System Generation Statements › RESOURCE TABLE Statement—Defines a Resource Table › RESOURCE TABLE Statement Usage

RESOURCE TABLE Statement Usage

What are Resources

A resource is either a database or a node (system) from which requests for a database are forwarded. You specify a node name as a DESTINATION when:

• You don't know the ultimate target node or
• No physical communication link exists except for the DC/UCF system you are defining and the final destination node

Using Wildcards for Resource Names

You can use a wildcard character with the db-name and destination-name variables. For example, you could define:

ADD RESOURCE TABLE
 DBNAME IS MIS* VIA SYSTEM84

MIS* would be a single entry in the resource name table. At runtime, any request for a database name with MIS, would be matched with MIS* and routed to SYSTEM84.

Additionally, CA IDMS automatically generates the following entries as the last two entries in the resource name table:

DBNAME * LOCAL
DESTINATION *.

This ensures that all database requests are routed to the DC/UCF system you are defining.

Sequence of Resource Names is Important

CA IDMS generates entries in the resource name table in the order they are defined on the RESOURCE TABLE statement. This is important because the resource name table is searched from the beginning of the table to the end until a match is found. The first match CA IDMS finds in the resource name table is the node name it will use to locate the requested resource.

You should define specific resource names first and less specific resource names next.

If the resource is not located in the resource name table or the node name does not match the node name specified on the request, an error is returned to the application program.

Specifying Resources

The type of resource you specify is either a database or a destination (nodename). In most cases, you will specify a database name.

The only time you need to explicitly define a destination resource is when the target node is not defined using a NODE statement. This can be the case because:

• There is no direct communications path from the system being defined to the target system, thus requiring database requests to be routed through an intermediate node. If this is the case, you must define the target node as a destination resource and specify the intermediate node in its VIA parameter.
• Dynamic routing through DBGROUPs is used to direct database connections to any of several systems capable of processing the request. The default access method is used to access the dynamically selected target node. If this is the case, you must define the members of the DBGROUP as destination resources and specify the name of the DBGROUP in their VIA parameter. If the node names of all DBGROUP members follow a unique naming convention, then wild-carding can be used in the destination nodename to reduce the number of required definitions and to allow new members to be added without necessitating changes to the resource table.

Modifying the Resource Table

You can modify and delete individual entries in the resource table without deleting the entire resource table. Use the EXCLUDE clause of the RESOURCE TABLE statement to delete a specific DBNAME or DESTINATION entry from the resource table.

Use the MODIFY RESOURCE TABLE statement to add new entries to an existing resource table. Note that new entries added to the resource table on a MODIFY operation are added to the end of the resource table. To control the sequence of entries in the resource table when adding new entries to an existing resource table, you have to delete and then add the resource table; submitting the entries in the sequence you want them to appear in the resource table.

You can also modify the LOCAL/VIA option to change the location of a database name resource.