Overview

The framework is capable of installing certain bundles without loading their classes until they are really needed. This class loading "on demand" speeds up greatly the initial startup time of the framework.

The OSGi framework implementation supports two approaches for lazy activation definition:

defined by the OSGi Service Platform Core Specification
defined by the Bosch IoT Gateway Software SDK

This document will focus on the second approach as the first one is already described in details by the OSGi Alliance.

Lazy bundles

Three types of bundles can be subject of lazy initialization:

Providing service classes
Consuming services
Having dependencies on other bundles, which have specific manifest headers

All of them are lazy bundles.

States of a Lazy bundle

This section discusses the states and transitions that a bundle passes during its lifecycle in regards to lazy initialization.

1	Resolve
2	Traditional OSGi bundle resolve
3	Failed resolve
4	Initial start when starting the framework Starting due to the start level of the bundle Starting by using the Framework Access service
5	Explicit start from the runtime console, from the Web Admin Console or from another bundle
6	Traditional OSGi bundle start
7, 8	Stop due to the start level of the bundle Explicit stop from the runtime console, from the Web Admin Console or from another bundle
9	Explicit stop
10	Explicit start

Lazy services and bundles in the text console

The framework's text console indicates lazy services and bundles in the following way:

As a result of the list command - By displaying the "[lazy]" keyword in front of the state of lazy bundles.
As a result of the services command - By displaying the "Fake Service Registration" notice after the object class of the corresponding lazy service. Otherwise, "Real Service Registration" is shown.

Enabling lazy initialization

By default, the lazy initialization of the framework is turned off. To enable it, before framework startup set the mbs.bundles.lazy system property to true.

On most JVMs the OSGi Runtime can be easily started in lazy initialization mode by passing the lazy option to the corresponding server script file.

After you have declared a bundle as lazy you need to specify the bundle as such in the boot.ini file with

as otherwise even if everything else is correct the bundle will start up normally.