Alan Gutierrez

I hate Ant.

I’ve been thinking about what a real build system for Java will be.

It will be dependency management system. One that does not execute a task unless necessary. One that maintains it’s own tree of dependencies. It knows how to check the expiration of file dependencies and networked dependencies.

Targets are not names of procedures, but artifacts that are constructed. This is how it is done in dependency management systems such as Make. Targets are represented by actual artifacts, such as object files produced by a C compiler, or an executable produced by a linker.

There will be imaginary targets, as well. Imaginary targets will force a build. Programmatic targets are imaginary targets that expire based on application specific logic.

Targets are built using rules. There are specific rules and generic rules. Specific rules might create a specific jar from a collection of class files. A generic rule might describe how to turn a C file into an object file.

It will be Java, all Java. You will invoke it using Java.

java -jar mix.jar compile

A Mix project is expressed in the Java programming language. No XML. No external languages. No property files, except those managed by Mix itself.

Mix will depend on a JDK 1.4 solution at every turn, forgoing the en vogue library, the shinny objects of the moment, in order to reduce the footprint of the build system. (You won’t have to download Commons Logging.)

Mix will be a client/server application. It will create a process that will listen on a port for commands. Commands are sent as serialized objects. Startup times are greatly reduced.

Reporting will be done with standards compliant XHTML that follows a strict set of formatting rules, for the application of the CSS stylesheet of your choice. No XML data dump. No transforms. Direct to something that you can read. Each build will create a website with a dashboard index and reports from each task.

Dependency management extends to external dependencies; libraries. Your build can use a local cache of any remote repository. To add a resource, you fire off Mix at the command line with a name and URL. A checksum will be generated and you will be prompted to add the resource and checksum pair to your build.

The resource now is available to your Mix project as an InputStream that can be read and written to file anywhere you like or you can reference the file in the local cache.

When you deploy the application and someone else builds your project on their machine, the resource manager will pull the resource and perform the checksum automatically.

As noted above, the tasks are written in Java. You can use a default task as the action to take for a target. You can use a chain of tasks that will be performed one after another. You can build write your own task in Java, it will get compiled an executed the next time you invoke Mix.

Thus, Mix is a dependency system for your command line Java applications.