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Programming with CCDS

The following components are needed to create and run applications with CCDS:

CCDS requires that the following environment variables are set:

CCDS data spaces are identified by a session name. A client that wishes to access a particular data space does so by calling the CCDS library function ccds_init with a session name as a parameter. During initialization CCDS searches for a /tmp/ccds_server_file_info.[session name] file. If this file exists, then a ccds_s server is already running on the machine for that session; otherwise, if the file is not found, a ccds_s server is spawned. A client can only access one data space at a time; however, two or more clients can run on the same machine and access different data spaces.

By default CCDS uses the /tmp path for permanent storage. For each session a /tmp/[session name] directory is created for that session. There is several ways to override the default value, listed here in order of selection:

  1. provide path as option to ccds_init call
  2. provide path in .ccfrc file in users home directory
  3. set optional environment variable: CCF_CCDSPATH

Clients should call ccds_leave before terminating. This ensures that resources are freed and also lets the ccds_s servers terminate when no clients are accessing the data space.

Soeren Peter Olesen (vss postdoc)
Wed Jan 7 14:44:20 EST 1998