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Non-Java Matchers / External Matcher Development

MELT allows to develop a matcher in any other programming language and additionally to wrap it as a SEALS or HOBBIT package. Therefore, class MatcherExternal has to be extended. The interface for the external process is simple. It receives the input variables via the command line and outputs the results via the standard output of the process - similar to many Unix command line tools. All external resources have to be placed in a directory named oaei-resources.

Wrapping non-Java matchers brings many advantages such as (1) automated matcher packaging as outlined below, (2) external matchers can be easily mixed with other matching components, and (3) the external matchers can be thoroughly evaluated in MELT.

Wrapping a Python Matcher

Project Overview

The example project can be found on GitHub.

The matcher is completely implemented in Python. All python resources can be found in directory oaei-resources. For parsing the ontologies, rdflib is used. Alignment services like serialization are handled in file AlignmentFormat.py. Note that MELT does not offer comprehensive matcher development tooling in other programming languages than Java.

Java class DemoPythonMatcher is used to wrap the python matcher. At runtime, this wrapper will call the python python matcher.

Packaging as Docker Web Package

As discussed above, the whole matching process is implemented in Python. The project is configured to be packaged as docker web package. You can find all the information conderning the packaging in the pom.xml file.

If any dependencies need to be installed in the docker container, you can add them in the pom.xml (plugin: docker-maven-plugin). In the demo project, you can see that we install the rdflib dependency (<run>pip install rdflib</run>).

When you run mvn clean install, MELT will wrap a server around your matcher and put everything neatly in a docker container that you can share. In the target directory of your project, you will find a sharable docker container (file ending with .tar.gz). Others can then execute your matcher without installing any dependencies etc.

You can read more about packaging in the packaging section. Note that you do not have to use MELT to create a docker container. You can also write your own server and implement the web interface protocol yourself.

Wrapping as SEALS/HOBBIT Package

You can also find an example project for SEALS packaging as well as for HOBBIT packaging.