/**
* Copyright 2007-2011 Zuse Institute Berlin
*
* 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 de.zib.scalaris.examples;
import java.util.List;
import com.ericsson.otp.erlang.OtpErlangList;
import com.ericsson.otp.erlang.OtpErlangString;
import de.zib.scalaris.ConnectionException;
import de.zib.scalaris.PubSub;
import de.zib.scalaris.UnknownException;
/**
* Provides an example for using the <tt>getSubscribers</tt> methods of the
* {@link PubSub} class.
*
* @author Nico Kruber, kruber@zib.de
* @version 2.5
* @since 2.5
*/
public class PubSubGetSubscribersExample {
/**
* Prints a list of all subscribers to a given topic, provided on the
* command line with the <tt>getSubscribers</tt> methods of
* {@link PubSub}.<br />
* If no topic is given, the default topic <tt>"topic"</tt> is used.
*
* @param args
* command line arguments (first argument can be an optional
* topic to get the subscribers for)
*/
public static void main(final String[] args) {
String topic;
if (args.length != 1) {
topic = "topic";
} else {
topic = args[0];
}
final OtpErlangString otpTopic = new OtpErlangString(topic);
OtpErlangList otpSubscribers;
List<String> subscribers;
System.out.println("Reading values with the class `PubSub`:");
try {
System.out.println(" creating object...");
final PubSub sc = new PubSub();
System.out
.println(" `OtpErlangList getSubscribers(OtpErlangString)`...");
otpSubscribers = (OtpErlangList) sc.getSubscribers(otpTopic).value();
System.out.println(" getSubscribers(" + otpTopic.stringValue()
+ ") == " + getSubscribers(otpSubscribers));
} catch (final ConnectionException e) {
System.out.println(" getSubscribers(" + otpTopic.stringValue()
+ ") failed: " + e.getMessage());
} catch (final UnknownException e) {
System.out.println(" getSubscribers(" + otpTopic.stringValue()
+ ") failed: " + e.getMessage());
}
try {
System.out.println(" creating object...");
final PubSub sc = new PubSub();
System.out
.println(" `List<String> getSubscribers(String)`...");
subscribers = sc.getSubscribers(topic).stringListValue();
System.out.println(" getSubscribers(" + topic + ") == "
+ getSubscribers(subscribers));
} catch (final ConnectionException e) {
System.out.println(" getSubscribers(" + topic + ") failed: "
+ e.getMessage());
} catch (final UnknownException e) {
System.out.println(" getSubscribers(" + topic + ") failed: "
+ e.getMessage());
}
}
/**
* converts the list of strings to a comma-separated list of strings
*
* @param subscribers
* the list of subscribers to convert
* @return a comma-separated list of subscriber URLs
*/
private static String getSubscribers(final List<String> subscribers) {
final StringBuffer result = new StringBuffer();
for (final String string : subscribers) {
result.append(string);
result.append(", ");
}
if (result.length() > 2) {
return "[" + result.substring(0, result.length() - 3) + "]";
} else {
return "[" + result.toString() + "]";
}
}
/**
* converts the list of erlang strings to a comma-separated list of strings
*
* @param subscribers
* the list of subscribers to convert
* @return a comma-separated list of subscriber URLs
*/
private static String getSubscribers(final OtpErlangList subscribers) {
final StringBuffer result = new StringBuffer();
for (int i = 0; i < subscribers.arity(); ++i) {
result.append(((OtpErlangString) subscribers.elementAt(i))
.stringValue());
result.append(", ");
}
if (result.length() > 2) {
return "[" + result.substring(0, result.length() - 3) + "]";
} else {
return "[" + result.toString() + "]";
}
}
}