Extensible Messaging and Presence Protocol (XMPP)
The Extensible
Messaging and Presence Protocol (XMPP) is a protocol for streaming XML elements
in order to exchange messages and presence information.
The XMPP Core uses main features like
- XML Streams
- TLS
- SASL
- <message/>, <presence/>, and <iq/> children of the stream root
The basic functionality expected of XMPP is
instant messaging (IM) and presence application.
Important requirement are
- Exchange messages with other users
- Exchange presence information with other users
- Manage subscriptions to and from other users
- Manage items in a contact list (in XMPP this is called a "roster")
- Block communications to or from specific other users
There are
many providers who had built in libraries as mentioned in XMPP Standard
foundation check link http://xmpp.org/xmpp-software/libraries/ .
The
example below described is based on the agsXMPP
SDK developed in
managed C# dedicated to .NET and Mono technologies. Since, it is dual licensed (GPL) free DLL
developed by ag-software.net and they also provide support for
issues.
Before moving onto example there is important requirement to implement
chat i.e., Chat server installation. I am using Openfire server to fulfill the
requirement. For installation follow the link http://www.igniterealtime.org/projects/openfire/documentation.jsp
Important particulars for this implementation is
- JID – Jabber Id, a unique id in the openfire server for each user.
- Roster- User’s contact is roster.
How to login to the server?
Add the following code after successful login from your
application.
AgsXMPP.XmppClientConnection objXmpp = new agsXMPP.XmppClientConnection();
Jid jid = new Jid ("xyz@server name"); //ex: xyz@gmail.com –
gmail.com is server for google.mail
objXmpp.Server = jid.Server;
objXmpp.Username = jid.User;
objXmpp.Password = ******; //your password of account.
objXmpp.AutoResolveConnectServer = true;
Try
{
objXmpp.OnLogin
+= loggedIn; // loggedIn is handler for successful login to server.
objXmpp.OnAuthError
+= loginFailed;
objXmpp.Open ();
}
Catch (exception ex)
{
}
The loggedin handler is shown below
Private void loggedIn (object o)
{
//lblStatus.Text = "Logged in and Active.";
}
The login failed handler is shown below
Private void loginFailed (object o,
agsXMPP.Xml.Dom.Element el)
{
//lblStatus.Text = "Invalid credentials.”
}
When
the loggedin handler executes it assures you that user credentials are valid
and logged in.
Part 1 we discussed only on the Login part using AgsXmpp.dll.
In next part i.e., Part 2 we shall discuss upon Recieving roster list of the user using AgsXmpp.
