Tentative Subsystems

In order to move from the architectural concept to a design it is good the subdivide the functions of the system into smaller part. This is done to:

• separate resonsabilities,
• clarify specifications and interfaces,
• ensure modularity of the system,
• make a parallel design and implementation possible.

List of subsystems

A first basic list of possible subsystems is given below with a short description. Most of them are similar to services defined for distributed object systems (e.g. CORBA). Although the concepts are the same, the actual detailed design and implementation may, but is not required to, use any specific existing implementation. In the definition of interfaces, it is important to ensure compatibility with major implementations so that such ones easily could be used. On the other hand, the interface definition must be independent so that one is not forced to adopt a specific implementation.

1. Message: The subsystem provides message services which both allow peer-to-peer messages and broadcast to a list of subscribers. This includes event type messages and alerts.
2. Logging: This service offers centralized logging of both general information and errors.
3. Parameter: The specifications of the mechanism for parsing parameters from clients to application components. This includes both the structures (e.g. XML schemas) and the appropriate interfaces.
4. Manager: This is the center piece of the environment and provides functions such as:
   • software bus which connects different parts,
   • naming service for finding explicit services
   • management of containers
   • connection to other manages on other systems
   • scheduling of tasks
5. Container: It is responsible for the design of the different container and the corresponding interfaces offered to components (i.e. applications).
6. Client: This subsystems defines standard clients which provide access points for other systems (e.g. VO).
7. DataIO: It defines the interface to general data which can be shared between several processes or task. This may be simple access to disk files containing images or tables in different formats (e.g. FITS and VO) but also database and network access must be provided.

-- PrebenGrosbol - 20 Sep 2005
to top