JSLEE

What is JSLEE ? is an event oriented application middleware. Its main job is to receive events from external resources and deliver these events to application installed fragments of code. is multi-protocol. Each protocol stack is a Resource with a corresponding Resource Adaptor. has the flavor of EJB but is oriented towards asynchronous low latency event oriented apps. manages application objects, lifecycle, isolation, deployment, management, concurrency, persistence and failover needs. provides the necessary facilities commonly needed by such applications (i.e. timers, management via JMX, profile, trace).

Simplified JAIN-SLEE Architecture

Parlay defines an architecture and set of abstracted interfaces No application server defined JSLEE is a standard event driven application server Parlay App servers are typically built on proprietary SLEE’s instead of J2EE in order to achieve performance Vendors should build Parlay application servers on a standard JSLEE, enabling portability of services JSLEE and Parlay

JSLEE and SIP Servlet SIP Servlet satisfies the ‘big bang’ approach to Voip All application development in SIP JSLEE satisfies the ‘migration’ approach to Voip Leverage existing IN investment Single environment for IN evolution Enables multiple protocol development Both servers will co-exist each finding certain application niches Each will make the other successful Same goal – replace proprietary systems with standard application infrastructure

JSLEE & J2EE JSLEE is a component model like EJB, Servlet or JSP and is most similar to EJB JSLEE builds upon concepts shared with J2EE and other component technologies but is specialized for event driven applications JSLEE can be implemented independent of J2EE and used stand-alone. It doesn’t depend on J2EE for critical functions ( e.g. concurrency control or failure resilience) JSLEE is not a J2EE component nor equivalent to J2EE JSLEE and J2EE are complementary technologies

JSLEE, EJB & JMS JSLEE has a built-in event model that is part of the component model while JMS is external to the EJB component model it’s more like a service JSLEE allows dynamic creation of activities like topics and queues and it allows dynamic association of event sources and event sinks to these activities. On the contarry binding between JMS topics and queues into the EJB runtime is static JSLEE event model facilitates component garbage collection JSLEE can be integrated with JMS through a Resource Adaptor just as with EJB via a Connector

Some Details The JSLEE abstracts the notion of an event bus and event triggered pieces of code called Service Building Blocks (SBBs) The event bus is called an Activity Context (AC). An Activity is a stream of related events. One-to-one mapping between Activities (Resource Adaptor domain) and Activity Contexts (SLEE domain). Activity Context is an event channel. Sbb Ent AC Activity R.A. (SIP Stack) SLEE

Benefits Traditional of-the-shelf software Leverage IDE’s for Service creation Co-location of services Reduce latency and resource consumption Open programming environment Tools can be leveraged by developers Leverage the best of the enterprise patterns Event driven design base Profile interface to subscriber/service data

JSLEE characterization Component Model and Description. Service Composition. Exposure methods.

Component Model JSLEE defines different kind of components: Services Service Building Blocks Events Resource Adaptors Profile Specification JSLEE defines how to deploy components and a management interface to manage installed component. Service Activation Service Versioning Component Usage, Alarm, Trace JSLEE defines how to compose components in order to create applications inside the container.

Service Composition A Service component inside JSLEE is composed by one SBB called Root SBB. A Root SBB can have child SBB Component. A JSLEE application logic is composed by SBB Components. The Service descriptor does not specify the composition of the SBBs. The Root SBB descriptor specify the child SBBs used by the Service The Root SBB has the burden to orchestrate the work of its child SBB components.

JSLEE Service Composition Pros: The execution environment is lightweight and does not define mechanisms to orchestrate all the components inside the service. This flexibility allows good flexibility in the development of JSLEE applications. Cons: Programming skills required to reuse and compose component

Exposure JSLEE interface with external entities can be done by means of: Resource Adaptor Deploy e Management J2EE Connector: Fire & Forget Request/ Response Session (Request/Response) JSLEE does not define any exposure method. Access to the platform can take place only by means of events or through the deploy interface

Mobicents Open JSLEE Project Mobicents is an open source project (LGPL License) The project is hosted on Provides an open source implementation of a JSLEE container Mobicents is compliant with JSR-24 – JSLEE 1.0 Active Community with several subproject: Parlay RA Eclipse plug-in for JSLEE services Examples Implemented as a Service inside the JBoss microkernel Can be integrated with several J2EE environment (BEA, Jonas, etc.)