WAS v8.5 > WebSphere applications > SIP applications

SIP in WAS

WebSphere Application Server delivers rich SIP functionality throughout its infrastructure.

SIP has grown considerably since it first became an IETF standard in 1999. SIP was originally intended purely for video and audio but has now grown to become the control protocol for many interactive services, particularly in the peer-to-peer realm. SIP, and the standards surrounding SIP, provide the mechanisms to look up, negotiate, and manage connections to peers on any network over any other protocol.

WAS v8.5 includes support for SIP Servlet Specification 1.1, also referred to as Java Specification Request (JSR) 289. The SIP Servlet Specification provides the Java API standards for Session Initiation Protocol (SIP). JSR 289 is an update to the existing SIP Servlet specification that addresses new requirements determined by industry users. WAS v8.5 continues to support the SIP Servlet 1.0 specification.

WAS also provides tooling for the development environment and high performing Edge Components to handle distributed application environments.

In the application server, the web container and SIP container are converged and are able to share session management, security and other attributes. In this model, an application that includes SIP servlets, HTTP servlets, and portlets can seamlessly interact, regardless of the protocol.

It's important to note the SIP function in the proxy server is stateless. The SIP RFC defines two types of proxy servers, one stateful and one stateless. Normally, a SIP proxy is a stateful instance and stateless proxies are specified as such. A stateful proxy participates in the call flows and is implemented using SIP servlets.

The stateless SIP proxy functionality in the proxy server allows the proxy to handle the workload, routing, and session affinity needs of the SIP container with less complexity. Being stateless, the proxy server can be fronted by a simple IP sprayer. If a proxy server fails, the affinity is to the container and not to the proxy itself so there is one less potential failure along the message flow.

SIP Infrastructure

The SIP infrastructure is a multi-tiered architecture made up of SIP containers, SIP proxies and an IP sprayer. The SIP container is a general purpose SIP application server. The SIP infrastructure consists of:

  • SIP container – web container extension that implements JSR 289.
  • SIP proxy – Stateless edge device that handles I/O concentration, load balancing, and other functions, in a similar manner to the reverse HTTP proxy. This is not the same as the SIP proxy defined by RFC 3261.

SIP is a key element for many new applications, especially when converged with HTTP, including:

  • Click-To-Call
  • Voice over IP
  • Third Party Call Control and Call Monitoring
  • Presence and Instance Messaging


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