Until version 7.1.2, each PowerCenter installation would contain at least one repository but might have contained more (if the customer had licensed more than one repository per installation).The Repository Server would maintain one Repository Agent per PowerCenter repository.
In those times, the communication between server components and Windows tools (Designer, Workflow Manager, Workflow Monitor, and Repository Manager) worked as follows:
Whenever a user tries to connect to a repository (e.g. in the Designer tool), the Windows PC running the Designer contacts the Repository Server with user name and password. If the combination of the two is valid in the requested repository, the Repository Server acknowledges the connection request and will accept other requests from that Windows PC (such as creating a flat-file source definition, saving changes to a mapping, and the like).
The Repository Service accepts many different kinds of such requests from its “customers” (client processes) and keeps the contents of the repository database intact and correct. It accepts logon requests, accepts requests to create new objects, accepts changes to existing metadata, and delivers information.
Whenever some task shall be executed, the PMServer is requested to start something (e.g. by clicking Workflows à Start Workflow in the Workflow Manager, starting a workflow in the Workflow Monitor, or by some enterprise scheduling system like Autosys). If this “something” is a session, the PMServer starts a new process to run the executable pmdtm (resp. exe on Windows); the pmdtm process connects to each source and target system (except for local files) or lookup databases. It coordinates transformation of data during the data load, writes all kinds of messages to the session log, and so on. When the session finishes, the pmdtm process writes statistic information about the session execution into the repository (by requesting the Repository Service to store these data) and terminates.
When a user wants to import e.g. a table structure from a relational database, an ODBC connection on the Windows PC running the Designer tool is needed. Usually a system administrator must set up the respective 32-bit “ODBC Data Sources” on the Windows PC. Once the connection is set up (in most cases using some of the ODBC drivers which are part of the installation of the PowerCenter client tools), a user only needs a user ID and a password to connect to the respective database.
The PMServer process never connects to source or target systems on its own. This is always done by a pmdtm process.
Read more//Stay tuned for: Exploring the general structure of PowerCenter – Part 3