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documentation/extensions/invitation.md

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+Group Chat Invitations
+======================
+
+The group chat invitation packet extension is used to invite other users to a
+group chat room.
+
+  * Inviting Other Users
+  * Listen for Invitations
+
+**XEP related:** N/A -- this protocol is outdated now that the Multi-User Chat (MUC) XEP is available ([XEP-45](http://www.xmpp.org/extensions/xep-0045.html)). However, most existing clients still use this older protocol. Once MUC support becomes more widespread, this API may be deprecated. 
+
+Inviting Other Users
+--------------------
+
+To use the GroupChatInvitation packet extension to invite another user to a
+group chat room, address a new message to the user and set the room name
+appropriately, as in the following code example:
+
+```
+Message message = new Message("user@chat.example.com");
+message.setBody("Join me for a group chat!");
+message.addExtension(new GroupChatInvitation("room@chat.example.com"));
+con.sendPacket(message);
+```
+
+The XML generated for the invitation portion of the code above would be:
+
+```
+<x xmlns="jabber:x:conference" jid="room@chat.example.com"/>
+```
+
+Listening for Invitations
+-------------------------
+
+To listen for group chat invitations, use a PacketExtensionFilter for the `x`
+element name and `jabber:x:conference` namespace, as in the following code
+example:
+
+```
+PacketFilter filter = new PacketExtensionFilter("x", "jabber:x:conference");
+// Create a packet collector or packet listeners using the filter...
+```