Release date: Monday 12.11.12 - Due date: Sunday, 18.11.12, 23:59

In June 1996, during the start of the Ariane 5 space launcher, the launcher veered off course and exploded less than one minute after takeoff.

a.) Research and describe the issues of this crash with a focus on software. (at least 1-3 sentences)

b.) Describe the motivation of software reuse. (at least 1-3 sentences)

c.) What are the challenges and implications of this crash for software reuse? (at least 1-3 sentences)

Hint: Don't forget to reference your source!

a.) Describe in your own words what Stateful and Stateless Beans are (1-3 sentences for each is sufficient) and give an example for each.

b.) Present an issue of Stateful Beans (Hint: Search for „Performance and Stateful Session Beans“).

c.) What is a benefit of using Stateful Beans?

Hint: If you use additional literature you have to reference it.

In this task you will generate Java CORBA code from an IDL file. For this purpose, you will need a JDK installed as you will need the “idlj” compiler. Download the given starting point a5t3.zip and extract the contained IDL “renting.idl”.

a.) Use the idlj compiler to generate Java code from the “renting.idl” file.

• Which files are generated? (Hint: It is sufficient to write down the names)
• What does the idlj argument “-fall” do?
• After using this argument, write down which generated files are skeletons and which are stubs.

b.) Write down the mapping between the elements (types, attributes, return types/parameter types) defined in the idl and the resulting Java elements of the interface “ManageRentings”.

For this task we provide an initial project: a5t4.zip. Import the contained project into your Eclipse workspace. Initially some dependencies are missing. Run the build.xml file (Right-click the file→Run As→Ant build). This will download OpenEJB and dependent libraries (ca. 20MB). In case the project still contains errors: Refresh it (select the project in the Package Explorer and press F5).

The project provides an excerpt of the Hotel System with three entity beans (Renting, RentalPeriod, Room) and two session beans (StatelessRentings, StatefullRentings). Further it contains the following JUnit test cases, which set-up a minimal EJB3 environment (based on OpenEJB) and test a stateless and a stateful session bean.

• src/test/java/org/iai/assignment/ejb3/StatelessTest.java
• src/test/java/org/iai/assignment/ejb3/ExtendedContextTest.java

Your tasks are marked in both test classes from 1-6. Your solution should only contain both test classes (as Java files), explanations of your solution and some tasks require you to answer questions (both in a PDF).

Hint: Do not commit the complete project (especially with the dependencies)! This will be rewarded with negative points.