JavaSpaces™ Principles, Patterns, and Practice

2.1. Entries

Entries are the common currency of all space-based applications; by exchanging entries, processes can communicate, synchronize and coordinate their activities.

An entry is just an object that follows a few conventions to make it safe for travel through a space. Let's define an entry:

import net.jini.core.entry.*;

public class SpaceShip implements Entry {
  // a no-arg constructor
  public SpaceShip() {
  }
}

Here we've defined an entry called SpaceShip. We first import the net.jini.core.entry package, which contains the Entry interface. For a class to be an entry it needs to implement the Entry interface. You can also create an entry by extending a class that already implements the Entry interface, which we will see later in this chapter. ...