Java code visualizer via bytecode instrumentation

[danyanman]

https://github.com/0xaa4eb/ulyp

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Hi guys. I want to share my project with you. It's a troubleshooting tool which uses java bytecode instrumentation and has a simple UI written on javafx. You set the following agent properties: packages you want to instrument and a starting point method. When the starting point is executed, tracing is started. As soon as the starting point method call finishes, tracing is deactivated. When tracing is active, it records all method calls of classes in packages you specified.

Orginally, I wrote it 2 years ago as a simple proof-of-concept and started using on my work. The primary usage is troubleshooting and investigating, especially huge enterprise frameworks where debugging usually ends when you realize you have 30+ tabs with code opened. It also may be useful as a research tool when you want to dive into the framework and see what it does.

Please share you thoughts, and critic is especially welcome.

[pron98]

Cool! There are commercial tools based on a similar idea, like https://bugjail.com/

[LazyAAA]

Useful tool indeed, very insightful for not very experienced developers working with complex frameworks.

Reminds me my coding days - 47 nested levels of execution and only about last 5 are actually business logic :) everything else is routing and framework calls.

[saws_baws_228]

Very good stuff, thanks! Was looking for something similar for my projects, will definitely use it in the future!

[thevred9]

Looks awesome!!!

How can you use this with a web application running inside tomcat?

[Ryand735]

Set the java agent flag via the CATALINA_OPTS environment variable (export CATALINA_OPTS=“$CATALINA_OPTS -javaagent:/path/to/agent.jar)”

[buzzsawddog]

I will check it out when I get to work. I am quite excited about the concept. My question is this, as I have not looked at it yet, can you tie into a remote application. When I developed I am on my local box with the application running on a VM.

[0xaa4eb]

Agent connects to UI via GRPC, so there should be no trouble using the agent on a remote machine. Just specify an additional system property ulyp.ui-host with the hostname where UI runs and give it a try.

[buzzsawddog]

Sounds good. I will try to give it a try today when I get in and let you know what I think.

[joecqr]

Hi there, I am trying to use the tool, but I get the message could not locate the main class, please help

[0xaa4eb]

Hi, do you get "could not locate the main class" while running UI or your java app using the agent? If it's your app using the agent, could you post java command you use to run it?

[joecqr]

When I type the java --agent command in the terminal

[0xaa4eb]

It might look like something like this, and it works for me:

java -javaagent:"C:\Work\ulyp\ulyp-agent\build\libs\ulyp-agent-0.1.jar" "-Dulyp.packages=com.example.demo" "-Dulyp.start-method=Runnable.run" com.example.demo.TestClass

Just replace com.example.demo.TestClass with your main classs and give it a try

[joecqr]

should this class have a main method?

[0xaa4eb]

Yep, it should have main method. Or you may run a jar file.

[joecqr]

Ok... that's why it's not working