Ant2 Goals

Even though Ant2 is expected to be incompatible with the current Ant1 series, it still has the same goals. Ant is a Java based build tool and this remains the main focus of it. The original goals of simplicity, understandability and extensibility still stand and Ant2 will try to achieve them even better than Ant1 does.

Simplicity and Understandability

These two goals are closely related. Ant build files shall be easy to read and understand - at the same time it should be easy to write a custom Ant task and to use the utility classes that Ant2 provides.

Ant2 shall be more consistent than Ant1 is - this means:

core tasks will use the same attribute names for common functionality
similar tasks will be unified to use similar forms.
different implementations for the same functionality will be hidden behind facade tasks.
properties and data types will be unified so that they share the same namespace and inheritance rules.

Furthermore some things will have to become more explicit:

remove all magic properties
make build file writers explicitly state which filters/filtersets a copy task will use
add scoping rules for properties so that not all of them will be inherited by sub-builds, only those that have been specified explicitly.

Extensibility

Ant2 like Ant1 uses build files written in XML as its main input, but it will not be restricted to it. The core of Ant2 will work on an object model of Project/Target/Task that is independent of any external representation.

As an extension of the current <taskdef> concept, tasks can be bundled into task libraries (together with data types and other utility classes). These task libraries are special JAR archives that somehow describe the contained tasks to Ant. Ant will automatically know all tasks contained in task libraries that have been placed into a special directory - in addition task libraries can be referenced and used in a build file explicitly.

New/Modified Features

Ant2 is going to break Ant1 in several ways:

Tasks written for Ant1 won't work in Ant2 as the API of Ant's core and the names of utility classes are going to change. There will probably be adaptors and utility classes to ease the transition for task writers.
Build files written for Ant1 will probably not be valid in Ant2 or at least not yield the same results. It is expected that Ant2 will come with a tool to translate Ant1 build files into equivalent Ant2 versions
magic properties like build.compiler may disappear and be replaced by a different customization concept.
Ant2 is going to require a JDK version 1.2 or above and a JAXP compliant parser version 1.1 or above.

Rejected Features

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