HTTP access to JVMTI

This project contains an implementation of HTTP server embedded into JVMTI agent that allows to access JVMTI-related functionality remotely over HTTP.

Access to JVMTI is implemented using handler functions. Each handler function takes an input string from HTTP URL and returns result string that is sent to client in HTTP response. Handler name is specified as a first part of the URL.

The following handlers are implemented:

• /jvmti/GetSystemProperty/<property_name> - returns value for the specified system property using GetSystemProperty function
• /jvmti/GetStackTrace/<thread_name> - returns a stack trace for the specified thread using GetStackTrace function
• /jvmti/GetLiveThreadsCount/ - returns a number of live threads in JVM using GetAllThreads function

How to build and run

Build and run steps tested on Windows and Linux and should work (with minor changes) on other platforms supported by OpenJDK.

On Windows the commands below should be run from the Visual Studio 2013 Express x86_64 development command prompt, additional argument should be specified for cmake .. - -G "Visual Studio 12 2013 Win64", and the following tools must be available in PATH:

• CMake as a build system
• pkg-config for dependency management
• perl for OpenSSL build
• zip for webapp bundling

Build and run commands:

git clone --recursive https://github.com/akashche/jvmti_http.git
cd jvmti_http
mkdir build
cd build
cmake .. -DJAVA_HOME=<path/to/jdk>
cmake --build .
cmake --build . --target webapp
javac -d . ../test/App.java && java -agentpath:bin/<shared_library_name>=8443,bin App

shared_library_name should be libjvmti_http.so on Linux and jvmti_http.dll on Windows.

HTTP server will be started on the specified port (8443 in this example). In this example server uses self-signed HTTPS certificate. Example can be easily extended to use different server certificate or to require clients to use HTTPS-client certificates for authentication.

Usage examples with cURL:

curl -k https://127.0.0.1:8443/jvmti/GetSystemProperty/java.home
curl -k https://127.0.0.1:8443/jvmti/GetSystemProperty/java.vm.version
curl -k https://127.0.0.1:8443/jvmti/GetStackTrace/main

Web application example

Example web app is included with this project as a git submodule. Web app is bundled into a ZIP file and web content is served using the same embedded HTTP server. Web app access link:

https://127.0.0.1:8443/webapp/index.html

How to add new handlers

• implement handler function with the following signature:

  std::string handle_Something(jvmtiEnv* jvmti, JNIEnv* jni, const std::string& input);

• put this function into separate source file into handlers directory

• add function declaration to handlers header

• add function pointer to the handlers map in JvmtiAccessor class

• run touch ../CMakeLists.txt to register new source file (cmake re-run is not required)

• build and run the project and test access to your new handler using cURL or web-browser

License information

This project is released under the Apache License 2.0

Changelog

2016-09-23

• dependencies cleanup
• windows support

2015-08-04

• web app example added

2015-07-12

• initial public version