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Hawkular client library that can be used to consume and produce bus messages using the bus' REST API.
/*
* Copyright 2015 Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags.
*
* 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.hawkular.bus.restclient;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.Map;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.jboss.logging.Logger;
/**
* You can use this to consume and produce messages on the Hawkular bus.
*
* This class is purposefully designed to be simple with very few dependencies (just
* requires Apache's httpclient and JBoss Logging). Specifically, you do not need
* any other Hawkular libraries to be able to use this to send messages to the
* Hawkular bus.
*/
public class RestClient {
private static final String DEFAULT_URL_PATH = "/hawkular-bus/message/";
private static final Logger LOG = Logger.getLogger(RestClient.class);
private final URL endpoint;
private final DefaultHttpClient httpclient;
public static enum Type {
QUEUE, TOPIC
}
/**
* Creates the sender with a default HTTP endpoint of the REST server.
*
* @param host the remote server
* @param port if null or -1, no port will be specified in the URL
* @throws RestClientException if the endpoint cannot be used to refer to queues or topics
* or if one of the parameters consists of invalid URL syntax
*/
public RestClient(String host, Integer port) throws RestClientException {
this("http", host, port);
}
/**
* Creates the sender with a default endpoint of the REST server.
*
* @param protocol http or https
* @param host the remote server
* @param port if null or -1, no port will be specified in the URL
* @throws RestClientException if the endpoint cannot be used to refer to queues or topics
* or if one of the parameters consists of invalid URL syntax
*/
public RestClient(String protocol, String host, Integer port) throws RestClientException {
this(buildDefaultURL(protocol, host, port));
}
private static URL buildDefaultURL(String protocol, String host, Integer port) throws RestClientException {
try {
return new URL(protocol, host, ((port != null) ? port.intValue() : -1), DEFAULT_URL_PATH);
} catch (MalformedURLException e) {
throw new RestClientException(e);
}
}
/**
* Endpoint of the REST server, not including the fragment that consists of the queue/topic name.
* For example: http://host:8080/hawkular-bus/message/
*
* If the given URL does not end with a "/", one will be added to it.
*
* @param endpoint the REST server endpoint, not including the queue/topic name
* @throws RestClientException if the endpoint cannot be used to refer to queues or topics
*/
public RestClient(URL endpoint) throws RestClientException {
// make sure the endpoint ends with a "/" since we later will append the queue/topic name to it
if (endpoint.toString().endsWith("/")){
this.endpoint = endpoint;
} else {
this.endpoint = appendToURL(endpoint, "/");
}
// Make sure this endpoint URL is a valid bus endpoint - see if it can be converted to topic or queue URLs.
// These will throw exceptions if the endpoint URL cannot be used for queues or topics.
getEndpointForType(Type.QUEUE, "Test");
getEndpointForType(Type.TOPIC, "Test");
this.httpclient = new DefaultHttpClient();
LOG.debugf("Created Hawkular Bus REST client for endpoint [%s]", this.endpoint);
}
/**
* @return the REST endpoint not inluding the fragment that consists of the queue/topic name.
*/
public URL getEndpoint() {
return this.endpoint;
}
/**
* Sends a message to the REST endpoint in order to put a message on the given topic.
*
* @param topicName name of the topic
* @param jsonPayload the actual message (as a JSON string) to put on the bus
* @param headers any headers to send with the message (can be null or empty)
* @return the response
* @throws RestClientException if the response was not a 200 status code
*/
public HttpResponse postTopicMessage(String topicName, String jsonPayload, Map headers)
throws RestClientException {
return postMessage(Type.TOPIC, topicName, jsonPayload, headers);
}
/**
* Sends a message to the REST endpoint in order to put a message on the given queue.
*
* @param queueName name of the queue
* @param jsonPayload the actual message (as a JSON string) to put on the bus
* @param headers any headers to send with the message (can be null or empty)
* @return the response
* @throws RestClientException if the response was not a 200 status code
*/
public HttpResponse postQueueMessage(String queueName, String jsonPayload, Map headers)
throws RestClientException {
return postMessage(Type.QUEUE, queueName, jsonPayload, headers);
}
protected HttpResponse postMessage(Type type, String name, String jsonPayload, Map headers)
throws RestClientException {
URL messageUrl = getEndpointForType(type, name);
URI uri;
try {
uri = messageUrl.toURI();
} catch (URISyntaxException e) {
throw new RestClientException(e);
}
HttpResponse response = sendPost(uri, jsonPayload, headers);
return response;
}
protected HttpResponse sendPost(URI uri, String jsonPayload, Map headers)
throws RestClientException {
LOG.tracef("Posting message to bus. uri=[%s], json=[%s], headers[%s]", uri, jsonPayload, headers);
HttpPost request = null;
HttpResponse httpResponse = null;
try {
request = new HttpPost(uri);
if (headers != null) {
for (Map.Entry entry : headers.entrySet()) {
request.setHeader(entry.getKey(), entry.getValue());
}
}
request.setEntity(new StringEntity(jsonPayload, ContentType.APPLICATION_JSON));
httpResponse = httpclient.execute(request);
StatusLine statusLine = httpResponse.getStatusLine();
if (statusLine.getStatusCode() != 200) {
throw new Exception("HTTP post request failed. status-code=[" + statusLine.getStatusCode()
+ "], reason=["
+ statusLine.getReasonPhrase() + "], url=[" + request.getURI() + "]");
}
return httpResponse;
} catch (Exception e) {
String errStr = String.format("Failed to post message to bus via URI [%s]", uri.toString());
LOG.debugf("%s. Cause=[%s]", errStr, e.toString());
throw new RestClientException(httpResponse, errStr, e);
} finally {
if (request != null) {
request.releaseConnection();
}
}
}
protected URL getEndpointForType(Type type, String name) throws RestClientException {
switch (type) {
case QUEUE:
return appendToURL(endpoint, name + "?type=queue");
case TOPIC:
return appendToURL(endpoint, name + "?type=topic");
default: {
throw new RuntimeException("Invalid type [" + type + "] - please report this bug");
}
}
}
protected URL appendToURL(URL url, String appendage) throws RestClientException {
String oldUrlString = url.toString();
String newUrlString = oldUrlString + appendage;
try {
return new URL(newUrlString);
} catch (MalformedURLException e) {
throw new RestClientException(String.format("URL [%s] cannot be appended with [%s]", url, appendage), e);
}
}
}
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