[Info-vax] OpenVMS async I/O, fast vs. slow

[Arne Vajhøj]

On 11/3/2023 8:35 PM, Jake Hamby (Solid State Jake) wrote:
> Something else just occurred to me. While file I/O performance is
> important, as well as local IPC, I've also been keeping in mind
> something else: simultaneous socket connections. One benefit of
> everyone going to RESTful APIs is you're not keeping a long-lived TCP
> socket open like you would with other types of protocols.

HTTP does support keep-alive.

And RESTful web services do use that. Especially for high volume
server to server setups.

> There have been a lot of posts on my LinkedIn feed from IBM
> mainframers and they are more excited than ever about IBM's latest
> hardware which is very fast at running COBOL, Java, Go, C++, Db2,
> CICS, IMS, TSO/E, ISPF, Python. Technologies from every decade.
> 
> Mainframes are great for all the applications that are difficult to
> shard. Giant databases of bank transactions. I think software
> engineers want every problem to be something you can shard and
> parallelize to run in an AWS or Google cluster, but you can't do that
> with billions of lines of COBOL. But the reason everyone's still
> using that COBOL is that there's no real gain from rewriting it
> because the problems can't be solved in some new way.

There are banks switching from Cobol on mainframe to newer
technologies. Newer technologies that reduce cost significantly
and are more online/24x7 friendly. The benefits from changing
are there.

But so are the cost. The migration will cost a fortune. All the
bugs introduced when migrating such large code bases will have
a huge indirect cost. And the lost profits from not adding new features
while migrating could be huge also.

So only a few CIO's chose to actually migrate. Most CIO's chose to
create new stuff using new technologies and put new technologies in
front of the mainframe instead of replacing the mainframe. A part of
those in the latter category has a "we will migrate in
<current year + 5 years>" roadmap.

Arne