OpenCCM - Writing the XML meta files

Table of Contents

Warning: The OpenCCM User's Guide is now split into the following documents:

  1. OpenCCM User's Guide home page
  2. The OpenCCM's Compilation Chain
  3. Generation and implementation rules
  4. The OpenCCM's Execution Chain
  5. Demonstrations
  6. Writing an application with OpenCCM
  7. Writing CCM XML meta files

Writing CCM XML meta files

Conforming to the CCM specification, you should have to provide three kinds of meta files, since the Corba Component Descriptor will be generated from CIDL.

  • The Component Assembly Descriptor: <assembly>.cad

    This is the main descriptor you must take care about when setting up a distributed application. It allows you to point out which packages will be involved, which Component Servers will be the targets for the homes, and which connections to do at deployment time.

    The actual version of OpenCCM's deployment tool (ccm_deploy) supports hostcollocation and processcollocation. That means you can describe your partitioning with these features, using homeplacement.

    The destination tag is simply used to mention the Component Server registered with the Naming Service.

    For each homeplacement, you select packages using a componentfileref refering to pre-defined packages. This is done in the componentfiles part of the file, using componentfile tags that will point to CSD files.

    Another important part is the connections one. For each connectinterface or connectevent you have to operate, you must simply fill the tags with references to components (with componentinstantiationref pointing the IDs defined in partitioning), and identifiers to specific connectors: usesidentifier, providesidentifier, consumesidentifier, publishesidentifier.

  • The Software Package Descriptor: <package>.csd

    This descriptor provides every information concerning a particular package: IDL reference, various implementations for specific languages, OS, compilers...

    Again, the OpenCCM's deployment tool does not need/support each of the tags from the CCM specification. Meta informations such as title, license, author,... are not used by the deployment tool, but should be filled in order to share components.

    At current stage, the ccm_deploy tool supports ONE implementation tag; that means you should need more than one CSD file in case of testing various OS, for example.

    The important tags are the fileinarchive and entrypoint contained in code. They refer to the JAR file containing your business code, and to the public static create_home method of the implementation.

  • The Property File Descriptor: <file>.cpf

    Setting properties on components is done using this meta descriptor. In CCM specification, you should be able to refer a properties file anywhere in the Assembly Descriptor, at home level or component level, or in the Software Package Descriptor, at package level or implementation level.

    The OpenCCM's deployment tool remains quite limited on properties. First, it only looks for a propertyfile reference into the Component Assembly Descriptor, at component level. Second, it only accepts simple tags describing string values.

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