[Info-vax] Real live example...

[Arne Vajhøj]

On 2/20/2023 11:14 AM, Jan-Erik Söderholm wrote:
> Den 2023-02-20 kl. 15:57, skrev Arne Vajhøj:
>> For a Cobol/VMS application there are multiple options:
>> 1) stay on Cobol/VMS
>> 2) change both language and platform like to Java/Linux (*)
>> 3) change just platform like to Cobol/Linux
>> 4) change just language like to Java/VMS
>>
>> Telia chose #2. They could have chosen #3.
>>
>> More companies pick #2 than #3. They want to get off
>> Cobol and if they need to start a huge migration project
>> to change platform then they want to change the language
>> as well (changes in some code due to different context +
>> changes to operations + full test + project overhead is
>> not that much smaller than change all code +
>> changes to operations + full test + project overhead).
>>
>> Note that the option VSI really want #4 is even rarer.
>>
>> :-(
>>
>> *) could also be C#/Linux or Go/Linux or polyglot/Linux
>> (like node.js for frontend and Java for backend all on Linux),
>> but Telia was supposedly Java.
> 
> It will be very interesting to follow this project.
> *If* it fails, it would be the first failed Java migration.

I assume you meant "not the first".

Big software migration projects are always risky.

My crystal ball provides the following probabilities:

20% it goes without problems
60% delayed and over budget but eventually succeed
20% fails

> One could think that a "mission-critical finance engine"
> would be a good target for a Cobol based platform...

Cobol can certainly do the job. It was what Cobol was
intended for. And Cobol has done that particular job
for a number of decades.

The main reasons behind the desire to move from
Cobol to Java are probably:
- easier to find developers
- easier integration with all sorts of new things
- faster implementation of changes due to more encapsulation
   and better tools
- an expectation of reducing the code base they have
   to maintain by utilizing various external libraries
   (random numbers: replace 1.5 MLOC of Cobol with
   300 KLOC of Java that uses external libraries for
   stuff that was one in Cobol before - those external
   libraries may be 25 MLOC of Java code, but Telia is
   not paying for maintenance of those)

Arne