While the JAIN APIs still play only a minor role on Sun's Java Web site, the JAIN initiative is getting stronger. The JAIN technologies (Java APIs for Integrated Networks) have the potential to radically change the existing service architecture for communications service providers.
Following the link "Other Java Technologies/JAIN APIs" from Sun's Java Web site, you'll probably find your way to a completely unknown world: Java technologies for telecommunication products and services. This article introduces you to the basics of JAIN and then explores JAIN/SLEE in greater detail. By the way, SLEE means Service Logic Execution environment and is abbreviated to JAIN/SLEE or JSLEE.
Motivation
The service architectures of many telecommunications service providers have become a lot more complex over the past few years. This is because many providers merged, or new technologies like GPRS or W-CDMA were or will be introduced. These architectures can be described as highly vertically integrated and heterogeneous. They miss common interfaces, based on standards. Instead, most architectures are quite proprietary. This makes it hard to introduce new services because the complexity of the overall architecture is augmented with each new feature that is added to the communications network. Services like the Multimedia Messaging Service (MMS) were introduced last year and again new protocols and new network elements had to be integrated with the existing networks. Managing the communications network as a whole is getting harder and harder.
The JAIN initiative tries to break these vertical structures and replace them with horizontal ones. Proprietary interfaces between the network components are replaced with standards-based interfaces. The JAIN APIs are specified using the Java Community Process, which allows everybody to contribute to the specifications. These companies include IBM, Motorola, NTT, and Vodafone.
JAIN and Other Java Technologies
As JAIN is a new Java technology for most developers, it's interesting to explore how it relates to other existing Java technologies such as the Java 2 Micro Edition (J2ME), the Standard Edition (J2SE), or the Enterprise Edition (J2EE).
Java technologies can be divided into server-side and client-side technologies (see Figure 1). J2SE and J2ME target the client side. While J2ME targets mobile and resource-constrained devices, J2SE targets standard desktop systems.
On the server side, J2EE technologies target enterprise systems and JAIN technologies target communications systems. Based on the JAIN and J2EE specifications, communications services running in a SLEE may communicate directly with existing enterprise systems using RMI or any other protocol that the J2EE server exposes. In contrast, if an enterprise service needs to trigger some functionality exposed by a telecommunications service, it needs to communicate with a SLEE's resource adapter. The resource adapter then maps the requests into SLEE events and routes these events to the services.
