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+--- Day changed Wed Aug 14 2013
+09:13 < jtanx> I've done a version using fastcgi, which was surprisingly quite easy to set up
+09:13 < jtanx> see here: https://github.com/jtanx/MCTX3420/tree/master/testing/fastcgi-approach
+10:41 < sam_moore> That looks interesting, I'd prefer that to the PHP/database solution
+10:42 < sam_moore> My concern is: You have to query the web server to start the process, even though it keeps running
+10:42 < sam_moore> Also, I know "write a custom HTTP server" sounds scary, but it does actually work
+10:43 < jtanx> nah
+10:43 < jtanx> fastcgi
+10:43 < jtanx> the process is started once and always runs
+10:43 < jtanx> so you have a request loop
+10:44 < jtanx> wait
+10:44 < jtanx> how do you envision it working?
+10:45 < sam_moore> Oh, right, I see how the fastcgi approach would work, it's basically the same idea; you have something responding to HTTP queries in one thread, something dealing with sensors/actuators in seperate threads
+10:45 < jtanx> yeah
+10:46 < jtanx> except that you don't have to worry about maintaining your own webserver
+10:46 < sam_moore> Cool
+10:46 < sam_moore> I do think that the HTTP server isn't that hard, and it's mostly working
+10:46 < sam_moore> But we can probably switch to fastcgi
+10:48 < sam_moore> I mean, we still have to parse a query string right?
+10:48 < jtanx> well yes
+10:48 < jtanx> if your request was
+10:48 < jtanx> http://blah/cgi/?key=value&anotherkey=value2
+10:48 < jtanx> you'd get back key=value&anotherkey=value2
+10:48 < jtanx> as query string
+10:50 < jtanx> try it out here: http://124.169.120.181:8080/cgi
+10:51 < jtanx> (hopefully that forwards ok)
+10:51 < sam_moore> Yep, that's cool
+10:51 < sam_moore> The HTTP server I wrote basically does that
+10:51 < sam_moore> But if it really bothers you, I'm fine with switching to fastcgi :P
+10:52 < jtanx> well whatever works
+10:52 < jtanx> but I thought it might be more maintainable if you used something that already exists :P
+10:52 < sam_moore> Yeah, but thinking about it, what maintainence does the HTTP server require?
+10:53 < sam_moore> Oh well, it's a good idea
+10:53 < jtanx> for this situation not much
+10:57 < sam_moore> We can pretty easily start with a structure that would allow us to switch, but I'd lean towards keeping the custom HTTP server
+10:58 < sam_moore> Have you done multithreading in C before?
+10:58 < jtanx> in windows yes
+10:58 < jtanx> on linux not really
+10:58 < sam_moore> Ah, I've only done it on linux
+10:58 < jtanx> i did a bit in operating systems
+10:59 < jtanx> but kinda forgot
+10:59 < sam_moore> It shouldn't be too hard for our purposes
+11:00 < jtanx> that thing with running a custom webserver is that if anyone wants to reuse this in the future, i doubt they'd really like the idea of that
+11:01 < jtanx> say they had some new fangled thing that requires php
+11:01 < jtanx> which isn't going to work
+11:01 < jtanx> but with a standard webserver like apache or nginx, it's really easy to just install an extra addon
+11:02 < sam_moore> I suppose... what would they need the new fangled php thing for?
+11:03 < jtanx> well that's the thing - for now I don't know, but it could be required
+11:03 < sam_moore> Yeah, good point
+11:03 < sam_moore> Ok, another reason to use an existing web server, is we might require some advanced features if we want to be serious about the safety stuff
+11:04 < sam_moore> For example, it would be a fair amount of work to add SSL to make the custom thing do https
+11:04 < jtanx> oh yeah
+11:04 < jtanx> that too
+11:04 < sam_moore> Also we might want some authentication on it
+11:04 < jtanx> nginx/apache are highly customisable
+11:05 < sam_moore> I've never used nginx, what are it'
+11:05 < sam_moore> s advantages over apache2?
+11:05 < jtanx> nginx
+11:05 < jtanx> yup
+11:05 < jtanx> its really good
+11:05 < sam_moore> Haha
+11:05 < jtanx> a lot of sites use it because it's fast
+11:05 < sam_moore> Fast is good
+11:05 < jtanx> faster than apache
+11:05 < sam_moore> Sold
+11:05 < sam_moore> Well, we only need one user as well
+11:05 < sam_moore> In fact, we deliberately do not want to have multiple clients able to use the thing at the same time
+11:05 < jtanx> haha true
+11:07 < sam_moore> Ok, so I think you've convinced me to use fastcgi
+11:07 < sam_moore> Most of the custom HTTP server was reused code, so I didn't waste too much time on it
+11:07 < jtanx> haha ok
+11:07 < jtanx> have you written one before?
+11:09 < sam_moore> Not specifically a HTTP server, but I've written a project for posix systems with a fair bit of networking
+11:09 < sam_moore> git.ucc.asn.au/?p=matches/swarm.git
+11:10 < jtanx> nice
+11:10 < sam_moore> It allows you to run a shell, eg: bash accross multiple machines at once
+11:11 < sam_moore> Not as useful as I thought it might be, but it was fun
+11:12 < jtanx> heh
+11:12 < jtanx> what did you end up using it for?
+11:13 < sam_moore> I was setting up a programming competition where you have AIs play against each other
+11:13 < sam_moore> I wanted to make a round robin
+11:13 < sam_moore> So I had a bash script setup to do that, but then I got impatient, because it would have to run the games in order
+11:14 < jtanx> oO
+11:14 < sam_moore> Well it turned out no one entered the competition, so I probably didn't need to go overboard
+11:14 < sam_moore> But maybe I can use it for something else
+11:15 < sam_moore> For the threading I'm thinking of using pthreads
+11:16 < sam_moore> The alternative is OpenMP, but it's more suited to numerical computation, rather than having seperate things talking to each other
+11:16 < jtanx> okay
+11:17 < sam_moore> My goal for this week was to have the framework started, so we just have some really basic threads running and then we can start implementing them
+11:17 < jtanx> yeah that would be good
+11:18 < sam_moore> If you want to do some work with the fastcgi part so that we'll be able to parse the query strings, that would probably be a good start
+11:18 < sam_moore> We don't have the exact details of pretty much anything yet
+11:18 < sam_moore> Maybe talk to James/Rowan about how the GUI is going to query the server
+11:19 < sam_moore> Also, did you see my suggested naming convention?
+11:19 < jtanx> no
+11:20 < sam_moore> I don't really mind, although I'd prefer not to have hungarian notation
+11:20 < sam_moore> As long as it'
+11:20 < sam_moore> s consistent
+11:21 < sam_moore> But the suggestion was: FunctionName, variable_name (local or member), Structure, ENUMVALUE, Extern_FunctionName, g_global
+11:21 < jtanx> okay I'll try to keep to that
+11:22 < sam_moore> Cool, I should probably go do something else
+12:33 < jtanx> i gotta go
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+16:56 < jtanx_> a beagleboard
+16:56 < jtanx_> hmm
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+17:03 < jtanx> is it the beaglebone black?
+17:03 < jtanx> sounds interesting
+17:04 < sam_moore> They didn't specify
+17:04 < sam_moore> Oh right, I accidentally cut out his message
+17:04 < sam_moore> tl;dr "Beagle Board"
+17:04 < jtanx> the beagle board is around $125 though
+17:04 < sam_moore> Probably the Beaglebone black
+17:04 < sam_moore> Oh really
+17:04 < sam_moore> Heh
+17:04 < jtanx> yeah
+17:05 < jtanx> the beaglebone black is $45
+17:05 < jtanx> but just looking the A/D converter on the black has a max voltage of 1.8v
+17:05 < sam_moore> That's probably what they meant, since they said it is "not much more expensive"
+17:05 < sam_moore> That should be fine; the sensors team says things are in mV
+17:05 < jtanx> okay
+17:05 < jtanx> that's good
+17:05 < sam_moore> Really though... electronics should be asking the sensors team stuff like this
+17:06 < jtanx> heh yeah
+17:06 < sam_moore> They should probably have asked us if it was feasable for software
+17:06 < sam_moore> Maybe they had someone who knew it would be, but still
+17:06 < sam_moore> It looks like it is anyway, so crisis averted
+17:07 < jtanx> just with the sensors, I think that the diferences need to be amplified so it covers the full range of the A/D converter
+17:07 < sam_moore> Yes, the sensors guy knows that
+17:07 < jtanx> yeah so if its only 1.8v there's less range than 0-5v
+17:08 < jtanx> is that compensated enough by having a 12 bit a/d converter vs a 10 bit (i think arduino is 10 bit) converter
+17:10 < sam_moore> I think so; you get ~4x more resolution from the 12 bit ADC and lose ~3x from the lower range
+17:10 < sam_moore> Also there's no set requirement yet on what the resolution should be
+17:11 < jtanx> true
+17:11 < jtanx> well in any case the bb black sounds quite nice
+17:11 < sam_moore> Yep, it'll probably be good to use
+17:14 < sam_moore> I'm much happier now that we actually have regular verbal communication with the other teams
+18:23 < sam_moore> I'm looking into getting doxygen working for this
+18:59 < jtanx> for the documentation?
+18:59 < jtanx> seems good, but never used it before myself
+19:01 < jtanx> looks a lot like javadoc
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+--- Day changed Thu Aug 15 2013
+08:21 < jtanx> hey
+08:22 < jtanx> just a suggestion for the logging functions, but you can use macros
+08:22 < jtanx> to get the function name (and even file name)
+08:22 < jtanx> v
+08:22 < jtanx> http://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html
+08:23 < jtanx> so you can do stuff like #define Log(level, fmt, ...) LogReal(level, __func__, fmt, __VA_ARGS__)
+08:25 < jtanx> it should be c99 conformant
+09:15 < jtanx> I created a pull request anyway
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+13:39 < sam_moore> Yeah, I probably should have looked at that
+13:46 < jtanx> back to the rpi+arduino
+13:47 < jtanx> didn't they know about the beagle board black, or can that not be used for some reason?
+13:48 < jtanx> beagle bone* black
+14:20 < sam_moore> I don't know what model they were looking at exactly
+14:20 < sam_moore> I told them the Beagle Bone was about $50, I haven't had much time to research it myself
+14:20 < sam_moore> I didn't know about the Beagle Board/Bone, which was why I suggeste the RPi + Arduino
+14:20 < sam_moore> They originally were just considering an Arduino
+14:21 < sam_moore> Which would not have been fun for the remote interfacing stuff
+14:21 < sam_moore> Well we could do it, but we wouldn't be able to have a nice web browser controlled GUI, probably some dedicated networked server/client with a GUI program installed on the client machine
+14:22 < sam_moore> Also image processing would have been interesting
+14:23 < sam_moore> Next time there's a combined groups meeting, hopefully we can talk to them more
+14:24 < jtanx> yeah
+14:24 < jtanx> there's quite a few
+14:24 < jtanx> there's a beagleboard which is ~150
+14:24 < jtanx> beaglebone which is ~90
+14:24 < jtanx> beaglebone black which is ~50
+14:24 < sam_moore> Right
+14:24 < sam_moore> So they were probably looking at the beaglebone for $90
+14:24 < jtanx> yeah probably
+14:24 < jtanx> it's weird because the black version has better specs, from what i can see
+14:25 < sam_moore> But still, even for $150, if it saves us 10 hours of writing code to interface the RPi with Arduinos, it will be worth it
+14:25 < jtanx> yeah exactly
+14:25 < sam_moore> Arduinos themselves cost a bit
+14:25 < jtanx> well
+14:25 < jtanx> you can get equivalents off ebay
+14:25 < jtanx> like an uno is $10
+14:26 < sam_moore> The only issue with the beaglebone to avoid having to use arduinos as well, is whether it has enough ADC by itself
+14:26 < jtanx> yeah
+14:26 < jtanx> well how many sensors are needed
+14:26 < sam_moore> If it doesn't, you might have to add an Arduino or two anyway
+14:26 < jtanx> you could just add on an adc chip
+14:26 < sam_moore> Yes, or something like that
+14:27 < jtanx> the beaglebone has like a bazillion gpio ports
+14:31 < sam_moore> Well without getting into the specific details, it sounds like we should recommend they use that
+14:32 < sam_moore> Apparently the sensors team will have a list ready by monday, which will be good
+14:33 < jtanx> that'd be good
+14:35 < jtanx> when are combined group meetings? just the 9am slot?
+14:36 < sam_moore> 9am Tuesday is the "official" time picked by Adrian, 2pm Wednesday is the time that we agreed between the teams
+14:36 < sam_moore> I'm going to go to both, if more people want to come from the team that's also good
+14:37 < sam_moore> Realistically not everyone is going to come, so I'll have to send emails a lot
+14:38 < jtanx> ok
+14:39 < sam_moore> What account do you need to be invited to the dropbox?
+14:39 < sam_moore> I think Alex invited everyone using their student email
+14:40 < sam_moore> Oh right, you wouldn't have been in the list that he used if you enrolled late
+14:40 < jtanx> yeah, through student email would be good
+14:41 < jtanx> last year's experiment ran with an arduino diecimila which only had 5 analogue inputs
+14:41 < jtanx> any reason why we need more?
+14:41 < jtanx> sorry that's 6
+14:42 < sam_moore> I think the estimate was: 4-6 strain gauges, 1 temperature sensor, 1 microphone, 2 pressure gauges, 1 (maybe 2) USB webcam
+14:43 < jtanx> ok
+14:44 < jtanx> At that rate you would definitely need something with more analogue inputs
+14:45 < sam_moore> We also might need a DAC for one of the pneumatics team's devices
+14:46 < sam_moore> But you can't get that on a microcontroller, there'd have to be a seperate module
+14:46 < jtanx> yep
+14:48 < jtanx> it'd be no point interfacing an arduino to the rpi/beaglebone if all you want is more analog inputs
+14:49 < sam_moore> If you can get modules for ADC that can talk to a rpi/beaglebone, then yes
+14:49 < jtanx> yeah
+14:49 < jtanx> I don't think they're too hard to wire up
+14:50 < sam_moore> I think the electronics team should be considering all this, but I don't know since we haven't verbally spoken
+14:50 < sam_moore> Well not at length anyway
+14:51 < sam_moore> Just when I happen to bump into Omid
+14:51 < jtanx> hmm
+14:54 < sam_moore> This project is probably going to be a good lesson in "Why you need a project manager"
+14:55 < jtanx> so true
+14:59 < jtanx> with the web interface, what sort of update times are we looking at?
+15:00 < sam_moore> My tests with apache2 and the custom HTTP server showed it took about 50us for jQuery to get an AJAX request
+15:01 < sam_moore> There was only one data point returned each time though, we can probably optimise it a bit by returning multiple data points with a request
+15:01 < jtanx> yeah
+15:07 < jtanx> I wonder what sort of performance impact running one (or two) cameras would have on the rpi/beaglebone
+15:44 < jtanx> urgh
+15:45 < jtanx> I was wondering why my nginx config wasn't working
+15:45 < jtanx> until I realised that gedit was creating a backup copy of the config file
+15:45 < jtanx> so nginx was reading both the original and backup
+17:28 < sam_moore> That's wierd, you'd think it would only read one config file
+17:34 < jtanx> well it was in a config directory
+17:36 < sam_moore> Oh, ok
+18:49 < jtanx> so the current idea i have with the web thing is
+18:49 < jtanx> you can query it like http://domain/api/module?key=value&key=value2
+18:50 < jtanx> and then you could return something in json format or whatever is most suitable for the ajax query
+19:46 < jtanx> you can test it at http://mctx.us.to:8080/apoi
+19:46 < jtanx> woops, http://mctx.us.to:8080/api
+19:46 < jtanx> the only 'module' which will give a response of '200 OK' is sensors
+19:47 < jtanx> which currently spits back any arguments you pass to it
+19:47 < jtanx> eg http://mctx.us.to:8080/api/sensors?k=v
+19:50 < jtanx> hopefully it doesn't break
+20:44 < sam_moore> I'll take a look
+20:45 < sam_moore> Looks good
+20:45 < sam_moore> I'm writing a dummy thread for a sensor now
+21:04 < jtanx> the code behind it (in the cgi module) is a bit clunky right now though
+21:04 < jtanx> is there a meeting tomorrow?
+21:05 < sam_moore> I don't think so, sorry
+21:06 < jtanx> ok that's alright
+21:06 < sam_moore> Things aren't urgent (yet)
+21:07 < jtanx> heh
+21:12 < sam_moore> For the progress report: I'd like everyone to write a page individually, then we can summarize those in the group report
+21:12 < sam_moore> Well you don't have to write a whole page, and if you miss a week or so it's not a big problem
+21:16 < jtanx> ok
+21:17 < jtanx> i'll try to remember that
+21:18 < jtanx> do you think we need to keep track of how long we spend on this project
+21:18 < jtanx> for that 'cost estimate'
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+22:23 < sam_moore> For the cost estimate: Yes, we are supposed to have a technical diary (hand written)
+22:23 < sam_moore> Including all notes and times worked on the project
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git.ucc.asn.au / matches / MCTX3420.git / blobdiff
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