The Whole Java/iX FAQ

Last changed on Mon Jan 10 14:18:10 2000 PST

(Entries marked with ** were changed within the last 24 hours; entries marked with * were changed within the last 7 days.)

1. General information and availability

2. Installing Java/iX

8. Common problems

99. Other

1. General information and availability

1.1. What versions of Java are available for MPE/iX

Version 1.1.5 was shipped with MPE/iX 6.0. Version 1.1.7B is being distributed via Jazz, and will also be released as a 6.0 patch (JAVKXQ8). Version JDK 1.2 is at a limited number of beta sites.

^ Last changed on Fri Apr 16 11:25:35 1999 by Mike Yawn

1.2. Is there an RMI Java server available for the HP 3000?

Java for the HP 3000 includes the standard RMI functionality. This includes the rmiregistry, which is used to register services. You can write application-specific servers that register their presence with the registry and then handle client requests.

The ServerImpl class in the TurboIMAGE Class Library is an example; it provides remote data base access to TurboIMAGE databases.

I'm not aware of any generic RMI server programs, but if any are available that are implemented completely in Java, then I would expect them to run on the HP 3000.

^ Last changed on Wed Dec 1 11:56:03 1999 by Mike Yawn

2. Installing Java/iX

2.1. How can I run tools like jar or javadoc from the CI prompt?

Here is an example how to look at a jar file's contents, and an example how to generate the javadoc documentation for a given class: 
:java "sun.tools.jar.Main -tvf mytest.jar"
:java "sun.tools.javadoc.Main -author -version MyClass"
As of Java/iX 1.1.7 the quotation marks are no longer required.

It might be helpful to place a command file like the one given below somewhere along your HPPATH (only jar example shown): 
anyparm x
java "sun.tools.jar.Main !x"
Calling the above command file should allow the following use: 
:jar -tvf mytest.jar
Notice the use of anyparm to prevent the need for enclosing "".

^ Last changed on Mon Mar 29 17:05:45 1999 by Lars Appel

8. Common problems

8.1. Why do I get 'exec function failed' when I run Java?

This is a very generic error message, which will result from any failure to run the java executable.

On JDK 1.1.5 and prior releases, the most common cause was incorrect permissions on the java program files or libraries. In particular, the shared libraries in /lib and /usr/lib frequently did not have permissions set to allow any user to have access. To fix this, as MANAGER.SYS type: 
:xeq /bin/chmod "755 /lib/libc.sl /lib/libm.sl"
:xeq /bin/chmod "755 /usr/lib/libsocket.sl"
You will also this error if you attempt to run Java without PH capability from within the POSIX shell.

^ Last changed on Tue Mar 30 15:26:09 1999 by Mike Yawn

8.2. Why do I see 'jit disabled' messages when I run Java?

First, this is just a warning message; the java class you're trying to execute should run normally, albeit slower than if the jit was available. (jit = just-in-time compiler)

There are two possible reasons for this, and the exact message you see will indicate which of the two cases are true.

If you see a message about PA 1.0 hardware detected, it means the system you're running on is an older system based on revision 1.0 of the PA-RISC architecture. PA 1.0 machines are the 950, 955, 960, 980; 925, 935, 949; 922, 932, 948, and 958. The just-in-time compiler requires at least a PA 1.1 architecture to operate.

If you see a message about not having a floating-point coprocessor, it means the system you're running on does not have a floating- point coprocessor, which is required for the jit to operate. All currently-produced PA-RISC machines have floating-point coprocessors standard, but the coprocessor was optional in many older machines.

^ Last changed on Tue Mar 30 15:36:39 1999 by Mike Yawn

8.3. Java Native Interface and HP C/iX versus GNU gcc

When trying to implement native method calls using JNI and the HP C/iX compiler, I get the following error during compile... 
cc: "/usr/local/java/jdk1.1.5/include/mpe/jni_md.h",
line xx: error 1642: Duplicate type specifier "long": ignored.
The same code compiles fine with the unsupported GNU gcc.

The HP C/iX compiler (at least at present) does not seem to support the "long long" data type. The following workaround might get you around the error, but -of course- it might not be a good idea, if jlong variables or parms are actually used...

Tweak for /usr/local/java/latest/include/mpe/jni_md.h file: 
#ifdef __GNUC__
typedef long long jlong;
#else
typedef double jlong;
#endif
You might prefer to create a local copy of jni.h and jni_md.h and tweak that copy instead of the original file. Just make sure to make those copies visible along your include file path (for example by adding a -I. compiler option).

(also see SR 1653288555 in HP's bug tracking system)

^ Last changed on Wed Aug 18 05:35:13 1999 by Lars Appel

99. Other

99.1. How can I scroll back longish Java output in my DOS Window?

When developing Java code on Windows 95 or NT, I sometimes get longish Java output or StackTrace information that scrolls off the DOS window top. In my HP 3000 terminal or emulator I could simply scroll back the buffer to view those additional lines.

Can I increase the DOS window buffer and/or add scrollbars?

Yes, you can. Simply choose the Properties item from the window menu (the small MSDOS icon in the left of the title bar) and change the Screen Buffer Height in the Layout tab to more than 25 lines.

You just have to make the above adjustments before the longish Java output messages occur. On the other hand, you can also adjust the default Screen Buffer Height by changing the Properties of the Shortcut or Start Menu item that launches your DOS window(s).

^ Last changed on Mon Jan 10 15:18:10 2000 by Lars Appel

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