--- /dev/null
+/*
+ * Copyright (c) 2003-2005 The BISON Project
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+package peersim.core;
+
+
+/**
+* Instances of classes implementing this interface can form networks (graphs)
+* in the simulator framework.
+* The interface is similar to one of a container (containing neighbors),
+* only the types of the contained elements have to be {@link Node}.
+* The neighbor collection is defined in a random access list style, but
+* it must follow the contract of a set too (elements must be unique).
+* <p>
+* Also note that there is no possibility to remove elements from the
+* neighbor set. This is because removal is usually costly and it does not make
+* sense in the context of our applications,
+* where this interface is used for 1) initialization and 2)
+* providing an interface for other protocols for accessing the neighbor list.
+* Protocols that manage links remove, refresh, etc their link set internally
+* or through custom methods.
+* Therefore it would only put an unnecessary burden on implementors.
+*/
+public interface Linkable extends Cleanable {
+
+
+ /**
+ * Returns the size of the neighbor list.
+ */
+ public int degree();
+
+ /**
+ * Returns the neighbor with the given index. The contract is that
+ * listing the elements from index 0 to index degree()-1 should list
+ * each element exactly once if this object is not modified in the
+ * meantime. It throws an IndexOutOfBounds exception if i is negative
+ * or larger than or equal to {@link #degree}.
+ */
+ public Node getNeighbor(int i);
+
+ /**
+ * Add a neighbor to the current set of neighbors. If neighbor
+ * is not yet a neighbor but it cannot be added from other reasons,
+ * this method should not return normally, that is, it must throw
+ * a runtime exception.
+ * @return true if the neighbor has been inserted; false if the
+ * node is already a neighbor of this node
+ */
+ public boolean addNeighbor(Node neighbour);
+
+ /**
+ * Returns true if the given node is a member of the neighbor set.
+ */
+ public boolean contains(Node neighbor);
+
+ /**
+ * A possibility for optimization. An implementation should try to
+ * compress its internal representation. Normally this is called
+ * by initializers or other components when
+ * no increase in the expected size of the neighborhood can be
+ * expected.
+ */
+ public void pack();
+}
+
