org.kiji.checkin.CheckinClient.java Source code

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Here is the source code for org.kiji.checkin.CheckinClient.java

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/**
 * (c) Copyright 2013 WibiData, Inc.
 *
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * 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.
 */

package org.kiji.checkin;

import java.io.Closeable;
import java.io.IOException;
import java.net.URI;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.util.EntityUtils;

import org.kiji.checkin.models.JsonBeanInterface;
import org.kiji.checkin.models.KijiCommand;
import org.kiji.checkin.models.UpgradeCheckin;
import org.kiji.checkin.models.UpgradeResponse;

/**
 * <p>Client for sending check-in messages to the BentoBox upgrade server. Use the static method
 * {@link #create(org.apache.http.client.HttpClient, java.net.URI)} to obtain an instance that
 * can communicate with a particular upgrade server. Then, use the method
 * {@link #checkin(UpgradeCheckin)} to send a check-in message to the upgrade server and receive
 * a response.</p>
 *
 * <p>Instance of this class are created using an instance of {@link HttpClient}. While the method
 * {@link #checkin(UpgradeCheckin)} will release any resources created for an individual request,
 * clients must close the underlying {@link HttpClient} when it is no longer needed by calling
 * {@link #close()}.</p>
 */
public class CheckinClient implements Closeable {

    /** The http client to use when making requests. */
    private final HttpClient mHttpClient;
    /** The URI to a BentoBox checkin server. */
    private final URI mCheckinServerURI;

    /**
     * Creates a new instance that will make requests to a {@link URI} using an http client.
     *
     * @param httpClient will be used to make http requests.
     * @param checkinServerURI where requests will be sent.
     */
    CheckinClient(HttpClient httpClient, URI checkinServerURI) {
        mHttpClient = httpClient;
        mCheckinServerURI = checkinServerURI;
    }

    /**
     * Creates a new instance that will make requests to a {@link URI} using an http client.
     *
     * @param httpClient will be used to make http requests.
     * @param checkinServerURI where requests will be sent.
     * @return a new upgrade server client.
     */
    public static CheckinClient create(HttpClient httpClient, URI checkinServerURI) {
        return new CheckinClient(httpClient, checkinServerURI);
    }

    /**
     * Sends a check-in message to the upgrade server and receives a response.
     *
     * @param checkinMessage to send to the upgrade server.
     * @return the response sent by the server.
     * @throws IOException if there is a problem making the http request, consuming the response
     *     to the request, or if the upgrade server responded with an error.
     */
    public UpgradeResponse checkin(UpgradeCheckin checkinMessage) throws IOException {
        return UpgradeResponse.fromJSON(genericPost(checkinMessage));
    }

    /**
     * Performs a POST of the given entity and returns the response.
     *
     * @param entityToPost is the entity to send.
     * @return the response from the POST
     * @throws IOException if there is an error.
     */
    private String genericPost(JsonBeanInterface entityToPost) throws IOException {
        // Create a POST request to send to the update server.
        HttpPost postRequest = new HttpPost(mCheckinServerURI);
        // Create an Entity for the message body with the proper content type and content taken
        // from the provided checkin message.
        HttpEntity postRequestEntity = new StringEntity(entityToPost.toJSON(), ContentType.APPLICATION_JSON);
        postRequest.setEntity(postRequestEntity);

        // Execute the request.
        HttpResponse response = mHttpClient.execute(postRequest);
        try {
            HttpEntity responseEntity = response.getEntity();
            String responseBody = EntityUtils.toString(responseEntity);
            // The response body should contain JSON that can be used to create an upgrade response.
            return responseBody;
        } finally {
            postRequest.releaseConnection();
        }
    }

    /**
     * POSTs the given command to the checkin server.
     *
     * @param command is the command to send.
     * @throws IOException if there is an error
     */
    public void postCommand(KijiCommand command) throws IOException {
        genericPost(command);
    }

    /**
     * @return the URI of the upgrade server check-in messages are sent to.
     */
    public URI getServerURI() {
        return mCheckinServerURI;
    }

    /**
     * Closes resources (specifically the http client) used by this instance.
     */
    public void close() {
        mHttpClient.getConnectionManager().shutdown();
    }
}