docs/application-discovery-via-the-classpath.adoc

= Application discovery via the classpath
:index-group: Testing Techniques
:jbake-date: 2018-12-05
:jbake-type: page
:jbake-status: published

This document
details the various ways to get OpenEJB to detect applications you would
like deployed while in an embedded mode.

= Empty ejb-jar.xml approach (recommended)

Simplify the issue of searching for annotated applications by adding an
ejb-jar.xml like this to your app:

[source,xml]
----
<ejb-jar/>
----

OpenEJB will find the app in the classpath and deploy it along with any
annotated beans it may contain.

The ejb-jar.xml can contain more than just "" as usual.

This is the recommended approach for people using OpenEJB for unit
testing as it allows OpenEJB to find your application in the classpath
without the need for you to specify any path information which tends to
complicate builds.

== Including/Excluding paths (advanced)

If you do not like the idea of having the ejb-jar.xml in your app or an
openejb.xml, we can search the classpath for annotated beans
(`@Stateless`, `@Stateful`, `@MessageDriven`) and load them automatically just
as if they contained an ejb-jar.xml.

This form of searching, however, is very expensive as it involves
iterating over every path in the classpath and reading in each class
definition contained thereunder and checking it for annotations.

This approach can only be made faster by helping us trim down or
pinpoint the paths we should search via the
_openejb.deployments.classpath.include_ property which can be specified
as a _system property_ or a property passed into the _InitialContext_.

The value of this property is a regular expression and therefore can be
absolute or relative. For example the path
"/Users/dblevins/work/swizzle/swizzle-stream/target/classes" which
contains the class files of an application you wish to test could be
included in any of the following values to the
"openejb.deployments.classpath.include" property:

* "file:///Users/dblevins/work/swizzle/swizzle-stream/target/classes/"
_(an absolute path)_
* "file:///Users/dblevins/work/swizzle/.*" _(relative)_
* ".*swizzle-stream.*" _(very relative)_
* ".*(swizzle-stream|swizzle-jira|acme-rocket-app).*" _(including
several paths)_
* ".*(swizzle-stream^|swizzle-jira^|acme-rocket-app).*" _(including
several paths with Win specific escapes)_

Note the filtering is done on URLs in the classpath, so forward slashes
should always be used even on OSs using backslash ("").

There are also the _openejb.deployments.classpath.exclude_ and
_openejb.exclude-include.order_ properties if you wish to work in the
opposite direction or change the processing order. The default values
for the properties are as follows:

[source,properties]
----
  openejb.exclude-include.order=include-exclude //Defines the processing order
   openejb.deployments.classpath.include=""      //Include nothing
   openejb.deployments.classpath.exclude=".*"    //Exclude everything
----

The exclude and the include are applied separately and the results of
each are combined together to create the list of paths OpenEJB will
scrape for annotations.

[source,java]
----
*Note:* by default these settings will only affect which jars OpenEJB will
 scan for annotated components when no descriptor is found.  If you would
 like to use these settings to also filter out jars that do contain
 descriptors, set the *openejb.deployments.classpath.filter.descriptors*
 property to _true_.  The default is _false_.
----

== Troubleshooting

If the include/exclude is not being processed as you expect first try
reversing the order to __openejb.exclude-include.order__=exclude-include
There are a number internal filters that may result in an unexpected
exclusion.

If you're having trouble determining if the META-INF/ejb-jar.xml file
for your ejb module is in the classpath, a little debug code like this
in your test setup will help you see what OpenEJB sees (which may be
nothing):

[source,properties]
----
Enumeration<URL> ejbJars =
this.getClass().getClassLoader().getResources("META-INF/ejb-jar.xml");
while (ejbJars.hasMoreElements()) {
    URL url = ejbJars.nextElement();
    System.out.println("app = " + url);
}
----