IDMS Essentials

CA-IDMS Networks and Sets

Each CA-IDMS database consists of database records that are grouped into record types. A record type consists of the record's name, all of its elements, and the elements' attributes, such as data types and sizes. These record types are linked together through different logical groups called sets. Sets are defined to the schema.

A set is a logical relationship established between two or more named record types. One record type is the owner of the set and the other record types are members. Record types can belong to more than one set, so a record type can be both an owner of one set and a member of another. That same record type can also be a member of more than one set. These sets and their interweaving relationships make up a network and give CA-IDMS its network capabilities.

To move through the database, each record type contains pointers to other record types in its set or sets. Pointers identify the next record in the set and link the records together in a chain. There are three kinds of pointers:

Next pointer (required pointer): points to the next record type in the set, regardless of whether the record type is an owner or a member of the set.
Prior pointer: works the same way as the Next pointer except that it points to the prior record type.
Owner pointer: points from a member record type to the owner record type.

Through these pointers, a program can navigate through the network and travel a specific path through one or many sets.

The database administrator is responsible for defining record types and sets in the schema.

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