It seems to me that maven is doing something perverse here. Usually
there are two options for invoking an ordinary (i.e. non-main()) Java
method: from within a Java program, one calls the method directly, and
gets the result as the method's return value; when running from the
command line, one invokes the main() method, which in turn calls the
ordinary method, and one gets the result as the process exit status.
With Ramon's configuration snippet, maven is not doing either of those
typical things. Instead, it invokes main() from within a Java program,
and then doesn't (and can't possibly) handle it gracefully when main()
calls System.exit().
exec-maven-plugin has two goals:
* exec:exec execute programs and Java programs in a separate process.
* exec:java execute Java programs in the same VM.
Ramon was using exec:java, but it looks like exec:exec would be more
appropriate.
That said, empirically I observe that if a program is invoked from the
command line and main() throws an exception, then the Sun JVM exits with
a status of 1, whereas in the case of normal termination its exit status
is 0. I don't know if that's part of the spec or if it's guaranteed to
be the case for all JVMs. If all we need is an indication of success or
failure, as opposed to a detailed error code, then you could throw an
exception rather than calling System.exit() and maybe it would be
handled more gracefully by maven.
-Aaron
On 06/30/2010 12:34 PM, Marshall Schor wrote:
On 6/29/2010 10:49 PM, Philip Ogren wrote:
It turns out that the main method of org.apache.uima.tools.jcasgen.Jg
was, in version 2.2.2, a single line of code which called a method
called main0. In version 2.3.0 there are two lines of code - the
second is a call to System.exit.
This line was added under https://issues.apache.org/jira/browse/UIMA-853
where users were complaining that shell scripts that ran JcasGen didn't
get notified if the run failed.
I wonder if there's a better way to solve this Jira that doesn't have
this other side effect - any ideas?
-Marshall
This was the source of my problems and explains (sort of) why eclipse
was actually crashing silently when I updated the dependency on uima
in my pom.xml file to version 2.3.0.
My workaround is to simply introduce a local class whose main method
only has the one line of code and I call that class instead.
Ramon, thanks again for the pom.xml snippet. We actually use the
execution phase "process-resources" or "process-test-resources"
depending on the scenario and that seems to work fine for us.
Philip
On 6/18/2010 2:50 PM, Philip Ogren wrote:
Hi,
We have been using a snippet for our pom.xml file pretty much exactly
like the one below to run JCasGen on our type system descriptor
before compilation. When I switched to 2.3.0 this doesn't work
anymore. For example, when I run "mvn test", JCasGen will generate
the files but then maven just exits without an error message and
without running the tests. If I remove this block of xml from the
pom, then everything works fine.
Any thoughts about how I would go about fixing this? Or, does anyone
have another snippet of xml I could insert into my pom.xml to get the
same behavior?
Thanks,
Philip
On 7/6/2009 7:58 AM, Ramon Ziai wrote:
Hi,
just as a follow-up to this, I found a solution to this that works for
me. Here's the relevant POM snippet, in the hope that it will be useful
for others:
[...]
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.1</version>
<executions>
<execution>
<phase>validate</phase>
<goals>
<goal>java</goal>
</goals>
</execution>
</executions>
<configuration>
<mainClass>org.apache.uima.tools.jcasgen.Jg</mainClass>
<arguments>
<argument>-jcasgeninput</argument>
<argument>desc/yourTypeSystem.xml</argument>
<argument>-jcasgenoutput</argument>
<argument>src/main/java</argument>
</arguments>
</configuration>
</plugin>
[...]
This will run JCasGen prior to the compile phase, ensuring that build
dependencies are satisfied. JCasGen is run without the merge
capability,
so manual changes to the generated Java files will be lost.
Best,
Ramon
Александър Л. Димитров schrieb:
Hello,
I'm currently working on a distributed project involving UIMA. At
this stage,
sometimes modifications to the UIMA descriptor files are absolutely
necessary
and, unfortunately, this confuses our VCS. Whenever JCasGen is run
from within
Eclipse or similar, it updates *all* generated class files, which
leads the VCS
to treating them as new commits. The problem here is, when editing the
descriptors on different branches, while the merging of the
descriptor files
goes well most of the time, the merging of the class files fails
most of the
time. This leaves the merger with several dozen conflicts.
The current policy is to then just delete those files and run
JCasGen on the
merged branch. Of course, the actual problem here is, that one
shouldn't really
track those files in the first place.
But the matter is slightly more delicate. After checking out the
project from
version control, the project should be readily compilable, without
further
setup. That's why we're using Maven to fetch all dependencies and
automate the
build process. Without having these files in source control, they
have to be
generated first.
So the real question is: is there any way to run a JCasGen from
within the Maven
build? Probably a plugin? Of course, one could just spawn a process
to call
org.apache.uima.tools.jcasgen.Jg, but I wanted to ask if such a
thing already
existed.
Thanks,
Aleks
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