Using the UDS/SQL configuration on a virtual host

A UDS/SQL configuration can also be used on a virtual host. This enables the distribution rules to be defined independently of real host names. To permit fault-free UDS-D operation, the communications partners (DBH and user tasks) must be assigned to the virtual host. If more than one UDS/SQL configuration exists on a real host, these can execute on different virtual hosts in UDS-D operation.
It must be pointed out that you should assign a unique BCAM prefix for each UDS/SQL configuration using the DBH start parameter BCAM-PREFIX (see also section “Defining a prefix for user tasks in UDS-D distributions (BCAM-PREFIX)” in chapter "DBH load parameters"). The UDS/SQL configuration and application are assigned to a special virtual host using an entry in the BCAM configuration file for applications (the default file name is SYSDAT.BCAM.APPLICATIONS).

If the application is operated in openUTM transaction mode, the DCAM name with which the application can be addressed in transaction mode should also be assigned to the same virtual host.

Names of user tasks

DCAM applications whose names consist of a prefix and the TSN are created for UDS/SQL communication which is distributed with UDS-D between the user task and the remote configuration.
By default the name is SUD$tsn. This name complies with the naming convention in BS2000 (S=SYSTEM, UD=product abbreviation for UDS/SQL).

However, you can also specify the prefix of the name in the load parameter BCAM-PREFIX of the independent DBH at the start of a session. This enables the user tasks of different configurations to be distinguished on the basis of the BCAM prefix and also to be assigned to different virtual hosts (see also section “Defining a prefix for user tasks in UDS-D distributions (BCAM-PREFIX)” in chapter "DBH load parameters" ).

If a value which differs from the default value is specified for the load parameter BCAM-PREFIX, it is recommended that you use at least UDS-D V2.6 on all remote configurations which participate via UDS-D, also in those participating configurations which do not execute on virtual hosts, otherwise on configurations with older UDS-D versions bottlenecks can occur which can also hinder other DML processing.

Assigning the communications partners

The communications partners are assigned to the virtual host in the BCAM configuration file for applications (the default file name is SYSDAT.BCAM.APPLICATIONS). For details, please refer to the “BCAM” manual.

Example:

The local UDS/SQL configuration UKONF1, together with the applications assigned to it, is to be connected to the virtual host VIRT01. The applications in transaction mode are all addressed with the names APPLIK11 through APPLIK99.
In this constellation the DCAM applications which take over distributed communication between the application and the remote configuration should be assigned the BCAM prefix VKO1.

Name of the UDS/SQL configuration: UKONF1
Name of the virtual host: VIRT01
BCAM prefix for communication between application and DBH: VKO1
Names of the applications for transaction mode: APPLIK11, ..., APPLIK99

The following entries must then be made in the BCAM configuration file:

NEA UKONF1* VIRT01
NEA APPLIK* VIRT01
NEA VKO1* VIRT01

However, if a special BCAM prefix for UDS-D communication between an application and a remote UDS/SQL configuration is to be dispensed with, the following entry (specification of the default prefix) must be contained in the BCAM communication file instead of the last entry above:

NEA SUD$* VIRT01