Serp

Overview

Serp is an open source framework for manipulating Java bytecode. If you have a suggestion for functionality that you would like to see incorporated into serp, please feel free to send it to me. Bug reports are also greatly appreciated. And if you choose to incorporate serp into any of your projects, I would love to hear about it!

Abe White
awhite@bea.com


Contents

  1. Bytecode
  2. Project Information
  3. Javadoc
  4. Download
  5. License


Bytecode

Bytecode manipulation is a powerful tool in the arsenal of the Java developer. It can be used for tasks from compiling alternative programming languages to run in a JVM, to creating new classes on the fly at runtime, to instrumenting classes for performance analysis, to debugging, to altering or enhancing the capabilities of existing compiled classes. Traditionally, however, this power has come at a price: modifying bytecode has required an in-depth knowledge of the class file structure and has necessitated very low-level programming techniques. These costs have proven too much for most developers, and bytecode manipulation has been largely ignored by the mainstream.

The goal of the serp bytecode framework is to tap the full power of bytecode modification while lowering its associated costs. The framework provides a set of high-level APIs for manipulating all aspects of bytecode, from large-scale structures like class member fields to the individual instructions that comprise the code of methods. While in order to perform any advanced manipulation, some understanding of the class file format and especially of the JVM instruction set is necessary, the framework makes it as easy as possible to enter the world of bytecode development.

There are several other excellent bytecode frameworks available. Serp excels, however, in the following areas:

Serp is not ideally suited to all applications. Here are a few disadvantages of serp:

The first step to using bytecode modification is to get familiar with the inner workings of class files. The class file format is covered here. Advanced manipulation involving changing or creating methods requires knowledge of the JVM instruction set, outlined here. Finally, learn to use the javap standard Java tool. Running javap -c on any class name will show you the opcodes of the class' methods -- this gives you an unlimited supply of examples to work from when writing your own opcodes.

The first class you should study in the serp bytecode toolkit is the serp.bytecode.Project type. From there, move onto the serp.bytecode.BCClass, and trace its APIs into serp.bytecode.BCField, serp.bytecode.BCMethod, and finally into actual serp.bytecode.Code.

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Serp Version 1.14.2

New in 1.14.x:

New in 1.13.x:

New in 1.12.x:

New in 1.11.x:

New in 1.10.x:

Download

Please contact awhite@bea.com for previous serp versions.

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License

Serp uses the BSD license. This is the most open license I could find; the goal is that regardless of your application -- commercial or non-commercial, open source or closed -- you can take advantage of the utilities serp provides, or even modify them to suit your needs... without any legal issues. Also, as in all open source, access to the source code means that you have the opportunity to fix blocking bugs without waiting for the next release. The following is the text of the license:

Copyright (c) 2002-2007, A. Abram White
All rights reserved.

Redistribution and use in source and binary forms, with or without 
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this 
  list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, 
  this list of conditions and the following disclaimer in the documentation 
  and/or other materials provided with the distribution.
* Neither the name of 'serp' nor the names of its contributors may
  be used to endorse or promote products derived from this software without 
  specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON 
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		

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