WWDC2003 Session 727

Transcript

Kind: captions Language: en welcome to the quicktime streaming server programming session and we'll be covering the quicktime streaming server and darwin streaming server source code and API programming one of the things that will be covering is how you add to nad your code to create your own server or modify the existing servers that is available and when you use darwin streaming server source you end up with a server that it can run on linux OS 10 bsd solaris and windows NT so there's forced features that we're going to cover we're be talking about the server architecture and there's other types of products applications inside the source code when you download it that will be covering finally building installing and a few debugging tips at the end and one of the things about this session that is a little bit different from previous API sessions that has been done with the QuickTime streaming server is this is an open source project so yes there is the API and there are times when you have a module that you want to write and there are other times when you just want to change some small behavior that's in the server or fix something that you think isn't done right and because it's open source you can just go in there and change that code so to help you do that we'll be talking about how the architecture the server and how you can go ahead and change the behavior or add behaviors to it and because this is open source it is covered under the apple public source license to a psl you can find it up on the web you want to download this and read it carefully follow the terms of the license then plan your changes and your addition great go ahead create your software if you find that you've had to modify the server you will want to post that you have modified the server and make those changes public so that was our message for my response to the source that will be talking about is the server of course you have your server modules inside the server there are files that are specific to porting the code to Windows NT or Linux you'll want to take a look at those if you have different OS than the ones that are already supported in the build of the server you have the various protocols that are supported inside the server so these files will be a bit are there when you download the source and there's a client development library we use this library in our product in the QuickTime streaming server and it basically gives you rtsp over RTP as a client some PCP skip detection if you want to see what a skip protection implementation looks like on from a science point of view there's artistic client library in the source code there's a proxy server there's mp3 and mpeg-4 file broadcasters you have the file parsing and reading code that's inside we need the source code when you download it and of course we have our web based server you I that's part of the Darwin streaming server product so all of these are available for you to look at use it at sample code or go ahead and change it modify it to whatever needs that you have this is a diagram high level diagram of server and how it works and it is a module based server there's very little actually that the core server does it's just basically there to run the modules and execute tasks those tasks are actually implemented each of the modules that is loaded it into the server so we start out with our clients connecting to the server over the network protocol on the other end is the key gssapi that's going to go ahead and call your module now this is the core server the execution of the core server there's one process and it contains four main threats the one main main thread is simply there to watch the state of the server and gather statistics so it's actually doing very little there is an event threat that's out there using select on linux and POSIX Kazakh systems it's using Windows Windows messages and macros head event queue to find out if there's a vent that he needs to process and once an event happens like a reed event it will then go ahead find a task that's associated with that file descriptor and it's going to put it on something called to task for it the tax rate is actually going to do the work so the vet thread accurate browser event throws it onto at a thread is simply going to go back to sleep again waiting for another event so there's just one event thread and all the work is done by the passwords those threads are going to be running through their cues one at a time and processing each task so some servers out there will throw off our fourth process for every request our server the QuickTime streaming server / star which gaming server has two threads there's I mean processes there is parent process which like the main thread is just checking the status of something else in this case it's the child process so it Forks off the child process and just wait to see if the child process has died in the case of some unknown reason the child process were to be killed or crash perhaps the parent process will go ahead and be executed now the child process is the server that we were just looking at and it contains the task Reds events resume red and the idol class hood which is a variation on the task but there's only one task threads per processor so that means all the work is really generally being done on one thread and this may mean that if you have a module or if you're doing something in the server and it's going to take a long time what you want to do is possibly create your own private thread and let's take a look at how these threads can affect a module or processing inside the server so let's switch over to demo one and I'm going to run a file module that I have modified and what this module is going to be doing is blocking in order to do some long task maybe what you can imagine it's doing is downloading a file from another server before constraint so a request comes in and it's going to have to download it first so I'm going to open up a just a regular movie saw here now I'm going to call my special module that's going to go off and do some work so here it is and it's busy downloading this file and it's doing it in this is just a tight loop just going to block the whole server because it's only the one test fit and it says okay when I'm done then I'm going to return from the service call into the module and respond to the request and you can see at that point what had happened to the previous client who was busy watching was that they was frozen so the server API does support having a module take a little while to do things and the way we do that is we provide a call called set idle timer which is going to tell the server to call it again because it is me doing some work so in this case yes this nemoj it might be busy downloading something copy a file it could be doing a DNS lookup which is completely blocking a server but at least the whole server isn't frozen so this is one of those things you have to be aware of when you're working in the server code now there is one last thing on a show you and that is what happens if you're going to make a call maybe it's get host by name that where it's going to go and you have no control over when it's going to come back it could be 10 seconds from now how do you deal with that since you can't at in the middle of the call return control back to the server but you need to do then is forked off your own thread now the potentium service source code has and I was grad class so I just decided to use that and what I did was I just instantiated the thread and told it to go ahead and make my blocking call so so in this case I have a tight loop but normally would be blocking the entire server however in this case because it's on its own thread I can still play movies so just something to think about there is in most cases you won't have to deal with any of these issues but if you do find yourself having to do something that's going to take a little while a long while it would be a bad thing block the entire server so this is basically the the architecture of the server and let's switch back to slides so the reason for the number of threads was to keep our thread count low and this is a performance optimization in the server and the same idea is true when it comes to having only one process it the server runs after it is much more efficient to have fewer numbers of threads it just means that as a programmer you have to be aware of this architecture and design appropriately so let's take a look at the core server now we have a few main objects that you're going to see two in the core server and the first one is the two TS s server this is face the class that's going to get infatuated and it's going to load up each of the modules and execute them there are the callbacks this is the API so every time a module makes a cute ESS API call back into the server it's implemented in something called GTFS call back we have cute ESS dictionaries in the core server these are data storage it's a key look up with the values associated with the key the GTS s dictionary it once again is there to support the API we have rtsp sessions which is the artistic protocol with the server supports and various other files associated with rtsp that protocol parsing and formatting there's RTP session yet another protocol class and its support finally we have server preferences that basically configure the server when it starts up so all of this actually could be summarized that there is a QT SS server class it's going to load up your modules there's some API support classes that provide your modules with callbacks into roll calls into the module and call back from them and protocol support inside the core server followed by configuration preferences this is an example of the file module every time we request a movie from the Dharma streaming server it's going to go through a series of calls into the file module in this case normally when you're looking at our API you're seeing the right hand side of this diagram which is the world calls that this module will be getting called in and these are the times in which the module gets called what that meat is on the server side is the Qt SS server which we said owns the modules loads them up is going to initialize the module when it first starts up and after that the module has already decided it wants to handle rtsp requests and has told the server that in the register role that if there's an rtsp request coming in I want to see it and I want to be able to process that so when an rtsp session gets an issue initialize on the server from an incoming client it's going to go ahead and call into this particular module to handle the request in this case let's say it was a play request the modules going to take that process it call it back into the server it's going to use which will go to the rtsp session and in doing a art by QT SS play call back this is going to kick off the rtsp session with clients what that means is now the server is ready to call the to respond to the client with the play request response and then start calling into this module 2 4 packets and so the next roll call that this module starts receiving from the server is going to be the same package will basically the server is going to keep saying give me a package give me a packet and the module in that role call is going to go out find a packet for each of the streams and do a cute ESS right so this covers pretty much a basic module it's going to get loaded it's going to say these are the roles that I want to support its going to get called in those roles and it's going to call back into the server after it's done processing so there are a number of modules that are pre-built into the server when you launch the server there's several modules and I've categorized them by content support and access control now what we have is the content modules here which starts with the file module this is your basic module that is going to do mpeg-4 streaming it's going to do 3gp support it does QuickTime movie file support it handles describes for rtsp basically it's and when it starts up this was we were seeing before it's going to say I want to handle rtsp requests and I want to stream out package so it's going to do those two roll calls the reflector module doesn't have the files what it does handle is incoming broadcast live streams it binds to a port it handles requests for ftp files which been the reflector modules when it comes time to write packets is going to be pulling in from an incoming broadcast stream and sending them off to the time so that's why we call it reflective is incoming broadcast like a live broadcast and this module here is going to be the one that's going to be sending those packets out to the clients we have a relay module which is similar to the reflector module except that it has a built-in broadcaster as well what it does is it goes in it grabs a a broadcast stream that's coming in and then it's forwarded on to another server it could actually be a multicast address so in which case you could just go ahead and forward it on to the multicast IP address but the idea here is that it's pushing a broadcast someplace instead of waiting for recline to come in and the broadcast which was the reflective module the mp3 streaming module is another broadcast support module what this does is it grabs an incoming mp3 stream kind of like an ice caps or she'll cast type of extreme that might be sent to a server and it's going to provide a response to any mp3 IC request for a potluck live at p3 broadcast so each of these is going to handle a request in a very particular way it's going to take it it's going to intercept the request decide if it belongs to itself and it's going to respond to the client and then handle the data now we have some service support modules built into the server some of these you know if you're thinking about changing the server what start here if it has to do with access logs or maybe pulling out some statistics out of the server these these modules are built into servers they're great pieces of sample code for you there is the error log module which obviously is just going to go ahead and record errors into a file but we also have the access log which has each bar each access to the file logged into the to the access logs and maybe there's something in there that you just need in addition to with already act already written out you know there's their average bit rate or there's the time connected but maybe there's something else that you want throw an Indian maybe the codec that was used well take a look at the access log maybe what you need to do is just change that or you could go ahead and rewrite your own log of course but this is built into the service there in the source for you to take a look at there is also some other modules like the web staff module it's a HTTP module that will return HTML web page and it will pull out some information from the server and generates the web page so it's not restrict a module isn't restricted to streaming protocol you can implement it's there the server it's going to call your module you can decide whether or not you want to handle RTSP requests or you can decide you want to handle something else like an HTTP request we have a web debug module and an admin module the admin module is an interesting one because what it does is it takes an HTTP style request and uses and looks for something called our admin protocol this is a URL based protocol that references any of the data that's in the server so this is how our UI is is implemented basically you can go ahead and grab anything out of the server using the admin protocol implemented in the admin module and set it as well and you can do this remotely as if you want to finally we have the POSIX file system module this one doesn't deal with requests that doesn't deal with logging what it is if the low level implement support for reading and file so each of the modules that are in the server called through the API to read a file and it all gets funneled through the politics file system module and this could be replaced so that if you needed to do something like a network file system you can go ahead and change the implementation to do some other kinds of pollicis call system calls maybe you're pulling the data out of the database instead of coming right off the local the disk so once again more modules that are built into the server more functionality that is available to you finally have the access control modules these start out with the access module which handles authentication authorization we have a patchy style users and groups files basically it's going to go and check that file to see if a user has access to any of the movies on the server there's a home directory module this one takes a look at the URL and says oh do I have a Tildy John in the beginning of the path and it says okay this means that this movie is coming out of the user's home directory movies directly folder not the main server movie folder so what it does is it allows users who have access only to their account their movie folders in their home directory and not to the main server to put up full movies onto the server and then everybody can reference them but it can only administered what they own there is an HD pop HTTP file module kind of interesting it's a dynamic module we usually have it turned off what it does is allows you to download a file so it's not it it could be an example would be like in a progressive download it also has the ability to on the fly create a wreck movie out of a folder of movie so it actually pulls up takes the request it says oh through the directory and then it looks inside that directory and says oh I got three files here creates a breast movie you know with the bit rate for each of those files and sends that back to the QuickTime fly so it just completely skipped over the requirement of having to author one of these refugees for the movies on the server however it is an optional module of someone once built in we call it these types of modules dynamic modules and mostly because we don't feel that they are necessarily the type of feature everybody wants running inside their server however they are there if you want to use them the spam defense module is another one of these optional modules that comes with the source basically it can limit the number of requests coming out of a single IP address so he threw hundreds of play requests coming out of a single client it's just spanning your machine the spam defense module can put a clamp on that and say look groaning and allow 10 movies being played from the single IP address so these are access control types of modules that there's the data ones the content modules is the basic support and then access control so I'm going to go over it and switch back to our demo system and one of the nice things about having the source code is that if there's a behavior in the server that you want to change then the code is there waiting for you and all you have to do is find the right place to throw your code in and you can basically change the behavior of service so what I did is I said I wanted a file module but every time I gave it a URL like next I wanted it to give me a different movie like this one or that one or this one so so downloading the source and going in there and say okay every before I pass the filename off to the the open file command I want to be able to replace it okay couple lines of code swap that in there and now I've got a new behavior in my server now you might want to create this as a module or you might if you have complete control of the servery then go ahead change it it's it's all right there add your behavior now another module that I had mentioned in our talk earlier was that the web stats module and that's a dynamic module we can see some of these modules installed on the system these are dynamic modules here basically what that means is every time you throw them into this module folder and monstrous server they're going to be executing when the server run these are other modules that can be thrown in there and run and once again these are all part of the Darwin streaming server source and are available to you to look at modify use a change so getting back to that web stats module that fits in the server what we can do with that is go ahead and call it let's see hmm what's my server comes back so I see what we're doing here is we're waiting for the system to come back from doing some sort of network I oh ok now i have a server back again so what I have inside of on the screen here is an admin module request into the server to find out a preference and this module preference is web stats and I'm going to take a look at what it's going to show me ok so this module just grabs the requests coming into the server and says hey its web Seth I'm going to handle it and what it's going to do is it's going to respond but instead of a since this was an HTTP GET coming into the server what this module decided to do is just going to generate an HTML web page and send back some information about the server now what may be what it could have been doing is copying a log file on demand over to some other machine thats collecting all these statistics or doing something like that this module here or maybe this command was coming in from another you are somebody has integrated the quicktime streaming server administration into their user interface for controlling multiple servers or something like that and this module perhaps is supporting that so once again there's various ways in which you can access and control the server and this is one of them just toss a module in there and away you go you have a new feature inside a QuickTime streaming server so we can switch back to slides ok so the server is a thin piece of code but there is actually when in terms of when it's executing but there is a lot already built into it stuff that maybe you don't want to have to rewrite and if you have the opportunity you want to be able to use so I mean so we are going to be supporting rtsp over TCP for you RTP over UDP Apple skip protection is built into the server that's RTP over reliable UDP what that mean is what that means is there's UDP packets going out with acts coming back and the server has ability to do retransmit using this protocol there's RTP and RTP tunneled in HTTP which is basically how do you get around far wall there's arch p of rtsp which is our to be on top of TCP so these are all standard protocols streaming protocols and they're built into surveyed automatically will handle these connections now one of the protocols that it doesn't automatically do for you as HTTP basically there's a request coming in but it itself is not going to do anything with it if you have to have a module that wants to basically you would grab that request and decide based on the URL whether it was meant for you and not and do something with it so some one example is the couch ESS admin module that's going to look for a tip URL path and it's going to decide yes this is a path it belongs inside of the server and I'm going to go ahead and respond to it the empty free streaming module is another type of HTTP support module it looks for I see a protocol request that coming into the streaming server let's fast module we just looked at that and so on and so forth there's the other types of modules here the ref movie module is going to take a HTTP GET on a file a movie file and generate a rtsp request send that back to and the response to the get and that tells the QuickTime 50 what I really should be doing here is not a dad's with an rtsp is on the file and it turns around and makes the Archaea spiritless looks like their website twice and a web debug module so that's very similar to the web stats except that gives debugging information when the servers compiled with debug enabled the debug module is going to show up with an HTML webpage for the programmer to see real time what the memory allocation in the server is maybe how many file descriptors are open things like that there are of course other ways of getting that type of information but this is one way in which a handy way in which is can be done ok so the server has these roll calls is calling to each of the modules in the roll calls look like you me here's a request here's a a route roll which is sort of a pre request call and along with each request is going to be something to call to keep ESS object and these are inside of the server basically a dictionary that goes with each of the classes that the server support so there's the Qt SS server class and it has an implementation called the TTS of server interface that's the dictionary that's going to support the API we have rtsp sessions that get generated whenever a client connects there's an rtsp session interface that goes with that class it's an rtsp session interface CPP file and basically what that is is the dictionary implementation for the API to access the data that's in the rtsp session object same is true with RTP session another type of protocol management classics in the server and eat for every request the there's a request object that shows up in part of our API that has an interface file associated with it's a dictionary that that gives access to the data so here's the object hierarchy that's built into the server you have your main server and once again the server object has it has a GPS interface file associated with it it contains modules server preferences and client session so when we look at server object will be able to pull out the clients message we can pull out service preferences that are currently active we can grab each of the modules of the server is running and then within the modules there's preferences for each module that is own instantiating inside of the service so what that means is when you create a module you can say hey I want to have my modules preferences added to the servers XML preference file and there's an API calls you allow you to do that all of our modules that come in source code do this so that means that the preference is for your module or immediately configurable or editable by the admin protocol meaning a user interface can go in there and remotely configure your preferences without you ever having to write anything to support remote admin of your module the client sessions of course you might want to find out some information about the stream it in real time know what's the current bitrate of the stream or the session all the streams that come that are currently playing for a given client and so the dictionaries give us this ability to walk this tree a data real-time pull it out of the server and if you want to log it or use it to maybe limit the number of users you know it's you're finding that the current bandwidth is just getting too high in real time you want to start limiting some the server in some way by number of users of my back let me go ahead and change the data that configures the server real time by accessing our data hierarchy so I want to use the admin module that we've been talking about just to show you what some of these objects look like and basically the admin module takes an H this admin protocol which is a you or else I'll request and maps that to the hierarchy that's inside the server and pulls out the information and can actually set it to so if I wanted to grab the server object and I want all the fields within the server object I'm going too far off a request to the admin module and here it is so now it's giving me back everything that it knows about one of the things it has the inside server object it is the list of modules so if it's a dictionary up here at the top I can see my path through the dictionary he called the server module objects and here are my module if I had were to draw a stop the server drop a new dynamic module into my modules folder and relaunch the servery would show up in this list now each of these modules has its own preference and C collection pull that out it has many different layers but each module you can see is has all of its settings and can be configured here remotely so none of the modules really have to worry about okay how am I going to configure this thing it's easily configurable once it's loaded up into the server and since this information is written back out to the server's XML file it can be edited even when the server isn't running can change the xml file to modify the preferences so let's take a look at some stream ok this one and I want to see the sessions that are currently running I have one client service session I want to drill down into that session ok so I have some session information right now I have a URL looks like i have a an average bitrate a movie file size I want to take a look at the streams like there are two streams I want to see if i can find the Codex looks like i have a impact for codec and looks like an impact for video displaying so for every single stream that's currently playing on the server I can grab real-time information and pull it up now I'm doing it through a module you if you had a theorem LT gather that data but if you have a module that's currently running in its its job is to be monitoring you know how many people are watching this particular movie right now and maybe I need to we start redirecting find someplace else or maybe I just need to start denying client you can imagine a module doing this ok so we're going to which back to our slides and talk about the source itself okay so when you on tar the source code you're going to see a whole bunch of files show up in some in a streaming server directory inside of that main top level folder are these source directories the server t podge directory which is the core server file you know the GPSS service apt that's going to load up your modules there's a main dot cpp that's going to handle all the command line options that you might be running now it also has you're going to see the rtsp session files inside the server dotty proj directory so if you're looking for something that's going on in the core server the protocols the module loading this is a place to go common utilities is it's just a set of classes that all of the modules and the server uses it's our convenience classes there is a string class as a parser class that we use there's also our thread class or socket class basically all the basic stuff that you need to either manipulate a request or just run the server is it started calming utility cutie file lives is the directory that if you are interested in finding out how we parse an impact for movie will be it this will be of interest to you because inside of beauty file ID is all of our epic for parsing code all of our quicktime movie code it basically handles any hinted mpeg-4 or quicktime streaming movie the api common code all of the modules use use it it's basically they're four sets of API calls they kind of seem to go together and you know I want to create a new preference and set its value and this is where usually we throw those types of commonly used code together so you might want to go ahead and see if there's any of that code in there for your module that you want to use or emulate the API modules themselves implementation for all the modules I've shown you is in this directory you can just walk through there now do a grep browse it and pull up the force for any of the modules rtsp client live is it's just a library but basically when you instantiate it it's going to give you the ability to connect to a streaming server as an artistic lion i'll go ahead and do it this time you can tell us we do a described i'll get back to the SBP response you can ask it to start playing and it will pull down a rtsp stream it'll do it over any of the protocols that the service support so this is how we test out our server using this library you know if you tell it connect to the instantiation for the rtsp client live to connect and download over tcp i'll do that or in HTTP using reliable UDP perhaps our script protection that's the rtsp flight line the server actually uses it in a couple places one of them is in the relay module the other is in our file broadcasters particular the playlist broadcaster has a built in client and it uses artistic lima and one last piece the streaming load tool is a little piece of binary code that goes out and does load testing and we use the rtsp client lives in that tool so rtcp utilities if you're interested in RTP protocol for some reason maybe there's a bug in the servers enough but the code is there for you to take a look at six or change if you need to same thing is true with HTTP and that's the top level of the forestry as you end hard and when you go ahead and build our code you're going to end up with more than just the streaming server you have the playlist broadcaster which is like the name side of the plate it takes a playlist of movie files and concatenate them together and streams the tooth into the server and these can then be turned around by the server and to support each client it may be requesting that the live stream actually it's a pseudo live stream of course players broadcaster will loop the list of movies if that's what you asked you to so how's this continually running playback of some keynote speech or something like that also there's an mp3 broadcaster which is the same same idea except it's doing a for mp3 instead of impact lawyers and QuickTime movies we have a straining proxy and that source code is there there's QT file tools those are for those people are once again her interested in the in the mpeg-4 movie file format and I want to see how it goes out and extracts the packets out of the file these tools basically our command line tools you can go ahead and rip out streams of packets from from any given hinted file the web admin is our user interface that we provide with the Dharma streaming server so let's say you want to personalize or privatize the web admin so it doesn't say apple quicktime streaming server all over it you want to throw in your own UI to the HTML going this web admin is in the source you can go ahead and change it it's the as well as the Qt pass as well i'm going to doesn't really do much if you want to add users and groups you've run the key key password file if you don't like the format for some reason go ahead and change it if you want to use our code fine so or you can replace to the course so one of the things that you might want to do is just change the name if you're deploying it with your product here now quicktime charged Dharma streaming server doesn't really work for you you want to call it my demo server or your server and so you can go ahead and change those constants that are available in the server there's a few places you have to go and look for things it so it was 10 you want to look in the project builder file there's a if you're dealing with the web admin and you're going to be looking in the pearl file that takes part of the web admin it was basically the Installer scripts you can find it pretty much by doing a fine text and file its and so then you can package it up in and distribute it with you know maybe you're a hardware server product or something like that that shifts with the darn streaming server once again building the software we have a builded script this is what you would run at the command line to build our POSIX version of the server you would just find the script and run it there's it's also works for OS 10 you don't want to use the project builder project you can just execute from the command line rebuild the binary and tested it show up inside of a bill directly on those 10 on Windows NT it's a little bit different we have a Windows NT support directory so those of you who are building your software for windows are going to go down in there find your visual c++ project or worksheet load that up you want to be able you want to do a batch build and it's going to generate a debug and release directory and throw all the binaries in there so once you have your software built you want to be able to create an installer now once at this point it kind of gets goes into how do you want to do it the pre-built binary says Apple has on our site for you to download we're all created using this build tarball script which you know goes ahead builds it generates a direct and install directory tars it up and then you go ahead and download it on Targ lens they install scripts and it goes ahead and throws it on to your machine and that would be for the POSIX platforms on ls10 we have a script that's going to build an LS can installer package for you so it's going to go off in front do all the pieces and throw it into this installer package the important piece about the bill dose can installer package that there is some logic when it's installing as to what how to upgrade existing installation or what to do about setting it up with the proper users and groups that the server might need on ls10 for example and version 5 we're going to be running as user QT SS and installer package will make sure that that user is on the machine so that when the server runs it can go ahead and strength when those windows NT we just use them exist package that the bat file goes ahead and organizes the files for you you might want to edit or change that yourself so we're going to move on to troubleshooting so after you've gone through you've created your module you've edited things you've built it you've been created installer if you find that you need to troubleshoot the server there's some commonly used debugging preferences that we have and the first three that i have here had to do with protocol and the first one is rtsp debug.print so I just want to see when a request comes in what is the server looking at what's it what's it think it's trying to casa now you could go ahead and take your network sniffer and put that on there each time but sometimes it's easier just to go ahead and turn on this precious run it to serve in the terminal and just watch what's happening now just following that is the packet header furnace which applies to our RTP and rtcp so the actual data packets themselves you don't want to it will just like the rtsp pronounced will show you the rtsp the packet header printf are there to show you the media packets that are being sent by the server so that means that if there is an RTP packet a receiver report send a report an application packet or a knack and the acts are for the Skip protection then you'll see them as they come into the server or get sent out and if you are if you do have these on you want to be able to see them you're going to need to run the server in debug mode which means at the command line at a dash D okay so I'm going to just turn on the debugging printf here just to show you what they look like I'm going to go ahead and add the preference with my admin protocol using the admin module and so the URL was set this value rtsp debug.print asked to true so at this point what we should have is a streaming server that has our debug printf in it whatever it wakes up hmm try different new 10 up okay okay so we don't need this anymore ok so the rtsp debug.print em we have an rtsp request here described and some more information and a file module that accepted it and sent back something called the SBP right here to the client and this is just handy information that as you're debugging your module you might need to take a look at these requests so another type of plus i'm going to try is what happens if i throw an HTTP GET at the server and i'm going to call it an mp4 okay looks like what happened is it started playing in fact started playing and it looks like it's streaming but i just did initially be get so we can take a look at what what all this thing is doing by looking at rtsp debug printers it looks like a get went to the server and a module there picked it up and return the HTTP GET with an rtsp URL which went to the client and told it oh I guess that means that what I should be doing is a RTS be described with this URL so that this could be a redirect actually it's not an rtsp redirect what is an HTTP GET that contains a redirect in the response now you can imagine this module that happens to be available inside the source code it's called the refs moving module being used in lots of different ways to generate different redirects or types of responses to the client so that you can go ahead and have an rtsp to some other movie or some other server even so that was how we take a look at what's going on in the server when we're debugging the using the rtsp debug printf and let's go back to the slides and in the slides we'll take a look at a couple more p bug printf basically you can turn these on when you compile the service one of the useful ones if you have a module that's doing something kind of tricky it's having a lot of different roll calls maybe it has its own thread you might want to take a look at one is actually getting executed and the way to do that it's fine in our comedy tildy's the base class for a task which is basic of entity that's getting executed in the server and if you would turn on the debugging there you'll find all these printouts that show up let's say oh the server is working on our kiss p session right now and there's an access log called right now that's being executed so you can find out exactly when all the modules and what their interactions are by turning on this p bug printf in the file source there is also another handy little flag you can turn this on and you can pretty much see what the breeze coming what kind of reading is a server doing how often is it hitting the disk is it you know they're reading all over the place or is it you know seem to be reading sequentially how's the caching working in the server and this is the file source debug there might be some some reason where you are transferring the reads off to maybe a database or something like that so the file system and you want to see how how the reads are being handled and server so another debug option for you so as I was talking about the server and its protocols I mentioned rtsp RTP SVP session description protocol and all of these that have RFC is available on the Internet so if you want to take a look at the protocol and find out more about what's what clients might be doing with the server what the server should be doing or what you can do to change the way the behavior of the servers you can take a look at these RFC's up on the web there's some other open source projects that handle rtsp and RTP one of them is the mpeg-4 RT on sourceforge so they have an open source slide that actually will play the audio and video and it will work with our artists are streaming service it's an open source client and in fact they even have an encoder I believe well as well so there are related streaming sources of our resources that you can find out there on the internet live media is yet another one these are open source and we interoperate because we have our standard space so as you can see that there's RFC's the when it comes to codex mpeg-4 is the standard that you believe strongly in and our server supports so the programming for our clip time streaming server is essentially just a matter going in there and getting the source code looking at the modules finding out what we already are doing thinking about what we want you want the server to be doing and go ahead change the code add your module add your functionality and now you have a new server and we hope that we can add more functionality to sort of server for you as well but we have where we're making Fargo each year there's new features into the server and and you'll be able to find out more in the next year so this is the follow-up to my talk and I'd like to bring up Guillermo Ortiz to tell you something about the other sessions that are available here at the show and Guillermo thank you much so go away okay so just as a side note you can see the big yellow ball there they quicktime feedback forum has changed venues so we will be moving to the marina as soon as we finish with this conversation here since most of these presentations already happened i was going to remind you that as these to the conference you will be getting access to the stream versions of the presentations in next few weeks so if you missed any of these you or you want to go back to see what was mentioned something that you means this will be the opportunity to it and you will also be receiving a package of dvds that contain all the stations of the conference so this is coming to you in a few weeks more than the download streaming movies which will be quite a portion for this code for decision so if you have any other question or if you need something for me showing a quick time man a double tom is the address that you want to write any questions and we'll try to route them to the right people documentation apple quicktime is the main page for any information on quicktime developers about that common documentation is for general information documentation a quick time I don't think that we have anything special for this session but again adding these to the conference there is a number of downloads that I available only to you right now so you have to go to the connected apple com log in as a member of ABC and you'll get the download under the WWDC 2003 many more information the streaming server mailing list if you want to have a conversation with all your colleagues all over the world who are using the technology and more information work to get for the swimming server modules we are getting to the ending of the conference but you still have a day to go to the QuickTime lab downstairs is in the Sacramento room and have engineering there to answer your questions or QuickTime programming you