Check out the new USENIX Web site. next up previous
Next: Comparisons Up: Conditions Previous: Model

Basic conditions

In JAVA, a condition object implements the Condition interface given in Figure 7. It is evaluated for a given message object m by invoking conforms() with m as argument. The condition classes we propose are conceptually similar to the predicates found in JGL [Obj99] that are used in conjunction with centralized collections. The main difference is that our condition objects are specific to publish/subscribe, by representing queries on future objects.

What differentiates our condition classes are the comparison functions they encapsulate. The other attributes, namely accessor and result, are initialization arguments and can thus be factored out.

public interface Condition {

  public boolean conforms(Object m);

Figure 7: Condition Interface

Patrick Eugster