System componentsThere are the following types of clients (and services): Clients which can be used to perform operations on the bit repository, e.g. PutFile, GetFileServices which actively perform tasks without user triggering, e.g. Alarm Serviceto handle errors and notifications and Monitoring Service to assist in operation of the coordination layer.components in a BitRepository system: PillarsPillars are responsible for maintaining copies of the store material and providing bit preservation related operations on these There are the following types of pillars seen from the data perspective: - A full copy pillar, which contains full copies of delivered files identified uniquely with a service level agreement
- A checksum pillar (with specific checksum type), which contains derived copies of delivered files, in form of a checksum. The checksums are identified uniquely with a service level agreement in the same way as for full copies pillars.
The necessary information for clients, pillars and coordination layer is: - The Clients know how to communicate via the coordination layer. Knowledge of how to identify pillars is defined in the Service Level Agreement (possibly via certificate and psudoname)
- The Coordination Layer has no direct knowlegde of Pillars or Clients
- The Pillars know how to communicate via the coordination layer, and can respond to messages according to definitions of certification and possible operations as specified in Service Level Agreements serviced by the pillar.
All need for specific knowledge of components in the system, e.g. physical location of pillars, must be avoided. |