Tutorial: Application Migration - Adding Function Emulation

This tutorial takes you through the process of migrating a DB2 application to a SQL Server application, using HCOSS to add function emulation.
This tutorial demonstrates adding function emulation by taking you through the process of:
  • Adding math functions to SQL Server that represent standard math functions in DB2.
  • Mapping the DB2 functions to the new SQL Server functions using the Customize SQL Name Mapping tool.

This tutorial also demonstrates binding the application using a post-build event in Eclipse.


Before attempting this tutorial, you must first complete the following tutorials to ensure you have an established SQL Server database named HCO_Test containing the required PROD and TEST schemas and a connection to the HCO_Test database:
  • Tutorial: Create a SQL Server Database
  • Tutorial: Create a Database Connection
  • Tutorial: DB2 Database Migration or Tutorial: Setup for Application Migration Tutorials

Eclipse Project

The Eclipse project we provide for this tutorial contains the FunctionEmulation project, which is a native COBOL project.

Phase 1: Create User-Defined Functions

  1. Launch SQL Server Management Studio, and select the HCO_Test database.
  2. Navigate to and open the FunctionEmulation.sql file, located in the %PUBLIC%\Documents\Micro Focus\Enterprise Developer\Samples\Mainframe\Eclipse\SQL\hcoss\FunctionEmulation directory.

    This file contains a script that creates some user defined math functions needed by the example code.

  3. Click Execute.
  4. From the Object Explorer expand and select HCO_Test > Programmability > Functions > Scalar-Valued Functions and Refresh this folder. You should now see the newly created functions.

Phase 2: Start Enterprise Developer and HCO for SQL Server

If Enterprise Developer and HCOSS for SQL Server tools are already running, skip this phase.

  1. Start Enterprise Developer as an administrator. This procedure varies depending on your Windows version. If you need instructions, see To start Enterprise Developer as an administrator.
  2. In Eclipse, click Run > Tools > HCO for SQL Server.

Phase 3: Map the Functions for HCOSS

  1. From the HCO for SQL Server interface, click Customize SQL Name Mappings.
  2. Scroll to the bottom of the grid and double-click in the first empty cell to activate it for editing. Type the following information in the appropriate rows and columns, and check the corresponding Is Function box for each:
    DB2 Function/Special Register SQL Server Equivalent
    atanh dbo.atanh
    cosh dbo.cosh
    sinh dbo.sinh
    tanh dbo.tanh
  3. Click Save to save the mappings.

Phase 4: Analyze, Build, and Bind the Native Application

Analyze the Native Application
  1. From the Eclipse IDE, click File > Import.
  2. Expand General, and select Existing Projects into Workspace; then click Next.
  3. Select Set root directory; then browse to the %PUBLIC%\Documents\Micro Focus\Enterprise Developer\Samples\Mainframe\SQL\hcoss\FunctionEmulation directory, and click OK.
  4. On the Projects list, check FunctionEmulation.
  5. Check Copy projects into workspace.
  6. Click Finish. Eclipse loads the project and builds it automatically.
  7. From the COBOL Explorer, expand FunctionEmulation > COBOL Programs; then double-click the FunctionEmulation.cbl file to view its contents.Pay particular attention to the EXEC SQL statement that references the user-defined functions.
  8. Close the code editor.
  9. Open the project properties for the FunctionEmulation project.
  10. Expand Micro Focus > Project Settings > COBOL; then select SQL Settings. Several OpenESQL compiler directives have been set for you. The following table offers a brief description of each:
    SQL(TARGETDB=MSSQLSERVER) Target database is SQL Server
    SQL(DB=HCODemo) SQL Server connection name is HCODemo
    SQL(DIALECT=MAINFRAME) HCOSS database syntax conversion is enabled
    SQL(DBRMLIB) EXEC-SQL commands are extracted and placed in database request module (DBRM)
    SQL(INIT) Initiates the database connection
    SQL(NOCHECK) No SQL compile-time checking performed
    SQL(BEHAVIOR=OPTIMIZED) Optimizes migration process
Define a Post-Build Event
  1. In the Properties window, expand Micro Focus > Build Configurations > Events.
  2. In the Post build event command line field, type the following command:
    DSN SYSTEM(HCODemo) @"FunctionEmulation.hcodsn"

    This command calls the DSN Bind utility, specifies the SQL database connection to use, and states the location and name of a bind script file. Eclipse executes this event immediately after building the application, automatically binding the application at that time.

  3. Click OK. Eclipse builds the native application automatically.
View the Contents of the Bind Script File
  • From the COBOL Explorer, open and review the content of FunctionEmulation.hcodsn. This bind script file contains one BIND PLAN command that binds the FunctionEmulation member into a plan named FunctionEmulation.
Verify the Results
  1. Using Microsoft SQL Server Management Studio, connect to your SQL Server instance.
  2. On the Object Explorer, expand Databases > HCO_Test > Programmability > Stored Procedures to see the stored procedures HCOSS created when you executed your packages and plan.
  3. Open one of the stored procedures that contains PLN as part of its name.

    In this, you see your application code making the calls to the user-defined functions.

Phase 5: Run the Native Application

  1. From the COBOL Explorer, open the FunctionEmulation.cbl source file.
  2. Set a break point on the line containing if sqlcode = 0.
  3. Click Run > Debug to start debugging.
  4. If prompted with the Debug As dialog box, select COBOL Application; then click OK.
  5. When prompted to open the Debug perspective, click Yes.
  6. Click Resume to continue to your breakpoint.

You should see from the output that the results are calculations performed by your user-defined functions.

Note: If the output window is not visible, minimize Eclipse to reveal it.

This completes the tutorial.