JBoss.orgCommunity Documentation

JBoss Communications Stream Library User Guide

by Amit Bhayani, Bartosz Baranowski, and Oleg Kulikov

Abstract

This User Guide introduces Stream library and protocol.


This manual uses several conventions to highlight certain words and phrases and draw attention to specific pieces of information.

In PDF and paper editions, this manual uses typefaces drawn from the Liberation Fonts set. The Liberation Fonts set is also used in HTML editions if the set is installed on your system. If not, alternative but equivalent typefaces are displayed. Note: Red Hat Enterprise Linux 5 and later includes the Liberation Fonts set by default.

Four typographic conventions are used to call attention to specific words and phrases. These conventions, and the circumstances they apply to, are as follows.

Mono-spaced Bold

Used to highlight system input, including shell commands, file names and paths. Also used to highlight key caps and key-combinations. For example:

The above includes a file name, a shell command and a key cap, all presented in Mono-spaced Bold and all distinguishable thanks to context.

Key-combinations can be distinguished from key caps by the hyphen connecting each part of a key-combination. For example:

The first sentence highlights the particular key cap to press. The second highlights two sets of three key caps, each set pressed simultaneously.

If source code is discussed, class names, methods, functions, variable names and returned values mentioned within a paragraph will be presented as above, in Mono-spaced Bold. For example:

Proportional Bold

This denotes words or phrases encountered on a system, including application names; dialogue box text; labelled buttons; check-box and radio button labels; menu titles and sub-menu titles. For example:

The above text includes application names; system-wide menu names and items; application-specific menu names; and buttons and text found within a GUI interface, all presented in Proportional Bold and all distinguishable by context.

Note the > shorthand used to indicate traversal through a menu and its sub-menus. This is to avoid the difficult-to-follow 'Select Mouse from the Preferences sub-menu in the System menu of the main menu bar' approach.

Mono-spaced Bold Italic or Proportional Bold Italic

Whether Mono-spaced Bold or Proportional Bold, the addition of Italics indicates replaceable or variable text. Italics denotes text you do not input literally or displayed text that changes depending on circumstance. For example:

Note the words in bold italics above username, domain.name, file-system, package, version and release. Each word is a placeholder, either for text you enter when issuing a command or for text displayed by the system.

Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example:

If you find a typographical error in this manual, or if you have thought of a way to make this manual better, we would love to hear from you! Please submit a report in the the Issue Tracker, against the product JBoss Communications Stream Library , or contact the authors.

When submitting a bug report, be sure to mention the manual's identifier: StreamLibrary_User_Guide

If you have a suggestion for improving the documentation, try to be as specific as possible when describing it. If you have found an error, please include the section number and some of the surrounding text so we can find it easily.

  1. Downloading the source code

    Use SVN to checkout a specific release source, the base URL is ?, then add the specific release version, lets consider 1.0.0.BETA1.

    [usr]$ svn co ?/1.0.0.BETA1 stream-1.0.0.BETA1
  2. Building the source code

    Important

    Maven 2.0.9 (or higher) is used to build the release. Instructions for using Maven2, including install, can be found at http://maven.apache.org

    Use Maven to build the binaries.

    				    [usr]$ cd stream-1.0.0.BETA1
    				    [usr]$ mvn install
    				    

    Once the process finishes you should have the binary jar file in the target directory.

As mentioned stream module is centered on three main interfaces:

Example use of this API looks as follows:



Stream s = ....
StreamSelector selector = ...
s.register(selector);
        
        while(true)
        {
            byte[] buff = new byte[....];
            Collection<SelectorKey> selected = selector.selectNow(selector.OP_READ,0); //0, immediate check
            for(SelectorKey key : selected)
            {
                int read = ket.getStream().read(buff);
                System.err.println("Read: "+read);
            
            }
            selected.clear();
        }
        
        

Datalink is basicaly small extension to async stream. Below example classes depict difference and use case:



import org.mobicents.protocols.link.DataLink;
import org.mobicents.protocols.link.LinkState;
import org.mobicents.protocols.link.LinkStateListener;
import org.mobicents.protocols.stream.api.SelectorKey;
import org.mobicents.protocols.stream.api.SelectorProvider;
import org.mobicents.protocols.stream.api.StreamSelector;
class XServer implements LinkStateListener 
{
    private DataLink link;
    
    private volatile boolean started = false;
    private StreamSelector selector;
    private int rxCount, txCount;
    private InetSocketAddress address, remote;
    
    public XServer(InetSocketAddress address, InetSocketAddress remote) throws Exception {
        link = DataLink.open(address, remote);
        link.setListener(this);
        selector = SelectorProvider.getSelector("org.mobicents.protocols.link.SelectorImpl");
        link.register(selector);
    }
    public void start() {
        started = true;
        new Thread(this).start();
        link.activate();
    }
    public void stop() {
        started = false;
        link.close();
        
        System.out.println("rx=" + rxCount);
        System.out.println("tx=" + txCount);
    }
    
    public void run() {
        byte[] rxBuffer = new byte[172];
        byte[] txBuffer = new byte[172];
        
        while (started) {
            try {
                
                Collection<SelectorKey> keys = selector.selectNow(StreamSelector.OP_READ, 20);
                for (SelectorKey key : keys) {
                    int len = key.getStream().read(rxBuffer);
                    rxCount++;
                    System.out.println("Read " + len  +" bytes: "+Arrays.toString(rxBuffer));
                }
                
                keys.clear();
                keys = selector.selectNow(StreamSelector.OP_WRITE, 20);
                txBuffer[txCount%txBuffer]++;
                for (SelectorKey key : keys) {
                    key.getStream().write(txBuffer);
                    txCount++;
                }
                
                Thread.currentThread().sleep(1000);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    public void onStateChange(LinkState state) {
        System.err.println("DatalinkState: "+state);
    }
}
class XClient implements LinkStateListener 
{
    private DataLink link;
    
    private volatile boolean started = false;
    private StreamSelector selector;
    private InetSocketAddress address, remote;
    
    public XClient(InetSocketAddress address, InetSocketAddress remote) throws Exception {
        link = DataLink.open(address, remote);
        link.setListener(this);
        selector = SelectorProvider.getSelector("org.mobicents.protocols.link.SelectorImpl");
        link.register(selector);
    }
    public void start() {
        started = true;
        new Thread(this).start();
        link.activate();
    }
    public void stop() {
        started = false;
        link.close();
        
    }
    
    public void run() {
        byte[] rxBuffer = new byte[172];
        //byte[] txBuffer = new byte[172];
        
        while (started) {
            try {
                
                Collection<SelectorKey> keys = selector.selectNow(StreamSelector.OP_READ, 20);
                for (SelectorKey key : keys) {
                    int len = key.getStream().read(rxBuffer);
               
                    System.out.println("Read " + len  +" bytes: "+Arrays.toString(rxBuffer));
                }
                
                keys.clear();
                keys = selector.selectNow(StreamSelector.OP_WRITE, 20);
                
                for (SelectorKey key : keys) {
                    key.getStream().write(rxBuffer);
         
                }
                
                Thread.currentThread().sleep(1000);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    public void onStateChange(LinkState state) {
        System.err.println("DatalinkState: "+state);
    }
}
        
        

Revision History
Revision 1.0Wed June 2 2010Bartosz Baranowski
Creation of the JBoss Communications Stream Library User Guide.