One of the interfaces available in our PowerMedia Extended Media Server (XMS) is the ability to use RESTFul web services to control the media server. RESTFul web services provides an easy paradigm to get access to call control and media resources via web services provided by XMS. A developer can use any programming or scripting languages they are familiar with to accomplish this, as long as it supports functions for dealing with http services. Development environments could include Java, C#, PERL, PHP, ... etc.. This post is to give a brief overview of the XMS RESTful interface.

 You are probably already familiar with the idea of http serving up, for example, web pages as shown below:

 

 

PowerMedia XMS provides a similar interface for communication media platforms:

 

 

 

The above shows a simple request to create a call. You’ll notice an application ID (appid) which allows you to define discrete appids so that multiple applications may be simultaneously run on a single XMS server. The payload that would go along with the request looks like this:

 <web_service version="1.0">

        <call destination_uri="SIP:user@192.168.0.5"

                 cpa="yes"      

          </call>

</web_service> 

 

The payload is straightforward in that it specifies the destination and whether you wish to have call progress analysis enabled, i.e. cpa=”yes”. Once sent to the XMS, a response comes back as 201 to let you know that the process of creating a call has been started. The 201 will also have a payload that will give a little more information on the call that has been initiated; most import is the call identifier which is a unique reference # for the call.

This is pretty much it to create call, i.e. (1) specify http command and (2) associated payload.

To be upfront, there is a little more work needed to make a full robust application. With communication applications there are unsolicited events such as call status information, play completion events, etc. that you would need to look out for. This can be done with http event streaming. With a typical http request, a connection is made between the client and the server and is closed out when the request is done. With http event streaming, the connection remains open which allows the web service to continue to send raw data across. You would want to open another thread or process that is monitoring for events.   For a call you would get back an event message with the call identifier that would let you know the state of the call.

For more information on PowerMedia XMS, please visit: http://www.dialogic.com/en/products/media-server-software/xms.aspx