SipDeveloperGuide
Version 179 (Adrian Georgescu, 06/20/2011 11:14 am)
1 | 156 | Adrian Georgescu | [[TOC(SipDeveloperGuide*, depth=3)]] |
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2 | 1 | Adrian Georgescu | |
3 | 155 | Adrian Georgescu | = SIP SIMPLE SDK Integration Guide = |
4 | 147 | Adrian Georgescu | |
5 | 163 | Adrian Georgescu | SIP SIMPLE client SDK is a Software Development Kit with a Python API designed for development of real-time communications end-points based on SIP and related protocols for multimedia like Audio, Instant Messaging, File Transfers, Desktop Sharing and Presence. Other media types can be added by using an extensible high-level API. The library has cross platform capabilities on Mac OSX, Microsoft Windows and Linux OS. |
6 | 73 | Adrian Georgescu | |
7 | 155 | Adrian Georgescu | == Current Status == |
8 | 1 | Adrian Georgescu | |
9 | 162 | Adrian Georgescu | SIP SIMPLE client SDK is reliable for production use and is used today in finished products that are downloaded daily more than 300 times. The products work on Linux, Mac OS, Windows desktop OS and Linux Servers. |
10 | 127 | Adrian Georgescu | |
11 | 155 | Adrian Georgescu | == Installation Instructions == |
12 | 1 | Adrian Georgescu | |
13 | 162 | Adrian Georgescu | SIP SIMPLE client SDK is available as debian package for the latest Ubuntu Linux distributions (Lucid, Maverick and Natty), Debian Linux distributions (Stable and Unstable) and can be manually installed on MacOSX 10.5, 10.6 and Microsoft Windows XP, Vista and 7 by following the documentation provided with the source code. |
14 | 1 | Adrian Georgescu | |
15 | 162 | Adrian Georgescu | To install the SDK on Debian or Ubuntu, configure your deb repository as described [http://www.ag-projects.com/projects-products-96/683-software-repositories here], then: |
16 | 162 | Adrian Georgescu | |
17 | 155 | Adrian Georgescu | {{{ |
18 | 1 | Adrian Georgescu | sudo apt-get update |
19 | 155 | Adrian Georgescu | sudo apt-get install python-sipsimple |
20 | 155 | Adrian Georgescu | }}} |
21 | 1 | Adrian Georgescu | |
22 | 162 | Adrian Georgescu | Detailed building instructions from source for the SDK and its dependencies are available [http://sipsimpleclient.com/wiki/SipInstallation here] |
23 | 1 | Adrian Georgescu | |
24 | 155 | Adrian Georgescu | == API Documentation == |
25 | 155 | Adrian Georgescu | |
26 | 1 | Adrian Georgescu | * Online documentation is available at http://sipsimpleclient.com/wiki/SipMiddlewareApi |
27 | 1 | Adrian Georgescu | * Printable documentation in PDF format is available at http://download.ag-projects.com/SipClient/SIPSIMPLE-Manual.pdf |
28 | 1 | Adrian Georgescu | |
29 | 155 | Adrian Georgescu | == Usage Instructions == |
30 | 1 | Adrian Georgescu | |
31 | 163 | Adrian Georgescu | The SDK works on any platform that supports Python and provides direct access to the input and audio devices using one of the supported backends. |
32 | 163 | Adrian Georgescu | |
33 | 171 | Adrian Georgescu | Using SIP SIMPLE client SDK library is no different than using any other Python library, after installing it in the system, one must import its modules into the program and use it. There is a [http://sipsimpleclient.com/wiki/SipMiddlewareApi#SIPApplication high level API] that automates and integrates most of the tedious tasks like starting and stopping all required sub-systems in the right order and performing most common applications like setting up an audio or a chat session so a developer can use the SDK by writing just a few lines of code without having to understand all the details or the used protocols. |
34 | 1 | Adrian Georgescu | |
35 | 178 | Adrian Georgescu | To setup a simple audio call, print the connection state and hangup one has to write just a few lines of code, see Hello World example below. |
36 | 169 | Adrian Georgescu | |
37 | 169 | Adrian Georgescu | A complete audio+chat conferencing application has been written in 300 lines of code. On the other side of the scale developing a complete end-point like Skype is the most complex example of what the SDK may be used for. The complexity grows as one needs to interact with the end-user for more actions like creating conferences, interacting with telephony like applications, adding chat or handle presence updates. The complexity is dictated mainly by the external UI design, the library provides easy to understand high-level functions and the develeper does not need to understand SIP or other related protocols used inside the kit to achieve his goal. |
38 | 1 | Adrian Georgescu | |
39 | 1 | Adrian Georgescu | === Deployment Scenarios === |
40 | 1 | Adrian Georgescu | |
41 | 155 | Adrian Georgescu | The SDK can be used to build real-time communications end-points that operates in the following scenarios: |
42 | 1 | Adrian Georgescu | |
43 | 167 | Adrian Georgescu | * On a LAN using Bonjour discovery mechanism for address resolution |
44 | 167 | Adrian Georgescu | * On the public Internet with any SIP Service provider using standard DNS for address resolution |
45 | 176 | Adrian Georgescu | * Part of a P2P overlay network like a DHT that provides routing and lookup service. For this, the SIP end-point built with the SDK will publish into the P2P overlay its Address of Records (AoR) address:port:protocol where it listens for incoming requests and will implement a lookup function to obtain the peer end-point addresses from the overlay when it wants to establish an outbound sessions. |
46 | 176 | Adrian Georgescu | |
47 | 176 | Adrian Georgescu | All topologies can be combined together in the same client application. |
48 | 1 | Adrian Georgescu | |
49 | 155 | Adrian Georgescu | == Sample Code == |
50 | 155 | Adrian Georgescu | |
51 | 155 | Adrian Georgescu | === Hello World Program === |
52 | 155 | Adrian Georgescu | |
53 | 164 | Adrian Georgescu | This is the hello world example that establishes a wideband audio session with a test number that plays a music tune. After installing the SDK, paste this code into a console and run it using Python. |
54 | 155 | Adrian Georgescu | |
55 | 155 | Adrian Georgescu | {{{ |
56 | 155 | Adrian Georgescu | #/usr/bin/python |
57 | 155 | Adrian Georgescu | |
58 | 155 | Adrian Georgescu | from application.notification import NotificationCenter |
59 | 155 | Adrian Georgescu | from sipsimple.account import AccountManager |
60 | 155 | Adrian Georgescu | from sipsimple.application import SIPApplication |
61 | 155 | Adrian Georgescu | from sipsimple.core import SIPURI, ToHeader |
62 | 155 | Adrian Georgescu | from sipsimple.lookup import DNSLookup, DNSLookupError |
63 | 155 | Adrian Georgescu | from sipsimple.storage import FileStorage |
64 | 155 | Adrian Georgescu | from sipsimple.session import Session |
65 | 155 | Adrian Georgescu | from sipsimple.streams import AudioStream |
66 | 155 | Adrian Georgescu | from sipsimple.threading.green import run_in_green_thread |
67 | 155 | Adrian Georgescu | from threading import Event |
68 | 155 | Adrian Georgescu | |
69 | 155 | Adrian Georgescu | class SimpleCallApplication(SIPApplication): |
70 | 155 | Adrian Georgescu | |
71 | 155 | Adrian Georgescu | def __init__(self): |
72 | 155 | Adrian Georgescu | SIPApplication.__init__(self) |
73 | 155 | Adrian Georgescu | self.ended = Event() |
74 | 155 | Adrian Georgescu | self.callee = None |
75 | 155 | Adrian Georgescu | self.session = None |
76 | 155 | Adrian Georgescu | notification_center = NotificationCenter() |
77 | 155 | Adrian Georgescu | notification_center.add_observer(self) |
78 | 155 | Adrian Georgescu | |
79 | 155 | Adrian Georgescu | def call(self, callee): |
80 | 155 | Adrian Georgescu | self.callee = callee |
81 | 155 | Adrian Georgescu | self.start(FileStorage('config')) |
82 | 155 | Adrian Georgescu | |
83 | 155 | Adrian Georgescu | @run_in_green_thread |
84 | 155 | Adrian Georgescu | def _NH_SIPApplicationDidStart(self, notification): |
85 | 155 | Adrian Georgescu | self.callee = ToHeader(SIPURI.parse(self.callee)) |
86 | 155 | Adrian Georgescu | try: |
87 | 155 | Adrian Georgescu | routes = DNSLookup().lookup_sip_proxy(self.callee.uri, ['udp']).wait() |
88 | 155 | Adrian Georgescu | except DNSLookupError, e: |
89 | 155 | Adrian Georgescu | print 'DNS lookup failed: %s' % str(e) |
90 | 155 | Adrian Georgescu | else: |
91 | 155 | Adrian Georgescu | account = AccountManager().default_account |
92 | 155 | Adrian Georgescu | self.session = Session(account) |
93 | 155 | Adrian Georgescu | self.session.connect(self.callee, routes, [AudioStream(account)]) |
94 | 155 | Adrian Georgescu | |
95 | 155 | Adrian Georgescu | def _NH_SIPSessionGotRingIndication(self, notification): |
96 | 155 | Adrian Georgescu | print 'Ringing!' |
97 | 155 | Adrian Georgescu | |
98 | 155 | Adrian Georgescu | def _NH_SIPSessionDidStart(self, notification): |
99 | 155 | Adrian Georgescu | audio_stream = notification.data.streams[0] |
100 | 155 | Adrian Georgescu | print 'Audio session established using "%s" codec at %sHz' % (audio_stream.codec, audio_stream.sample_rate) |
101 | 155 | Adrian Georgescu | |
102 | 155 | Adrian Georgescu | def _NH_SIPSessionDidFail(self, notification): |
103 | 155 | Adrian Georgescu | print 'Failed to connect' |
104 | 155 | Adrian Georgescu | self.stop() |
105 | 155 | Adrian Georgescu | |
106 | 155 | Adrian Georgescu | def _NH_SIPSessionDidEnd(self, notification): |
107 | 155 | Adrian Georgescu | print 'Session ended' |
108 | 155 | Adrian Georgescu | self.stop() |
109 | 155 | Adrian Georgescu | |
110 | 155 | Adrian Georgescu | def _NH_SIPApplicationDidEnd(self, notification): |
111 | 155 | Adrian Georgescu | self.ended.set() |
112 | 155 | Adrian Georgescu | |
113 | 155 | Adrian Georgescu | # place an audio call to the specified SIP URI in user@domain format |
114 | 155 | Adrian Georgescu | target_uri="sip:3333@sip2sip.info" |
115 | 155 | Adrian Georgescu | application = SimpleCallApplication() |
116 | 1 | Adrian Georgescu | application.call(target_uri) |
117 | 155 | Adrian Georgescu | print "Placing call to %s, press Enter to quit the program" % target_uri |
118 | 155 | Adrian Georgescu | raw_input() |
119 | 1 | Adrian Georgescu | application.session.end() |
120 | 1 | Adrian Georgescu | application.ended.wait() |
121 | 1 | Adrian Georgescu | }}} |
122 | 1 | Adrian Georgescu | |
123 | 1 | Adrian Georgescu | === Full Demo Programs === |
124 | 155 | Adrian Georgescu | |
125 | 172 | Adrian Georgescu | Fully featured sample programs are available in 'sipclients' package available in the [http://www.ag-projects.com/projects-products-96/683-software-repositories same repository] as python-sipsimple. |
126 | 1 | Adrian Georgescu | |
127 | 172 | Adrian Georgescu | These programs operate in a Linux or MacOSX terminal and implement most of the functions provided by the the SDK. |
128 | 172 | Adrian Georgescu | |
129 | 155 | Adrian Georgescu | {{{ |
130 | 1 | Adrian Georgescu | sudo apt-get install sipclients |
131 | 155 | Adrian Georgescu | }}} |
132 | 162 | Adrian Georgescu | |
133 | 1 | Adrian Georgescu | * sip-register - REGISTER a SIP end-point or detect Bonjour neighbors |
134 | 1 | Adrian Georgescu | * sip_audio_session - Setup a single SIP audio session using RTP/sRTP media |
135 | 172 | Adrian Georgescu | * sip_session - Complete client with multiple sessions for Audio, IM and File Transfer |
136 | 162 | Adrian Georgescu | * sip_message - Send and receive short messages using SIP MESSAGE method |
137 | 162 | Adrian Georgescu | * sip_publish_presence- PUBLISH presence information for a given SIP address |
138 | 1 | Adrian Georgescu | * sip_subscribe_winfo - SUBSCRIBE to the watcher list for given SIP address |
139 | 162 | Adrian Georgescu | * sip_subscribe_presence - SUBSCRIBE to Presence Event for a given SIP address |
140 | 162 | Adrian Georgescu | * sip_subscribe_rls - SUBSCRIBE for Presence Event to a list of SIP addresses |
141 | 162 | Adrian Georgescu | * sip_subscribe_mwi - SUBSCRIBE for Voicemail Message Waiting Indicator |
142 | 155 | Adrian Georgescu | |
143 | 155 | Adrian Georgescu | For a description of the sample programs see http://sipsimpleclient.com/wiki/SipTesting |
144 | 155 | Adrian Georgescu | |
145 | 155 | Adrian Georgescu | === Finished Products === |
146 | 155 | Adrian Georgescu | |
147 | 162 | Adrian Georgescu | The SDK is used in several products since end of 2009. These are end-products that use the SDK and provide exhaustive examples for how the SDK was used to achieve the goals. |
148 | 155 | Adrian Georgescu | |
149 | 155 | Adrian Georgescu | 1. Multiparty Conference Application with Wideband Audio, IM and File Transfer: http://sylkserver.com |
150 | 155 | Adrian Georgescu | 1. SIP client implementation for MacOS X available in the Mac App Store: http://itunes.apple.com/us/app/blink-pro/id404360415?mt=12&ls=1 |
151 | 155 | Adrian Georgescu | 1. SIP Client for Linux: Blink for Ubuntu, and Debian, use same repositories from AG Projects and do 'sudo apt-get install blink' |
152 | 162 | Adrian Georgescu | 1. SIP client for Windows: https://blink.sipthor.net/download.phtml?download&os=nt |
153 | 155 | Adrian Georgescu | |
154 | 155 | Adrian Georgescu | == Non-Python environments == |
155 | 155 | Adrian Georgescu | |
156 | 162 | Adrian Georgescu | As the programming choice was Python this SDK will appeal to people that want to develop applications in Python. |
157 | 155 | Adrian Georgescu | |
158 | 173 | Adrian Georgescu | If one want to use the library into another environment it must check if is feasible or not as embedding a high-level programming language into another is not a straight forward process if at all possible. |
159 | 162 | Adrian Georgescu | |
160 | 155 | Adrian Georgescu | === Cocoa Objective C === |
161 | 155 | Adrian Georgescu | |
162 | 155 | Adrian Georgescu | MacOS platform is using Objective C for native development. But it also provide a bridge between Python and Objective C. This makes it possible to write pure Python programs that run into the native OS without much changes. |
163 | 155 | Adrian Georgescu | |
164 | 155 | Adrian Georgescu | http://pyobjc.sourceforge.net/ |
165 | 1 | Adrian Georgescu | |
166 | 155 | Adrian Georgescu | The SDK was fully used without any problems to build Blink for MacOSX by using this bridge. |
167 | 155 | Adrian Georgescu | |
168 | 155 | Adrian Georgescu | === Qt Framework === |
169 | 155 | Adrian Georgescu | |
170 | 155 | Adrian Georgescu | Qt Framework from Nokia (formerly Trolltech) is using C for native development. But it also has Python bindings. This makes it possible to write pure Python programs that integrate with Qt framework. |
171 | 155 | Adrian Georgescu | |
172 | 155 | Adrian Georgescu | http://qt.nokia.com/ |
173 | 155 | Adrian Georgescu | |
174 | 157 | Adrian Georgescu | The SDK was fully used without any problems to build Blink for Windows and Linux by using Qt Framework and its Python bindings. |
175 | 1 | Adrian Georgescu | |
176 | 157 | Adrian Georgescu | === Web Browser Plugin === |
177 | 157 | Adrian Georgescu | |
178 | 179 | Adrian Georgescu | Today, web browsers do not give direct access to the input and output audio devices to their plugins, which is required by a real-time audio application. Browsers do not support direct embedding of Python code either. If one looks for example at how Google Talk plugin in the browser works, it actually installs a regular server daemon into the system that performs similar functions to SIP SIMPLE Client SDK and the web browser interacts with it by using a proprietary API running on the same host between the daemon and the browser plugin. The software that handles the media, signaling, integration with the audio device does not run in the browser itself and the browser is used only as a GUI. |
179 | 155 | Adrian Georgescu | |
180 | 155 | Adrian Georgescu | There is a recent initiative to form a work group in both W3C and IETF to address this important issue of accessing and processing audio data within the browser itself as today this is not possible. This requires cooperation from the browser manufacturers, third-party developers cannot do this on their own without cooperation from the web browser makers (like Adobe has obtained for its Flash product). This initiative is called RTCweb: |
181 | 155 | Adrian Georgescu | |
182 | 155 | Adrian Georgescu | http://rtc-web.alvestrand.com. |
183 | 155 | Adrian Georgescu | |
184 | 155 | Adrian Georgescu | Google published a first specification and code drop in May 2011 and IETF and W3C had a few initial conference calls to setup the future agenda but no more at this stage. |
185 | 155 | Adrian Georgescu | |
186 | 162 | Adrian Georgescu | SIP SIMPLE Client SDK cannot run in the browser today for the reasons highlighted above as browsers won't support Python nor direct access to audio devices both required by the SDK to operate. However one could build a program that stays behind the browser in the same way as Google Talk daemon does. |
187 | 155 | Adrian Georgescu | |
188 | 155 | Adrian Georgescu | === C Language === |
189 | 155 | Adrian Georgescu | |
190 | 170 | Adrian Georgescu | How to possibly integrate Python into C is described here: |
191 | 155 | Adrian Georgescu | |
192 | 155 | Adrian Georgescu | http://docs.python.org/extending/embedding.html |
193 | 155 | Adrian Georgescu | |
194 | 155 | Adrian Georgescu | === Java Language === |
195 | 155 | Adrian Georgescu | |
196 | 155 | Adrian Georgescu | There is a bridge between Python and Java. |
197 | 155 | Adrian Georgescu | |
198 | 155 | Adrian Georgescu | http://www.jython.org/ |
199 | 155 | Adrian Georgescu | |
200 | 1 | Adrian Georgescu | === Translating into other languages === |
201 | 158 | Adrian Georgescu | |
202 | 170 | Adrian Georgescu | The state machine for a multimedia real-time application is orders of magnitude more complex than a non-real-time file transfer protocols like BitTorent. |
203 | 158 | Adrian Georgescu | |
204 | 155 | Adrian Georgescu | * SIP signaling has 10 states with 16 possible transitions between them, a diagram is [http://sipsimpleclient.com/raw-attachment/wiki/SipCoreApiDocumentation/sipsimple-core-invite-state-machine.png here] |
205 | 155 | Adrian Georgescu | * RTP media used for audio and video has 6 to 10 states depending on the type of media |
206 | 155 | Adrian Georgescu | * MSRP media used for chat functionality has multiple states |
207 | 177 | Adrian Georgescu | * ICE NAT traversal has many states interrelated with both SIP signaling and RTP media plane |
208 | 1 | Adrian Georgescu | * Presence Publish/Subscribe/Notify mechanism has multiple states |
209 | 1 | Adrian Georgescu | |
210 | 168 | Adrian Georgescu | One must describe the transitions of states, which may contain complex data and can be raised in different threads. There are multiple sockets in use using several transports. When all combined together the final application is quite complex and achieving the same in a low level programming language like C for example would be a major undertaking. While building the SDK in Python took about 3 years, expressing this complexity into a low level language like C requires many years of work with a large team of well qualified people. |