IBM Workplace Client Technology Micro Edition Version 5.7.1: Application Development and Case Study

Chapter 3. Service Management Framework Runtime 43

and managed deployment of services. The primary targets for the OSGi

specifications are set top boxes, service gateways, cable modems, consumer

electronics, PCs, industrial computers, cars and more. These devices that

implement the OSGi specifications will enable service providers like telcos, cable

operators, utilities, and others to deliver differentiated and valuable services over

their networks.

The OSGi specification enables the separation of the service interface from the

service implementation, allowing scalability and extensibility. The SMF

framework uses the information in the bundle manifests to populate its service

registry and to manage and resolve bundle dependencies. Each bundle has it’s

own class loader and name space, and the references between bundles, to

access each others services, is managed by the framework.

There are tools designed specifically for bundle creation and management. Many

are wizard-based, to allow you to easily create the required classes, methods

and other template code for your packages, whereupon you then write the core

logic to those services. WebSphere Device Developer is extended by a number

of tools including the Bundle Development Kit and the other Extension Services

tools. There is also a reference platform for the tooling that includes a bundle

server for testing your code without the need for a production level server.

In sum, the OSGi platform is designed to enable devices of any shape and size

to execute a consistent, modular program model, on a well-architected set of

frameworks and core services. This framework provides services and bundle life

cycle management to enable dynamic loading, starting and stopping, and more

importantly, bundle and service sharing in the VM instance that is running the

SMF platform.

3.1.2 What is SMF?

The Service Management Framework (SMF) Runtime is IBM’s implementation of

the OSGi Service Platform.

SMF is a Java application, running in a JVM. In essence, SMF is the host

environment in which the bundles execute. It manages the life cycle of bundles

(installing, starting, stopping, updating and uninstalling) and through the bundle

manifest, the dependencies of bundles on one another. These bundles can

represent several separate applications or portions of applications, all running in

the same JVM.

Core and custom bundles

Core bundles provide the basic functionality of the platform. More simply, system

bundles are the SMF platform itself, and custom bundles are the ones you and

44 WCTME: Application Development and Case Study

other developers create to extend the framework and to form applications to

perform other useful problem solving tasks.

Custom bundles can be created to expose new interfaces or Java packages and

new services. For our sample application and case study, we created several

custom bundles. Applications are constructed by using these services and

interfaces. Each of these bundles can be managed separately, each having their

own life cycle. Bundles can be installed into the framework; started, stopped, and

updated independently of each other.

Bundles can implement an interface, BundleActivator, that allows the bundle to

be started and stopped cleanly by the framework. During the start and stop calls,

the bundle activator logic is called to manage the bundle, which can include the

registering or un-registering of a service, starting and stopping threads, and

allocation and de-allocation of resources.

Bundles must include a manifest file that includes information used by the

framework to install and activate the bundle and determine dependencies

between bundles. Import dependencies and export definitions of packages and

services are described in the manifest file.

Running the framework

You can run the SMF Runtime inside the WebSphere Device Developer

workspace (see the SMF Bundle Developer Tools documentation) and from a

command line.

Consult the following sections of the SMF Runtime documentation in Table 3-1

for detailed information concerning the execution of the SMF runtime:

Table 3-1 SMF Runtime documentation

Tip: See the SMF Bundle Developer Tools documentation and the SMF

Bundle Server documentation, especially the Documentation and Web Links,

for more information about development, life cycle and bundle management.

smf.properties Service Management Framework

򐂰 SMF Runtime User’s Guide

򐂰 Getting Started

򐂰 Getting Started with the SMF Runtime

򐂰 Using the smf.properties file