JWS and Java CommAPI: any working examples please?
Hi all,
(sorry for the length of this post, but I hope that the completeness will help)
I have tried for some time to get the Java Communications API to work with JWS,
but have failed in all my attempts.
First, I am hoping that someone posts a reply that he/she has a working configuration, and
is willing to share it.
Second, I will describe what I have tried so far, and hope that someone can point out
what I still can try differently.
As you may or may not know, the Comm API (2.0) requires three files to be `available' on the
client machine: a JAR (comm.jar), a DLL (win32com.dll - I have so far only tried this under NT4.0)
and a properties file (javax.comm.properties - containing the line Driver=com.sun.comm.Win32river)
For a "standard" install, not using JWS the JAR goes into JRE\lib, the DLL into JRE\bin and
the prop-file into JRE\lib as well. This works fine. I can then access the Chipcardreader on COM2
without problems.
Now comes JWS.
I deploy comm.jar in the usual way.
I pack win32com.dll into win32com.jar (in the `root' of this file
as the spec says about loading native libs. Then at first I decided that the prop-file should
in principle also not be pre-installed on the client machine, so at first I naively packed it
in the win32com.jar (either in the root or as lib/javax.comm.properties).
When I do this I get a "NullPointerException: name can't be null" the first time the
code tries to CommPortIdentifier.getPortIdentifier("COM2").
I studied this carefully and after some debugging decided that probably the properties
file was the problem. I came to this conclusion since my debugging code was able
to load the classes from comm.jar without problems (by using the classloader obtained
by this.getClass().getClassLoader), and to load the native library
win32com.dll as well (by calling System.loadLibrary("win32com")).
The next step was to put the properties file on the client, in JRE\lib. This dramatically changes
the message I got: "NullPointerException: name can't be null while loading
com.sun.comm.Win32Driver". Thus the properties file is found, but loading the driver
failes for some 'name' is still null.
Needless to say I attempted the same with a non-existent drivername, I then got
"ClassNotFoundException: while loading <name of driverclass>"
Another attempt was made where the DLL was in JRE\bin and not deployed thru JWS (only
comm.jar was in the comm.jnlp extension file), giving the exact same result as above where
the DLL is deployed in a JAR by JWS.
So: I have the properties file where the API reads it, I have comm.jar where the API
can find the com.sun.comm.Win32Driver.class (see the ClassNotFoundException if I change
the name of the driver) and I have the DLL in a place where a simple call to System.loadLibary()
can load it (changing the name yields an Exception, I tried) -- but still no success.
This describes the attempts. Some more context:
The app is deployed through a couple of signed JAR's (certificate signed by an official CA)
that are listed in one jnlp. I have tried deploying the Comm API in the same .jnlp file
and as an extension .jnlp file: no difference. (Probably no difference as all jar's are signed
by the same ceritificate, comm.jar from Sun is not signed so I sign it with our own cert.)
Any reasonable suggestions very much appreciated!
Paul
