Chapter 20: Migrating from Mainframe Express 2.0

This chapter describes differences between Mainframe Express 2.0 and Mainframe Express 2.5 that might require you to make alterations in existing applications that you are migrating, or to change familiar methods of working.

20.1 Overview

The overall product shape of Mainframe Express 2.5 is very similar to that of 2.0.

20.2 Details

20.2.1 Assembler Option

In Mainframe Express 2.5 Assembler Option has been extended to provide:

• Support for the Assembler instruction ICTL.

• Support for the MVS macro CONVTOD, which converts the the date and time of day between formats. For more details see the online help: click Help Topics on the Mainframe Express Help menu, then on the Contents tab click Reference, Assembler Option, Macro Instructions and MVS macro instructions.

• Support for the DOS/VSE macro DTFCD, which you use to define a punched card file.

• Support for the CHANGE link file command, which enables you to change the names of external symbols in a module included in an executable file. For more details see the online help: click Help Topics on the Mainframe Express Help menu, then on the Contents tab click Reference, Assembler Option and Link file commands.

• Support for the following Linker directives:
  • COMPOSITE, which allows you to stop the Linker from automatically searching for an object file with the same name as the linker file.
  • NOEXPORT, which allows you to stop the Linker from making all CSECT names and entry names in the executable program available for other programs to call.

  For more details see the online help: click Help Topics on the Mainframe Express Help menu, then on the Contents tab click Reference, Assembler Option and Linker directives

• A new debugging aid called the Generalized Trace Facility. For more details see the chapter Using the Generalized Trace Facility in the Assembler Option Technical Guide.

• A Micro Focus extension to the DFHEISTG CICS Assembler macro; this is the keyword DSECT=Yes|No

20.2.2 CICS Option

In Mainframe Express 2.5 CICS Option has been extended to provide:

• Support for additional inter-system communication methods. For more details see the chapter Using CICS Option in a Client/Server Environment in the CICS Option Technical Guide.

• The option to use the catalog to store information about VSAM files. For more details see the chapter CICS Resource Definitions in the Administrator's Guide.

The impact is as follows:

• Mainframe Express 2.5 provides a new graphical user interface for maintaining system initialization tables (SITs) and this interface has additional fields that were not present in Mainframe Express 2.0. The interfaces for maintaining FCT entries and TCT entries also have new fields. The layout of resource definition files has changed to accommodate these fields. When you first open a SIT or an FCT entry that you maintained in Mainframe Express 2.0, CICS Option asks you if you would like to upgrade the resource definition file in use to the new layout. If you choose not to upgrade then the resource will be available read-only. If you choose to upgrade then any existing Mainframe Express 2.0 users will be unable to use the resource definition file. When Mainframe Express upgrades the resource definition file, it backs up the old file, displaying a message with the name and location of the backup file. If you then want to revert to Mainframe Express 2.0, you can recover the old resource definition file from the backup.

  The default resource definition file supplied with Mainframe Express 2.5 contains new resource definitions to support the running of applications that have been Web-enabled using EnterpriseLink. When a resource definition file is upgraded, the new resource definitions are added to it.

• New fields have been added to the CICS project settings and CICS system properties overrides to support the running of applications that have been Web-enabled using EnterpriseLink Component Generator. When you open an existing project in Mainframe Express 2.5, Mainframe Express upgrades the project file (.mvp) to include the new fields, and backs up the old project file, displaying a message with the name and location of the backup file. If you then want to revert to Mainframe Express 2.0, you can recover the old project file from the backup.

• You now configure CICS Option for IBM MQSeries® using the new graphical user interface to the SIT, or the CICS system properties overrides. If you have an existing project in which you have already configured CICS Option for MQSeries Version 2.0 using an XA interface table (XAT) entry, then CICS Option will behave accordingly unless you override the configuration details in the System Properties dialog box.

• In Net Express programs that make calls to the ECI, it is no longer necessary to include an initial call to dfhtexst to establish the ECI entry point names. Instead you link your progam to the library dfhtexst.lib at build time. However, there is no need to remove the initial call from existing programs.

In addition, CICS Option to CICS Option communications have changed in Mainframe Express 2.5, such that when security is specified on an ISC connection, the user ID and password are now converted to EBCDIC. As a result, if security is required you cannot connect a region from CICS Option in Mainframe Express 2.5 (or later) with a region from CICS Option in Mainframe Express 2.0 (or earlier).

20.2.3 Host Compatibility Option

In Mainframe Express 2.5, Host Compatibility Option provides the ability to check EXEC SQL statements included in copybooks for syntax errors. The default behavior is that EXEC SQL statements are checked for syntax errors. If you do not want EXEC SQL statements in copybooks to be checked, you should specify the compiler directive DB2(COPY).

20.2.4 SQL Option

In Mainframe Express 2.5, XDB Server runs as a service, that is, it starts automatically whenever you boot your machine, whereas in previous versions, you started it manually using a menu option. One result of this is that if you upgraded from Mainframe Express 1.1 to Mainframe Express 2.5 without changing the details of your client and server configuration, and you use the Win32Local protocol, there could be a mismatch between the name of the server in the server configuration and the name of the server in the client configuration. If you find that after upgrading, your client applications cannot connect to the XDB Server (that is, they receive a N511 error message), you should do the following:

1. Create a project that uses SQL Option:
   1. Click New>Project on the File menu.

   2. On the Create new project - optional features page of the Project Wizard, check SQL Option.

2. Find out your server's name:
   1. Click SQL For DB2>XDB Server on the Options menu.

   2. Press F5 to see the XDB Server Name.

   3. Press Escape twice

3. Use this name in the definition of the client:
   1. Click SQL For DB2>Client on the Options menu.

   2. On the Connect tab, change Server Name to the name seen in step 2b.

   3. Click OK.

After doing this, you should find that your applications can connect to the XDB Server.

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