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/*!
* \mainpage Janus - General purpose WebRTC Gateway
*
* \par Developer Documentation for the Janus WebRTC Gateway
* This is the main developer documentation for the Janus WebRTC
* Gateway, generated with the help of
* <a href="http://www.doxygen.org">Doxygen</a>. Make sure you
* check the \ref DEPS before attempting a compilation. If you are
* interested in how to compile, install and use the gateway,
* checkout the \ref README information. A \ref FAQ page is also available.
*
* \par A general purpose gateway
* The Janus WebRTC Gateway has been conceived as a <tt>general purpose</tt>
* gateway. As such, it doesn't provide any functionality per se
* other than implementing the means to set up a WebRTC media communication
* with a browser, exchanging JSON messages with it, and relaying RTP/RTCP
* and messages between browsers and the server-side application logic they're attached to. Any specific
* feature/application needs to be implemented in server side plugins,
* that browsers can then contact via the gateway to take advantage of
* the functionality they provide. Example of such plugins can be
* implementations of applications like echo tests, conference bridges,
* media recorders, SIP gateways and the like.
*
* The reason for this is simple: we wanted something that would have a
* <tt>small footprint</tt> (hence a C implementation) and that we could only
* equip with what was <tt>really needed</tt> (hence pluggable modules). That is,
* something that would allow us to deploy either a full-fledged WebRTC
* gateway on the cloud, or a small nettop/box to handle a specific use case.
*
* \par Architecture and APIs
* The core of the gateway is specified in the \ref core section. The protocols
* implemented in the gateway are listed in the \ref protocols group
* instead. A list of plugins made available out of the box by Meetecho
* are available in the \ref plugins group: these plugins can be changed
* or extended to match your requirements, or just used as a simple
* reference should you be interested in writing a new plugin from
* scratch (and you're definitely welcome to!). A \ref pluginapi to
* create new plugins, or understand how they're conceived, is documented
* as well. A documentation on the available API tranports and the
* HTTP/WebSocket JavaScript API to use the gateway and the plugins it
* makes available in your web application can be found in the \ref JS
* and \ref rest pages. New API transports can be created referring to
* the \ref transportapi page. If you're interested in monitoring Janus
* resources, you can refer to the \ref admin page. Event handler
* plugins can also be used for the purpose: refer to the \ref eventhandlerapi
* page if you're interested in creating your own.
*
* Finally, some information on how to deploy Janus and your web
* applications that want to make use of it are provided in the \ref deploy
* page. If you're interested in starting Janus as a service/daemon rather
* than launching it normally, check the information provided in the
* \ref service page. Some additional \ref resources are also listed in
* case you're interested in talking to Janus from different languages
* and platforms.
*
* This is only the first version of the gateway, and as such it is a bit
* rough at the edges: there is definitely room for improvement, there are
* bugs, limitations, and things that need to be done. Make also
* sure you read the \ref debug page for info on how you can help us
* fixing issues you might encounter along the road.
*
* \section copyright Copyright and author
*
* Janus WebRTC Gateway © 2014-2017 <a href="http://www.meetecho.com/">Meetecho</a> (http://www.meetecho.com/)
*
* \author Lorenzo Miniero <[email protected]> ( \ref CREDITS )
*
* \section license License
* This program is free software, distributed under the terms of
* the GNU General Public License Version 3. For more details and licensing
* options, including a commercial license, see the \ref COPYING page.
*
*/
/*! \page DEPS Dependencies
*
* The application and the plugins depend on the following open source
* software and libraries, so make sure you install the related development
* versions before attempting a compilation:
*
* - \b GLib: http://library.gnome.org/devel/glib/
* - \b pkg-config: http://www.freedesktop.org/wiki/Software/pkg-config/
* - \b gengetopt: http://www.gnu.org/software/gengetopt/ (command line)
* - \b libini-config: https://fedorahosted.org/sssd/ (INI configurations)
* - \b Jansson: http://www.digip.org/jansson/ (JSON)
* - \b libnice: http://nice.freedesktop.org/wiki/ (ICE/STUN/TURN)
* - \b OpenSSL: http://www.openssl.org/ (DTLS, at least v1.0.1e)
* - \b libsrtp: https://github.com/cisco/libsrtp (SRTP, at least v1.5 suggested)
* - \b usrsctp: http://code.google.com/p/sctp-refimpl/ (\c optional, Data Channels)
* - \b libmicrohttpd: http://www.gnu.org/software/libmicrohttpd/ (\c optional, Web server)
* - \b libwebsockets: https://libwebsockets.org/ (\c optional, WebSockets)
* - \b rabbitmq-c: https://github.com/alanxz/rabbitmq-c (\c optional, v1.0.4, RabbitMQ)
* - \b paho.mqtt.c: https://eclipse.org/paho/clients/c (\c optional, v1.1.0, MQTT)
* - \b Sofia-SIP: http://sofia-sip.sourceforge.net/ (\c optional, only needed for the SIP plugin)
* - \b libopus: http://opus-codec.org/ (\c optional, only needed for the bridge plugin)
* - \b libogg: http://xiph.org/ogg/ (\c optional, only needed for the voicemail plugin)
* - \b libcurl: https://curl.haxx.se/libcurl/ (\c optional, only needed for the TURN REST API,
* RTSP support in the Streaming plugin and the sample Event Handler plugin)
*
*/
/*! \page JS JavaScript API
* The gateway exposes, assuming the HTTP transport has been compiled, a
* pseudo-RESTful interface, and optionally also WebSocket/RabbitMQ/MQTT/UnixSockets
* interfaces as well, all of which based on JSON messages. These
* interfaces are described in more detail in the \ref plainhttp \ref WS
* \ref rabbit \ref mqtt and \ref unix documentation respectively, and all allow clients to
* take advantage of the features provided by Janus and the functionality
* made available by its plugins. Considering most clients will be web browsers,
* a common choice will be to rely on either the REST or the WebSockets
* interface for the purpose. To make things easier for web
* developers, a JavaScript library (\c janus.js) is available that can
* make use of both interfaces using exactly the same API. This library
* eases the task of creating sessions with the gateway, attaching WebRTC
* users to plugins, send and receive requests and events to the plugins
* themselves and so on. For real examples of how this library can be
* used, check the demos in the \b html folder of this package.
*
* \note The current \c janus.js library makes use of jQuery (http://jquery.com/)
* as a support. A version without that dependency is available as
* \c janus.nojquery.js in the same folder, so you can use that one instead
* if required by your web application: all the documentation related to
* \c janus.js applies to \c janus.nojquery.js as well.
*
* In general, when using the gateway features, you would normally do the following:
*
* -# include the Janus JavaScript library in your web page;
* -# initialize the Janus JavaScript library;
* -# connect to the gateway and create a session;
* -# create one or more handles to attach to a plugin (e.g., echo test and/or streaming);
* -# interact with the plugin (sending/receiving messages, negotiating a PeerConnection);
* -# eventually, close all the handles and shutdown the related PeerConnections;
* -# destroy the session.
*
* The above steps will be presented in order, describing how you can use
* the low level API to accomplish them. Consider that in the future we might
* provide higher level wrappers to this API to address specific needs, e.g.,
* a higher level API for each plugin: this would make it even easier to use
* the gateway features, as a high level API for the streaming plugin, for
* instance, may just ask you to provide the server address and the ID of
* the \c <video> element to display the stream in, and would take care of all the
* above mentioned steps on your behalf. Needless to say, you're very welcome
* to provide wrapper APIs yourself, if you feel a sudden urge to do so! :-)
*
* <hr>
*
* As a first step, you should include the \c janus.js library in your project:
*
\verbatim
<script type="text/javascript" src="janus.js" ></script>
\endverbatim
*
* The core of the JavaScript API is the \c Janus object. This object needs
* to be initialized the first time it is used in a page. This can be done
* using the static \c init method of the object, which accepts the
* following options:
*
* - \c debug: whether debug should be enabled on the JavaScript console, and what levels
* - \c true or \c "all": all debuggers enabled (Janus.trace, Janus.debug, Janus.log, Janus.warn, Janus.error)
* - array (e.g., <code>["trace", "warn"]</code>): only enable selected debuggers (allowed tokens: trace, debug, log, warn, error)
* - \c false: disable all debuggers
* - \c callback: a user provided function that is invoked when the initialization is complete.
*
* Here's an example:
*
*
\verbatim
Janus.init({
debug: true,
callback: function() {
// Done!
});
\endverbatim
*
* Once the library has been initialized, you can start creating sessions.
* Normally, each browser tab will need a single session with the gateway: in
* fact, each gateway session can contain several different plugin handles
* at the same time, meaning you can start several different WebRTC sessions
* with the same or different plugins for the same user using the same
* gateway session. That said, you're free to set up different gateway
* sessions in the same page, should you prefer so.
*
* Creating a session is quite easy. You just need to use the \c new constructor
* to create a new \c Janus object that will handle your interaction with the
* gateway. Considering the dynamic and asynchronous nature of Janus sessions
* (events may occur at any time), there are several properties and callbacks you
* can configure when creating a session:
*
* - \c server: the address of the gateway as a specific address (e.g.,
* http://yourserver:8088/janus to use the plain HTTP API or ws://yourserver:8188/
* for WebSockets) or as an array of addresses to try sequentially to allow
* automatic for fallback/failover during setup;
* - \c iceServers: a list of STUN/TURN servers to use (a default STUN server
* will be used if you skip this property);
* - \c ipv6: whether IPv6 candidates should ge gathered or not;
* - \c withCredentials: whether the \c withCredentials property of XHR requests
* should be enabled or not (false by default, and only valid when using HTTP
* as a transport, ignored for WebSockets);
* - \c max_poll_events: the number of events that should be returned when polling;
* the default is 1 (polling returns an object), passing a higher number will
* have the backend return an array of objects instead (again, only valid for
HTTP usage as this is strictly related to long polling, ignored for WebSockets);
* - \c destroyOnUnload: whether we should destroy automatically try and
* destroy this session via Janus API when \c onbeforeunload is called (true by default);
* - \c token , \c apisecret: optional parameters only needed in case you're \ref auth ;
* - a set of callbacks to be notified about events, namely:
* - \c success: the session was successfully created and is ready to be used;
* - \c error: the session was NOT successfully created;
* - \c destroyed: the session was destroyed and can't be used any more.
*
* These properties and callbacks are passed to the method as properties
* of a single parameter object: that is, the \c Janus constructor takes a
* single parameter, which although acts as a container for all the available
* options. The \c success callback is where you tipically start your application
* logic, e.g., attaching the peer to a plugin and start a media session.
*
* Here's an example:
*
\verbatim
var janus = new Janus(
{
server: 'http://yourserver:8088/janus',
success: function() {
// Done! attach to plugin XYZ
},
error: function(cause) {
// Error, can't go on...
},
destroyed: function() {
// I should get rid of this
}
});
\endverbatim
*
* As anticipated, the server may be a specific address, e.g.:
*
\verbatim
var janus = new Janus(
{
server: 'http://yourserver:8088/janus',
// or
server: 'ws://yourserver:8188/',
[..]
\endverbatim
*
* or an array of addresses. Such an array can be especially useful if
* you want the library to first check if the WebSockets server is
* reachable and, if not, fallback to plain HTTP, or just to provide
* a link multiple instances to try for failover. This is an example of
* how to pass a 'try websockets and fallback to HTTP' array:
*
\verbatim
var janus = new Janus(
{
server: ['ws://yourserver:8188/','http://yourserver:8088/janus'],
[..]
\endverbatim
*
* Once created, this object represents your session with the gateway.
* you can interact with a \c Janus object in several different ways.
* In particular, the following properties and methods are defined:
*
* - \c getServer(): returns the address of the gateway;
* - \c isConnected(): returns \c true if the Janus instance is connected
* to the gateway, \c false otherwise;
* - \c getSessionId(): returns the unique gateway session identifier;
* - \c attach(parameters): attaches the session to a plugin, creating an handle;
* more handles to the same or different plugins can be created at the same time;
* - \c destroy(parameters): destroys the session with the gateway, and closes
* all the handles (and related PeerConnections) the session may have with any plugin as well.
*
* The most important property is obviously the \c attach() method, as
* it's what will allow you to exploit the features of a plugin to manipulate
* the media sent and/or received by a PeerConnection in your web page.
* This method will create a plugin handle you can use for the purpose,
* for which you can configure properties and callbacks when calling the
* \c attach() method itself. As for the \c Janus constructor, the \c attach()
* method takes a single parameter that can contain any of the following
* properties and callbacks:
*
* - \c plugin: the unique package name of the plugin (e.g., \c janus.plugin.echotest );
* - \c opaqueId: an optional opaque string meaningful to your application (e.g., to map all the handles of the same user);
* - a set of callbacks to be notified about events, namely:
* - \c success: the handle was successfully created and is ready to be used;
* - \c error: the handle was NOT successfully created;
* - \c consentDialog: this callback is triggered just before \c getUserMedia is called
* (parameter=<b>true</b>) and after it is completed (parameter=<b>false</b>); this means it can
* be used to modify the UI accordingly, e.g., to prompt the user about the need to accept the device access consent requests;
* - \c webrtcState: this callback is triggered with a <b>true</b> value
* when the PeerConnection associated to a handle becomes active (so ICE, DTLS and
* everything else succeeded) from the Janus perspective, while <b>false</b> is
* triggered when the PeerConnection goes down instead; useful to figure out
* when WebRTC is actually up and running between you and Janus (e.g., to notify
* a user they're actually now active in a conference); notice that in case
* of <b>false</b> a reason string may be present as an optional parameter;
* - \c iceState: this callback is triggered when the ICE state for the
* PeerConnection associated to the handle changes: the argument of the callback
* is the new state as a string (e.g., "connected" or "failed");
* - \c mediaState: this callback is triggered when Janus starts or stops
* receiving your media: for instance, a \c mediaState with type=<b>audio</b> and
* on=<b>true</b> means Janus started receiving your audio stream (or started
* getting them again after a pause of more than a second); a \c mediaState with
* type=<b>video</b> and on=<b>false</b> means Janus hasn't received any video
* from you in the last second, after a start was detected before; useful to
* figure out when Janus actually started handling your media, or to detect
* problems on the media path (e.g., media never started, or stopped at some time);
* - \c slowLink: this callback is triggered when Janus reports trouble
* either sending or receiving media on the specified PeerConnection, typically
* as a consequence of too many NACKs received from/sent to the user in the
* last second: for instance, a \c slowLink with uplink=<b>true</b> means
* you notified several missing packets from Janus, while uplink=<b>false</b>
* means Janus is not receiving all your packets; useful to figure out when
* there are problems on the media path (e.g., excessive loss), in order to
* possibly react accordingly (e.g., decrease the bitrate if most of our
* packets are getting lost);
* - \c onmessage: a message/event has been received from the plugin;
* - \c onlocalstream: a local \c MediaStream is available and ready to be displayed;
* - \c onremotestream: a remote \c MediaStream is available and ready to be displayed;
* - \c ondataopen: a Data Channel is available and ready to be used;
* - \c ondata: data has been received through the Data Channel;
* - \c oncleanup: the WebRTC PeerConnection with the plugin was closed;
* - \c detached: the plugin handle has been detached by the plugin itself,
* and so should not be used anymore.
*
* Here's an example:
*
\verbatim
// Attach to echo test plugin, using the previously created janus instance
janus.attach(
{
plugin: "janus.plugin.echotest",
success: function(pluginHandle) {
// Plugin attached! 'pluginHandle' is our handle
},
error: function(cause) {
// Couldn't attach to the plugin
},
consentDialog: function(on) {
// e.g., Darken the screen if on=true (getUserMedia incoming), restore it otherwise
},
onmessage: function(msg, jsep) {
// We got a message/event (msg) from the plugin
// If jsep is not null, this involves a WebRTC negotiation
},
onlocalstream: function(stream) {
// We have a local stream (getUserMedia worked!) to display
},
onremotestream: function(stream) {
// We have a remote stream (working PeerConnection!) to display
},
oncleanup: function() {
// PeerConnection with the plugin closed, clean the UI
// The plugin handle is still valid so we can create a new one
},
detached: function() {
// Connection with the plugin closed, get rid of its features
// The plugin handle is not valid anymore
}
});
\endverbatim
*
* So the \c attach() method allows you to attach to a plugin, and specify
* the callbacks to invoke when anything relevant happens in this interaction.
* To actively interact with the plugin, you can use the \c Handle object
* that is returned by the \c success callback (pluginHandle in the example).
*
* This \c Handle object has several methods you can use to interact with
* the plugin or check the state of the session handle:
*
* - \c getId(): returns the unique handle identifier;
* - \c getPlugin(): returns the unique package name of the attached plugin;
* - \c send(parameters): sends a message (with or without a jsep to
* negotiate a PeerConnection) to the plugin;
* - \c createOffer(callbacks): asks the library to create a WebRTC compliant OFFER;
* - \c createAnswer(callbacks): asks the library to create a WebRTC compliant ANSWER;
* - \c handleRemoteJsep(callbacks): asks the library to handle an incoming WebRTC compliant session description;
* - \c dtmf(parameters): sends a DTMF tone on the PeerConnection;
* - \c data(parameters): sends data through the Data Channel, if available;
* - \c getBitrate(): gets a verbose description of the currently received stream bitrate;
* - \c hangup(sendRequest): tells the library to close the PeerConnection; if the optional \c sendRequest argument is
* set to \c true, then a \c hangup Janus API request is sent to Janus as well (disabled by default, Janus can usually
* figure this out via DTLS alerts and the like but it may be useful to enable it sometimes);
* - \c detach(parameters): detaches from the plugin and destroys the handle, tearing
* down the related PeerConnection if it exists.
*
* While the \c Handle API may look complex, it's actually quite straightforward
* once you get the concept. The only step that may require a little more
* effort to understand is the PeerConnection negotiation, but again, if
* you're familiar with the WebRTC API, the \c Handle actually makes it
* a lot easier.
*
* The idea behind it's usage is the following:
*
* -# you use \c attach() to create a \c Handle object;
* -# in the \c success callback, your application logic can kick in: you may
* want to send a message to the plugin (<code>send({msg})</code>), negotiate
* a PeerConnection with the plugin right away ( \c createOffer followed
* by a <code>send({msg, jsep})</code>) or wait for something to happen to do anything;
* -# the \c onmessage callback tells you when you've got messages from the plugin;
* if the \c jsep parameter is not null, just pass it to the library, which will take
* care of it for you; if it's an \b OFFER use \c createAnswer (followed by a
* <code>send({msg, jsep})</code> to close the loop with the plugin), otherwise use
* \c handleRemoteJsep ;
* -# whether you took the initiative to set up a PeerConnection or the plugin did,
* the \c onlocalstream and/or the \c onremotestream callbacks will provide
* you with a stream you can display in your page;
* -# each plugin may allow you to manipulate what should flow through the
* PeerConnection channel: the \c send method and \c onmessage callback
* will allow you to handle this interaction (e.g., to tell the plugin
* to mute your stream, or to be notified about someone joining a virtual room),
* while the \c ondata callback is triggered whenever data is received
* on the Data Channel, if available (and the \c ondataopen callback
* will tell you when a Data Channel is actually available).
*
* The following paragraphs will delve a bit deeper in the negotiation
* mechanism provided by the \c Handle API, in particular describing
* the properties and callbacks that may be involved. To follow the approach
* outlined by the W3C WebRTC API, this negotiation mechanism is heavily
* based on asynchronous methods as well.
*
* - \c createOffer takes a single parameter, that can contain any of the
* following properties and callbacks:
* - \c media: you can use this property to tell the library which media (audio/video/data)
* you're interested in, and whether you're going to send and/or receive any of them; by default
* audio and video are enabled in both directions, while the Data Channels are disabled;
* this option is an object that can take any of the following properties:
* - \c audioSend: \c true/false (do or do not send audio);
* - \c audioRecv: \c true/false (do or do not receive audio);
* - \c audio: \c true/false (do or do not send \b and receive audio, takes precedence on the above);
* - \c audio: object with \c deviceId property (specify ID of audio device to capture, takes precedence on the above;
* devices list can be accessed with \c Janus.listDevices(callback) );
* - \c videoSend: \c true/false (do or do not send video);
* - \c videoRecv: \c true/false (do or do not receive video);
* - \c video: \c true/false (do or do not send \b and receive video, takes precedence on the above);
* - \c video: \c "lowres"/"lowres-16:9"/"stdres"/"stdres-16:9"/"hires"/"hires-16:9"
* (send a 320x240/320x180/640x480/640x360/1280x720 video, takes precedence on the above; default is \c "stdres" )
* this property will affect the resulting getUserMedia that the library will issue; please
* notice that Firefox doesn't support the \c "16:9" variants, which will fallback
* to the ones; besides, \c "hires" and \c "hires-16:9" are currently synonymous, as
* there's no 4:3 high resolution constraint as of now;
* - \c video: \c "screen" (use screensharing for video, disables audio, takes precedence on both audio and video);
* - \c video: object with \c deviceId , \c width and/or \c height properties (specify ID of video device to capture
* and optionally resolution to use, takes precedence on the above; devices list can be accessed with \c Janus.listDevices(callback) );
* - \c data: \c true/false (do or do not use Data Channels, default is false)
* - \c failIfNoAudio: \c true/false (whether a getUserMedia should fail if audio send is asked, but no audio device is available, default is false)
* - \c failIfNoVideo: \c true/false (whether a getUserMedia should fail if video send is asked, but no video device is available, default is false)
* - \c screenshareFrameRate: in case you're sharing a screen/application, allows you to specify the framerate (default=3);
* - \c trickle: \c true/false, to tell the library whether you want
* Trickle ICE to be used (true, the default) or not (false);
* - \c stream: optional, only to be passed in case you obtained a MediaStream object yourself with a \c getUserMedia
* request, and that you want the library to use instead of having it get one by itself (makes
* the \c media property useless, as it won't be read for accessing any device);
* - a set of callbacks to be notified about the result, namely:
* - \c success: the session description was created (attached as a parameter) and is ready to be sent to the plugin;
* - \c error: the session description was NOT successfully created;
* - \c createAnswer takes the same options as createOffer, but requires
* an additional one as part of the single parameter argument:
* - \c jsep: the session description sent by the plugin (e.g., as received
* in an \c onmessage callback) as its OFFER.
*
* Whether you use \c createOffer or \c createAnswer depending on the scenario,
* you should end up with a valid \c jsep object returned in the \c success
* callback. You can attach this \c jsep object to a message in a \c send request
* to pass it to the plugin, and have the gateway negotiate a PeerConnection
* with your application.
*
* Here's an example of how to use \c createOffer, taken from the Echo Test demo page:
*
\verbatim
// Attach to echo test plugin
janus.attach(
{
plugin: "janus.plugin.echotest",
success: function(pluginHandle) {
// Negotiate WebRTC
echotest = pluginHandle;
var body = { "audio": true, "video": true };
echotest.send({"message": body});
echotest.createOffer(
{
// No media property provided: by default,
// it's sendrecv for audio and video
success: function(jsep) {
// Got our SDP! Send our OFFER to the plugin
echotest.send({"message": body, "jsep": jsep});
},
error: function(error) {
// An error occurred...
}
});
},
[..]
onmessage: function(msg, jsep) {
// Handle msg, if needed, and check jsep
if(jsep !== undefined && jsep !== null) {
// We have the ANSWER from the plugin
echotest.handleRemoteJsep({jsep: jsep});
}
},
[..]
onlocalstream: function(stream) {
// Invoked after createOffer
// This is our video
},
onremotestream: function(stream) {
// Invoked after handleRemoteJsep has got us a PeerConnection
// This is the remote video
},
[..]
\endverbatim
*
* This, instead, is an example of how to use \c createAnswer, taken from the Streaming demo page:
*
\verbatim
// Attach to echo test plugin
janus.attach(
{
plugin: "janus.plugin.streaming",
success: function(pluginHandle) {
// Handle created
streaming = pluginHandle;
[..]
},
[..]
onmessage: function(msg, jsep) {
// Handle msg, if needed, and check jsep
if(jsep !== undefined && jsep !== null) {
// We have an OFFER from the plugin
streaming.createAnswer(
{
// We attach the remote OFFER
jsep: jsep,
// We want recvonly audio/video
media: { audioSend: false, videoSend: false },
success: function(ourjsep) {
// Got our SDP! Send our ANSWER to the plugin
var body = { "request": "start" };
streaming.send({"message": body, "jsep": ourjsep});
},
error: function(error) {
// An error occurred...
}
});
}
},
[..]
onlocalstream: function(stream) {
// This will NOT be invoked, we chose recvonly
},
onremotestream: function(stream) {
// Invoked after send has got us a PeerConnection
// This is the remote video
},
[..]
\endverbatim
*
* Of course, these are just a couple of examples where the scenarios
* assumed that one plugin would only receive (Echo Test) or generate
* (Streaming) offers. A more complex example (e.g., a Video Call plugin)
* would involve both, allowing you to either send offers to a plugin,
* or receive some from them. Handling this is just a matter of checking
* the \c type of the \c jsep object and reacting accordingly.
*
* <hr>
*
* This is it! For more information about the API, have a look at the
* demo pages that are available in the \b html folder in this package.
*
*/
/*! \page rest RESTful, WebSockets, RabbitMQ, MQTT and UnixSockets API
*
* Since version \c 0.0.6, there are three different ways to interact with a
* Janus instance: a \ref plainhttp (the default), a \ref WS, a \ref rabbit, \ref mqtt
* and a \ref unix (both optional, need an external library to be available). All of
* the interfaces use the same messages (in terms of requests, responses
* and notifications), so almost all the concepts described in the
* \ref plainhttp section apply to the WebSocket/RabbitMQ/MQTT/UnixSockets interfaces as well.
* Besides, since version \c 0.1.0 the transport mechanism for the Janus API
* has been made modular, which means other protocols for transporting
* Janus API messages might become available in the future: considering the
* Janus protocol is supposed to be mostly agnostic to the protocol it is
* transported on, the concepts explained in the following sections should
* apply to those as well.
*
* As it will be explained later in the \ref WS, \ref rabbit and \ref unix sections
* below, the only differences come when addressing specific sessions/handles
* and in part in how you handle notifications using something different than
* the REST interface: in fact, since with WebSockets, RabbitMQ, MQTT and UnixSockets
* (and, as anticipated, with other protocols that may be added in the future too)
* there's no REST-based path involved, you'll need a couple of additional
* identifiers to bridge the gap.
* Some details are also provided in case you're interested in \ref auth.
*
* \section plainhttp Plain HTTP REST Interface
* As anticipated in the \ref JS documentation, the gateway deploys a
* RESTful interface that clients can exploit. The \c janus.js library
* makes use of it in a transparent way, but if you're interested in
* more details about it (e.g., because you want to talk to the gateway
* your own way), this page described the interface and the protocol
* the API exposes and uses.
*
* There are basically three types/levels of endpoints you can meet:
*
* -# \ref root (\c /janus by default, but configurable), which
* you only \b POST to in order to create a gateway session;
* -# \ref sessions (e.g., \c /janus/12345678, using the
* identifier retrieved with a previous create), which you either send
* a \b GET to (long poll for events and messages from plugins) or a \b POST
* (to create plugin handles or manipulate the session);
* -# \ref handles (e.g., \c /janus/12345678/98765432, appending
* the handle identifier to the session one) which you only send \b POST
* messages to (messages/negotiations for a plugin, handle manipulation),
* as all events related to this handle would be received in the session
* endpoint \b GET (the \c janus.js library would redirect the incoming
* messages to the right handle internally).
*
* Messages and requests you can send to and receive from any of the
* above mentioned endpoints are described in the following chapters.
* In general, all messages share at least two fields:
*
* - \c janus: the request/event (e.g., "create", "attach", "message", etc.);
* - \c transaction: a random string that the client can use to match incoming
* messages from the gateway (since, as explained in the \ref plugins
* documentation, all messages are asynchronous).
*
* Different messages will of course add different information to this
* base syntax. Error message, instead, usually have these fields:
*
* - \c janus: this would be "error";
* - \c transaction: this would be the transaction identifier of the request
* that failed;
* - \c error: a JSON object containing two fields:
* - \c code: a numeric error code, as defined in apierror.h;
* - \c reason: a verbose string describing the cause of the failure.
*
* An example of an error is presented here:
*
\verbatim
{
"janus" : "error",
"transaction" : "a1b2c3d4"
"error" : {
"code" : 458
"reason" : "Could not find session 12345678"
}
}
\endverbatim
*
*
* \section info Getting info about the Janus instance
* The API exposes an \c info endpoint you can query to get information
* about the Janus instance you're talking to. Specifically, it returns
* information about the version of the Janus server, whether some of the
* optional features (e.g., Data Channels or IPv6) are supported or not,
* and which transports and plugins are available.
*
* To get this information, just send an HTTP \b GET message to the \c info
* endpoint (e.g., http://yourserver:8088/janus/info), which will return
* something like this:
*
\verbatim
{
"janus": "server_info",
"transaction": "i1bzIL341Kl2",
"name": "Janus WebRTC Gateway",
"version": 10,
"version_string": "0.1.0",
"author": "Meetecho s.r.l.",
"data_channels": "true", // Data channels are supported
"ipv6": "false", // IPv6 is not configured
"ice-tcp": "false", // ICE-TCP support is disabled
"transports": {
"janus.transport.http": {
"name": "JANUS REST (HTTP/HTTPS) transport plugin",
"author": "Meetecho s.r.l.",
"description": "This transport plugin adds REST (HTTP/HTTPS) support to the Janus API via libmicrohttpd.",
"version_string": "0.0.1",
"version": 1
},
[..] // Other transport plugins
},
"plugins": {
"janus.plugin.sip": { // The SIP plugin is available
"version_string": "0.0.2",
"description": "This is a simple SIP plugin for Janus, allowing WebRTC peers to register at a SIP server and call SIP user agents through the gateway.",
"author": "Meetecho s.r.l.",
"name": "JANUS SIP plugin",
"version": 2
},
"janus.plugin.videoroom": { // The Video MCU plugin is available
"version_string": "0.0.3",
"description": "This is a plugin implementing a videoconferencing MCU for Janus, something like Licode.",
"author": "Meetecho s.r.l.",
"name": "JANUS VideoRoom plugin",
"version": 3
},
[..] // Other plugins
}
\endverbatim
*
* You can use this information to selectively enable or disable features
* in your application according to what's available in the Janus instance
* you're trying to contact.
*
*
* \section root The gateway root
* The gateway root is \c /janus by default but, as anticipated, it is
* configurable, either via command line or in the \c janus.cfg configuration.
*
* You can only contact the gateway root when you want to create a new
* session with the gateway. To do so, you need to \b POST the a \c janus "create"
* JSON message to the gateway:
*
\verbatim
{
"janus" : "create",
"transaction" : "<random alphanumeric string>"
}
\endverbatim
*
* If the request is successful, you'll receive the unique session identifier
* in a response formatted like this:
*
\verbatim
{
"janus" : "success",
"transaction" : "<same as the request>",
"data" : {
"id" : <unique integer session ID>
}
}
\endverbatim
*
* In case of an error, you'll receive an error message as the one introduced
* before. This request, if issued with a POST to the gateway root, can only
* fail if you miss any of the required fields in the request.
*
*
* \section sessions The session endpoint
* Once you've created a session, a new endpoint you can use is created
* in the gateway. Specifically, the new endpoint is constructed by
* concatenating the gateway root and the session identifier you've been
* returned (\c e.g., \c /janus/12345678).
*
* This endpoint can be used in two different ways:
*
* -# using a parameter-less \b GET request to the endpoint, you'll
* issue a long-poll request to be notified about events and incoming
* messages from this session;
* -# using a \b POST request to send JSON messages, you'll interact
* with the session itself.
*
* <hr>
*
* \par Long-poll requests
* The long-poll will only trigger events related to messages you're
* being sent from plugins, and as such will be clearer to understand
* once you read the \ref handles section. That said, the events are formatted
* this way:
*
* - \c janus: this would be "event";
* - \c sender: this would be the unique numeric plugin handle identifier;
* - \c transaction: this is optional: it is either related to a request
* you sent to a plugin before, or it may be missing in case this is an
* event the plugin sent on its own account;
* - \c plugindata: a JSON object containing the info coming from the plugin itself:
* - \c plugin: the plugin's unique package name (e.g., \c janus.plugin.echotest);
* - \c data: an opaque JSON object that is plugin specific.
* - \c jsep: an optional JSON object containing the JSEP SDP (offer or
* answer) the plugin may send to negotiate a WebRTC PeerConnection with
* the client (check the \ref handles section for more details).
*
* An example of such an event (in this case, sent by the janus_echotest.c
* plugin in response to a request) is presented here:
*
\verbatim
{
"janus" : "event",
"sender" : 1815153248,
"transaction" : "sBJNyUhH6Vc6",
"plugindata" : {
"plugin": "janus.plugin.echotest",
"data" : {
"echotest" : "event",
"result" : "ok"
}
},
}
\endverbatim
*
* The long-poll request has a 30 seconds timeout. If it has no event to
* report, a simple \em keep-alive message will be triggered:
*
\verbatim
{
"janus" : "keepalive",
}
\endverbatim
*
* As with all long-poll based approaches, it's up to your application
* to send a new polling request as soon as an event or a keep-alive
* has been received.
*
* Notice that, by default, the long poll returns a single event: that is,
* as soon as a message becomes available in the session queue, that event
* is returned and the long poll closes. If you want to receive more events
* within the context of the same long poll, you can pass the \c maxev
* query string parameter to the GET, e.g.:
*
\verbatim
GET http://host:port/janus/<sessionid>?maxev=5
\endverbatim
*
\verbatim
[
{
// Event #1
"janus" : "event",
[..]
},
{
// Event #2
"janus" : "event",
[..]
},
[..]
]
\endverbatim
*
* This request will instruct the gateway to return at maximum 5 events
* within the context of the same long poll, formatted as a JSON array
* of events. Please beware that this does \b NOT mean that you'll
* always get 5 events this way: it only means that, if a message becomes
* available in the queue and more events are present as well, Janus will
* return more than one without needing you to send multiple long polls
* immediately thereafter to get them. For this reason, don't be surprised
* if even with a \c maxev parameter set, you'll still get a single
* event being notified as the sole object in the returned array.
*
* <hr>
*
* \par Interacting with the session
* To interact with the session, e.g., to create a new handle to attach
* to a plugin or destroy the current session, you need to send a \b POST
* JSON message to the session endpoint.
*
* To attach to a plugin in order to exploit its features, you need to
* \b POST a \c janus "attach" JSON message to the gateway; you'll need
* of course to provide information on the plugin you want to attach to,
* which can be done using the \c plugin field:
*
\verbatim
{
"janus" : "attach",
"plugin" : "<the plugin's unique package name>",
"transaction" : "<random string>"
}
\endverbatim
*
* Notice that you can also provide an optional \c opaque_id string
* identifier (for more details on why this might be useful, read more
* <a href="https://github.com/meetecho/janus-gateway/pull/748">here</a>).
* If the request is successful, you'll receive the unique plugin handle
* identifier in a response formatted the same way as the session create
* one, that is like this:
*
\verbatim
{
"janus" : "success",
"transaction" : "<same as the request>",
"data" : {
"id" : <unique integer plugin handle ID>
}
}
\endverbatim
*
* In case of an error, you'll receive an error message as the one introduced
* before. This request, if issued with a POST to a valid session endpoint, can only
* fail if you miss any of the required fields in the request or if the
* plugin you requested is not available in the gateway.
*
* To destroy the current session, instead, just send a "destroy" \c janus
* request:
*
\verbatim
{
"janus" : "destroy",
"transaction" : "<random string>"
}
\endverbatim
*
* This will also destroy the endpoint created for this session.
* If your session is currently managing one or more plugin handles,
* make sure you destroy them first (as explained in the next section).
* The gateway tries to do this automatically when receiving a session
* destroy request, but a cleaner approach on the client side would help
* nonetheless avoid potential issues.
*
* \section handles The plugin handle endpoint
* Once you've created a plugin handle, a new endpoint you can use is created
* in the gateway. Specifically, the new endpoint is constructed by
* concatenating the gateway root, the session identifier and the new
* plugin handle identifier you've been returned (\c e.g.,
* \c /janus/12345678/98765432).
*
* You can use this plugin handle for everything that is related to the
* communication with a plugin, that is, send the plugin a message,
* negotiate a WebRTC connection to attach to the plugin, and so on.
*
* To send a plugin a message/request, you need to \b POST the handle
* endpoint a \c janus "message" JSON payload. The \c body field will
* have to contain a plugin-specific JSON payload. In case the message
* also needs to convey WebRTC-related negotiation information, a \c jsep
* field containing the JSON-ified version of the JSEP object can be
* attached as well.
*
* \note If you attach a \c jsep object, whether it's an offer or an answer,
* you're stating your will to negotiate a PeerConnection. This means that
* an empty or invalid \c jsep object will trigger a validation and will
* cause the whole request to fail, so make sure you exclude the field
* completely from your request if all you're interested into is sending
* a message to a plugin.
*
* Here's an example of a message you may send the janus_echotest.c plugin
* to mute your audio:
*
\verbatim
{
"janus" : "message",
"transaction" : "sBJNyUhH6Vc6",
"body" : {
"audio" : false
}
}
\endverbatim
*
* The same message containing negotiation information as well, instead,
* (an OFFER, in this example), is presented here:
*
\verbatim
{
"janus" : "message",
"transaction" : "sBJNyUhH6Vc6",
"body" : {
"audio" : false
},
"jsep" : {
"type" : "offer",
"sdp" : "v=0\r\no=[..more sdp stuff..]"
}
}
\endverbatim
*
* Please notice that, if for any reason you don't want to use the
* trickling of ICE candidates from your application (which means you'll
* include them all in the SDP OFFER or ANSWER, which is usually not
* recommended), you'll have to add an additional <code>"trickle" : false</code>
* attribute to the "jsep" object, to explicitly tell Janus you won't
* send any \c trickle candidate (by default Janus will always assume
* support for trickle).
*
* If you're going to \c trickle candidates, instead, there is an ad-hoc
* message you can use to do so which is called, unsurprisingly, \c trickle
* and which you can use to send one or more trickle candidates to Janus.
* Since such a message is related to a specific PeerConnection, it will
* need to be addressed to the right Handle just as the \c message introduced
* previously. A \c trickle message can contain three different kind of
* information:
*
* - a single trickle candidate;
* - an array of trickle candidates;
* - a null candidate or a \c completed JSON object to notify the end of the
* candidates.
*
* This is an example of a single candidate being trickled:
*
\verbatim
{
"janus" : "trickle",
"transaction" : "hehe83hd8dw12e",
"candidate" : {
"sdpMid" : "video",
"sdpMLineIndex" : 1,
"candidate" : "..."
}
}
\endverbatim
*
* This, instead, is an example of how to group more trickle candidates
* in a single request (particularly useful if you're wrapping Janus in
* your server and want to reduce the number of transactions):
*
\verbatim
{
"janus" : "trickle",
"transaction" : "hehe83hd8dw12e",
"candidates" : [
{
"sdpMid" : "video",