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A server mapping file (SVM) enables the RPC server to correctly support special COBOL syntax such as REDEFINEs, JUSTIFIED, SYNCHRONIZE and OCCURS DEPENDING ON clauses, LEVEL-88 fields, etc. If one of these elements is used, the EntireX Workbench automatically extracts an SVM file in addition to the IDL (interface definition language), or an SVM file is generated by the COBOL Wrapper for a server skeleton. The SVM file is used at runtime to marshal and unmarshal the RPC data stream.

This document covers the following topics:

• SVM Files in the EntireX Workbench

• SVM Files in the RPC Server

• Source Control of SVM Files

• Change Management of SVM Files

• Compare SVM Files

• List Deployed SVM Files

• Check if an SVM File Revision has been Deployed

• Access Control: Secure SVM File Deployment

• Ensure that Deployed SVM Files are not Overwritten

• When is an SVM File Required?

• Is There a Way to Smoothly Introduce SVM Files?

SVM Files in the EntireX Workbench

In the EntireX Workbench, an SVM file has to relate to an appropriate IDL file. Therefore, you always have to keep the IDL file and the SVM file together in the same folder.

If there is an SVM file and a corresponding IDL file,

• at least one of the IDL programs in the corresponding IDL file requires server-mapping information to correctly call the target server. For those IDL programs, there is an SVM entry (line) in the Workbench SVM file.

• deployment of the SVM file to the RPC server is mandatory, see Server Mapping Deployment.

If there is an IDL file but no corresponding SVM file,

• there is no IDL program that requires server mapping information.

SVM Files in the RPC Server

Under z/VSE, SVM entries of the EntireX Workbench SVM files are stored as records within one VSAM file (containing all SVM entries from all Workbench SVM files). The unique key of the VSAM file consists of the first 255 bytes of the record: for the type (1 byte), for the IDL library (127 bytes) and for the IDL program (127 bytes). The CICS, Batch and IMS RPC servers use a VSAM file as the container.

If one server requires an SVM file, you need to provide this to the RPC server:

• Development environments: to allow the deployment of new SVM files, enable the deployment service. See Enabling the Deployment Service.

• Production environments: provide SVM files to the RPC server. See ERXMAIN macro parameter SVM.

If no server requires an SVM file, you can execute the RPC server without SVM files:

• Development environments: you can disable the deployment service. See Disabling the Deployment Service.

• Production environments: there is no need to provide SVM files to the RPC server. See ERXMAIN macro parameter SVM.

Source Control of SVM Files

Because SVM entries within an SVM file contain text data only, a Workbench SVM file is text-based (although it is not intended for human consumption). Therefore, you can include it in your source control management together with the IDL file and the COBOL source(s) as a triplet that should always be kept in sync.

Change Management of SVM Files

Under z/VSE, change management for a VSAM file (SVM container) is similar to change management for a database. The complete VSAM file can be backed up at any time, for example by using IDCAMS. All updates to the VSAM file done after a backup must be kept.

All Workbench SVM files added since the last backup should be available.

Compare SVM Files

For SVM files in the EntireX Workbench format, you can use a third party file/text compare tool to check if two files are identical.

The SVM entries (corresponding to lines in a Workbench SVM file) contain a creation timestamp at offset 276 (decimal) in the format YYYYMMDDHHIISST. The precision is 1/10 of a second.

List Deployed SVM Files

Use IDCAMS:

* $$ JOB JNM=VSAMPRNT,CLASS=0,DISP=D
* $$ LST CLASS=A,DISP=K
/* ------------------------------------------------------------ */
/*  PRINT CONTENT OF AN SVM VSAM CLUSTER                        */
/* ------------------------------------------------------------ */
// JOB VSAMPRNT
// DLBL ERXSVM,'ENTIREX.SVMDEV.KSDS',0,VSAM,CAT=VSESPUC
// EXEC IDCAMS,SIZE=AUTO
   PRINT INFILE(ERXSVM) CHAR
/*
/&
* $$ EOJ

Check if an SVM File Revision has been Deployed

SVM entries (corresponding to lines in Workbench SVM files) contain a creation timestamp at offset 276 (decimal) in the format YYYYMMDDHHIISST. Precision is 1/10 of a second. The creation timestamp can be checked.

The timestamp can be found on the same offset in the records in the VSAM file (SVM container).

Access Control: Secure SVM File Deployment

For deployment with the Server Mapping Deployment Wizard, use EntireX Security if the broker is running on platforms z/OS, UNIX , Windows or z/VSE. See Enabling the Deployment Service.

For IBM deployment tool IDCAMS, use RACF to secure deployment.

Ensure that Deployed SVM Files are not Overwritten

For IDCAMS, use the NOREPLACE option to disallow overwriting of duplicate SVM records in the VSAM file (container). See Server Mapping Deployment using FTP and IDCAMS.

When is an SVM File Required?

For the IDL Extractor for COBOL

For the COBOL Wrapper

This depends on the interface type chosen and the IDL type:

Is There a Way to Smoothly Introduce SVM Files?

All EntireX RPC servers can be executed without SVM files. There is no need to install the SVM container (see SVM Files in the RPC Server) as long as you do not use features that require SVM files (see When is an SVM File Required?). You can also call COBOL servers generated or extracted with previous versions of EntireX mixed with a COBOL server that requires SVM files. All EntireX RPC servers are backward compatible.

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