Loading a DLL in MATLAB through JAVA

Hi,

I have a running application in Mathlab, that also uses some C DLL files.

I have created a JAVA package using the JA builder of mathlab functions. Then I put the DLLs in the JAVA main project folder.

I could invoke any method that doesnt use the DLL and it works fine. But whenever I invoke a method that uses the DLL files, it crashes and here is the stacktrace.

{??? Error using ==> loadlibrary at 477 FAiled..Error using ==> loadlibrary at 477 There was an error loading the library There was an error loading the library "C:\Users\AUG\Documents\Backup\SourceTracing\epanet2.dll" "C:\Users\AUG\Documents\Backup\SourceTracing\epanet2.dll" Undefined function or variable 'epanet2_proto'. Undefined function or variable 'epanet2_proto'.

Error in ==> epanetloadfile at 31

Caused by: Error using ==> feval Undefined function or variable 'epanet2_proto'. } ... Matlab M-code Stack Trace ... file C:\Program Files\MATLAB\R2010b\toolbox\compiler\mcr\matlab\general\loadlibrary.m, name loadlibrary, line 477. file C:\Users\AUG\AppData\Local\Temp\AUG\mcrCache7.14\Source12\SourceTrace\epanetloadfile.m, name epanetloadfile, line 31. com.mathworks.toolbox.javabuilder.MWException: Error using ==> loadlibrary at 477 There was an error loading the library "C:\Users\AUG\Documents\Backup\SourceTracing\epanet2.dll" Undefined function or variable 'epanet2_proto'. at com.mathworks.toolbox.javabuilder.internal.MWMCR.mclFeval(Native Method) at com.mathworks.toolbox.javabuilder.internal.MWMCR.access$600(MWMCR.java:23) at com.mathworks.toolbox.javabuilder.internal.MWMCR$6.mclFeval(MWMCR.java:902) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.mathworks.toolbox.javabuilder.internal.MWMCR$5.invoke(MWMCR.java:800) at $Proxy0.mclFeval(Unknown Source) at com.mathworks.toolbox.javabuilder.internal.MWMCR.invoke(MWMCR.java:475) at SourceTrace.SourceTrace.epanetloadfile(SourceTrace.java:580) at leakdetection.water.source.tracing.Test.<init>(Test.java:46) at leakdetection.water.source.tracing.Test.main(Test.java:19) BUILD SUCCESSFUL (total time: 13 seconds)

Answer 1

[Friedrich]

Hi,

When compiling code which uses loadlibrary you have to take care of some things first:

If you need to distribute your shared library to other users who will use it in MATLAB themselves or who will use your MATLAB functions which call the library; they would also need a compiler to create a thunkfile, unless you create one for them and work with a prototype M-file:

1. Use the 'mfilename' option of LOADLIBRARY, this will generate a prototype M-file and the thunkfile:

loadlibary('myLibrary','myLibrary.h','mfilename','myLibrary.m')

2. In the code which uses the library, instead of using the header:

loadlibrary('myLibrary','myLibrary.h')

Now use the prototype M-file:

loadlibrary('myLibrary',@myLibrary)

If your end-users call the library by themselves you may need to tell them this.

3. Distribute the actual library (myLibrary.dll), the prototype M-file (myLibrary.m) and the thunkfile (myLibrary_thunk_pcwin64.dll) to your end-users.

[Nick B]

Thanks! I will try.

Answer 2

[Kaustubha Govind]

As the error suggests:

Undefined function or variable 'epanet2_proto'

You need to add the prototype file epanet2_proto.m to the archive (add it under "Additional Files" if using DEPLOYTOOL or append using -a option if using MCC).