uk.ac.ncl.aries.entanglement.player.spi.CreateEdgePlayer.java Source code

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Here is the source code for uk.ac.ncl.aries.entanglement.player.spi.CreateEdgePlayer.java

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/*
 * Copyright 2012 Keith Flanagan
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 * File created: 27-Nov-2012, 11:56:00
 */

package uk.ac.ncl.aries.entanglement.player.spi;

import com.mongodb.BasicDBObject;
import com.torrenttamer.util.UidGenerator;
import uk.ac.ncl.aries.entanglement.graph.EdgeDAO;
import uk.ac.ncl.aries.entanglement.player.LogPlayerException;
import uk.ac.ncl.aries.entanglement.graph.NodeDAO;
import uk.ac.ncl.aries.entanglement.revlog.commands.CreateEdge;
import uk.ac.ncl.aries.entanglement.revlog.data.RevisionItem;

/**
 * Creates an edge.
 * 
 * @author Keith Flanagan
 */
public class CreateEdgePlayer extends AbstractLogItemPlayer {
    @Override
    public String getSupportedLogItemType() {
        return CreateEdge.class.getSimpleName();
    }

    @Override
    public void playItem(NodeDAO nodeDao, EdgeDAO edgeDao, RevisionItem item) throws LogPlayerException {
        try {
            CreateEdge ce = (CreateEdge) item.getOp();

            /*
             * Edges MUST have a UID, a type, a 'from node uid', and a 'to node uid', as
             * well as a 'from node type' and a 'to node type'.
             * Edges may optionally have from/to node names, if those nodes have well
             * known names. 
             * 
             * However, the DBObject that we receive in the <code>RevisionItem<code>
             * here may not have one or more of these required items set. For example,
             * if the process that created the RevisionItem knows only the node name(s),
             * and not their IDs, then it won't have specified the IDs. 
             * Another example is the edge unique ID - the caller potentially doesn't 
             * care about what UID is assigned to the edge, and therefore for efficiency
             * reasons, won't specify one.
             * 
             * Here, we need to set any required values that don't currently have values
             * specified for them by the incoming RevisionItem.
             */

            BasicDBObject serializedEdge = ce.getEdge();

            //Check that both node's type names are set
            if (!serializedEdge.containsField(EdgeDAO.FIELD_FROM_NODE_TYPE)
                    || !serializedEdge.containsField(EdgeDAO.FIELD_TO_NODE_TYPE)) {
                throw new LogPlayerException("Can't play operation: " + item.getOp() + ". Either "
                        + EdgeDAO.FIELD_FROM_NODE_TYPE + " or " + EdgeDAO.FIELD_TO_NODE_TYPE + " were not set.");
            }

            // Generate a unique ID for this edge, if one doesn't already exist
            if (!serializedEdge.containsField(EdgeDAO.FIELD_UID)) {
                serializedEdge.put(EdgeDAO.FIELD_UID, UidGenerator.generateUid());
            }

            //If no 'from' node UID is specified, then locate it from the name field
            if (!serializedEdge.containsField(EdgeDAO.FIELD_FROM_NODE_UID)) {
                if (!serializedEdge.containsField(EdgeDAO.FIELD_FROM_NODE_NAME)) {
                    throw new LogPlayerException("Can't play operation: " + item.getOp()
                            + ". You must set at least at least one of these: " + EdgeDAO.FIELD_FROM_NODE_UID + ", "
                            + EdgeDAO.FIELD_FROM_NODE_NAME);
                }
                String nodeType = serializedEdge.getString(EdgeDAO.FIELD_FROM_NODE_TYPE);
                String nodeName = serializedEdge.getString(EdgeDAO.FIELD_FROM_NODE_NAME);
                String nodeUid = nodeDao.lookupUniqueIdForName(nodeType, nodeName);
                serializedEdge.put(EdgeDAO.FIELD_FROM_NODE_UID, nodeUid);
            }

            //If no 'to' node UID is specified, then locate it from the name field
            if (!serializedEdge.containsField(EdgeDAO.FIELD_TO_NODE_UID)) {
                if (!serializedEdge.containsField(EdgeDAO.FIELD_TO_NODE_NAME)) {
                    throw new LogPlayerException("Can't play operation: " + item.getOp()
                            + ". You must set at least at least one of these: " + EdgeDAO.FIELD_TO_NODE_UID + ", "
                            + EdgeDAO.FIELD_TO_NODE_NAME);
                }
                String nodeType = serializedEdge.getString(EdgeDAO.FIELD_TO_NODE_TYPE);
                String nodeName = serializedEdge.getString(EdgeDAO.FIELD_TO_NODE_NAME);
                String nodeUid = nodeDao.lookupUniqueIdForName(nodeType, nodeName);
                serializedEdge.put(EdgeDAO.FIELD_TO_NODE_UID, nodeUid);
            }

            edgeDao.store(serializedEdge);
        } catch (Exception e) {
            throw new LogPlayerException("Failed to play command", e);
        }
    }

}