopher M.
ANONYMOUS wrote: Yes. My buildrandomtimetables.c program guarantees it and, I imagine, that Transperth don't drive their busses to no-where. There's no need for your project to check if a destination exists (i.e. only give it destinations that do exist,...
photo Re: Non blocking Sockets Java (both)
Tue 12th May, 12:10pm, Christopher M.
Hi Alex, If that's the path you've taken, and it's working, then don't change away from it (and congratulations, I find Java's support/explanation for their equivalent of select to be the most difficult of the 3). Any process has to allocate and bind to...
photo Re: Clarification (all 5)
Tue 12th May, 12:02pm, Christopher M.
ANONYMOUS wrote: A good question, but we don't want/need to overcomplicate it by throwing in extra things not related to networking. Let's say that if you can't get to the destination *today*, then there's no bus/train available today. Easiest solution,...
photo Re: buildtransperth.sh (all 5)
Mon 11th May, 5:23pm, Christopher M.
ANONYMOUS wrote: ?? shell> unzip -l google_transit.zip Archive: google_transit.zip Length Date Time Name ... 3432 05-07-2020 09:04 agency.txt 16066 05-07-2020 09:07 calendar.txt 57386 05-07-2020 09:07 calendar_dates.txt ...
photo Re: buildtransperth.sh (all 5)
Mon 11th May, 5:12pm, Christopher M.
ANONYMOUS wrote: Is there a file names calendar.txt in the current directory? Have you downloaded and expanded the Transperth dataset?
photo Re: Do we have to use select? (all 4)
Mon 11th May, 5:11pm, Christopher M.
ANONYMOUS wrote: Yes, because it's a standard module, BUT, threads will just use select() anyway, adding unnecessary overhead for little gain for this problem. Using select really is not difficult, (I believe) easier than using threads.
photo Re: Java - UDP (both)
Mon 11th May, 5:09pm, Christopher M.
You can both send and receive using the socket bound to port 4000. When you send a datagram, srcport=4000 destport=other when you receive a datagram srcport=other destport=4000
photo Re: Do we have to use select? (all 4)
Mon 11th May, 1:47pm, Christopher M.
You don't *have* to, but it's really the correct solution for the task. Other ways, such as using non-blocking sockets, would be a poor choice, becuase you would end up polling, constantly checking to see if new input has arrived. select unblocks when I/O...
photo Re: Exam (both)
Mon 11th May, 12:13pm, Christopher M.
ANONYMOUS wrote: For those sitting the exam using Examplify, the format *will* be as usual - answering 3 of 4 questions, possibly with subparts, just trying your answers in rather than writing them by hand. There will be a sample exam (as usual).
photo Re: Performance and marks (all 7)
Mon 11th May, 11:17am, Christopher M.
ANONYMOUS wrote: I suggest that you follow this plan. We can safely assume, and I'll add a Clarification, that no UDP datagrams will be lost on (within) a single machine, else we'd need to add a reliability layer on top of each UDP transmission (or use RDP)....
photo Re: buildrandomtimetables.c - No implementation of strdup (both)
Mon 11th May, 10:57am, Christopher M.
Pesky Linux! Better yet: {{{ #if defined(__linux__) extern char *strdup(const char *string); #endif }}}
photo Re: Help on Project Understanding (all 3)
Mon 11th May, 6:16am, Christopher M.
>> A few questions from me that I hope can be answered: Your understanding seems all correct. Have a look at the updated Clarifications page; there's a new program to generate random timetable files and their adjacency file. Should save you a lot of boring...
photo Can a pandemic significantly change what we program?
Mon 11th May, 4:57am, Christopher M.
C passes Java and becomes number 1 programming language https://jaxenter.com/c-programming-may-2020-171598.html "Java and C were already very close in April, but this month C surpasses Java again. The last time C was number one was back in 2015. We can...
photo Re: Portability, Endianness, etc (all 6)
Mon 11th May, 4:31am, Christopher M.
As you're going to be sending station names as strings anyway, I don't believe you'll improve performance by worrying host/network representations of integers that won't exceed 4 digits (24*60). I can't imagine any need for floats, either. (how do you, and...
photo Re: Some Question about the result return for Project (both)
Mon 11th May, 4:27am, Christopher M.
ANONYMOUS wrote: The output should be human-readable and, if you think about it, will be one of the lines from the source station's timetable file, such as: "At 7.15am, bus number 12 leaves Stop1, arriving at 7.54am at East_Station" (as described on the...
photo Re: HTTP GET Request Problems (all 7)
Mon 11th May, 4:19am, Christopher M.
ANONYMOUS wrote: A favicon is the small 16x16 image/icon that appears in your browser's address bar, but it only appears if your website (your server process) provides one. Our project doesn't need to provide a favicon, so the request from the browser is...
photo Re: How to close a socket upon keyboard interrupt in Python? (all 4)
Mon 11th May, 4:16am, Christopher M.
ANONYMOUS wrote: What are you wanting to happen when your process receives a ^C ? If the ^C is given to terminate the process, then all socket descriptors (and file descriptors) will be closed when the process terminates. There's no need for any special...
photo Re: Performance and marks (all 7)
Mon 11th May, 4:12am, Christopher M.
ANONYMOUS wrote: There's a gulf between 'high performance', gained through wise management of memory, minimizing cache misses, choice of well suited data-structures and algorithms, and taking 150 billion CPU instructions to investigate at most 12 links in...

UWA week 19 - 1st semester, week 9

photo Re: Project Design Question (all 10)
Sun 10th May, 7:50am, Christopher M.
ANONYMOUS wrote: In practice, you don't even need to know your neighbour's names, just their UDP ports provided on the command-line - you won't need to contact a particular station by its name (and each station's timetable file only contains lines for trip...
photo Re: Performance and marks (all 7)
Sun 10th May, 7:41am, Christopher M.
ANONYMOUS wrote: No need to focus on performance; it's a project focused on the networking, not the absolute best discovery algorithm employed by the station servers (their business logic). That said, avoid any completely random, fingers-crossed, brute-force,...
photo Re: Will same startstations.sh file be run more than once? (all 4)
Sun 10th May, 7:38am, Christopher M.
ANONYMOUS wrote: A subsequent process can re-use a particular port, but: - not while another process is still using it, - and (usually) not within ~60 seconds of the first process's termination. To remove that 60 second restriction (it's there for good reason),...
photo Re: Project Design Question (all 10)
Fri 8th May, 4:10pm, Christopher M.
ANONYMOUS wrote: Hi, There's really no need for a phonebook stored in a file (on disk?); any information need only be stored in a server's data structures (memory). Discussing the use of a file suggests you're thinking about some data shared amongst servers....
photo Re: Are we allowed to use the threading module in Python? (both)
Fri 8th May, 4:03pm, Christopher M.
ANONYMOUS wrote: Yes, because it's one of the standard modules (other than HttpServer). But I'm interested to know why (for which part of the project) you believe it would provide benefit? At the expense of spawning and managing the threads, possibly requiring...
photo Re: Will same startstations.sh file be run more than once? (all 4)
Fri 8th May, 4:00pm, Christopher M.
ANONYMOUS wrote: You run it to simultaneously start off one 'set' of station servers. You wouldn't want to run it again until all of those original servers have terminated, or been killed, as the original servers own the set of port numbers specified in...
photo Re: Localhost of Linux WSL (both)
Fri 8th May, 4:36am, Christopher M.
ANONYMOUS wrote: Sorry, I don't know (and don't have access to WSL). Hopefully someone using WSL will be able to answer.
photo Re: Project - Java Sockets (both)
Fri 8th May, 4:34am, Christopher M.
ANONYMOUS wrote: Using Java's ServerSocket class is a good choice for station-server's role communicating with a client (which might be a browser, or curl, or anything else communicating with HTPP/HTML). "...while the html is the client..." Unsure what...
photo Re: Project - assignports.sh (all 12)
Fri 8th May, 4:10am, Christopher M.
ANONYMOUS wrote: Thanks; I think you were also seeing the 'no end-of-line' problem; now handled correctly. Adding the ".txt" extension would not have helped - file extensions don't change the 'nature' of a file's contents.
photo Re: Project - assignports.sh (all 12)
Fri 8th May, 4:08am, Christopher M.
ANONYMOUS wrote: Thanks, that was helpful. I've updated the script to account for a final 'line' without an end-of-line sequence. Interesting that this is handled differently by some Linux tools and macOS tools. [c.f. https://stackoverflow.com/questions/729692/why-should-text-files-end-with-a-newline...
photo Re: Week 8 Lecture Recording (all 5)
Thu 7th May, 7:22pm, Christopher M.
6 is there. Hopefully 8 added tomorrow.
photo Re: Project - assignports.sh (all 12)
Thu 7th May, 12:22pm, Christopher M.
ANONYMOUS wrote: Great; can you please tell us what you typed in that stopped it from working, because another student reported a similar error, too? Something other than the spaces and tabs? I'm happy to modify the script to catch likely problems.
photo Re: can't run portsinuse.sh (all 7)
Thu 7th May, 4:40am, Christopher M.
You are using: chmod -x filename which *removes* execute permission. You want: chmod +x filename to add execute permission. (don't use sudo unless you're very sure what it does, and why it's required for each case).
photo Re: Project - assignports.sh (all 12)
Thu 7th May, 4:34am, Christopher M.
ANONYMOUS wrote: What do you mean by 'now'? Is the output non-deterministic, or did you change something?
photo Re: Project - assignports.sh (all 12)
Thu 7th May, 4:34am, Christopher M.
ANONYMOUS wrote: The correct output has one station name per-line, with all other names replaced by port numbers. I cannot repeat the problem (on macOS Catalina, Ubuntu 20 Linux, or Fedora 31 Linux). What system are you using? What does your adjacency textfile...
photo Re: Number of command line arguments (all 3)
Thu 7th May, 4:29am, Christopher M.
ANONYMOUS wrote: Can be any number, > 0. (In the Transperth data, Oats Street Stn has the most neighbours, with 5)
photo Re: Project - Python Library (both)
Thu 7th May, 4:17am, Christopher M.
ANONYMOUS wrote: No. There's really no need to make our project dependent on a large 3rd-party module that may not be installed where your project in used (tested). To open a file, read it line-by-line, split the line into a list, and store each list in...
photo Re: Project: Running multiple processes at once (all 7)
Wed 6th May, 4:48pm, Christopher M.
Hello Jai, SocketServer.ThreadingMixIn seems to provide way more complexity for our simple task. Have you had a look at Python's select, which provides all of the support we need without requiring threads or 'wrapping it all up' in a large abstraction :...
photo Re: Concurrent requests? (both)
Wed 6th May, 4:29pm, Christopher M.
ANONYMOUS wrote: The short answer is yes, but it's not as frightening a task to think about or to code as you may initially worry. Each station receiving an initial request via TCP does not need to block until the answer to that query is known/solved. ...
photo Re: Change to "makeform.sh" - important? (all 3)
Wed 6th May, 12:42pm, Christopher M.  O.P.
ANONYMOUS wrote: Isn't the character after ...tion just a space or tab? No need to parse until the end-of-line sequence.
photo Re: Project - Final Returned Result to Browser (all 4)
Wed 6th May, 12:41pm, Christopher M.
Hi Lemar, Just this. The answer should just provide those starting/ending details. Once the passenger gets on the bus, they don't care how it gets there. The (single line) of output will be read/marked by a human, so no need for a fancy regular format for...
photo Re: Some Project Questions (all 3)
Wed 6th May, 12:38pm, Christopher M.
No need to compile the Python. Just change the contents of the file for any stations written in Python or in Java. Yes, identical functionality as, say, a C server may need to talk to a Python or a Java server, all within the same network. (yes) there's...
photo Change to "makeform.sh" - important? (all 3)
Wed 6th May, 11:43am, Christopher M.
A keen-eyed student asked this question: Hi, You're correct, I modified the output of makeform.sh (8am Monday) to *not* generate a leaving time. The reason I made the change was because, by having the webpage provide the leaving time, you'd have to generate...
photo Re: Project: Running multiple processes at once (all 7)
Wed 6th May, 11:29am, Christopher M.
ANONYMOUS wrote: Not a stupid question at all; sounds like you're making good progress, have thought it through, and have just hit the next speed-bump. There's a (another) system call that you're haven't yet reached in your reading of a book or tutorial,...
photo Re: comparison returning -ve values (all 4)
Wed 6th May, 11:23am, Christopher M.
ANONYMOUS wrote: :-)
photo Re: Initial Landing page as HTML document or sent via http (all 3)
Wed 6th May, 11:17am, Christopher M.
ANONYMOUS wrote: There is no requirement to use any specific HTML starting page at all. In the example I've provided, the starting HTML was read from a textfile. That file was generated by a shellscript but, again, just as an example. There's no need for...
photo Re: comparison returning -ve values (all 4)
Wed 6th May, 11:08am, Christopher M.
ANONYMOUS wrote: If strcmp() says that two strings are different, it returns the arithmetic difference between the first two characters that are different. The null-byte are integer value 0; the newline character '\n', has the integer value 10. You've found...
photo Re: Week 8 Lecture Recording (all 5)
Tue 5th May, 4:36pm, Christopher M.
Hoping for a big, fun, day of lecture recording tomorrow - 6, 8, and 9, (as my partner goes back to work - that'll get back)
photo Re: The shellscripts provided on the Getting Started page (all 3)
Tue 5th May, 4:30pm, Christopher M.
ANONYMOUS wrote: Your choice; just thought they'd make life easier, particularly in assigning port numbers for larger networks.
photo Re: setsockopt works for some server instances but not others (all 5)
Tue 5th May, 1:16pm, Christopher M.
ANONYMOUS wrote: Any chance your system has some other long-running processes interfering with this; is there another process owning port 2606 ?
photo Re: project client (all 3)
Tue 5th May, 11:49am, Christopher M.
ANONYMOUS wrote: Hi, You're correct - no need to write any code for initiating queries required - the webform that I've provided via the Getting Started webpage is all we need (or, if you don't wish to fiddle with that, you could generate queries from curl...
photo Re: Small Typo in getting started page. (both)
Tue 5th May, 10:31am, Christopher M.
ANONYMOUS wrote: Hi Brayden (not so anonymous now!). Have your friends on discord read the second half of this announcement: https://secure.csse.uwa.edu.au/run/help3002?p=np&a=184 Try this command with UWA's VPN enabled: curl -ks https://secure.csse.uwa.edu.au/images/testfile.html...
photo Re: setsockopt works for some server instances but not others (all 5)
Tue 5th May, 7:27am, Christopher M.
ANONYMOUS wrote: Untested, but I'm pretty sure you'll need to call setsockopt() after calling bind(), else the socket doesn't yet have an address that you're requesting be re-used.
photo Re: Remote acces/Cnet without personal device (both)
Tue 5th May, 7:20am, Christopher M.
Hello Logan, If cnet hasn't been added to the UniDesk Linux image, then you can still download and build a private copy anywhere within your Linux home directory. Download a copy of cnet to anywhere in your Linux directory, edit the top-level Makefile to...
photo Re: Project Design Question (all 10)
Mon 4th May, 5:32pm, Christopher M.
ANONYMOUS wrote: No. Network connectivity and port assignments will not change with your project (parts) are running.
photo Re: CSV Input (both)
Mon 4th May, 5:31pm, Christopher M.
ANONYMOUS wrote: I believe that this is answered on the project's sheet - "Each station's timetabling data, recorded in one textfile for each station, may change at any time (for example, if a bus breaks down, its next trip will be cancelled). Every query...
photo Re: preparation of project (both)
Mon 4th May, 5:30pm, Christopher M.
ANONYMOUS wrote: Just 'Chris' will be fine. You can assume that project markers will be looking for these 'problems'; they'll be compiling (if necessary) your code, and running it against some simple examples. Why not use zip or tar when you submit your project,...
photo Re: Two Programming Languages...Can we mix or one for AtoZ and another for AtoZ? (both)
Mon 4th May, 5:28pm, Christopher M.
ANONYMOUS wrote: Hi, I'm very confused by the wording of your question (AtoZ? and four files?). We require one instance of a server to be completely written in one programming language, and another instance to be written in a different programming language....
photo Re: Project Design Question (all 10)
Mon 4th May, 5:47am, Christopher M.
ANONYMOUS wrote: All questions are fine, particularly while clarifying understanding :-) If you had a telephone-number, but didn't know the name of the owner of that number, what would you do? Having solved that problem, you may assume that the owner of...
photo Re: Is using the sockets module allowed for Python? (both)
Mon 4th May, 5:42am, Christopher M.
ANONYMOUS wrote: Yes (thanks for asking), and you'll probably wish to combine it with sockerserver, too.
photo Re: can't run portsinuse.sh (all 7)
Mon 4th May, 5:36am, Christopher M.
ANONYMOUS wrote: Are you sure that your portsinuse.sh script is owned by you, and executable? Check, or send us, a the output of ls -l portinuse.sh It's not clear if you're on Linux or macOS - I'm guessing that MSI is your laptop's brand, so using WSL?...
photo Re: UDP (both)
Mon 4th May, 5:26am, Christopher M.
ANONYMOUS wrote: Yes, your numbers are correct (but don't forget to provide the station's name immediately before the TCP/IP port number). As soon as your program starts, you'll need to establish sockets for the TCP and 1st UDP port, so that other processes...

UWA week 18 - 1st semester, week 8

photo Project description updated
Sat 2nd May, 10:04am, Christopher M.
The project description has been updated, and the Getting Started page completed. The project's specification has not changed but, hopefully, the wording on the webpages has improved to make things clearer. There's an example of a simple 4-station network...
photo Re: Project (all 11)
Fri 1st May, 1:33pm, Christopher M.
ANONYMOUS wrote: Thanks for that; I must have installed it long ago, and since forgotten. I'll modify the script to check that it's been installed.
photo Re: nc server receives weird request from browser (all 3)
Fri 1st May, 10:16am, Christopher M.
ANONYMOUS wrote: Using the https: protocol requests that the traffic is encrypted, but nc does not know how to decrypt it. Just us http: for this step, and for the whole project.
photo Re: Week 8 Lecture Recoording (both)
Fri 1st May, 8:15am, Christopher M.
When completed, that's where it will be.
photo Re: Project (all 11)
Thu 30th Apr, 5:23pm, Christopher M.
That wasn't the shellscript you're seeking. That was just one to find free ports, and I thought I'd include that in the Getting Started discussion. After I've finished my lab this evening, I'll extend that document, to explain the (basic) file formats. ...
photo Re: Project (all 11)
Thu 30th Apr, 5:10pm, Christopher M.
ANONYMOUS wrote: OK, I'm still struggling with the wording again, a bit. You want your server, listening on 4444 to provide the HTML on its output (if C, say, printed with printf). So, you have the browser connect to 4444, the station server will receive...
photo Re: Project (all 11)
Thu 30th Apr, 12:27pm, Christopher M.
ANONYMOUS wrote: Hi, Your station servers that you write, in 2 different languages, will be given a the port that they should use on their command-line (see the project description, but I'll expand on this in the Getting Started document). So you won't...
photo Re: Project (all 11)
Wed 29th Apr, 9:22pm, Christopher M.
Getting Started guide begins here: https://teaching.csse.uwa.edu.au/units/CITS3002/project2020/getting-started.php
photo Re: Any starter code for the project? (all 4)
Wed 29th Apr, 4:59pm, Christopher M.
Some starting discussion available, and being extended, at: https://teaching.csse.uwa.edu.au/units/CITS3002/project2020/getting-started.php Use the Pulse Secure VPN to access that website.
photo Re: Language Choice (all 4)
Wed 29th Apr, 1:38pm, Christopher M.
ANONYMOUS wrote: Yes.
photo Re: Project (all 11)
Wed 29th Apr, 9:26am, Christopher M.
ANONYMOUS wrote: It does not need anything as fancy as JS, just basic HTML will do. A starting guide explaining this, and lectures...., coming soon.
photo Re: http rewritten as https (all 4)
Wed 29th Apr, 9:24am, Christopher M.
Yes, thanks Jared. You cannot force a particular port to use a particular protocols, but it's clear that access to port-80 is now/currently being blocked from off-campus. Using the VPN makes you appear 'on-campus', and demonstrates that the web-server is...
photo Problems reaching teaching.csse.uwa.edu.au - use VPN
Wed 29th Apr, 3:30am, Christopher M.
THE PROBLEM NOW APPEARS TO BE FIXED! As many of you have seen, and reported, access to teaching.csse.uwa.edu.au has been very intermittent over the past 24 hours. Unfortunately, this is not a problem that I, or other CSSE staff, can fix because the host...
photo Re: Language Choice (all 4)
Tue 28th Apr, 8:49am, Christopher M.
ANONYMOUS wrote: Admittedly I only updated this on Friday, but the project sheet does (now) say: ...selected from Java and Python and (C or C++) - note, not C and C++ Not this year, sorry; the markers deny sufficient familiar with Rust.
photo Re: How will the project account for routes with multiple stops? (both)
Tue 28th Apr, 8:46am, Christopher M.
ANONYMOUS wrote: Hi, Your points and other similar ones are good, and it's made the writing of the shellscript a bit trickier than I'd first thought (including things like the 998/999 circle routes). Each station's timetable won't provide the final *destination*...
photo Re: Project Clarification: Language Versions (both)
Tue 28th Apr, 8:27am, Christopher M.
Hi Jared, The support for the networking features and APIs we're using in this project (TCP streamed connections, and UDP unconnected datagrams) have not changed in most programming languages for (many) years, so the actual version won't matter too much...
photo Re: Lab Sessions (both)
Mon 27th Apr, 2:05pm, Christopher M.
ANONYMOUS wrote: Closed, thanks. Wasn't me (I'm having my weekend ;-)

UWA week 17 - 1st semester, week 7

photo Re: Any starter code for the project? (all 4)
Sun 26th Apr, 6:25pm, Christopher M.
ANONYMOUS wrote: Yes, but please be patient, and try to enjoy the weekend (as I'm trying to do).
photo Project is now available
Fri 24th Apr, 10:29am, Christopher M.
Details of the project are now available from: https://teaching.csse.uwa.edu.au/units/CITS3002/project2020/ (that's http colon, not https colon) There is still some wording to be added to the description, and a shellscript to be completed (so you won't be...
photo Re: Lab3 Q3- how to send multiple frames (both)
Mon 20th Apr, 3:01pm, Christopher M.
Protocols in cnet are written in an event-driven style - your functions (event handlers) are called when events of interest occur. In this case, you have an event handler being called when the AL has a new message for delivery. cnet (internally) will call...
photo Re: Getting plot-to-html.sh for labsheet 2 (all 9)
Mon 20th Apr, 2:45pm, Christopher M.
Hi Kirra, You'll have noticed that the part of the script that produces the rows of stats: data.addRows([ [10, 2], [20, 5], [30, 8], [40, 12], .... [7200, 1342], [7210, 1342], ]); involves running...
photo Re: Wireless Network Monitoring paper (all 5)
Mon 20th Apr, 2:38pm, Christopher M.
Hi Jared, I wrote a good chunk of the code involving the data collection, and more recently anonymization, (except for the FFT matching algorithms to match spoofed AP signatures), but I did so while working there, not at UWA, and much of it is owned by the...

UWA week 16 - 1st semester, mid-semester break

photo Re: End of semester exam (all 14)
Thu 16th Apr, 10:30am, Christopher M.
ANONYMOUS wrote: None yet. UWA, centrally, strongly wants to go with ExamSoft, and has come back to unit coordinators for more opinions and alternatives.
photo Re: Lecture 6 Recording (all 7)
Thu 16th Apr, 10:29am, Christopher M.
ANONYMOUS wrote: Yes; it's still coming, not forgotten, but it's been delayed by a staff deadline for our exams, and this unit's project (and there was supposed to be some days away from the computer in there :-( "looking forward to it" - thanks, but no...

UWA week 15 - 1st semester, non-teaching week

photo Re: Individual Project Submission (all 3)
Fri 10th Apr, 8:27am, Christopher M.
ANONYMOUS wrote: Yes, working individually was always to be an option. My thinking, at present, is that it'll now be a project just for individuals anyway. We've lost the opportunity to use the computers in the CSSE labs (as each student can only login ...
photo Re: Wireless Network Monitoring paper (all 5)
Fri 10th Apr, 8:22am, Christopher M.
Hi Jared, I trust that you've now found them on the Resources page? I recently added a copy of the slides presented at the end of the lecture.
photo Re: End of semester exam (all 14)
Wed 8th Apr, 6:48am, Christopher M.
ANONYMOUS wrote: I certainly agree with your last sentence. UWA is simply waiting on replies from EA and ACS (and Inst. of Physics, Chemical Inst., .....) to ensure they get the correct message, rather than just making a lone decision. Sounds like UNSW already...
photo Re: How to interpret the Lab3 Q2 Graph (both)
Wed 8th Apr, 6:40am, Christopher M.
ANONYMOUS wrote: Have a peek at the sample solution which, I believe, explains this: "Remember why we are considering piggybacking - to reduce the number of frames crossing the Physical Layer and, thus, to reduce the number of hardware interrupts managed...
photo Re: End of semester exam (all 14)
Tue 7th Apr, 3:53am, Christopher M.
ANONYMOUS wrote: This is the very question, asked by many students via email too, and will be discussed in a Faculty meeting today. There are similarly students from other degrees taking just one or two CITS units as electives. It's unclear if this UP matter...
photo Re: End of semester exam (all 14)
Tue 7th Apr, 3:48am, Christopher M.
ANONYMOUS wrote: I don't know, but I doubt that that would be an option - neither accredited, or not, is printed on your academic transcript.
photo Re: PDF download links are broken (all 3)
Mon 6th Apr, 6:46pm, Christopher M.
No, not intentional at all; you (and the silent majority?) should be able to fetch them all, now. Thanks.
photo Re: Stop examplify petition (all 11)
Mon 6th Apr, 4:33pm, Christopher M.
And this from the Vice Chancellor, to staff, just now: Privacy and online exams "A number of students have emailed me expressing concerns around how conducting online exams will affect their privacy, given they will be required to download the Examplify...
photo Re: Stop examplify petition (all 11)
Mon 6th Apr, 4:05pm, Christopher M.
I believe that a better approach, over a "shut it all down" petition, would be for concerned people to identify the risks to privacy and security and possible ways to mitigate them. Haven't seen any discussion around that. I cannot see the connection you're...
photo Re: End of semester exam (all 14)
Mon 6th Apr, 12:22pm, Christopher M.
ANONYMOUS wrote: Yes, fully appreciated. I am not sitting around delaying this decision; I'm waiting for our forthcoming meetings with other academic staff discussing ideas about how to run final exams, and awaiting a demonstration of how it is anticipated...
photo Re: End of semester exam (all 14)
Mon 6th Apr, 9:39am, Christopher M.
No, nothing yet certain, certainly not its format, other than it contributing 60%. It will be centred around medium-length written answers, as with past exams, but I don't (even) yet know if diagrams will be possible.
photo Re: Lecture 6 Recording (all 7)
Mon 6th Apr, 9:25am, Christopher M.
https://secure.csse.uwa.edu.au/run/help3002?p=np&a=112&all=y2
photo Blame it all on 5G Networks!
Mon 6th Apr, 8:47am, Christopher M.
https://www.npr.org/sections/coronavirus-live-updates/2020/04/04/827343675/u-k-cellphone-towers-ablaze-as-conspiracy-theories-link-5g-networks-to-covid-19 Conspiracy theories tying 5G networks to the coronavirus pandemic are troubling telecom authorities...
photo Re: Stop examplify petition (all 11)
Mon 6th Apr, 8:37am, Christopher M.
Thanks for posting this Eric; it's important that students can make an informed opinion about what's going on. ExamSoft has been selected to address a significant problem in difficult times; I've not seen a statement that anyone at UWA believes this to...
photo Re: [SBS TV] Amazon Empire: The Rise and Reign of Jeff Bezos (both)
Mon 6th Apr, 5:19am, Christopher M.  O.P.
Another TV documentary on Amazon tonight: Amazon: What They Know About Us Monday 6th April at 8.30pm. https://www.abc.net.au/4corners/amazon:-what-they-know-about-us/12113904 Amazon is a corporate colossus that dominates the global retail landscape,...
photo Re: Installing cnet on your own laptop (all 28)
Mon 6th Apr, 4:37am, Christopher M.  O.P.
ANONYMOUS wrote: Hi, the previous reply sounds correct - the cnet distribution (file) is not located in the directory where you are trying to unpack it. If you downloaded the distribution on your Windows (+WSL) machine using a Windows browser, then it will...
photo Re: Where to find week six lecture? (both)
Mon 6th Apr, 4:29am, Christopher M.
ANONYMOUS wrote: I am going to re-record it this morning, as Echo360 was (twice) unable to transcode the MP4 I uploaded last week.

UWA week 14 - 1st semester, week 6

photo Moving to pre-recorded lectures
Wed 1st Apr, 7:41am, Christopher M.
Hello Everyone, Due to the worsening conditions I'm experiencing with my NBN service at home, all future lectures will be prerecorded, and not live-streamed using Zoom. Lecture recordings will continue to be uploaded to our standard Echo360 location within...
photo Re: Installing cnet on your own laptop (all 28)
Tue 31st Mar, 10:32am, Christopher M.  O.P.
Great news; good luck,
photo Re: Installing cnet on your own laptop (all 28)
Mon 30th Mar, 6:51pm, Christopher M.  O.P.
Hello Alan, Have you followed all of the WSL-based instructions, here: https://www.csse.uwa.edu.au/cnet/install-all.php specifically the steps involving VcXsrv ?

UWA week 13 - 1st semester, week 5

photo Re: Just in case anyone thought Zoom actually wasn't too bad... (both)
Sun 29th Mar, 4:50am, Christopher M.
...and with Facebook https://www.vice.com/en_us/article/k7e599/zoom-ios-app-sends-data-to-facebook-even-if-you-dont-have-a-facebook-account which Zoom now claims to have addressed https://www.vice.com/en_us/article/z3b745/zoom-removes-code-that-sends-data-to-facebook...
photo Re: Weighting for project this semester (all 8)
Thu 26th Mar, 7:14pm, Christopher M.
ANONYMOUS wrote: Wondering if students have yet been informed about the changes (upheaval) to semester dates....?
photo Re: Latest Lab Discussion and Sample Solution (both)
Thu 26th Mar, 7:13pm, Christopher M.
ANONYMOUS wrote: Yes, but as answered here: https://secure.csse.uwa.edu.au/run/help3002?p=np&a=90 Greater priority is the lab sheet for tomorrow, and to then modify our Schedule for the modified semester structure.
photo Re: Weighting for project this semester (all 8)
Thu 26th Mar, 9:35am, Christopher M.
ANONYMOUS wrote: Thanks, yes, Section 9.2.2 c) of the current Assessment Policy (which all units with modified assessment structures are still following). It's notable that this is being discussed (and elsewhere) - does anyone have any concerns about it...
photo Re: Lecture recordings (all 7)
Thu 26th Mar, 3:34am, Christopher M.
ANONYMOUS wrote: Hello, Yesterday's lecture recording, made through Zoom, is now available through LMS->Echo360. It seems to take a long time from uploading the original MP4 recording to when it is published; I can see that software automatically slaps...
photo Re: Solutions for labs (all 6)
Thu 26th Mar, 3:00am, Christopher M.
ANONYMOUS wrote: As soon as available; the change to online teaching, online everything, is consuming a lot of time, and I'm presenting two units this semester.
photo Re: Lecture recordings (all 7)
Wed 25th Mar, 4:11pm, Christopher M.
ANONYMOUS wrote: Yes, but I'm busy in another Zoom meeting (Consultation hours) at present.
photo Re: Getting plot-to-html.sh for labsheet 2 (all 9)
Wed 25th Mar, 3:54am, Christopher M.
Ahh, my too-quick mistake. A good rant wasted. I note that the man entry for dash says: "The current version of dash is in the process of being changed to conform with the POSIX 1003.2 and 1003.2a specifications for the shell." So many of the problems...
photo Re: Installing cnet on your own laptop (all 28)
Wed 25th Mar, 3:50am, Christopher M.  O.P.
Thanks for pointing out the problem. My error. From cnet's top-level directory, edit src/Makefile At lines 37+38 you should see two definitions of LIBELF, one commented out, one not. 'Swap the comments around', so that it just uses LIBELF = -lelf...
photo cnet updated to v3.4.1, now running on WSL under Windows-10
Tue 24th Mar, 1:31pm, Christopher M.
cnet has been updated to v3.4.1, with the following changes: www.csse.uwa.edu.au/cnet/changelog.php - if you have successfully installed the previous version on Linux, there's no urgent need to change to this version. - if you use DarkMode on an Apple...
photo Re: Weighting for project this semester (all 8)
Tue 24th Mar, 12:56pm, Christopher M.
A project completed by a team, with all students receiving the same mark for the 30% part, and an individual contribution of up to 10%. (and best to read the current Assessment Policy: https://www.governance.uwa.edu.au/procedures/policies/policies-and-procedures?method=document&id=up15/5...
photo Re: Getting plot-to-html.sh for labsheet 2 (all 9)
Tue 24th Mar, 12:45pm, Christopher M.
On what platform are you seeing this Eddie - probably that troublesome "we refuse to be compatible" Arch? It's their own fault if they've symbolically linked the standard shell to dash; they shouldn't admit that their dash is incompatible with sh, link...
photo Re: LMS Quiz/Lab Submissions (all 7)
Tue 24th Mar, 3:47am, Christopher M.
ANONYMOUS wrote: That probably explains it, then. Jin Hong presented this unit last year, and has probably asked the LMS Overlords to restore some of last year's teaching materials for '3004, which Jin presented in 2nd semester. The Overlords may have...
photo Re: LMS Quiz/Lab Submissions (all 7)
Mon 23rd Mar, 7:22pm, Christopher M.
I cannot see any mention of these items in LMS; no-one has magically added them for me. Are you sure that you have the correct unit?
photo Re: LMS Quiz/Lab Submissions (all 7)
Mon 23rd Mar, 6:05pm, Christopher M.
ANONYMOUS wrote: Hello, I have absolutely no idea - certainly not something that I set up. Are any other students seeing the same?
photo Re: make doc problem (all 5)
Mon 23rd Mar, 2:21pm, Christopher M.
ANONYMOUS wrote: I'm a bit stumped (and have just installed it, again, on my Ubuntu Linux machine without problems). In the interim, don't forget that the full documentation is also available here: https://www.csse.uwa.edu.au/cnet/ which should keep you...
photo Re: Installing cnet on your own laptop (all 28)
Mon 23rd Mar, 1:57pm, Christopher M.  O.P.
ANONYMOUS wrote: What is your newly created alias - is it to the fullpathname of the cnet binary? What is the value of your PREFIX in the Makefile?
photo Re: make doc problem (all 5)
Mon 23rd Mar, 1:51pm, Christopher M.
ANONYMOUS wrote: You may not have permissions to install files in /home/httpd/html/cnet on your computer. Try is as the superuser: sudo make doc (enter your password) ??
photo Seeking cnet on WSL?
Mon 23rd Mar, 1:44pm, Christopher M.
Hi, wondering if anyone has had success installing and running cnet on Windows WSL? Please get back to me, as I'd like to help a few students out with it. Thanks.
photo Re: No one in the labs? (all 3)
Mon 23rd Mar, 12:41pm, Christopher M.
Problem resolved; Daniel was 'there', but his Zoom app. had frozen, and he was wondering where everyone else had gone! Teething problems.
photo Re: No one in the labs? (all 3)
Mon 23rd Mar, 12:15pm, Christopher M.
Daniel should be there; hang on....
photo Re: Recommended readings (both)
Mon 23rd Mar, 10:01am, Christopher M.
ANONYMOUS wrote: Yes, just a bit harried for time this past week.
photo Re: Installing cnet on your own laptop (all 28)
Mon 23rd Mar, 3:50am, Christopher M.  O.P.
ANONYMOUS wrote: I think this one: https://secure.csse.uwa.edu.au/run/help3002?p=np&a=47 (please read other topics).

UWA week 12 - 1st semester, week 4

photo Re: Installing cnet on your own laptop (all 28)
Sun 22nd Mar, 5:17am, Christopher M.  O.P.
ANONYMOUS wrote: That suggests that you have not followed the instructions, because cnet cannot find its images/icons from directory where they need to be. - did you do both a 'make' and 'make install'? Run cnet -v Near the bottom of its output is should...
photo Re: Installing cnet on your own laptop (all 28)
Sat 21st Mar, 5:41pm, Christopher M.  O.P.
Hello Chris, I am your cits3002 student and have a problem with installing cent. My windows laptop has a virtual machine with ubuntu and ubuntu system on Windows. However, on virtual machine, the file like /use/local/lib could not be modified...
photo On frequency division multiplexing
Sat 21st Mar, 5:31pm, Christopher M.
In Wednesday's lecture we saw that Star Trek's "scanning all frequencies Captain" wasn't a realistic possibility for wireless networking. Well, seems that that comment has been quashed just 2 days later: https://phys.org/news/2020-03-scientists-quantum-sensor-entire-radio.html...
photo Re: Is there a way to increase the font size of the cnet output? (both)
Thu 19th Mar, 1:58pm, Christopher M.
ANONYMOUS wrote: There's no provided way to modify font size dynamically, but you can change it permanently: Find out where you've install the cnet library files, probably /usr/local/lib/cnet Edit the text file cnet.tcl On lines 12 and 13 you'll see something...
photo Re: CITS3002 Computer / Data Science Unofficial Discord (Learning space in light of moving online) (all 3)
Thu 19th Mar, 6:51am, Christopher M.
ANONYMOUS wrote: Certainly allowed; I'm not wishing to deny that it exists, or that some students wish to use it. To be clear, I will not be participating in the CITS3002 channels. Personally, I don't believe the format of Discord is as conductive to learning...
photo New LEO satellites launched
Thu 19th Mar, 6:13am, Christopher M.
Falcon 9 rocket overcomes engine failure to deploy Starlink satellites https://spaceflightnow.com/2020/03/18/falcon-9-rocket-overcomes-engine-failure-to-deploy-starlink-satellites/ "The first phase of the Starlink network will include more than 1,500 satellites...
photo Re: Solutions for labs (all 6)
Tue 17th Mar, 10:29am, Christopher M.
There's now a sample solution and discussion for Q4 of Labsheet-2, available from our Schedule page.
photo Re: Installing cnet on your own laptop (all 28)
Mon 16th Mar, 12:58pm, Christopher M.  O.P.
ANONYMOUS wrote: Shouldn't really modify /etc/paths, that's for global changes to PATH, for all users and all shells. But if you did, you'd need to fire up a new shell to read in the updated contents. You only need to modify your *own* PATH variable, perhaps...
photo Re: Solution to my Installation Error: (tk.h: No such file or directory) (both)
Mon 16th Mar, 12:19pm, Christopher M.
Thanks Oscar!
photo Re: Exams and COVID-19 (all 5)
Mon 16th Mar, 11:12am, Christopher M.
ANONYMOUS wrote: (Agreed) while 'state of emergency' certainly sounds severe, it's quite unclear what it means, and there must be more elevated states (terms) coming. I'm receiving, as are all staff, about 5 emails a days describing possible plans, but...
photo Re: Installing cnet on your own laptop (all 28)
Mon 16th Mar, 9:43am, Christopher M.  O.P.
That's great. Where did you install the cnet binary, and any idea why adding that directory to your PATH did not help?
photo Re: Exams and COVID-19 (all 5)
Mon 16th Mar, 9:42am, Christopher M.
ANONYMOUS wrote: Sorry, but I have no more confirmed information than you do. There's still too many possibilities, and no firm deadlines/timelines/durations. (what were the rapid developments over the weekend, that you think currently affect UWA - though...
photo Re: Installing cnet on your own laptop (all 28)
Mon 16th Mar, 3:48am, Christopher M.  O.P.
ANONYMOUS wrote: Unsure what that could be. The only use of mkdir when installing the documentation is the line: mkdir -p -m 755 $(DOCDIR) $(DOCDIR)/images Is that command successful if executed by hand? Both -p and -m are options supported by both Linux...

UWA week 11 - 1st semester, week 3

photo [SBS TV] Amazon Empire: The Rise and Reign of Jeff Bezos (both)
Sun 15th Mar, 11:26am, Christopher M.
Tonight, SBS Ch 30 @9.40pm Amazon Empire: The Rise and Reign of Jeff Bezos Part 1/2. "Examines Amazon CEO Jeff Bezos' ascent to power and the global impact of the empire he built. The film also investigates the darker side of the company's rapid growth,...
photo Re: Installing cnet on your own laptop (all 28)
Sat 14th Mar, 5:53pm, Christopher M.  O.P.
I want to complete the lab, but I am having trouble installing the program using the 'make install' command. Even though I used sudo commands like 'sudo' to have the allowed permissions to install. Is there anyway you can help me with this...
photo Installing cnet on your own laptop (all 28)
Sat 14th Mar, 5:48pm, Christopher M.
I've received a couple of email asking about help with installing cnet on personal laptops. I'll post the questions my answers here as they may help other students, too. ... .... while I have managed to get it installed I just have a few questions...
photo Re: Crc checking error probability (both)
Tue 10th Mar, 10:31am, Christopher M.
ANONYMOUS wrote: Hello, There's a short discussion about this in Tan 5/e, p214-15. There's also a modified corrupt_frame() function, which allows you to set the burst length, in the sample solutions for Labsheet-1. You may like to experiment with that to...
photo Re: Solutions for labs (all 6)
Tue 10th Mar, 10:25am, Christopher M.
There's now some sample solutions and discussion available from our Schedule page: https://teaching.csse.uwa.edu.au/units/CITS3002/schedule.php
photo UWA Young Engineers - Industry Analysis Night, Thu 19th March
Mon 9th Mar, 5:25am, Christopher M.
Been asked to highlight this event, likely of interest to many students: https://secure.csse.uwa.edu.au/run/csforum?p=np&a=8
photo Re: Solutions for labs (all 6)
Mon 9th Mar, 5:07am, Christopher M.
ANONYMOUS wrote: Yes, though keep in mind that the 'first' labs for each labsheet are on Fridays, following by two labs on Mondays. So we'll see posted solutions after Mondays.
photo Re: Lab 1 Q2 (both)
Mon 9th Mar, 5:05am, Christopher M.
Hi Eddie, For these exercises, we're treating the provided CRC functions as 'black boxes', that we use without needing to understand their operation. For any given message, we use the CRC to calculate a 'summary' of the message, transmit both the message...

UWA week 10 - 1st semester, week 2

photo Re: OSI Model question (both)
Wed 4th Mar, 5:32am, Christopher M.
ANONYMOUS wrote: The part about top-down or bottom-up refers to the order that textbooks introduce the distinct concepts in each OSI layer - downwards Application-to-Physical or upwards Physical-to-Application - and, thus, the order in which you may learn...
photo Re: PDF Lecture Notes (all 5)
Tue 3rd Mar, 1:46pm, Christopher M.
ANONYMOUS wrote: OK, it's now automated, again, with links on our Schedule page. ... I'm guessing that you completed '2002 a year or two ago; I had stopped producing PDFs for my units, as very few students were downloading them, citing that they were too...
photo Re: PDF Lecture Notes (all 5)
Tue 3rd Mar, 11:57am, Christopher M.
Not quite ready yet; testing, testing.

UWA week 9 - 1st semester, week 1

photo Seminar: Back To The Future With HPC
Thu 27th Feb, 10:13am, Christopher M.
May be of interest to some of our '3002 students: 4th March, Wednesday, 4-5pm Room 2.15, Physics Building Dr Stuart Midgley, Systems Architect, DUG. ABSTRACT: The first super computer was built 60 years by UNIVAC and kick started the tussle between...
photo Flaw in billions of Wi-Fi devices left communications open to eavesdropping
Thu 27th Feb, 6:34am, Christopher M.
While vendor-supplied patches have been available for most affected devices for several months, such widespread vulnerabilities clearly demonstrate the extent to which we're employing wireless. Flaw in billions of Wi-Fi devices left communications open...
photo Predictions and discussions from our 1st lecture
Wed 26th Feb, 1:46pm, Christopher M.
Here's some quick links to articles/topics raised in today's discussions: ... An Artist Used 99 Phones to Fake a Google Maps Traffic Jam https://www.wired.com/story/99-phones-fake-google-maps-traffic-jam/ The Ride-Hail Utopia That Got Stuck in Traffic...
photo Re: Readings relating to topics (all 3)
Wed 26th Feb, 1:22pm, Christopher M.
ANONYMOUS wrote: Hi. Anonymous? In 3rd year :-)? Yes; I'll be adding section numbers on the Schedule page, at the bottom of each lecture's summary. I hope that this is what you're seeking.
photo Welcome to Computer Networks '3002 for 2020
Tue 25th Feb, 4:46am, Christopher M.
Hello Everyone, Welcome to Computer Networks '3002 for 2020. I'm the unit-coordinator for this semester, and will be presenting all of the lectures and some of the laboratory sessrion. Laboratories commence in week 2. We'll spend part of the first lecture...
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Last modified:  3:57pm Aug 06 2020