THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
OSGi Integration
Layers for Tuscany/SCA OSGi integration
Assembling Tuscany runtime from OSGi bundles for tuscany modules and 3rd party jars
1. OSGi providing modularity of the Tuscany runtime itself (business
as usual for OSGi and not a programming model relationship). Package tuscany runtime modules and 3rd party dependencies as OSGi bundles, and use an OSGi runtime such as Felix or Equinox to install/run these bundles. This feature enables the assembly of Tuscany runtime as OSGi bundles and it formalizes the SPI contracts (class visibility across modules) using the OSGi Import-Package/Export-Package headers.
Objectives:
- Formalize the SPI contracts and enforce the class dependencies across modules
- Provide versioning and isolation support that so different tuscany extensions can depend on different versions of the same library
- Provide dynamic lifecycle for extensions, install/uninstall/start/stop a module
Key Modules:
- tuscany-extensibility-osgi: https://svn.apache.org/repos/asf/tuscany/java/sca/modules/extensibility-osgi (Based on Felix for testing)
- tuscany-extensibility-eclipse: https://svn.apache.org/repos/asf/tuscany/java/sca/modules/extensibility-equinox (based on Equinox)
These two modules enable the META-INF/services provider pattern to work with the OSGi bundles.
- tuscany-node2-launcher-osgi: https://svn.apache.org/repos/asf/tuscany/java/sca/modules/node2-launcher-osgi
This special launcher will discover tuscany bundles and 3rd party jars on paths defined by TUSCANY_HOME and TUSCANY_PATH system properties/environment variables. It will start an embedded OSGi runtime (Felix, Equinox or other), install (or wrap plain jars into) bundles, and use the SCA Node/Domain APIs to create/launch SCA nodes or domain manager.
The following testcase demonstrates the usage of this launcher to run HelloWorld composite and SCA Domain Manager:
/tuscany-node2-launcher-osgi/src/test/java/org/apache/tuscany/sca/node/osgi/launcher/NodeLauncherTestCase.java
Using OSGi bundles as SCA contributions
Package application artifacts into OSGi bundles and contribute them to SCA domain as SCA contributions
- tuscany-contribution-osgi: https://svn.apache.org/repos/asf/tuscany/java/sca/modules/contribution-osgi
2. OSGi bundles as SCA contributions (OSGi providing modularity for
Java implementation types (e.g. implementation.osgi and
implementation.java)).
Implementing SCA components using OSGi bundles
Support OSGi bundle as a component implementation type for Tuscany/SCA, expose OSGi services as SCA services and inject references to OSGi services
- tuscany-implementation-osgi: https://svn.apache.org/repos/asf/tuscany/java/sca/modules/implementation-osgi
3. OSGi bundles as an implementation technology for SCA components
(implementation.osgi). Here OSGi services and references are mapped
to SCA services/references and can be integrated with other
implementation technologies (e.g. BPEL, POJO, Groovy, etc...) and
invoked or can invoke over the various SCA bindings. This is business
as usual for SCA, which is designed to enable the assembly of
heterogeneous implementation technologies.
Running environment
- JSE with embedded OSGi runtime such as Eclipse Equinox and Apache Felix
- Running inside Eclipse workspace
- Maven surefire plugin for testing
- External OSGi runtime such as Eclipse or Felix Shell
- Other environment such as JEE (Web Container, EJB container)
Different approaches to convert 3rd party jars into OSGi
Strategy | Options | Pros | Cons | Note |
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Build-time conversion | Using tools (such as maven-bundle-plugin) to convert plain jars into OSGi bundles |
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| Maven Bundle Plugin: http://felix.apache.org/site/maven-bundle-plugin-bnd.html\\\\\\\\\\\\\\\\\\\\\\\\ Felix Commons: http://felix.apache.org/site/apache-felix-commons.html |
| Use already-converted 3rd party bundles from Spring DM, Felix Common or Eclipse Orbit |
| Not all 3rd party jars are available in OSGi bundles |
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Runtime converstion | Before the jar is installed (BundleContext.installBundle()) |
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| Add a hook to the OSGi runtime to wrap the jar (such as |
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| Equinox Hooks: |
Hybrid conversion | Build-time will generate the META-INF/MANIFEST.MF as a side file |
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Virtual Libary Bundle for 3rd party jars
1) The launcher looks for runtime JARs and class folders in a Tuscany distribution install or just the classpath entries used to start it.
2) Then it looks for OSGi Bundle-SymbolicName entries in their manifests to determine if they are OSGi bundles or just regular JARs.
3) It creates a single in-memory bundle for these regular JARs, in an Equinox BundleFileFactoryHook:
- export and import all their packages
- import * with a DynamicImport
- reference the JARs outside of the bundle in Bundle-classpath
That step is fast as it just writes a Manifest to a byte[] in memory, with no need to copy the JARs and re-package them, as the manifest
simply references their actual locations.
4) Bundle tuscany-extensibility-equinox contains a DynamicImport *, enabling ServiceDiscovery to access the 3rd party packages.
5) Instead of Thread.getContextClassLoader(), Tuscany code must use Class.forName() from modules that have the proper imports, and the
Tuscany ServiceDiscovery to discover META-INF/services.
The above seems to work well in the following environments:
- an installed distro, JARs and bundles are loaded from the distro
- Maven surefire, classes are loaded from the Maven repos
- an Eclipse project, classes are loaded from the project's classpath
Build a distribution with the OSGi bundle layout
tuscany-sca
...modules
......tuscany-module.jar
...lib
......3rd-party-non-osgi
.........META-INF/MANIFEST.MF
.........3rd-party-non-osgi.jar
......3rd-party-osgi.jar
Tuscany OSGi Integration
Enable Tuscany runtime with OSGi (Use OSGi under the cover for Tuscany runtime or work with existing OSGi environment such as Eclipse RCP)
Work Items | Status | |
Package Tuscany modules as OSGi bundles | Partially done. The following items remain:
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Package all of the 3rd party jars as an OSGi bundle | Partially done. The following items remain:
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Provide a SCA node launcher to run SCA application with OSGi-enabled Tuscany runtime | The launcher now works with SCA node.
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Support different bundle packaging and distribution schemes (jars and class folders, distribution and Eclipse workspace) | ||
Bring up the calculator sample with Equinox Node Launcher | Done |
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Bring up the calculator RCP with Eclipse Equinox | Under bring-up | |
Use the Import/Export packages for Tuscany modules to enforce the SPI contracts, Refactor SPIs if necessary, Split a few modules into model and runtime | ||
Change how JDK factories are discovered and instantiated | Done for the core | |
Rationalize and clean up the SCA contribution classloading strategy |
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Convert samples and itests to use the OSGi-enabled Tuscany runtime |
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OSGi bundles as SCA contributions
Work Items | Status |
Support packaging of SCA contributions as OSGi bundles |
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Support the OSGi import/export as SCA contribution import/export |
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Convert some samples or itests to use OSGi bundle as the SCA contributions |
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Integrate SCA assembly with OSGi services
Work Items | Status |
First step: Define a set of scenarios to better understand the resulting programming model (OSGi + SCA) |
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