NOD4J

This tool shows the values of variables in the execution.

Each variable contains the values at most "k" times. (You can set "k" when you execute logger named selogger)

You can read the detail Implementation here .

Our tool comprises three components: trace recorder, post-processor, and interactive view.

• The trace recorder component records an execution trace of a Java program in storage.
• The post-processor component links the recorded trace to the source files of the program.
• The interactive view shows the source code contents annotated with trace information.

Sample

Interactive view demo is available at http://sel-nod3v.ics.es.osaka-u.ac.jp and instructions are described in the viewer section of wiki page.

Try our sample and viewer following wiki page.

Requirements

• JDK 1.8
• Node.js (16.14.0 LTS)
• npm (>= 8.5.2)
• (for build jar files) Apache Maven (>= 3.5.4)

Usage

Setup

Clone our repository.

$ git clone https://github.com/k-shimari/nod4j.git

After cloning, prepare nod4j.jar and selogger-0.2.3.jar in this project root.

• nod4j.jar is available on releases page.
• selogger-0.2.3.jar is already included in this project root.

If you want to build them by yourself, follow the next section.

(optional) Build jar files

To build nod4j.jar, a post-processor component, run Maven and you can find it in target/ directory.

$ mvn package

To build selogger-0.2.3.jar, a recorder component, follow the selogger) page.

Trace Recorder Usage

Run the following command to collect information about the execution of your program.

$ (prepare something to run your program)
$ java -jar -javaagent:/path/to/selogger-0.2.3.jar=output=/path/to/<EXECUTION_TRACE_OUT> <YOUR_APP.jar>

• Options are described at https://github.com/takashi-ishio/selogger/tree/v0.2.3

/path/to/<EXECUTION_TRACE_OUT> is the directory that you want to output the execution trace. After running your program for a while, you can get the execution trace in /path/to/<EXECUTION_TRACE_OUT>.

If you are using a build tool like maven to run the target program, pass the same option to java. (A sample in the project wiki contains an example of running with maven.)

Post Processor Usage

Change directory back to the cloned project root and run nod4j.jar to convert the execution trace in the format of JSON.

$ cd /path/to/nod4j
$ java -jar nod4j.jar /path/to/<YOUR_PROJECT_DIRECTORY> /path/to/<EXECUTION_TRACE_OUT> <PROJECT_ROOT>/src/main/frontend/src/assets/project/<YOUR_PROJECT_NAME>

• /path/to/<YOUR_PROJECT_DIRECTORY> is your project directory which contains the source code.
• /path/to/<EXECUTION_TRACE_OUT> is the directory contains the execution trace where you specified in the previous step.
• <PROJECT_ROOT>/src/main/frontend/src/assets/project/<YOUR_PROJECT_NAME> is the output destination for this command.
  • If you are runninng this command other than the cloned project root, point the output destination to the assets directory in the frontend (interactive view).

You can find fileinfo.json and varinfo.json at <PROJECT_ROOT>/src/main/frontend/src/assets/project/<YOUR_PROJECT_NAME>.

fileinfo.json contains the information of source code.

varinfo.json contains the information of values of variable.

Interactive View Usage

Getting started

Run the following commands to install the packages.

$ cd src/main/frontend
$ npm install

Build and Run

Run the following commands to build the project and start the server. If the execution trace in the assets directory has changed, re-run from here.

$ npm run build
$ npm run server

Open your project

1. Access localhost:8070
2. Open your project in the list of "Open project"

Viewer

1. You can find down and up arrows at right side of each value.
2. The down arrow means the start point and the up arrow means the end point.
3. This interactive view can filter the value based on the execution order of each instruction by setting the start and/or end point.
4. You can check filter information at INSTRUCTION FILTER and delete filters by clicking buttons.
5. If no values are contained in the variable during the filtered period, the highlighting of the variable is turned off.

Raw logs Viewer

Clicking ALL LOGS button, you can see all raw execution trace.

• ID is a unique ID for each source code location.
• Line means the line number of the variable and Variable means the variable name.
• Seqnum is the sequence number of the instruction and Data is the value of variable.

Limitation

• This tool does not display the following variables in the current implementation, or does not display them correctly.
  • Method return value at caller method
  • Related to some kinds of operand correctly
    • ++, +=, --, -=
  • multiple lines expression
• You can confirm these invisible values clicking ALL LOGS button in view.