The more protocols you know, the more of the IMS you are. Right, the IMS is not only about SIP, Diameter or RTP. There are many various protocols involved. This time we’ll take a look at self-provisioning and configuration of services via http, more specifically XML Configuration Access Protocol (XCAP). We have seen it already in the posts about Ut Interface and Aggregation Gateway.
XCAP protocol is a kind of RESTful protocol. If you know a bit about the RESTfull approach, then you should easily become familiar with XCAP.
However the XCAP was created separately and has its own specifics. It was designed as a dedicated protocol for telecommunication environment as a set of conventions for mapping XML documents and document components into HTTP URIs, along with operations allowing to read/write/modify/delete these documents. That means it is not a general purpose XML search protocol. Still the XCAP is meant to support the configuration needs for a multiple applications such as supplementary services, capabilities, resource lists, presence rules and others.
Let’s take as an example the management of VoLTE supplementary services. XCAP allows an user to retrieve the information about the provisioned services and manage the content.
As we want to limit the amount of the exchanged data, XCAP allows to define the scope of the document we are working with. The scope can be the whole document, or an xml element or even only an attribute.