EAOP 1.0 realizes the EAOP model through the following characteristics:

•  Dynamic aspect management: Aspects may be instantiated, composed and destroyed at runtime.
•  Expressive crosscuts: execution points can be represented by events and crosscuts can be expressed which denote arbitrary relations between events.
•  Aspects of aspects: Aspects may be applied to other aspects.
•  Explicit aspect composition: Aspects may be combined using a (extensible) set of aspect composition operators.

Definition of expressive aspect languages is a major research issue of AOP. However, none of the common approaches to AOP allows for the flexible and powerful definition of new language constructs.

That’s why the Event-based Aspect-Oriented Programming model (EAOP) is developed and as a general-purpose, well-defined support for AOP with the following characteristics:

• Execution events (e.g., method calls) represent points of interest of an application. Crosscuts, defined as sequences of events, explicitly represent relationships between points of interest.
• Two aspects interact when two actions are triggered at the same point of interest. In order to support conflict resolution, EOAP model makes composition explicit through a tree whose nodes are composition operators and leaves are aspects. Such operators realize aspect compositions by controlling event propagation in the tree of aspects.

EAOP supports an arbitrary number of aspect instances at run time. Aspect instances may be created and composed dynamically. Composition operators are responsible for dynamically creating aspects and inserting (i.e., composing) them in the aspect tree.

Aspects may be applied to other aspects and not only the base program: the monitor is re-entrant. In this case, composition operators can filter events to be propagated and thus define scope of aspects.

It is implemented in Java the EAOP tool as a testable for the definition of expressive aspect languages. Aspect composition can be performed in EAOP by means of expressive and powerful composition operators. In particular, composition operators can be used for resolution of aspect interactions, for aspect instantiation, and for definition of aspects of.

The base program to be woven by our EAOP tool can be either Java source code (by instrumentation with the transformation tool GV Re-coder or Java byte code (by instrumentation using Reflex). Conceptually, aspects run in parallel with the base program. Already has investigated two implementations: a general one based on threads and an optimized one based on continuations (implemented by B. Lewis). The distribution of the EAOP tool is publicly available at http://www.emn.fr/x-info/eaop

EAOP is used for master lectures at EMN. Besides The Early Academic Outreach Program (EAOP) serves thousands participants from schools in Sacramento, Yolo and Solano Counties. The EAOP visits each school site to provide students with educational, career, academic and personal counseling.

The tool provides a testable experimentation of aspect languages. As such, it does not provide specialized languages for point cuts and advice (such as AspectJ) but offers a framework for the definition of arbitrary aspects.
Note that version 1.0 provides EAOP support for non-distributed applications.

The (GPL-licensed) distribution is available and free. It contains the complete source code, several examples and rudimentary documentation.