The DBB Git Migration Modeler utility

Description

This asset provides a guided approach to plan and migrate source codebase from MVS datasets to z/OS UNIX System Services (USS) folders, and helps to identify and document the boundaries of mainframe applications.

The main capabilities of the DBB Git Migration Modeler utility are:

• the identification of applications based on naming conventions applied to datasets members names
• the copy of source code files contained in datasets members to files on USS following a standard repository layout,
• the usage assessment of include files and submodules across all applications to understand application-level dependencies, documented in the Application Descriptor file,
• the generation of build properties based on existing types and configuration in the legacy SCM solution
• the initialization of Git repositories, pipeline templates and other configuration files related to the applications

The different phases of the migration workflow are described in the Migration Storyboard section.

How does it work

The DBB Git Migration Modeler comes with 3 main scripts:

• The Setup script is used to define parameters that will be used throughout the migration process with the DBB Git Migration Modeler. It must be executed first and once, to set the defined parameters and create a configuration file that will be used in subsequent steps.
• The Migration-Modeler-Start script runs the different phases of the migration process.
• The Refresh-Application-Descriptor-Files script can be used to refresh Application Descriptor files for applications that were already migrated to Git.

Required configuration

The DBB Git Migration Modeler is using two types of configuration information:

• Environment variables that are set up during the Setup phase.
• Configuration files, shipped in the samples directory that must to tailored to meet requirements.

The environment variables that are populated during the Setup phase are described in Setting up the DBB Git Migration Modeler configuration section. The different Configuration files are described in the Tailoring the input files section.

Cross-application dependencies and the Application Descriptor files

The DBB Git Migration Modeler utility is used to better scope applications' repositories and helps to understand dependencies between applications. After the execution of the Assessment Phase, the dependencies between applications are knwon and documented in each Application Descriptor file. For a given application, its Application Descriptor file lists:

• the other applications that are considered as dependencies (i.e., the build and the deployment of the given application cannot be correctly performed without these dependencies),
• the other applications that are consuming a service (either an Include File or a Submodule) that the given application provides

The Application Descriptor files are meant to also describe the list of artifacts belonging to their application. Artifacts are classed into groups, each group represent a type of artifact (COBOL programs, COBOL copybooks, BMS maps, etc.).

Migrations scenarios for the DBB Git Migration Modeler

The DBB Git Migration Modeler can support multiple scenario, from simple configuration to complex architecture. Complexity is generally due to the number of input datasets that contain sources.

In such situations, it is recommended to run the Framing phase multiple times, with different Applications Mapping files, that may contain different or potentially no naming conventions.

Different migration scenarios are described in the Migrations scenarios for Migration-Modeler-Start script section.