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COSMOS Programming Model

Revision as of 13:30, 12 October 2007 by (Talk | contribs) (Creating an MDR)

COSMOS provides a framework for collecting and visualizing data for system administration applications. By leveraging the COSMOS framework and providing the necessary extensions, programmers can quickly and easily create applications for collecting data from disparate data sources, and making data available through standard-based APIs or an easy-to-use user interface. This document explains the programming model used in extending the COSMOS framework.

Creating a Data Manager

Getting Code from CVS

The code for data manager (both the framework and examples for using the framework) is checked into the sandbox directory of the COSMOS CVS.

Host: Repository: /cvsroot/technology Path: org.eclipse.cosmos/sandbox

Here is the list of bundles and their purposes:

Framework code for data manager:

  • org.eclipse.cosmos.dc.sandbox.datamanager
  • org.eclipse.cosmos.dc.sandbox.datamanager.common
  • org.eclipse.cosmos.dc.sandbox.datamanager.client

MDR for SML repository (an example of an MDR, and can also be used to work with the SML repository provided by the *resource modeling subproject)

  • org.eclipse.cosmos.rm.sandbox.dataManager.sml

Example MDR that provides custom capabilities and operations:

  • org.eclipse.cosmos.dc.sandbox.datamanager.example
  • org.eclipse.cosmos.dc.sandbox.datamanager.example.common
  • org.eclipse.cosmos.dc.sandbox.datamanager.example.client

Test programs:

  • org.eclipse.cosmos.dc.sandbox.datamanager.test

Class Diagram


WSDM and Annotiations

Creating an MDR

Prerequisite: Import the framework bundles into workspace or install them in the target plaform. Note: org.eclipse.cosmos.rm.sandbox.dataManager.sml bundle is an implementation of an MDR that uses an SML repository as the backend datastore. Please refer to it as an example for creating an MDR. The following steps show how to create an MDR.

  • Create a plugin project. In the "Target Platform" section, select "an OSGi framework", and select "standard" from the dropdown box. Click next to provide plugin ID, name, etc, and click Finish.
  • Edit the MANIFEST.MF file in the Plug-in Manifest Editor. On the Dependencies tab, add the following dependencies and save the file:
    • org.apache.muse.complete
    • org.eclipse.cosmos.dc.sandbox.dataManager
    • org.eclipse.cosmos.dc.sandbox.mdr
  • Create a class in this bundle that provides the implementation of the
    • Annotate the class as a ManagedResource
    • Extend AbstractMDR class
    • Implement IDataManager and IMdrQuery (Although the superclass already implements these interfaces, we need this step as a temporary workaround for a bug in the management bundle.) The class signature looks something like this:
public class MyMDR extends AbstractMdr implements IDataManager, IMdrQuery
  • Implemnet methods declared in interfaces and abstract methods from super class. For example, the query method takes a CMDBf query as input. Provide adapter code here to parse the query, talk to the data source, and return the response in CMDBf response format. The logic for parsing the query, invocation of APIs of data source and transforming the query output to CMDBf query response can take place in another class or OSGi bundle.
  • An activator class is generated when the OSGi bundle is created. Open the Activator java file in the editor. COSMOS framework comes with an abstract activator that contains code required by the activators of all data managers. Make the following updates in the activator java class:
    • Remove the "start" and "stop" method stubs generated by the eclipse.
    • Make the Activator class extend AbstractDataManagerActivator
    • Implement the getDataManagerInstance abract method. The method will return an instance of the class that implements the capabilities. The activator will look like the following.
public class Activator extends AbstractDataManagerActivator {

	protected IDataManager getDataManagerInstance() {
		return new MyDataManager();

  • Provide data manager configuration file: add a file call in the META-INF directory. This file contains configurable parameters for the data manager. The keys in the properties files are defined as constants in the IDataManager interface. The config values can be retrieve from the data manager implementation class using the getConfigProperty method inherited from AbstractDataManager. Here is a template of the config file:
# URI of the management domain

# Resource ID of the management domain

# URI of the data manager EPR

# Resource ID of the data manager

# Display name of the data manager

# Classification of the data manager

# Dialect of the data manager
DIALECT=my dialect

=== Providing Custom Capabilities ===
A data manager can expose operations that are not part of the CMDBf specification by providing a custom capability and implementation.  The org.eclipse.cosmos.dc.sandbox.example.* bundles provide an example on how to create a data manager with custom APIs.  

The convention is to put code for the data manager in three bundles:
# API bundle: (e.g. org.eclipse.cosmos.dc.sandbox.example.common)  This "common" bundle is used by both the server and the client.  
# Implementation bundle: Server code that provides implementation of the custom capability.  
# Client proxy: remote API for the data manager.

A capability is declared as a Java interface.  (See org.eclipse.cosmos.dc.dataManager.example.api.ICustomCapability as an example.  Please note the following components in the capability interface:
* The interface declaration is decorated by the following annotation.  Namespace is declared as a public constant in the interface class.
* Methods are decorated by the @ManagedOperation annotation.  
* The URI and QName of each operation and their parameters are also declared in the interface.

The steps for creating the implemtation bundle is same as those used to create a basic MDR as described in the prvious section.  The difference is that the data manager implementation class will also implement the custom capability API in the class delaration, and provide the implementation in the class.

=== Client proxy for MDR and Data Manager ===
The org.eclipse.cosmos.dc.sandbox.dataManager.client and org.eclipse.cosmos.dc.sandbox.mdr.client bundles provide the client proxies for the data manager and MDR.  If the client applications is simply invoking the COSMOS data manager capabilities and the CMDBf query API from remote, these two client implementation is sufficient.  (See how a client application can use the proxies in the test code in org.eclipse.cosmos.dc.sandbox.dataManager.test.)

Subclass from MDRClient or DataManagerClient when you need to provide a client proxy of a data managner that provides custom capabilities.

=== Deployment ===

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