Hi Rodrigo
I took you mail from the contact section of the Github. Feel free to
forward this to the whole team if you like.
First I want to thank the whole IXA pipes team team for providing all
those extensions and especially high quality NER models for OpenNLP.
As a German speaking person I especially enjoy using the German NER
model a lot.
With this message I want let you know about the integration of the IXA
pipe nerc module with Apache Stanbol (see STANBOL-1422 [1]).
The mein contribution of this Integration is code that allows to use
your models for and extensions to OpenNLP to be used in applications
running within an OSGI environment (such as Apache Stanbol).
The reminder of this (long) mail will provide details on how to make
IXA pipes nerc wok within an OSGI environment.
- - -
OpenNLP as such does support OSGI. However for extensions to be
useable in OSGI they need as well support OSGI. As the documentation
of OpenNLP on how to achieve this is very sparse I will provide all
the necessary information for doing so in this mail based on the
example of integrating the `eus.ixa:ixa-pipe-nerc` module with Apache
Stanbol.
Typically OpenNLP will load those extensions via the Classpath baed on
information provided by the `manifest.properties` contained in the
`{model}.bin` file.
Here an example taken from the `it-clusters-evalita09.bin` file of the
1.5.0 release:
Training-Eventhash=d41d8cd98f00b204e9800998ecf8427e
Manifest-Version=1.0
Language=it
serializer-class-itwikiprecleantokc1000p1txt=eus.ixa.ixa.pipe.nerc.dict.BrownCluster$BrownClusterSerializer
The last line tells OpenNLp to use the class
`eus.ixa.ixa.pipe.nerc.dict.BrownCluster$BrownClusterSerializer`
implementing the `ArtifactSerializer` interface to load the artifact
with the name `itwikiprecleantokc1000p1txt` contained in the model.
When running within OSGI OpenNLP can not load such extensions via the
classpath because in OpenNLP modules do have only access to packages
they are explicitly importing. In OSGI Extensions are typically
handled by registering them as Services with the OSGI ServiceRegistry.
This is also the way how OpenNLP searches for extensions when it is
used within an OSGI framework.
To use the IXA NERC models within an OSGI environment one needs to
provide two things:
1. an OSGI Bundle
2. register the extensions as OSGI services.
(1) is done by be pom.xml file o.a.stanbol.commons.ixa-pipe-nerc
module [2]. The configuration of the `maven-bundle-plugin` does all
the work.
The `Import-Package` section defines ignored, optional and required
dependencies. I used this to ignore `net.sourceforge.argparse4j`; make
the dependencies to `org.jdom2` and the `opennlp.tools.cmdline`
package optional as those seam only to be required for training and
not during runtime.
The `Export-Package` section defines functionality this bundle
provides to other modules. Currently all `eus.ixa.ixa.pipe.nerc`
packages are exported. Note also that the `maven-bundle-plugin` will
copy all classes of exported packages to the bundle. By this way the
code provided by the `eus.ixa:ixa-pipe-nerc` is getting into the
bundle.
The `Private-Package` section defines functionality the stays private
to this bundle. This incudee the BundleActivator I implemented to
register your extensions as services (see below).
(2) The registration of the IXA pipes nerc extensions as OSGI service
is done by a BundleActivator. The class implemdntic the
BundleActivator is configured by the `Bundle-Activator` directive in
the `maven-bundle-plugin` configuration.
The BundleActorvator itself [3] is simple. It has two lifecycle method
`start(BundleContext context)` and `stop(BundleContext context)`. The
start method registers all the extensions as OSGI services. The stop
method unregisters them.
In OSGI services are registered for a 1..n names (typically the class
names of the service interfaces) and a dictionary of parameters.
Parameters can be used by Service consumers to query for Services.
OpenNLP requires to the the class name of the service implementation
as value of the `opennlp` parameter.
So a typical ServiceRegistration looks like
Dictionary<String,Object> prop = new Hashtable<String,Object>();
prop.put("opennlp", Word2VecClusterSerializer.class.getName());
registeredServices.add(context.registerService(
ArtifactSerializer.class.getName(),
new Word2VecClusterSerializer(),
prop));
Where `registeredServices` is a set holding references to all
registered service needed to unregister them in the
`stop(BundleContext context)` method.
With this in place it is now possible to successfully load all the IXA
pipe nerd models of the 1.5.0 release with OpenNLP when running in an
OSGI environment.
If you would like to directly support OSGI in one of your next
releases feel free to ask. I am sure I can find some time to help out
with bringing this feature directly to IXA pipe nerc (and possible the
other) modules
best
Rupert
[1] https://issues.apache.org/jira/browse/STANBOL-1422
[2] http://svn.apache.org/repos/asf/stanbol/trunk/commons/ixa-pipe-nerc/pom.xml
[3]
http://svn.apache.org/repos/asf/stanbol/trunk/commons/ixa-pipe-nerc/src/main/java/org/apache/stanbol/commons/ixa/pipe/nerc/Activator.java
--
| Rupert Westenthaler rupert.westentha...@gmail.com
| Bodenlehenstraße 11 ++43-699-11108907
| A-5500 Bischofshofen
