Thanks.
This is all ... overwhelming ... and amazing. Very nice.
I build packages from source, so I'm keen on following that where
possible. But it's gonna take some time.
-- R; <><
On 11/22/23 12:37, Rony G. Flatscher wrote:
Hi Rick,
On 22.11.2023 16:09, Rick Troth wrote:
Are you saying that you can call Java from ooRexx?
Yes.
How does that happen?
There is a DLL/shared object that can be linked by both, ooRexx and
Java. It allows for going either direction: call Java from ooRexx, but
also call ooRexx from Java or from any JVM language (you mentioned
Scala, Clojure, Groovy and friends, also the very first JVM language
NetRexx).
Do you spin-up a JVM running in standby mode?
ooRexx allows for libraries of Rexx/ooRexx code (named "packages"). If
that library gets called by any Rexx/ooRexx program it will check
whether a JVM is already running or not, if not, it will use the
DLL/shared object to demand load the JVM.
Do you run ooRexx in a JVM?
Yes, that is possible too.
I can call native code from Java, but always have to transit the JNI.
JNI gets used behind the curtain, but the Rexx or Java programmer will
never get to see JNI.
Never been able to go the other direction.
The ooRexx-Java bridge works in both directions.
The JVM is the single most difficult (for me, but I have lots to
learn) barrier to inter-language operation with Java (other than
Scala, Clojure, Groovy and friends which already run "in" the JVM).
The way to go from Java is via the Java scripting framework in the
Java package named javax.script (while the JSR-223 group developed
that framework I served as one of the experts). Here a Java example of
how to run a Rexx or ooRexx script, supplying arguments to Rexx and
fetching and showing the return Rexx result:
import javax.script.*;
public class TestCallRexx
{
public static void main (String args[])
{
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine se =
manager.getEngineByName("rexx");
String rexxCode = "say '(Rexx) argument from Java:'
arg(1) \n" +
"do i=1 to arg() /* iterate over
arguments */ \n" +
" say '(Rexx) arg #' i':'
arg(i) \n" +
"end \n" +
"parse version v /* Rexx
version */ \n" +
"say '(Rexx) parse version:'
v \n" +
"parse source s /* Rexx
version */ \n" +
"say '(Rexx) parse source:'
s \n" +
"/* get the operating system and version
via Rexx\n" +
" and return it within the following
string */ \n" +
"return 'from ooRexx:'
sysVersion() \n";
try
{
ScriptContext sc=se.getContext(); // get the default
ScriptContext
// add the fileName to the ENGINE_SCOPE bindings
sc.setAttribute(ScriptEngine.FILENAME, "TestCallRexx",
ScriptContext.ENGINE_SCOPE);
// add arguments for the script to the
ENGINE_SCOPE bindings
Object args4script[]=new Object[] {"one", "zwei",
"tre", "quatre"};
sc.setAttribute(ScriptEngine.ARGV, args4script,
ScriptContext.ENGINE_SCOPE);
// the RexxScriptEngine always compiles the last
script and makes it available with the getCurrentScript() method
Object o=se.eval(rexxCode,sc); // now let us
re-execute the Rexx script
System.out.println("(Java) received from Rexx: "+o);
}
catch (Exception exc)
{
System.err.println(exc);
System.exit(-1);
}
System.exit(0);
}
}
Here the output running the above Java program:
G:\test\java\jsr223>java TestCallRexx
REXXout>(Rexx) argument from Java: one
REXXout>(Rexx) arg # 1: one
REXXout>(Rexx) arg # 2: zwei
REXXout>(Rexx) arg # 3: tre
REXXout>(Rexx) arg # 4: quatre
REXXout>(Rexx) arg # 5: a Slot.Argument
REXXout>(Rexx) parse version: REXX-ooRexx_5.1.0(MT)_64-bit 6.05 22
Oct 2023
REXXout>(Rexx) parse source: WindowsNT SUBROUTINE TestCallRexx
(Java) received from Rexx: from ooRexx: Windows 10.0.19045
Not sure whether the formatting is distorted (used preview style).
You can supply any type of argument to Rexx and fetch any type of
return value from Rexx.
As you can see it is very easy to use from Java.
---
Here a sample that would automatically load the JVM in order to use
the Java class java.awt.Dimension:
dim=.bsf~new("java.awt.Dimension", 100, 200) /* create a Java
object */
say dim~toString /* will invoke the Java method toString */
::requires BSF.CLS /* ooRexx package (ooRexx-Java bridge) */
Here the output:
java.awt.Dimension[width=100,height=200]
As you can see, truly a Java object is being used from ooRexx, without
a need to know any of the Java syntax, just the documentation of those
Java classes. In the case of java.awt.Dimension cf. e.g.
<https://docs.oracle.com/javase/8/docs/api/java/awt/Dimension.html>.
The above oRexx program could also be executed via the Java scripting
framework as demonstrated above without a need to change anything in
the code.
---rony
On 11/17/23 10:00, Rony G. Flatscher wrote:
On 16.11.2023 22:54, David Crayford wrote:
I don't find ooRexx useful on the PC as it's basically on life support
where Python has millions of contributors. Take data validation as an
example. There is a first class library
https://docs.pydantic.dev/latest/.
Python isn't my favorite language by a large margin. But it is
useful so it
wins. Same same with Java. Personal preference is secondary to a
pragmatic
choice.
The combination of ooRexx [1] with Java [2] - on all platforms -
allows one to exploit all of Java (the Java runtime environment) as
a huge external class library for ooRexx. Unlike with Python there
would be no need to locate, choose and import specific modules with
the needed functionality, rather one can use the Rexx skills to
immediately exploit all of the Java functionality on all platforms.
It is hard to realize/assess the potential of this combination
without a little bit of curiosity and the will to learn new tricks.
---rony
[1] ooRexx download site:
<https://sourceforge.net/projects/oorexx/files/oorexx/>
[2] ooRexx-Java bridge (BSF4ooRexx850) download site:
<https://sourceforge.net/projects/bsf4oorexx/files/beta/20221004/>
On Fri, Nov 17, 2023 at 5:32 AM Seymour J Metz <[email protected]> wrote:
I find REXX extremely useful on PCs, but TSO/E REXX is a backwater
compared to ooRexx, and I would be tempted to use Java or Python for
complicated TSO scripts. But on z/Linux ooRexx with BSF4REXX is a
viable
option.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
עַם יִשְׂרָאֵל חַי
________________________________________
From: IBM Mainframe Discussion List <[email protected]> on
behalf
of David Crayford <[email protected]>
Sent: Thursday, November 16, 2023 4:02 PM
To: [email protected]
Subject: Re: External Functions in C on z/OS
I choose a language on capabilities rather than personal
preference. I’ve
been accused on this forum by my ex-colleague and pal Wayne
Bickerdyke of
having a pathological dislike of REXX. That’s not true, but I do
find it
less useful than other languages. Python has a useful library
called ctypes
which includes classes for mapping data structures with Python
classes. We
use BigEndianStructure for mapping control blocks
https://docs.python.org/3/library/ctypes.html#ctypes.BigEndianStructure.
It would be cool if the tooling that we worked on with Peter
Relson to
create C header files could be reused to generate Python mappings.
With the
recent zIIP offloading Python is strategic.
On 17 Nov 2023, at 12:38 am, Charles Mills <[email protected]> wrote:
Different strokes for different folks.
1. I was not aware of that pointer. This is the classic
documentation
problem. The answer is right there in the manual, clear as day --
provided
you know where to look. A lot of these answers are easy to find,
assuming
you already know the answer.
2. My code is running a complex Rexx environment that frankly I
do not
fully understand. (I didn't write it and it isn't "mine.") I
wanted to be
sure I had THE right environment block, not SOME environment
block. An
11-instruction assembler module seemed like a great solution. I still
believe that it was.
Charles
On Thu, 16 Nov 2023 11:31:20 +0800, David Crayford
<[email protected]>
wrote:
There's a TSO/E vector table that has the address of the REXX
routines.
// get the address of the TSO/e vector table
CVT * cvt = *(( CVT ** ) CVTPTR);
TSVT * tsvt = cvt->cvttvt;
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