[Info-vax] VMS Software: New US Mailing Address

[Jan-Erik Söderholm]

Den 2022-10-13 kl. 02:14, skrev Bill Gunshannon:
> On 10/12/22 19:22, Arne Vajhøj wrote:
>> On 10/12/2022 6:58 PM, Bill Gunshannon wrote:
>>> On 10/12/22 17:33, Arne Vajhøj wrote:
>>>> On 10/12/2022 4:20 PM, Bill Gunshannon wrote:
>>>>> Using a compatibility layer and trying to make PostGres look like
>>>>> RDB (or Oracle) would be a major mistake. Better to bite the bullet
>>>>> and move into the current century.
>>>>
>>>> It is a tradeoff.
>>>>
>>>> There are benefits from doing things the standard way instead of
>>>> doing it the compatibility way.
>>>>
>>>> But there are also huge cost of changing the client applications.
>>>
>>> Maybe and maybe not as much as you think.  Granted, most of my
>>> experience doing it has been with COBOL but I have been able to
>>> take programs using databases from other systems and moved them
>>> quite easily.  I would  love to have someone send me a COBOL
>>> program that uses RDB just for a look-see.
>>
>> Cobol embedded SQL is probably one of the more portable. But it is
>> not supported by PostgreSQL project itself.
> 
> No, but this is the Open Source world.  A need arose and someone
> rushed in to fill it.  And it works quite well.
> 
>>
>> An extremely simple Cobol embedded SQL to Rdb example:
>>    https://www.vajhoej.dk/arne/articles/vmsdb.html#rdb_cob_emb
> 
> I saw nothing in there that would not compile using ESQL and GnuCOBOL
> with PostGres.  Even the module stuff (which I am not familiar with)

Think of it as a compiler for a language called "SQL".
The default file type for these files (on VMS) is .SQLMOD

It's more or less "just" as a compiler for any other language.
And it creates a object files that are no different from any
other object file, may it come from C, Pascal or whatever.

That object file can then be linked into any other application
following the VMS calling standard. That other language does not
need to have any native support for Rdb, it just has to follow the
VMS calling standard.

It is just a function call with some parameters that returns some
defined result. The caller does not need to know that it was Rdb
that returned the result.