Re: Ada and JVM? Why not AdaVM?

[dvdeug@x8b4e53cd.dhcp.okstate.edu (David Starner)]

On Sat, 27 Jan 2001 16:47:45 -0000, chris.danx <chris.danx@ntlworld.com> wrote:
>Hi,
>    I'm curious to know why everyones so keen to stick Ada 95 on the JVM.
>Would a VM designed specifically for Ada 95 be of any benefit?  Or would it
>be a pointless exercise (considering the development of JGNAT)?

The advantages of the JVM are:

* Big name - everyone's heard of Java.
* There are a number of platforms that run JVM's that don't have an Ada 
  compiler ported to them.
* Allows you to run stuff in a web browser.
* Runs on the Java chip.
* Access to a huge API.

In comparasion, an AVM:

* No one has heard of it, and people would complain a lot less around
  here if everyone had heard of Ada in a positive light.
* AVM doesn't run on anything yet; written in C, you'll find it nearly
  as easy to port GNAT to anything gcc supports as port your AVM 
  (threading difficulties and the like); written in Ada makes it run on
  a subset of the platforms that Ada runs on. Java seems to be the only
  language that runs a significant number of platforms that Ada doesn't
  that supports threading, and besides performance problems, it's just 
  a little ironic . . . (Maybe Forth, but I'm not sure Forth's threading
  model would provide good support of Ada. You could portably emulate 
  threading in C or something, but that wouldn't be pretty.)
* You could make an AVM web plugin. Making a little bit more miserable for
  those of us who browse the web, and insuring that a large number of
  people (those who don't have compiled AVM plugins for their platform
  and those who don't care to download one) don't see it.
* The Ada chip is dead, and you'd lose a lot of flexibility designing 
  around it. ("Ada chip" = "the CPU of the computers Rational designed
  for running Ada". My knowledge of this is limited, so feel free to 
  correct me.)
* The API would be in direct proporition to the number of man-hours found
  to create and upkeep it. The Java API has had a lot of work put into
  it that will be hard to duplicate - the Classpath project has several
  years of work put into it, and they still have significant parts of the
  Java API unimplemented. Can you get even the level of support they have?

>I suppose I want to know the answer to the following.
>
>    Does Ada have a VM which serves a similar purpose to the JVM for Java
>(and is used in the same area)?

The JVM?

>    If not, why not?

No point? No need?

>    And would there be any benefits in the design of such a system?

Yes. You could make its quirks fit the quirks of Ada instead of those of
Java. It still doesn't outway the negatives.

-- 
David Starner - dstarner98@aasaa.ofe.org
Recovering from a hard drive "crash" - website down