Extractors Core

This core library contains main communication interface between all extraction-related OSGi-based projects.

This project cannot be used as a standalone.

How to get the code

$ git clone https://opensourceprojects.eu/git/p/timbus/context-population/extractors-core

Requirements

• Java Development Kit (>= 1.6) how to install
• Maven (>= 2)
• core and osgi parents
• Internet access or manually download and install OSGi 4.3 core companion code to Maven local repository

Usage

Virgo server

To deploy this project on Virgo from source code, execute the following command line in project's root folder:

$ mvn clean package

Install to Maven local repository

In order to be able to develop new extractors or compile extraction-related projects, run the following command from project's root folder:

$ mvn clean install

This page contains a comprehensive tutorial on how to develop an extractor that complies with TIMBUS architecture

Within an Extractor project

The most relevant component of Extractors Core is the interface IExtractor. To develop an extractor that is recognized within the Context Population Framework, it is mandatory to implement this class. The extract method returns a String and this is where the result of the Extraction must be provided.
In Timbus Project Extractors, the Spring Framework was used to implement the OSGI framework. A typical Timbus extractor declares the following dependency in the pom.xml file:

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>3.2.3.RELEASE</version>
    <scope>provided</scope>
</dependency>

With this dependency within the project build path, it is now possible to declare the BundleContext object within the main Extractor class that implements IExtractor:

@Autowired
private BundleContext bundleContext;

This object is to be used in overriding the IExtractor methods, which ask information about the extractor to be used in the Osgi Framework.
Further on, in order for this bundle to be recognized within the Osgi framework, two .xml files are added in the resources folder, under META-INF --> spring:

bundle-context-osgi.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:osgi="http://www.springframework.org/schema/osgi"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
                  http://www.springframework.org/schema/osgi http://www.springframework.org/schema/osgi/spring-osgi.xsd">

    <!-- definitions using elements of the osgi namespace can be included
       in this file. There is no requirement to keep these definitions
       in a separate file if you do not want to. The rationale for 
       keeping these definitions separate is to facilitate integration
       testing of the bundle outside of an OSGi container -->

    <osgi:service interface="net.timbusproject.extractors.core.IExtractor" ref="extractor"/>

    <osgi:reference id="log" interface="org.osgi.service.log.LogService"/>

</beans>

bundle-context.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <!-- regular spring configuration file defining the beans for this
         bundle. We've kept the osgi definitions in a separate
         configuration file so that this file can easily be used
         for integration testing outside of an OSGi environment -->

    <bean name="extractor" class="net.timbusproject.extractors.modules.linuxhardware.remote.LinuxHardwareExtractor"/>

    <context:annotation-config/>
</beans>

bundle-context-osgi.xml states that there is an Osgi service called extractor that implements the interface IExtractor, and bundle-context.xml specifies which class is actually implementing IExtractor, consequently representing this service.
Note: These examples are from the Linux Hardware Extractor. To implement a new extractor, values in the .xml files obviously have to be updated.

Author

• Luís Duarte
• Jorge Simões (jorge.simoes@caixamagica.pt)
• Miguel Nunes (miguel.nunes@caixamagica.pt)

License

Copyright (c) 2014, Caixa Magica Software Lda (CMS).
The work has been developed in the TIMBUS Project and the above-mentioned are Members of the TIMBUS Consortium.
TIMBUS is supported by the European Union under the 7th Framework Programme for research and technological development and demonstration activities (FP7/2007-2013) under grant agreement no. 269940.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTIBITLY, or FITNESS FOR A PARTICULAR PURPOSE. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law or agreed to in writing, shall any Contributor be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work.
See the License for the specific language governing permissions and limitation under the License.