IIScCampusMapGETProxyService.java

package se252.jan15.calvinandhobbes.project0;

/*
 * Copyright 2010-2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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.
 */
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.services.sqs.AmazonSQS;
import com.amazonaws.services.sqs.model.DeleteMessageRequest;
import com.amazonaws.services.sqs.model.Message;
import com.amazonaws.services.sqs.model.ReceiveMessageRequest;
import com.amazonaws.services.sqs.model.SendMessageRequest;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

/**
 * This sample demonstrates how to make basic requests to Amazon SQS using the
 * AWS SDK for Java.
 * <p>
 * <b>Prerequisites:</b> You must have a valid Amazon Web
 * Services developer account, and be signed up to use Amazon SQS. For more
 * information on Amazon SQS, see http://aws.amazon.com/sqs.
 * <p>
 * Fill in your AWS access credentials in the provided credentials file
 * template, and be sure to move the file to the default location
 * (~/.aws/credentials) where the sample code will load the credentials from.
 * <p>
 * <b>WARNING:</b> To avoid accidental leakage of your credentials, DO NOT keep
 * the credentials file in your source directory.
 */

@Path("dataProxy")
public class IIScCampusMapGETProxyService {
	private static LoadingCache<String, String> categoryCache = null;
	
	public static void cacheInit() {
		categoryCache = CacheBuilder.newBuilder()
	            .maximumSize(7) // maximum 7 records can be cached
	            .expireAfterAccess(10, TimeUnit.MINUTES) // cache will expire after 10 minutes of access
	            .build(new CacheLoader<String, String>(){ // build the cacheloader
	               @Override
	               public String load(String category) throws Exception {
	                  return getCategoryData(category);
	               }
	            });
	}

	private static String getCategoryData(String category) {
		AmazonSQS queueClient = Queues.getQueue();
		String resp = null;
        try {
            // Send a message
            queueClient.sendMessage(new SendMessageRequest(Queues.req, category));

            // Receive messages
            Boolean flag = true;
            while(flag) {
            	ReceiveMessageRequest receiveReq = new ReceiveMessageRequest(Queues.resp);
            	receiveReq.setWaitTimeSeconds(10);
            	List<Message> messages = queueClient.receiveMessage(receiveReq).getMessages();
            	for (Message message : messages) {
            		String[] strs = message.getBody().split("\\$");
            		if(strs[0].equals(category)) {
            			flag = false;
            			resp = strs[1];
            			queueClient.deleteMessage(new DeleteMessageRequest(Queues.resp, message.getReceiptHandle()));
            			break;
            		}
            	}
            }
        } catch (AmazonServiceException ase) {
            System.out.println("Caught an AmazonServiceException, which means your request made it " +
                    "to Amazon SQS, but was rejected with an error response for some reason.");
            System.out.println("Error Message:    " + ase.getMessage());
            System.out.println("HTTP Status Code: " + ase.getStatusCode());
            System.out.println("AWS Error Code:   " + ase.getErrorCode());
            System.out.println("Error Type:       " + ase.getErrorType());
            System.out.println("Request ID:       " + ase.getRequestId());
        } catch (AmazonClientException ace) {
            System.out.println("Caught an AmazonClientException, which means the client encountered " +
                    "a serious internal problem while trying to communicate with SQS, such as not " +
                    "being able to access the network.");
            System.out.println("Error Message: " + ace.getMessage());
		}
        return resp;
	}
	
	@GET
    @Produces(MediaType.APPLICATION_JSON)
    public Response IIScDataProxyServer(@DefaultValue("AllCategories") @QueryParam("category") String category) {
		String resp = null;
		try {
			resp = categoryCache.get(category);
		} catch (ExecutionException e) {
			e.printStackTrace();
		}
        return Response.ok(resp, MediaType.APPLICATION_JSON).header("Access-Control-Allow-Origin", "*").build();
    }
}