This chapter describes how to develop Session Initiation Protocol (SIP) Servlets that work with indirect content specified in the SIP message body, and how to use the Oracle Communications Converged Application Server content indirection API.
Data provided by the body of a SIP message can be included either directly in the SIP message body, or indirectly by specifying an HTTP URL and metadata that describes the URL content. Indirectly specifying the content of the message body is used primarily in the following scenarios:
When the message bodies include large volumes of data. In this case, content indirection can be used to transfer the data outside of the SIP network (using a separate connection or protocol).
For bandwidth-limited applications. In this case, content indirection provides enough metadata for the application to determine whether or not it must retrieve the message body (potentially degrading performance or response time).
Converged Application Server provides a simple application program interface (API) that you can use to work with indirect content specified in SIP messages.
The content indirection API provided by Converged Application Server helps you quickly determine if a SIP message uses content indirection, and to easily retrieve all metadata associated with the indirect content. The basic API consists of a utility class, com.bea.wcp.sip.util.ContentIndirectionUtil, and an interface for accessing content metadata, com.bea.wcp.sip.util.ICParsedData.
SIP Servlets can use the utility class to identify SIP messages having indirect content, and to retrieve an ICParsedData object representing the content metadata. The ICParsedData object has simple ”getter” methods that return metadata attributes.
Complete details about content indirection are available in RFC 4483:
http://www.ietf.org/rfc/rfc4483.txt
See also the Converged Application Server Java API Reference for additional documentation about the content indirection API.