JavaInspect - Utility to visualize java software

1. General
- 1.1. Source code
2. Goal and operating principle
3. Example graphs
4. Installation
5. Usage
- 5.1. Usage as commandline utility
  - 5.1.1. Available commandline arguments
  - 5.1.2. Specifying classes to render
- 5.2. Usage via Java API
6. TO DO
7. See also

1. General

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Program authors:
- Svjatoslav Agejenko
  - Homepage: https://svjatoslav.eu
  - Email: mailto://svjatoslav@svjatoslav.eu
  - Other software projects hosted at svjatoslav.eu
- Tony Bargnesi
  - GitHub fork for the project: https://github.com/abargnesi/javainspect

1.1. Source code

Download latest snapshot in TAR GZ format
Browse Git repository online

Clone Git repository using command:

git clone https://www2.svjatoslav.eu/git/javainspect.git

2. Goal and operating principle

Goal: simplify/speed up understanding the computer program code by automatically visualizing its structure.

See example produced graphs for Sixth 3D - 3D engine project.

JavaInspect can be used as a standalone commandline utility as well as java library. JavaInspect uses primarily Java built-in reflection to discover and visualize any part of Java program.

JavaInspect currently has no graphical user interface, configuration files, embedded scripting support, direct Maven, Gradle or Ant integration. See usage to learn how to instuct Javainspect what to do.

After discovering application structure and optionally filtering out unimportant parts, JavaInspect produces GraphViz dot file that describes data to be visualized. Then launches GraphViz to generate bitmap graph in PNG or SVG format.

Notes:

JavaInspect is developed and tested so far only on GNU/Linux.

3. Example graphs

A very simple example:

Graph legend:

See example produced graphs for Sixth 3D - 3D engine project.

4. Installation

GraphViz - shall be installed on the computer.

On Ubuntu/Debian GraphViz can be installed using:

sudo apt-get install graphviz

To use JavaInspect via Java API, no further installation is needed. JavaInspect will be embedded into your project as dependency. This is described in usage via Java API. It will expect GraphViz to be available in the system.

To use JavaInspect as a commandline tool, JavaInspect source repository has to be cloned locally: See Source code.

Then study and execute installation script:

commandline launcher/install

After installation, new commandline tool should be available

javainspect

Quick commandline usage help can be viewed by issuing

javainspect --help

5. Usage

JavaInspect can be controlled in 2 different ways:

as standalone commandline utility
as embedded Java library via Java API

5.1. Usage as commandline utility

5.1.1. Available commandline arguments

-j (existing files)…
    JAR file(s) to render.

-c (existing directories)…
    Classpath directories

-n (string)
    Graph name. (default: "graph")

–debug
    Show debug info.

-h, –help
    Show commandline usage help.

-k
    Keep dot file.

-ho
    Hide orphaned classes.

-w (one to many strings)…
    Whitelist glob(s).

-b (one to many strings)…
    Blacklist glob(s).

-r (one to many strings)…
    root class(es).

-d (existing directory)
    Target directory. Default is current directory.

-t (options: png, svg)
    Target image type. Default is: svg.

5.1.2. Specifying classes to render

Normal Java application has immense complexity. In addition to code that was directly written by particular project developers, lots of functionality is typically added as frameworks or libraries to the project. In addition there is significant Java standard library.

Because JavaInspect uses reflection, it does not easily distinguish between those. In normal situation you would rather want to visualize only code that was developed specifically for your project and leave frameworks like Spring etc. out. If you visualize all classes that are possibly reachable from you project, you will easily get huge and incomprehensible graph.

JavaInspect can digest compiled Java classes in 2 modes:

Provide list of Jar files. Use -j option.
Provide list of filesystem directories that can be used as classpath root. Use -c option.

Currently JavaInspect uses following algorithm to add classes to rendered graph:

All classes that were found in Jar files are added to graph by default.
None of the classes that were found in filesystem directories are added to the graph by default (unless explicitly referenced). (TODO: for consistency it would be better to add them too by default)
If whitelist is specified (-w option) everything that is not matched by whitelist pattern(s) will be removed from the graph.
If blacklist is specified (-b option) everything that is matched by blacklist pattern(s) will be removed from the graph.
Root classes can be specified using -r option. Root classes will be added to the graph. JavaInspect will then try to recursively discover all classes that were referenced by root class and add those also to the graph.

5.2. Usage via Java API

Requires that classes to be visualised are available in the classpath.

To get JavaInspect into same classpath with your projecs I so far came up with 2 solutions:

Add JavaInspect library in your project as a dependency.
Create new Java project for the purpose visualizing your other projects and include JavaInspect and your projecs binary artifacts (Jar's) into new project classpath. Built binary Jar's (with no source code) are sufficient because JavaInspect operates via reflection.

Simple Java based control/configuration code needs to be written for each project. I usually put such code into directories devoted for JUnit tests. Because it needs not to be compiled/embedded into final product or project artifact I'm just willing to visualize.

Control code in general does the following:

Create graph object.
Java reflection/classloaders does not provide mechanism for discovering all classes under given package. Therefore you need to declare at least some classes to be added to the graph by manually adding individual classes to the graph. For every class added to the graph, GraphViz will recursively inspect it and add all referecned classes to the graph as well.
Graphs easilly get very big and complex so optionally we filter important code using classname glob patterns based blacklist and/or whitelist.
Optionally we can tune some rendering parameters like:
- Possibility to remove orphaned classes (classes with no references) from the graph.
- Specify target directory for generated visualization files. (Default is current directory)
- Keep intermediate GraphViz dot file for later inspection.
Render graph.

5.2.1. Example 1: individually picked objects

This example demonstrates generating of class graph from hand picked classes and visualizing GraphViz itself.

// Create graph
final ClassGraph graph = new ClassGraph();

// Add some random object to the graph. GraphViz will detect Class from
// the object.
graph.add(graph);

// Also add some random class to the graph.
graph.add(Utils.class);

// Keep intermediary GraphViz DOT file for reference.
graph.setKeepDotFile(true);

// Produce bitmap image titled "JavaInspect.png" to the user Desktop
// directory
graph.generateGraph("JavaInspect");

Note: if desired, more compact version of the above:

new ClassGraph().add(randomObject, RandomClass.class)
                .setKeepDotFile(true).generateGraph("JavaInspect");

Result:

Generated DOT file: JavaInspect.dot
Generated PNG image: JavaInspect.png

5.2.2. Example 2: GraphViz embedded in another project

Download project Sixth code snapshot.
Inspect and run DataGraph.java.

5.2.3. Embedding JavaInspect in your Maven project

Declare JavaInspect as dependency:

<dependencies>
    ...
    <dependency>
        <groupId>eu.svjatoslav</groupId>
        <artifactId>javainspect</artifactId>
        <version>1.7</version>
    </dependency>
    ...
</dependencies>

Add Maven repository to retrieve artifact from:

<repositories>
    ...
    <repository>
        <id>svjatoslav.eu</id>
        <name>Svjatoslav repository</name>
        <url>http://www3.svjatoslav.eu/maven/</url>
    </repository>
    ...
</repositories>

6. TO DO

Note: Because this is side project (and I have many of them) I can only contribute few hours per year at average. Any help is welcome. A LOT of cool ideas could be implemented. For intstance:

BUG: Should not hide references if there are too many of them to classes if referring classes are not visible anyway because of blacklist/whitelist rules. Basically reference counting should exclude not visible classes.
BUG: Orphaned class removal does not work always. There are many bugs and corner cases to find and fix still.
BUG: Code is not very readable. Document and refactor for better maintainability.
FEATURE: Create installable DEB package.
- Submit it to some Debian developer for integration or become Debian package maintainer.
FEATURE: Make it modular. That is: central part, an application model could be standalone and serializable.
- There could be multiple ways to acquire model:
  - By introspecting application via Java reflections (current mode of operation).
  - By parsing java source. (unfinished)
- There could be ways to manipulate model:
  - Store/load/compare.
  - Trim uninteresting parts.
  - Highlight important parts.
- There could be multiple ways to render model:
  - PNG/SVG (currently implemented)
  - PlantUML (TODO)
  - Interactive 3D visualization (TODO)
FEATURE: Implement (or integrate existing java parser https://javaparser.org/) to be able to produce code visualizations based on source code (in addition to current reflection based approach).
FEATURE: Integarte with PlantUML.
FEATURE: Add dark theme for generated graphs.
FEATURE: Sort Class fields by alphabet.
FEATURE: Visualize also concrete field values so it could be used as ultra cool runtime logging/debugging framework.
FEATURE: Possibility to visualize structure and data from JVM snapshot.
FEATURE: Possibility to attach to remote process to visualize data/structure using JVM debug port and mechanism.
FEATURE: Possibility to attach to JVM using JVM agent.
FEATURE: Possibility to inspect graphs in 3D using Sixth 3D engine.
FEATURE: Possibility to select classes/fields/values to be visualized in some graph query language. For greater flexibility in comparison to currently supported glob syntax.
FEATURE: Add option to control JavaInspect via JSON or XML config file. For example different graphs for given project could be defined once in plain text config, possibly with the aid of some interactive utility. Then defined graphs could be updated as part of project build or release process.
FEATURE: Configurable maven plugin to generate graphs as part of the project build/release process.