Deployment runthrough

This is an example deployment, on a 64-bit Linux host. There are various different ways to do this and the details will vary from one platform to another. This is a deployment of a very early version of the code.

See Deployment troubleshooting for notes about Java and Tomcat versions and on things that might go wrong.

1. Obtain the current code from Mercurial repository

$ hg clone
http authorization required for
realm: Mercurial repository for Human Echolocation WebApp
user: chrisca
destination directory: human-echolocation-java-webapp
requesting all changes
adding changesets
adding manifests
adding file changes
added 41 changesets with 93 changes to 40 files
updating to branch default
23 files updated, 0 files merged, 0 files removed, 0 files unresolved

2. Install the MATLAB Compiler Runtime

Navigate to and find the download URL, then use as follows.

$ mkdir mcr
$ cd mcr
$ wget ''
--2014-02-24 10:00:10--
Resolving (
Connecting to (||:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 488473010 (466M) [application/zip]
Saving to: ‘’

100%[======================================>] 488,473,010 7.81MB/s   in 60s    

2014-02-24 10:01:11 (7.71 MB/s) - ‘’ saved [488473010/488473010]
$ unzip 
  inflating: archives/mpc_resources_common_1348598029.enc  
  inflating: archives/cgir_mi_core_glnxa64_1375749553.xml  
$ ./install

The installer window then pops up (X server connection required for graphical interaction here).

The default installation folder is /usr/local/MATLAB/MATLAB_Compiler_Runtime. I'm going to accept that.

The installer runs, and then prints out the following:

On the target computer, append the following to your LD_LIBRARY_PATH environment variable:


Next, set the XAPPLRESDIR environment variable to the following value:


3. Bring dependent JAR files into the webapp folder

Make sure we're back in the webapp folder (the one we cloned from Mercurial earlier)

$ cd ../human-echolocation-java-webapp

Copy in the Servlet API library from our application server (in this case Tomcat):

$ cp /usr/share/java/tomcat7/servlet-api.jar .

(Note that sometimes that file appears to live at /usr/share/java/servlet-api-3.0.jar or similar -- it should be the same file anyway)

And the MATLAB MCR JavaBuilder library:

$ cp /usr/local/MATLAB/MATLAB_Compiler_Runtime/v82/toolbox/javabuilder/jar/javabuilder.jar ./WebContent/WEB-INF/lib/

4. Build the WAR file bundle

Simple enough:

$ ant
Buildfile: /work/human-echolocation-java-webapp/build.xml

    [javac] Compiling 2 source files to /work/human-echolocation-java-webapp/WebContent/WEB-INF/classes

      [war] Building war: /work/human-echolocation-java-webapp/echoapp.war

Total time: 1 second

5. Deploy the bundle and start the app server

$ sudo cp echoapp.war /var/lib/tomcat7/webapps/
$ sudo /usr/share/tomcat7/bin/

Note: on many Linux distros you can start Tomcat as a system service, e.g. using "systemctl start tomcat7". I tried this initially but later on found that logs weren't being written where I expected and config changes weren't taking effect, so I started running it directly from the script in the Tomcat directory instead

Then navigate to the Tomcat manager URL http://localhost:8080/manager/html in a browser. (This URL may vary. The default admin username and password are admin/admin; of course these must be changed and the manager port firewalled in any real deployment.)

Because the WAR file was present when Tomcat was started, it should be listed as running in the manager interface. If it isn't, we can hit the Start button on the line listing echoapp (and if we have redeployed it since last time, we should hit Reload).

6. Test the app

Now the app has been deployed, we can run it by going to the http://localhost:8080/echoapp URL linked in the Tomcat manager page. This should display the basic Human Echolocation Webapp page. If I enter a value into the Distance field and hit Generate... nothing happens.

I can debug this by trying to retrieve the result from the HumanEchoServlet directly, through the URL http://localhost:8080/echoapp/HumanEcho. This shows a stack trace, of which the pertinent lines are:

java.lang.NoClassDefFoundError: Could not initialize class com.mathworks.toolbox.javabuilder.internal.MWMCR<init>(

OK, so this is where the library path from the MCR comes into play. We can set environment variables for Tomcat in a script in the directory where the other Tomcat shell scripts are found. In my case that is /usr/share/tomcat7/bin, so I create a file in there called with the following content

export LD_LIBRARY_PATH=/usr/local/MATLAB/MATLAB_Compiler_Runtime/v82/runtime/glnxa64:/usr/local/MATLAB/MATLAB_Compiler_Runtime/v82/bin/glnxa64:/usr/local/MATLAB/MATLAB_Compiler_Runtime/v82/sys/os/glnxa64:/usr/local/MATLAB/MATLAB_Compiler_Runtime/v82/sys/java/jre/glnxa64/jre/lib/amd64/native_threads:/usr/local/MATLAB/MATLAB_Compiler_Runtime/v82/sys/java/jre/glnxa64/jre/lib/amd64/server:/usr/local/MATLAB/MATLAB_Compiler_Runtime/v82/sys/java/jre/glnxa64/jre/lib/amd64

and run

$ sudo chmod +x
$ sudo ./
$ sudo ./

On reloading the app and re-requesting the servlet, the error message has disappeared and instead we see

java.lang.NumberFormatException: null
    HumanEchoServlet.doGet(Unknown Source)

OK, this is just (!) a bug in our servlet -- it isn't handling the absent dist and azim parameters correctly. If I add some random values by retrieving http://localhost:8080/echoapp/HumanEcho?dist=8&azim=4 instead, then I get served a WAV file. Hurrah!