Master of Computer Science - University of Grenoble

Aspect-Oriented Programming / AspectJ

Contact : Sara Bouchenak, Sara.Bouchenak@imag.fr

TP 3: Dependability

1. Objective

Design and implement transactions with AOP/AspectJ.

2. Software environment

If not already installed, install the following software:

• Java 2 SDK
• AspectJ
• Ant
• McKoi database server
• IDE (e.g. Eclipse)

If not already defined, define the following environment variables:

• JAVA_HOME

• ASPECTJ_HOME

• ANT_HOME

• MCKOI_HOME

• PATH (includes JAVA_HOME/bin, ASPECTJ_HOME/bin, ANT_HOME/bin, MCKOI_HOME/bin)

Examples for defining such variables are given in the file named env-tcsh for Unix/tcsh (run: source env-tcsh), and in the file named env-win.bat for Windows (run: env-win.bat).

3. Original banking application

Download the application code.

The banking application is available in TP3/Basic/:

• TP3/Basic/docs/api/index.html provides the API documentation of the application.

• TP3/Basic/src contains the source code of the application.

Configure the database:

• Choose a port number for the McKoi database server

  • Configure file db.conf with theport number in jdbc_server_port

  • Configure file build.xml with port number in mckoi.port

Compile and run the application:

• Compile: ant compile
   

• Start the database server: ant create_db
   

• Create and initialize database content: ant pop_db
   

• Start the database GUI client for interactive execution of SQL queries: ant client_db
  Examples: SHOW TABLES or SELECT * FROM accounts
   

• Run the main program: ant run
   

• Use the GUI client to browe the new content of the database

4. Hand-coded dependability of banking application

As an example, TP3/Transactions_HandCoded/ contains a "hand-coded" version of the banking application extended with dependability and transaction features:

1. Database connection auto-commit mode is deactivated by the calling setAutoCommit(false) method on banking.DatabaseImpl.getConnection.   
    
2. Multiple database queries inside the same transaction are executed within the same database connection.   
   See new versions of methods debit, credit, getBalance and setBalance in banking.DatabaseAccountImpl class, and new versions of methods query and  update in banking.DatabaseImpl class.   
    
3. Commit/abort a transaction.    
   See new version of method banking.InterAccountOperations.transfer.

The hand-coded version of the application is organized as follows:

• TP3/Transactions_HandCoded/docs/api/index.html provides the API documentation of the application.

• TP3/Transactions_HandCoded/src contains the source code of the application.

Compile and run the application:

• Compile: ant compile
   

• Start the database server: ant create_db
   

• Create and initialize database content: ant pop_db
   

• Start the database GUI client for interactive execution of SQL queries: ant client_db
  Examples: SHOW TABLES or SELECT * FROM accounts
   

• Run the main program: run-win.bat (for Windows), run-tcsh.sh (for Unix/tcsh) or run-bash.sh (for Unix/bash), configure the DB server port number accordingly
   

• Use the GUI client to browse the new content of the database

5. Description of work

Implement transactions using AspectJ in the TP3/Transactions_Aspects/ directory, by writing an aspect in TP3/Transactions_Aspects/aspects/transactions/TransAspect.java

The AspectJ-based solution should provide the following:

1. Use the same java.sql.Connection object for queries within the same transaction: use AspectJ percflow.   
    

2. Deactivate auto-commit when creating a new database connection by calling setAutoCommit(false).   
    

3. If nested operations, commit/rollback on highest-level operation: use AspectJ percflowbelow.

To compile and run the application:

• Compile: ant compile_aj
   

• Start the database server: ant create_db
   

• Create and initialize database content: ant pop_db
   

• Start the database GUI client for interactive execution of SQL queries: ant client_db
  Examples: SHOW TABLES or SELECT * FROM accounts
   

• Run the main program: run-win.bat (for Windows), run-tcsh.sh (for Unix/tcsh) or run-bash.sh (for Unix/bash), configure the DB server port number accordingly
  Modify run-win.bat (run-tcsh.sh, run-bash.sh) to use the AspectJ-based implementation
   

• Use the GUI client to browse the new content of the database

5. Combine aspects

Combine the Logging aspect implemented in TP2, Dependability aspect implemented in TP3 and Security aspect implemented in TP4, and automatically include all to the banking application.

Do not modify the aspects' code, neither the application code.