ByteCodeManipulation

What is here?

Some code I wrote for a job interview to demonstrate Java byte code manipulation.

Done:

• A Java Agent
  • Performs the following instrumentations when an HTTP request occurs:
    • Instruments the response to include a unique ID
• Tests
  • Unit Tests
  • Integration Tests
• This AMAZING README

TODO:

• Computes the following data points:
  • Counts how many string objects were created for a single page request or RESTful request
  • Times the request from start to finish
  • Counts how many classes are loaded during one request
• Provides an interface that instruments the application to provide the computed data points to:
  • An endpoint
  • The console
  • A log file

How to build

Building with maven from the root project directory will build the agent and run all tests.

mvn clean install

The build will output the agent jar here:

./bytecodemanipulationz-agent/target/bytecodemanipulationz-agent-1.0-SNAPSHOT-jar-with-dependencies.jar

How to deploy

Attach the agent jar to your webapp when launching the webapp. Use the -javaagent JVM flag, passing the full path to the agent jar.

For Example:

A small spring boot app exists as part of the bytecodemanipulationz-test-integration project.

You can find it here:

./bytecodemanipulationz-test/bytecodemanipulationz-test-integration/target/bytecodemanipulationz-test-integration-2.0.5.RELEASE.jar

Normally you would launch this webapp using java -jar:

java -jar ./bytecodemanipulationz-test/bytecodemanipulationz-test-integration/target/bytecodemanipulationz-test-integration-2.0.5.RELEASE.jar

Here is how you would launch the spring boot webapp with the agent attached (replacing $REPLACE_WITH_FULL_PATH with the full path to the agent jar):

java -javaagent:$REPLACE_WITH_FULL_PATH/bytecodemanipulationz-agent-1.0-SNAPSHOT-jar-with-dependencies.jar -jar ./bytecodemanipulationz-test/bytecodemanipulationz-test-integration/target/bytecodemanipulationz-test-integration-2.0.5.RELEASE.jar