eclipse con2010 composites

© 2010 by IBM Corp.; Licensed under the Creative Commons Att. Nc Nd 2.5 license

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)


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

A1

A3

A2



Framework

What if they are

subsystems?

A1

A3

A2



Framework

Maybe they want private

packages

A1

A3

A2



FrameworkAnd private

services

A1

A3

A2



Framework

A1

A3

A2

Need subsystem

encapsulation



Framework

A1

A3

A2

Private detailsare hidden



Framework

A1

A3

A2

Public packages

are exposed



Framework

A1

A3

A2

External packages

are imported



Framework

A1

A3

A2

Public servicesare exposed



Framework

A1

A3

A2

This blob is acomposite

bundle


Implementing Composites


Composites are composed of bundles with resolved states


C

Composite Bundle

exportorg.foo.b

exportorg.foo.c

A

B

Importing and Exporting Packages

Export


C

Composite Bundle

exportorg.foo.b

exportorg.foo.c

importorg.foo.b

A

importorg.foo.c

B


Import


B

C

A

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

A

C

B

org.foo.c.CService


Composite Bundle

Publish and Consume Services

Bind

org.foo.c.CService

org.foo.b.BServiceA

B

C


This looks very similar to a Framework!



Framework

A1

A3

A2

Can this blob be anested

framework?



A1

A3

A2

How are imports, exports

and serviceshandled?

Framework

Nested Framework


Defining a Sharing Policy



A1

A3

A2

Framework

Bundle

To the outside this looks like a normal bundle

Bundle

C



A1

A3

A2

A representation is needed inside for the

exports, imports and services

Framework

C

Nested Framework



A surrogate bundle canprovide this representation

Framework

Composite

A1

A3

A2

Sur

roga

te B

undl

eC



Framework

A1

A3

A2

Composite

C

The surrogate imports packages exported

by the composite

Sur

roga

te B

undl

e



Framework

A1

A3

A2

Composite

Sur

roga

te B

undl

eC

The surrogate exports packages imported

by the composite



Framework

A1

A3

A2

Composite

Sur

roga

te B

undl

eC

The surrogate consumes services published outside

by the composite



Framework

A1

A3

A2

Composite

Sur

roga

te B

undl

eC

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

A1

A3

A2

Composite

Sur

roga

te B

undl

eC

What happens if the composite is

stopped – the composite

framework is shutdown



Framework

A1

A3

A2

Composite

Sur

roga

te B

undl

eC

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

A1

A3

A2

Composite

Sur

roga

te B

undl

eC

Composite and Surrogate must proxy all shared

resources



Framework

A1

A3

A2

Composite

Sur

roga

te B

undl

eC

Difficulties with proxying service

factories. No way to guarantee

unique locations or bundle IDs



Framework

A1

A3

A2

Composite

Sur

roga

te B

undl

eC

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

A1

A3

A2

C



Framework

Composite

A1

A3

A2

C

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



Framework

Composite

A1

A3

A2

C

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?



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”);...




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

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



Framework

Resolved Composite

B

A

C


Sharing Policy

exportb

exportc

Importb

Importc


Framework

Active Composite

A


Sharing Policy

c.CService

b.BService

C

B


Demo


Isolating SWT and e4 applications

Root Framework

SWT

AppConsoleWeb UI

e4PhotoDemo

e4Contacts

Demo

Each Composite contains their own stack of bundles

which are isolated from each other



Root Framework

SWT

AppConsoleWeb UI

e4PhotoDemo

e4Contacts

Demo

SWT is installed in the root

framework and shared with the

composites which require SWT



Root Framework

SWT

AppConsoleWeb UI

e4PhotoDemo

e4Contacts

Demo

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

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