EMF is one of the most powerful MDSD tools. Unfortunately it comes with strong ties to Eclipse and Equinox, because it uses Extension Points. It can be used in Java SE and other OSGi frameworks, but it usually requires a lot of manual work to register EPackages, ResoureFactories etc.
GeckoEMF sets out to provide a way to use EMF in pure OSGi environments regardless of the framework you use. It is an extension on top of EMF, so EMF can be used as before, without any changes. The project is based on the eModelling project of Bryan Hunt.
The sense of Gecko EMF is to register all EMF models as OSGi services. So EMF ResourceSet can be injected as service using:
@Reference
private ResourceSet resourceSet;This is achieved registering a prototype service factory for the resource sets. Alternatively a ResourceSetFactory can also be injected.
To ensure that a model is regsitered in a resource set, the target filtering against the emf.name and other supported properties can be used:
@Reference(target="(emf.name=foo)")
private ResourceSet resourceSet;There are different interfaces that can be implemented and registered as service. For them the emf.configurator.name property can be set, to give the implamantation a name. This can be used for filtering afterwards:
org.gecko.emf.osgi.ResourceFactoryConfigurator- Configurator for a resource factory. The used ResourceFactory registry will be provided by the framework.org.gecko.emf.osgi.ResourceSetConfigurator- Configurator for a resource set. These configurators are usually called before creating a new ResourceSet instanceorg.gecko.emf.osgi.EPackageConfigurator- Configurator for registering a new model using the EPeckage and the EPackageRegsitry.
There are additional properties that can be provided.
Supported properties are defined in the EMFNamespaces constant:
- emf.name - the model name (String[])
- emf.nsUri - the model package namenspace uri
- emf.fileExtension - file extension for resource factories
- emf.protocol - protocol value for resource factories
- emf.contentType - content type definition for resource factories
- emf.version - the model version
- emf.feature - property for special feature of a model
- emf.configuratorName - name of the configurator, when creating an own one
- emf.dynamicEcoreUri - Uri to the ecore when using the dynamic pacakge registration
Usually the right properties are autoamtically set during registration via code generator or extender or the configuration based model registration.
When you create an own configurator based implementation, these properties can be used and are forwarded to the service factory for set ResourceSet. The properties are merged to a list of values in the factory service property map.
If a configurator disappears, the properties of the ResourceSet service factory are updated in a way that the removed properties also disappear.
Example:
- FooEPackageConfigurator with emf.configuratorName=foo
- BarEPackageConfigurator with emf.configuratorName=bar
- ResourceSet would get merged property emf.configuratorName=[foo, bar]
The service lifecycle dynamics are handled by Gecko EMF!
As described above, the emf.feature property can indicate any feature-string. You can filter against this in the ResourceSet or ResourceSetFactory.
In addition to that sometimes you may want to forward a certain, self defined property to the whole Gecko EMF. You can use the prefix emf.feature. for your property:
Puttinf emf.feature.foo=bar as service property of a configurator, will end up as foo=bar in the ResourceSet or ResourceSetFactory service properties.
This functionality works for all configurators and also for the dynamic model registration.
The model registration can happen:
- using the GeckoEMF Code Generator
- using the GeckoEMF Extender from org.gecko.emf.osgi.extender
- using Dynamic Model Registration with a configuration based setup
The provided Code generator is based on the default EMF code generator as declared in the dependencies. As the use is not intended for Eclipse PDE use, no Manifest, plugin.xml or any other PDE Project specific files will be created.
A few additions have been made though. It will create a Component that will register your EPackage, EPackageFactory and a Condition for you. If a ResourceFactory is generated, it will be an OSGi Component as well. All generated Packages will be served with a package-info.java as well. If a EAnnotation with the source Version and a detailed entry with value as key is present on any EPackage this will define you exported version. If non is present the default is 1.0.
This generator is triggered setting the Genmodel - All - OSGi Campatible to true.
After that a new configuration package is created and two two classes are generated:
- EPackageConfigurator - Class to configure the EPackage in a proper way
- ConfigurationComponent - to register all needed stuff as service in a safe way
The following services are registered with the generated code and can be used:
- EPackage, GeneratedEPackage - Service with the generated EPackage instance, with the provided properties e.g. emf.name, emf.fileExt, emf.contentType, emf.protocol
- EFactory, GeneratedEFactory - Service with the generated EFactory instance, with the provided properties e.g. emf.name, emf.fileExt, emf.contentType, emf.protocol
- Resource.Factory, GeneratedResourceFactory - Service with the generated ResourceFactory and provided properties e.g. emf.name, emf.fileExt, emf.contentType, emf.protocol
- Condition - OSGi Condition service with all model related properties
Compared to the static access to EFactory or EPackage, one can access these instances using services, by either injecting the generated EPackage or EFactory interface or the abstract EFactory or EPackage directly. To filter the right model the target filter can be used against the service properties e.g. emf.name=
To use this mechanism the bundle org.gecko.emf.osgi.extender is needed.
Follow the instructions here: Extender Documentation
To dynamically register a EMF model package via configuration you can use a configuration PID DynamicModelConfigurator with a custom identifier. A sample configuration can look like this:
{
":configurator:resource-version": 1,
":configurator:symbolicname": "org.gecko.emf.osgi.demo",
":configurator:version": "0.0.0",
"DynamicPackageLoader~demo": {
"emf.dynamicEcoreUri": "https://mymodelpage.org/demo/demo.ecore",
"emf.feature": ["foo", "bar"],
"emf.feature.my": "own"
}
}
This configuration registers a model package loaded from the given dynamicEcoreUri property. The package is then registered with the given properties as EPackage and EPackageConfigurator service. The package nsUri is also provided from the package.
In this case the properties are:
- emf.name -
EPackage#getName() - emf.nsUri -
EPackage#getNsUri() - emf.feature - forwarded from the configuration, if set
- emf.feature.* - forwarded as described in the feature property section. From the example above the result of emf.feature.my would be my=own
This setup works with the configurator as well with the config admin.
If a package location uri via dynamicEcoreUri property changes, this will lead into an un-registration of the former model and a try to reload the model from the new location.
If some of the other properties change, the properties will be updated without any re-registration of the EPackage.
The latest Version is named here:
https://github.com/geckoprojects-org/org.geckoprojects.emf/blob/master/cnf/ext/version.bnd#L1
We provide a maven BOM on central under the following coordinates:
<dependency>
<groupId>org.geckoprojects.emf</groupId>
<artifactId>org.gecko.emf.osgi.bom</artifactId>
<version>${geckoemf.version}</version>
</dependency>or as short GAV
org.geckoprojects.emf:org.gecko.emf.osgi.bom:${geckoemf.version}
Besides the BOM we provide an OSGi Repository as well.
We additionally provide a Workspace extension that provides some more comfort including a bnd code generator and project templates for EMF projects.
Since bnd Version 6.1.0 the concept of libraries was introduced, which provides some easy extensions for your bnd workspace setup.
Add the following maven dependency from maven central to you workspace:
org.geckoprojects.emf:org.gecko.emf.osgi.bnd.library.workspace:${geckoemf.version}
You can now activate the library bi adding the following instruction to your workspace (e.g. build.bnd)
# If you are brave you can use the develop for the latest and greatest. We are ususally pretty stable
-library: geckoEMFThis will include a repository with all required dependencies together with the codegenerator and BND Tools Template for an example Project (klick next in the wizard or you will miss the required template variables).
An example project bnd file can look as follows:
# sets the usually required buildpath, you can extend it with the normal -buildpath to your liking
-library: enable-emf
# The code generation takes a bit of time and makes the build a bit slower.
# It might be a good idea to put comments around it, when you don't need it
-generate:\
model/mymodel.genmodel;\
generate=geckoEMF;\
genmodel=model/mymodel.genmodel;\
output=src
# Add this attribute to find some logging information
# logfile=test.log;\
# always add the model in the same folder in jar as in your project
-includeresource: model=model
Bundle-Version: 1.0.0.SNAPSHOT- Documentation
- Source Code (clone with
scm:git:git@github.com:geckoprojects-org/org.gecko.emf.git)
- Juergen Albert (jalbert) / j.albert@data-in-motion.biz @ Data In Motion - architect, developer
- Mark Hoffmann (mhoffmann) / m.hoffmann@data-in-motion.biz @ Data In Motion - developer, architect
- Stefan Bischof (bipolis) / stbischof@bipolis.org - developer
EPL 2.0
Data In Motion Consuling GmbH - All rights reserved
Data In Motion Consuling GmbH - info@data-in-motion.biz