The Mobile Service Architecture Specification

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Twin Java Specification Requests (JSRs) are under way that will define the new Mobile Services Architecture (MSA), the next generation of the Java platform for mobile devices. Ultimately, JSRs 248 and 249 will define a comprehensive structure of APIs aimed at facilitating development and deployment of the widest possible variety of applications, in a form that will be easily portable across the broadest possible spectrum of mobile devices.

JSR 249, Mobile Service Architecture Advanced, based on an update of the Connected Device Configuration (CDC), will underpin applications that need the resources of the more powerful devices on the market, such as top-end PDAs, with their greater memory, heftier batteries, and more elaborate interfaces.

JSR 248, based on the Connected Limited Device Configuration (CLDC), will necessarily be leaner and meaner, but specifies a large subset of its stable mate's capabilities. JSR 248 is being pushed ahead of JSR 249 so developers can make the earliest possible start on MSA-compliant applications that will run on the highest-volume mobile devices.

At this writing, JSR 248 is close to final approval - a good time to get a firm idea of what it includes, and what kinds of products and services it will support.

As its name suggests, MSA is a complete architecture for mobile services. Like its predecessor, JSR 185: Java Technology for the Wireless Industry, MSA is an umbrella over a collection of familiar, updated, and new JSRs that cooperate to support applications with a wide range of standardized capabilities. It broadens the architecture defined by JSR 185 to incorporate new technologies for high-volume mobile devices. To ensure greater compatibility among implementations, MSA also documents a set of clarifications that removes or reduces ambiguities that have been uncovered in some JSRs.

The Mobile Service Architecture defines two stacks: a full MSA stack that comprises 16 JSRs, and a subset of eight JSRs:

Image Source: The MSA specification (JSR 248)

Some of the JSRs are mandatory, others are conditionally mandatory. To comply with MSA, an implementation must support a JSR if it's mandatory, or if it's conditionally mandatory and the relevant conditions are true. A typical example of the latter is JSR 82, the Bluetooth API, which is not always required, but must be supported if the device claims to support the Bluetooth wireless technology.

Here's a summary of the pertinent JSRs, beginning with JSR 248 itself:

JSR 248: Mobile Services Architecture - The MSA umbrella that identifies included JSRs, and makes related clarifications.

The MSA subset comprises eight JSRs:

• JSR 139: J2ME Connected Limited Device Configuration 1.1 is the configuration, which provides basic application support.
  
  
• JSR 118: Mobile Information Device Profile 2.1 is the profile, which provides capabilities required by most mobile applications, such as user interface.
  
  
• JSR 75: PDA Optional Packages for the J2ME platform specifies two packages to support functionality often needed in personal digital assistants, one for access to the device's local file system and other for personal information management.
  
  
• JSR 82: Java APIS for Bluetooth gives you access to Bluetooth functionality, and the OBEX protocol (conditionally mandatory).
  
  
• JSR 135: Mobile Media API provides access to media capabilities such as audio and video playback.
  
  
• JSR 184: Mobile 3D Graphics API supports three-dimensional graphics.
  
  
• JSR 205: Wireless Messaging API profiles messaging features such as SMS and MMS.
  
  
• JSR 226: Scalable 2D Vector Graphics API for J2ME supports two-dimensional scalable vector graphics.

The full MSA stack consists of the eight JSRs in the subset, and eight more:

• JSR 172: J2ME Web Services supports XML parsing and basic web services in a mobile device.
  
  
• JSR 177: Security and Trust Services API provides access to cryptographic services (mandatory), communication with smart cards (conditionally mandatory), and access to public key infrastructure services (conditionally mandatory). Note that SATSA-JCRMI is not part of MSA or MSA Subset.
  
  
• JSR 179: Location API for J2ME supports location-based services (conditionally mandatory).
  
  
• JSR 180: SIP API for J2ME provides access to the Session Initiation Protocol (SIP).
  
  
• JSR 211: Content Handler API supports launching of Java applications based on content type.
  
  
• JSR 229: Payment API provides access to payment mechanisms.
  
  
• JSR 234: Advanced Multimedia Supplements extends JSR 135 to provide more advanced multimedia capabilities.
  
  
• JSR 238: Mobile Internationalization API supports the development of localized applications.

If you hope to deploy a mobile application into the flood of next-generation handsets that will soon sweep into the market, you should investigate the Mobile Service Architecture. A good start would be to download the MSA specification.