#+TITLE: JavaInspect - Utility to visualize java software

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* General
- This program is free software: you can redistribute it and/or modify
  it under the terms of the [[https://www.gnu.org/licenses/lgpl.html][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
    - [[https://www.svjatoslav.eu/projects/][Other software projects hosted at svjatoslav.eu]]

  - Tony Bargnesi
    - GitHub fork for the project:
      https://github.com/abargnesi/javainspect

** Source code
:PROPERTIES:
:ID:       032b7997-f582-4203-b31a-43ef7b654ed6
:END:
- [[https://www2.svjatoslav.eu/gitweb/?p=javainspect.git;a=snapshot;h=HEAD;sf=tgz][Download latest snapshot in TAR GZ format]]

- [[https://www2.svjatoslav.eu/gitweb/?p=javainspect.git;a=summary][Browse Git repository online]]

- Clone Git repository using command:
  : git clone https://www2.svjatoslav.eu/git/javainspect.git

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

[[https://www3.svjatoslav.eu/projects/sixth-3d/graphs/][See example produced graphs]] for [[https://www3.svjatoslav.eu/projects/sixth-3d/][Sixth 3D - 3D engine project]].

JavaInspect can be used as a [[id:acf1896a-74b4-4914-acf6-a77075e07f25][standalone commandline utility]] as well as
[[id:bbeeffc8-3767-440d-8d93-ec9124dd60ee][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 [[id:2ad2889e-6c95-4662-b3f4-2c341fc74522][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 [[https://graphviz.org/][GraphViz]] to generate
bitmap graph in PNG or SVG format.

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

* Example graphs
+ A very simple example:

    [[file:example.png][file:example-thumbnail.png]]

    Graph legend:

    file:legend.png


+ [[https://www3.svjatoslav.eu/projects/sixth-3d/graphs/][See example produced graphs]] for [[https://www3.svjatoslav.eu/projects/sixth-3d/][Sixth 3D - 3D engine project]].

* Installation
[[http://www.graphviz.org/][GraphViz]] - shall be installed on the computer.

On Ubuntu/Debian GraphViz can be installed using:
#+BEGIN_SRC sh
sudo apt-get install graphviz
#+END_SRC

To use JavaInspect via Java API, no further installation is
needed. JavaInspect will be embedded into your project as dependency.
This is described in [[id:bbeeffc8-3767-440d-8d93-ec9124dd60ee][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 [[id:032b7997-f582-4203-b31a-43ef7b654ed6][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

* Usage
  :PROPERTIES:
  :ID:       2ad2889e-6c95-4662-b3f4-2c341fc74522
  :END:
JavaInspect can be controlled in 2 different ways:
+ [[id:acf1896a-74b4-4914-acf6-a77075e07f25][as standalone commandline utility]]
+ [[id:bbeeffc8-3767-440d-8d93-ec9124dd60ee][as embedded Java library via Java API]]

** Usage as commandline utility
   :PROPERTIES:
   :ID:       acf1896a-74b4-4914-acf6-a77075e07f25
   :END:
*** Available commandline arguments
#+BEGIN_VERSE
-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.
#+END_VERSE
*** 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:
1. Provide list of Jar files. Use *-j* option.
2. 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.

** Usage via Java API
   :PROPERTIES:
   :ID:       bbeeffc8-3767-440d-8d93-ec9124dd60ee
   :END:
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:

1. Add JavaInspect library in your project as a dependency.

2. 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:
1. Create graph object.
2. 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.
3. Graphs easilly get very big and complex so optionally we filter
   important code using classname [[https://en.wikipedia.org/wiki/Glob_(programming)][glob]] patterns based blacklist and/or
   whitelist.
4. 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.
5. Render graph.


*** Example 1: individually picked objects
This example demonstrates generating of class graph from hand picked
classes and visualizing GraphViz itself.

#+BEGIN_SRC java

// 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");

#+END_SRC

Note: if desired, more compact version of the above:
#+BEGIN_SRC java
new ClassGraph().add(randomObject, RandomClass.class)
                .setKeepDotFile(true).generateGraph("JavaInspect");
#+END_SRC


Result:
    - Generated DOT file: [[file:JavaInspect.dot][JavaInspect.dot]]
    - Generated PNG image: [[file:JavaInspect.png][JavaInspect.png]]

*** Example 2: GraphViz embedded in another project
1. Download project Sixth [[https://www2.svjatoslav.eu/gitweb/?p=sixth.git;a=snapshot;h=HEAD;sf=tgz][code snapshot]].
2. Inspect and run *DataGraph.java*.

*** Embedding JavaInspect in your Maven project

Declare JavaInspect as dependency:
#+BEGIN_SRC xml
<dependencies>
    ...
    <dependency>
        <groupId>eu.svjatoslav</groupId>
        <artifactId>javainspect</artifactId>
        <version>1.7</version>
    </dependency>
    ...
</dependencies>
#+END_SRC


Add Maven repository to retrieve artifact from:
#+BEGIN_SRC xml
<repositories>
    ...
    <repository>
        <id>svjatoslav.eu</id>
        <name>Svjatoslav repository</name>
        <url>http://www3.svjatoslav.eu/maven/</url>
    </repository>
    ...
</repositories>
#+END_SRC

* 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 [[http://plantuml.com/class-diagram][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 [[https://www3.svjatoslav.eu/projects/sixth-3d/][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.
* See also
Similar or alternative solutions:
+ http://www.class-visualizer.net/
+ [[https://github.com/pahen/madge][Madge - similar tool for JavaScript]]