2003-06-19 20:15:28 +02:00
|
|
|
<html>
|
|
|
|
|
<head>
|
|
|
|
|
<title>Smack: Roster and Presence - Jive Software</title>
|
|
|
|
|
<link rel="stylesheet" type="text/css" href="style.css" />
|
|
|
|
|
</head>
|
|
|
|
|
|
|
|
|
|
<body>
|
|
|
|
|
|
|
|
|
|
<div class="header">
|
|
|
|
|
Roster and Presence
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="nav">
|
|
|
|
|
« <a href="index.html">Table of Contents</a>
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
|
2003-09-29 01:08:33 +02:00
|
|
|
The roster lets you keep track of the availability ("presence") of other users.
|
|
|
|
|
A roster also allows you to organize users into groups such as "Friends" and
|
|
|
|
|
"Co-workers". Other IM systems refer to the roster as the buddy list, contact list,
|
|
|
|
|
etc.<p>
|
2003-08-19 15:22:31 +02:00
|
|
|
|
|
|
|
|
A <tt>Roster</tt> instance is obtained using the <tt>XMPPConnection.getRoster()</tt>
|
2003-09-29 01:08:33 +02:00
|
|
|
method, but only after successfully logging into a server.
|
|
|
|
|
|
|
|
|
|
<p class="subheader">Roster Entries</p>
|
|
|
|
|
|
|
|
|
|
<p>
|
|
|
|
|
Every user in a roster is represented by a RosterEntry, which consists of:<ul>
|
|
|
|
|
<li>An XMPP address (e.g. jsmith@example.com).
|
|
|
|
|
<li>A name you've assigned to the user (e.g. "Joe").
|
|
|
|
|
<li>The list of groups in the roster that the entry belongs to. If the roster
|
|
|
|
|
entry belongs to no groups, it's called an "unfiled entry".
|
|
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
The following code snippet prints all entries in the roster:
|
|
|
|
|
|
|
|
|
|
<pre>
|
|
|
|
|
Roster roster = con.getRoster();
|
|
|
|
|
<b>for</b> (Iterator i=roster.getEntries(); i.hasNext(); ) {
|
|
|
|
|
System.out.println(i.next());
|
|
|
|
|
}
|
|
|
|
|
</pre>
|
|
|
|
|
|
|
|
|
|
Methods also exist to get individual entries, the list of unfiled entries, or to get one or
|
|
|
|
|
all roster groups.
|
|
|
|
|
|
|
|
|
|
<p class="subheader">Presence</p>
|
|
|
|
|
|
|
|
|
|
<img src="images/roster.png" width="166" height="322" vspace="5" hspace="5" alt="Roster" border="0" align="right">
|
|
|
|
|
|
|
|
|
|
<p>Every entry in the roster has presence associated with it. The
|
|
|
|
|
<tt>Roster.getPresence(String user)</tt> method will return a Presence object with
|
|
|
|
|
the user's presence or <tt>null</tt> if the user is not online or you are not
|
|
|
|
|
subscribed to the user's presence. <i>Note:</i> typically, presence
|
|
|
|
|
subscription is always tied to the user being on the roster, but this is not
|
|
|
|
|
true in all cases.</p>
|
|
|
|
|
|
|
|
|
|
<p>A user either has a presence of online or offline. When a user is online, their
|
|
|
|
|
presence may contain extended information such as what they are currently doing, whether
|
|
|
|
|
they wish to be disturbed, etc. See the Presence class for further details.</p>
|
|
|
|
|
|
|
|
|
|
<p class="subheader">Listening for Roster and Presence Changes</p>
|
|
|
|
|
|
|
|
|
|
<p>The typical use of the roster class is to display a tree view of groups and entries
|
|
|
|
|
along with the current presence value of each entry. As an example, see the image showing
|
|
|
|
|
a Roster in the Exodus XMPP client to the right.</p>
|
|
|
|
|
|
|
|
|
|
<p>The presence information will likely
|
|
|
|
|
change often, and it's also possible for the roster entries to change or be deleted.
|
|
|
|
|
To listen for changing roster and presence data, a RosterListener should be used.
|
|
|
|
|
The following code snippet registers a RosterListener with the Roster that prints
|
|
|
|
|
any presence changes in the roster to standard out. A normal client would use
|
|
|
|
|
similar code to update the roster UI with the changing information.
|
|
|
|
|
|
|
|
|
|
<br clear="all">
|
|
|
|
|
|
|
|
|
|
<pre>
|
|
|
|
|
final Roster roster = con.getRoster();
|
|
|
|
|
roster.addRosterListener(new RosterListener() {
|
|
|
|
|
<b>public void</b> rosterModified() {
|
|
|
|
|
<font color="gray"><i>// Ignore event for this example.</i></font>
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
<b>public void</b> presenceChanged(String user) {
|
|
|
|
|
<font color="gray"><i>// If the presence is unavailable then "null" will be printed,
|
|
|
|
|
// which is fine for this example.</i></font>
|
|
|
|
|
System.out.println(<font color="green">"Presence changed: "</font> + roster.getPresence(user));
|
|
|
|
|
}
|
|
|
|
|
});
|
|
|
|
|
</pre>
|
|
|
|
|
|
|
|
|
|
<p class="subheader">Adding Entries to the Roster</p>
|
|
|
|
|
|
|
|
|
|
<p>Rosters and presence use a permissions-based model where users must give permission before
|
|
|
|
|
they are added to someone else's roster. This protects a user's privacy by
|
|
|
|
|
making sure that only approved users are able to view their presence information.
|
|
|
|
|
Therefore, when you add a new roster entry it will be in a pending state until
|
|
|
|
|
the other user accepts your request.</p>
|
|
|
|
|
|
|
|
|
|
If another user requests a presence subscription so they can add you to their roster,
|
|
|
|
|
you must accept or reject that request. Smack handles presence subscription requests
|
|
|
|
|
in one of three ways: <ul>
|
|
|
|
|
|
|
|
|
|
<li> Automatically accept all presence subscription requests.
|
|
|
|
|
<li> Automatically reject all presence subscription requests.
|
|
|
|
|
<li> Process presence subscription requests manually.
|
|
|
|
|
</ul>
|
|
|
|
|
|
|
|
|
|
The mode can be set using the <tt>Roster.setSubscriptionMode(int subscriptionMode)</tt>
|
|
|
|
|
method. Simple clients normally use one of the automated subscription modes, while
|
|
|
|
|
full-featured clients should manually process subscription requests and let the
|
|
|
|
|
end-user accept or reject each request. If using the manual mode, a PacketListener
|
|
|
|
|
should be registered that listens for Presence packets that have a type of
|
|
|
|
|
<tt>Presence.Type.SUBSCRIBE</tt>.
|
2003-06-19 20:15:28 +02:00
|
|
|
|
|
|
|
|
<br clear="all" /><br><br>
|
|
|
|
|
|
|
|
|
|
<div class="footer">
|
2004-03-12 15:23:26 +01:00
|
|
|
Copyright © Jive Software 2002-2004
|
2003-06-19 20:15:28 +02:00
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
</body>
|
|
|
|
|
</html>
|
