Why transform z/Architecture Assembler to C#?

This research paper explores automated code transformation as a fit-for-purpose strategy for migrating existing z/Architecture Assembler (HLASM) code bases (originating on source operating systems like z/OS, z/VSE, z/VM, z/TPF, …).

Some of the topics discussed in this page include:

  • Some of the key business drivers for transforming z/Architecture Assembler to C#.
  • How Anubex’s CodeTurn makes this transformation possible, and the added value Anubex migration offers over other approaches.
  • A demystification of the migration process with a step-by-step look at the way z/Architecture Assembler can be transformed into working, maintainable C# code.
Reasons to choose C#

There are many good reasons to make the move to C# from z/Architecture Assembler, but the following are among the most often cited concerns for businesses:

  • High (and continuously increasing) mainframe maintenance and runtime fees.
  • Very strong vendor and platform lock-in.
  • A shortage of skilled mainframe Assembler developers (even more pronounced than for other more approachable mainframe technologies like COBOL, Natural, ADABAS).
  • A general lack of interest in mainframe technologies among younger developers.
  • Lack of (easy) application extensibility and interoperability .
  • Overall lack of agility (not being able to implement new business features in a timely fashion).

C# and the Microsoft .NET platform offer answers to all of the above concerns:

  • Support fees are negligible (or even non-existing, depending on the choices made).
  • C# is one of the most widely-used programming languages today, and it is the language of choice for instruction in the IT programs of many schools. Documentation of the language, software libraries, and development tools are also available free of charge.
  • C# and .NET are actively being developed by Microsoft and the product and its documentation are publicly available on the Internet (earlier versions were also official ISO/IEC and ECMA standards).
  • Interoperability with all Microsoft platforms and technologies is a given and portability to other platforms is being actively developed by Microsoft in the form of .NET Core; with the Mono project also providing cross-platform capabilities.

Next to that, moving to C#/.NET also means:

  • Enabling the use of a state-of-the-art IDE in the form of Visual Studio, with extensive debugging, refactoring, profiling and (unit)testing support.
  • Enabling the use of thousands of third-party libraries, covering almost all imaginable computing needs:  UI‑development, database interaction, web services, parsing, XML processing ,…
  • Enabling the use of modern application architectures (multi-tier, SOA or micro-service based) and deployment techniques (cloud, docker, …).


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