Lab 5 - OpenEJB

OpenEJB

Open-source implementation of EJB, part of Apache TomEE.

Download OpenEJB Standalone at https://tomee.apache.org/download-ng.html

Download source code

https://d3s.mff.cuni.cz/files/teaching/nswi080/labs/Files/sources-5.zip.

• Example - example and lab activity
• Input - base for homework task

Example

EJB application consisting of remotely accessible session beans and persistent entity beans.

• A stateless session bean which prints a message to standard output.
• A stateful session bean which implements a shared counter.
• Entity beans.

The client application shows how to call methods of the remote session beans, then using another session bean, creates and queries the entities.

Explore example source

mwy/ExampleStateless.java:

• interface for a remote stateless bean

mwy/ExampleStatelessBean.java:

• implementation of a stateless bean

mwy/ExampleStateful.java:

• interface for a remote stateful bean

mwy/ExampleStatefulBean.java:

• implementation for a remote stateless bean

mwy/Director.java, mwy/Movie.java:

• entity beans for a movie database
• auto-generated id
• property-based access (annotating getters and setters, not fields)
• one-to-many relationship between directors and movies

mwy/ExampleEntities.java:

• interface for a remote bean which manipulates the entities

mwy/ExampleEntityBeans.java:

• implementation of a remote stateless bean
• creates movies and directors
• EntityManager accesses a persistence context
• queries movies and directors
• using Persistence Query Language (similar to SQL)

classes/META-INF/persistence.xml

• configures persistence of the Director and Movie entity beans
• synchronize database schema the object-relational mapping of entity beans
• the data source may be configured in $OPENEJB_HOME/conf/openejb.xml
• automatic configuration stores data in a HSQLDB database
  • data stored in $OPENEJB_HOME/data/hsqldb

ExampleClient.java:

• connects to the server
• looks up the session beans
• calls methods of the session beans
• using the methods of the ExampleEntities bean, creates persistent entities, then prints their content

Scripts:

make.sh:

• adds Java EE API to the classpath
• compiles bean classes
• creates an EJB jar
• compiles the client

run-server.sh:

• starts an OpenEJB standalone server

stop-server.sh:

• stops the running server

run-deploy.sh:

• deploys the beans to the running OpenEJB server
• (copies the EJB jar to $OPENEJB_HOME/apps)

run-client.sh:

• runs the client application

Run the example

Download OpenEJB Standalone from https://archive.apache.org/dist/tomee/tomee-8.0.6/openejb-standalone-8.0.6.tar.gz, or a choose different version from https://tomee.apache.org/download-ng.html. Extract openejb-standalone-8.0.6.tar.gz.

Configure OPENEJB_HOME as the path to OpenEJB in setenv.sh.

Compile source codes (the beans and the client): bash make.sh

Run the server: bash run-server.sh

Deploy the beans to the running server: bash run-deploy.sh

Run a client: bash run-client.sh

Stop the server: bash stop-server.sh

Re-deploying the application

If you change the application, after compilation use bash run-deploy.sh -u to undeploy the old version and deploy the new version.

Lab activity task

Run the example as described above, but run the client two times. Look at and send the following by e-mail to the teaching assistant.

• output of the server
• output of the deploy script
• output of the client, when run for the second time
• contents of the file in $OPENEJB_HOME/data/hsqldb/hsqldb.log

Read the homework assignment

https://d3s.mff.cuni.cz/files/teaching/nswi080/labs/Files/task-5-en.html.

Explore assignment source code

mwy/Node.java

• data structure representing a graph of nodes

mwy/Searcher.java

• interface for creating the graph and searching for shortest paths in it

mwy/SearcherImpl.java

• implemenation of Searcher which stores nodes in a local Map

Main.java

• local implementation of the client application
• creates a random local graph
• measures times random searches