JAIN SLEE 1.0 (JSLEE, JSR22 is an application server designed specifically for asynchronous event processing networks, by telecommunications vendors and carriers. It integrates a well defined event model with a generic component model. JSLEE is gaining traction worldwide with a variety of applications - IN replacement, Calling Card applications, Presence and Location, VoIP, VPN, etc. However, specific to SIP, JSLEE deployments in Europe for building out IMS networks. By plugging in a SIP resource such as JAIN SIP JSIP, JSR32 into JSLEE, a SIP application server is created to handle any number of SIP appllications. Yet JSLEE is network agnostic allowing operators to plug in other protocols to the application sever such as H.323 and Megaco. Network functions such as call control server, presence servers, registrar servers and location servers can all be built using the JSLEE platform.
So why is JSLEE ideal as a SIP server?
The JSLEE application container offers a unified and efficient way to build and manage components for highly available and accountable services. While this is important for any application server, the strength of JSLEE for SIP networks is event processing. All SIP messages are converted into JSLEE events and routed to the Services within the framework. The JSLEE container framework understands the relationship between the event producer and event consumer enabling the container to implement the event routing logic, automatically instantiate objects based on event type and automatically garbage collect objects based on activity status. This is ideal for SIP processing since IP Network Elements are required to handle a variety of media and communications asynchronously.
JSLEE is component based were services are built from Service Building Block(SBB). SBBs are designed for application re-use and packaging across many services and based on availability, across multiple JSLEEs. The component model is developer friendly and ideal for building event orientated communications applications. It includes delegation of event processing to components and object priority for receiving events. JSLEE defines a feature interaction model based on an activity, which is a related stream of events. This permits a JSLEE SIP application server to incorporate feature rich services that allow a standard programming model for presidence and order of between services. There is no other standard in the industry for SIP to handle feature interaction.
JSLEE also integrates a transaction model for concurrency control explicitly defining transaction boundaries to the application components. This way a SIP developer or administrator has the tools to manage transactions suchs as an INVITE thread, Presence subscription, or Instant Messaging. Also JSLEE specifies a generic provisioned data schema that is easy to use to define, manage, and access profiles. SIP services may access a variety of data through this definition, such as user profiling, presence data, or ENUM translation.
Additionally JSLEE defines a standard set of interfaces for:
- Managing the application server
- Managing the Services and SBBs
- Facility services that monitor and measure:
- Performance,
- Utilization and availability of application usage, services, event flow and resources.
The JSLEE 1.1 expert group (JSR240) is currently defining the Resource Adapter (RA) architecture, which will specify the system contract for resource portability across different JSLEE's. This coupled with a standard application contract such as JSIP and a JSLEE standard execution environment ensures complete application portability and vendor neutrality across different application servers.
Several Network Operators and Network Equipment Providers have turned their attention to JSLEE and JSIP. Much work is being carried out in the industry to build out JSIP to support the necessities of the IMS network, by filling these and other gaps JSLEE is positioned well as the platform of choice for standardized SIP and IMS network development in Java.
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