eclipse con2010 composites

EclipseCon 2010

Isolating Applications in a Collaborative OSGi World

Composite Bundles

Thomas Watson

Warning!

Not for the faint of heart!Lots of details.

No fancy slides.

(What would you expect from a framework implementer?)

OSGi R4.2 Review

● New Enterprise Specifications– Remote Services

– Blueprint

● And more on the way ...– Remote Services Admin

– JTA, JMX, JDBC, JNDI, JPA

– Web Applications

– etc.

Forget the High-Level Stuff!

● R4.2 Core framework changes– Service registry hooks

– Security enhancements● Ordered conditions● Fine-grained service and package permissions based on

identity of the provider

– Bundle tracker

– Standard launching and embedding

– Composite bundles (provisional spec.)

What can we expect from R4.3 Core?

● Still early in the process● Early access to draft RFCs

● OSGi API update (RFC 151)– Use of generics and adaptor patterns

● Composite Bundles (RFC 138)– Much has changed since the R4.2 provisional spec.

● Generic capabilities and requirements (RFC 154)

What can we expect from R4.3 Core?

● Still early in the process● Early access to draft RFCs

● OSGi API update (RFC 151)– Use of generics and adaptor patterns

● Composite Bundles (RFC 138)– Much has changed since the R4.2 provisional spec.

● Generic capabilities and requirements (RFC 154)

Standard Launching & Embedding

Framework Implementations

● Bundles are portable● What about the framework?

– Launching and configuring

– Controlling its life cycle

– Externally interacting with bundles, services, and state

● Seems like a slam dunk● What does it give us?

– A standard way to create framework instances

– A standard API for controlling and interacting with framework instances

● What does this help?

● Seems like a slam dunk● What does it give us?

– A standard way to create framework instances

– A standard API for controlling and interacting with framework instances

● What does this help?– Portable scripts and launchers

Standard Interfaces

public interface FrameworkFactory { Framework newFramework(Map config);}

Standard Interfaces

public interface FrameworkFactory { Framework newFramework(Map config);}

public interface Framework extends Bundle { void init() throws BundleException; FrameworkEvent waitForStop(long timeout) throws InterruptedException;}

Standard Configuration Properties

● org.osgi.framework.bootdelegation

● org.osgi.framework.system.packages

● org.osgi.framework.system.packages.extra

● org.osgi.framework.startlevel.beginning

● org.osgi.framework.storage

● org.osgi.framework.storage.clean

● And others...

Out Of Scope

● Multiple framework instances– e.g., no support for sharing/collaboration among

instances or multiplexing of VM singletons

– May or may not work, but implementation dependent

Multiple Instances

● Pose interesting challenges● Promise potentially interesting capabilities● This use case uncovers potential framework

issues

Composite Bundles

Framework Limitations

● Applications are either all bundles collaborating or an individual bundle● All global or completely local

● No application/subsystem concept● Isolation/protection (bundles, services, packages)● Visibility (bundles, services, packages)● Grouping (lifecycle)

FrameworkWhere is theapplication?

Framework

Assume thesebelong to anapplication

Framework

What if they are

subsystems?

Framework

Maybe they want private

packages

FrameworkAnd private

services

Framework

Need subsystem

encapsulation

Framework

Private detailsare hidden

Framework

Public packages

are exposed

Framework

External packages

are imported

Framework

Public servicesare exposed

Framework

This blob is acomposite

bundle

Implementing Composites

Composites are composed of bundles with resolved states

Composite Bundle

exportorg.foo.b

exportorg.foo.c

Importing and Exporting Packages

Export

Composite Bundle

exportorg.foo.b

exportorg.foo.c

importorg.foo.b

importorg.foo.c

Import

importorg.foo.b

exportorg.foo.b

importorg.foo.c

exportorg.foo.c

Composite Bundle

Resolve

Composites are composed of bundles that publish and bind to

services

Composite Bundle

org.foo.b.BService

Publish and Consume Services

Publish

org.foo.c.CService

Composite Bundle

Publish and Consume Services

org.foo.c.CService

org.foo.b.BServiceA

This looks very similar to a Framework!

Framework

Can this blob be anested

framework?

How are imports, exports

and serviceshandled?

Framework

Nested Framework

Defining a Sharing Policy

Framework

Bundle

To the outside this looks like a normal bundle

Bundle

A representation is needed inside for the

exports, imports and services

Framework

Nested Framework

A surrogate bundle canprovide this representation

Framework

Composite

Framework

Composite

The surrogate imports packages exported

by the composite

Framework

Composite

The surrogate exports packages imported

by the composite

Framework

Composite

The surrogate consumes services published outside

by the composite

Framework

Composite

The surrogate registers services consumed by the composite from

the outside

● Issues with modeling composites as real bundles with nested frameworks

● Issues with modeling composites as real bundles with nested frameworks● Sharing everything through a surrogate creates

lifecycle issues

Framework

Composite

What happens if the composite is

stopped – the composite

framework is shutdown

Framework

Composite

What happens if the composite is

stopped – the composite

framework is shutdown

Framework

Composite

But C is still resolved and

expecting to be able to load

classes from the exported package

lifecycle issues

lifecycle issues● Consumers and Providers loose their identity to the

composite and surrogate– No support for Require-Bundle– ServiceFactory support is limited– Introspecting system dependencies is combersome.

Framework

Composite

Composite and Surrogate must proxy all shared

resources

Framework

Composite

Difficulties with proxying service

factories. No way to guarantee

unique locations or bundle IDs

Framework

Composite

Exports loose the identity of their

exporting symbolic name. Require-

Bundle is not possible

Transparent Sharing Policy

Virtualizing Framework Isolation

● Model isolation in a single framework instance

● Model isolation in a single framework instance● Each composite has a virtual framework that hides

outside bundles, services, and packages.

outside bundles, services, and packages.● A sharing policy can be declared

– What is visible to the inside from the outside (imported)– What is visible to the outside from the inside (exported)

A Sharing Policy controls the

visibility of shared resources

Framework

Composite

Framework

Composite

What is visible from the point of view of a bundle in a composite

Framework

Composite

What is visible from the point of view of a bundle

in the parent

● Enforce rules to ensure unique bundle identification● All bundle locations and bundle IDs must be unique● Important for supporting shared service factories

Installing a Composite

Configure?

Create?

Configure?

Create?Reference?

Configure

String location = “myComposite; composite=true”;Map config = HashMap();config.put(“...startlevel.beginning”, “25”);

Map manifest = HashMap();manifest.put(“Bundle-SymbolicName”, location);manifest.put(“Composite-PackageExportPolicy”, “b”);manifest.put(“Composite-PackageImportPolicy”, “c”);manifest.put(“Composite-ServiceImportPolicy”, “(objectClass=c.CService)”);manifest.put(“Composite-ServiceExportPolicy”, “(objectClass=b.BService)”);...

Configure

Framework launching configuration

Configure

Specify the package export policy

Configure

Specify the package import policy

Configure

Specify the service import policy

Configure

Specify service filters to publish

Reference?

String location = “myComposite”;Map config = HashMap();Map manifest = HashMap();...

Create?

Reference? CompositeAdmin. installCompositeBundle( location, manifest, config);

Obtained from the service registry.

CompositeBundle comp

CompositeBundleextends Bundle

CompositeAdmin. installCompositeBundle( location, manifest, config);

Framework

Empty Installed Composite

Sharing Policy

Composite Bundle: myComposite

Managing a Composite

Access?

Install?Access?

Install?

Start?

Access?

Install?

Start?

BundleContext ctxt = comp.getSystemBundleContext();...

Start?

Bundle a = ctxt.installBundle( “file:a.jar”);Bundle b = ctxt.installBundle( “file:b.jar”);...

a.start();b.start();comp.start();...

Framework

Resolved Composite

Sharing Policy

exportb

exportc

Importb

Importc

Framework

Active Composite

Sharing Policy

c.CService

b.BService

Isolating SWT and e4 applications

Root Framework

AppConsoleWeb UI

e4PhotoDemo

e4Contacts

Each Composite contains their own stack of bundles

which are isolated from each other

Root Framework

AppConsoleWeb UI

e4PhotoDemo

e4Contacts

SWT is installed in the root

framework and shared with the

composites which require SWT

Root Framework

AppConsoleWeb UI

e4PhotoDemo

e4Contacts

Application Descriptor and

Handle services are shared with

the Web UI

Benefits of Composites

● Composite Bundles are persistent

– Content of composite is reified when the parent framework restarts

– Like a normal bundle, the active state is persisted

● Bundles can be grouped together into one executable unit

– Stopping a composite stops all constituent bundles

– Starting a composite starts the constituent bundles (which are marked for start)

● Bundles can be grouped together into one executable unit

– Stopping a composite stops all constituent bundles

– Starting a composite starts the constituent bundles (which are marked for start)

● High level of isolation

– Strict control over what is imported to and exported from the composite.

– Sharing is fine grained and transparent

Difficulties with Composites

● Low-level API for installing content into composites– Equivalent to managing a complete framework

● Limitations for sharing resources– Extenders do not understand composites (DS, Spring,

Blueprint, Extension Registry, iPOJO)

– Transparent sharing policy● Simplifies most things

– Transparent sharing policy● Simplifies most things● But violates academic notion of a composite

Conclusion

● OSGi R4.3 is shaping up to be a big release– Still early, but some interesting things are far along

– OSGi API Updates

– Composite Bundles

● Composite Bundles– A powerful way to establish application isolation

– Provides a basis for defining subsystems

Legal Notices

● Java and all Java-based trademarks are trademarks of Sun Microsystems, Inc. in the United States, other countries, or both

● Other company, product, or service names may be trademarks or service marks of others

eclipse con2010 composites

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standard api

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composite bundles provisional

osgi r4

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