Smack/documentation/extensions/muc.md

Multi User Chat

Allows configuration of, participation in, and administration of individual text-based conference rooms.

• Create a new Room
• Join a room
• Manage room invitations
• Discover MUC support
• Discover joined rooms
• Discover room information
• Start a private chat
• Manage changes on room subject
• Manage role modifications
• Manage affiliation modifications

XEP related: XEP-45

Create a new Room

Description

Allowed users may create new rooms. There are two types of rooms that you can create. Instant rooms which are available for immediate access and are automatically created based on some default configuration and Reserved rooms which are manually configured by the room creator before anyone is allowed to enter.

Usage

In order to create a room you will need to first create an instance of MultiUserChat. In order to do so, get a instance of MultiUserChatManager and call getMultiUserChat(String) to retrieve a MultiUserChat instance. The next step is to send create(String nickname) to the MultiUserChat instance where nickname is the nickname to use when joining the room.

Depending on the type of room that you want to create you will have to use different configuration forms. In order to create an Instant room just send sendConfigurationForm(Form form) where form is an empty form. But if you want to create a Reserved room then you should first get the room's configuration form, complete the form and finally send it back to the server.

Examples

In this example we can see how to create an instant room:

// Get the MultiUserChatManager
MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);

// Get a MultiUserChat using MultiUserChatManager
MultiUserChat muc = manager.getMultiUserChat("myroom@conference.jabber.org");

// Create the room
muc.create("testbot");

// Send an empty room configuration form which indicates that we want
// an instant room
muc.sendConfigurationForm(new Form(Form.TYPE_SUBMIT));

In this example we can see how to create a reserved room. The form is completed with default values:

// Get the MultiUserChatManager
MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);

// Create a MultiUserChat using a XMPPConnection for a room
MultiUserChat muc = = manager.getMultiUserChat("myroom@conference.jabber.org");

// Create the room
muc.create("testbot");

// Get the the room's configuration form
Form form = muc.getConfigurationForm();
// Create a new form to submit based on the original form
Form submitForm = form.createAnswerForm();
// Add default answers to the form to submit
for (Iterator fields = form.getFields(); fields.hasNext();) {
	FormField field = (FormField) fields.next();
	if (!FormField.TYPE_HIDDEN.equals(field.getType()) && field.getVariable() != null) {
		// Sets the default value as the answer
		submitForm.setDefaultAnswer(field.getVariable());
}
}
// Sets the new owner of the room
List owners = new ArrayList();
owners.add("johndoe@jabber.org");
submitForm.setAnswer("muc#roomconfig_roomowners", owners);
// Send the completed form (with default values) to the server to configure the room
muc.sendConfigurationForm(submitForm);

Join a room

Description

Your usual first step in order to send messages to a room is to join the room. Multi User Chat allows to specify several parameter while joining a room. Basically you can control the amount of history to receive after joining the room as well as provide your nickname within the room and a password if the room is password protected.

Usage

In order to join a room you will need to first get an instance of MultiUserChat. In order to do so, get a instance of MultiUserChatManager and call getMultiUserChat(String) to retrieve a MultiUserChat instance. The next step is to send join(...) to the MultiUserChat instance. But first you will have to decide which join message to send. If you want to just join the room without a password and without specifying the amount of history to receive then you could use join(String nickname) where nickname if your nickname in the room. In case the room requires a password in order to join you could then use join(String nickname, String password). And finally, the most complete way to join a room is to send join(String nickname, String password, DiscussionHistory history, long timeout) where nickname is your nickname in the room, , password is your password to join the room, history is an object that specifies the amount of history to receive and timeout is the milliseconds to wait for a response from the server.

Examples

In this example we can see how to join a room with a given nickname:

// Get the MultiUserChatManager
MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);

// Create a MultiUserChat using a XMPPConnection for a room
MultiUserChat muc2 = manager.getMultiUserChat("myroom@conference.jabber.org");

// User2 joins the new room
// The room service will decide the amount of history to send
muc2.join("testbot2");

In this example we can see how to join a room with a given nickname and password:

// Get the MultiUserChatManager
MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);

// Create a MultiUserChat using a XMPPConnection for a room
MultiUserChat muc2 = manager.getMultiUserChat("myroom@conference.jabber.org");

// User2 joins the new room using a password
// The room service will decide the amount of history to send
muc2.join("testbot2", "password");

In this example we can see how to join a room with a given nickname specifying the amount of history to receive:

// Get the MultiUserChatManager
MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);

// Create a MultiUserChat using a XMPPConnection for a room
MultiUserChat muc2 = manager.getMultiUserChat("myroom@conference.jabber.org");

// User2 joins the new room using a password and specifying
// the amount of history to receive. In this example we are requesting the last 5 messages.
DiscussionHistory history = new DiscussionHistory();
history.setMaxStanzas(5);
muc2.join("testbot2", "password", history, conn1.getPacketReplyTimeout());

Manage room invitations

Description

It can be useful to invite another user to a room in which one is an occupant. Depending on the room's type the invitee could receive a password to use to join the room and/or be added to the member list if the room is of type members-only. Smack allows to send room invitations and let potential invitees to listening for room invitations and inviters to listen for invitees' rejections.

Usage

In order to invite another user to a room you must be already joined to the room. Once you are joined just send invite(String participant, String reason) to the MultiUserChat where participant is the user to invite to the room (e.g. hecate@shakespeare.lit) and reason is the reason why the user is being invited.

If potential invitees want to listen for room invitations then the invitee must add an InvitationListener to the MultiUserChatManager class. Since the InvitationListener is an interface, it is necessary to create a class that implements this interface. If an inviter wants to listen for room invitation rejections, just add an InvitationRejectionListener to the MultiUserChat. InvitationRejectionListener is also an interface so you will need to create a class that implements this interface.

Examples

In this example we can see how to invite another user to the room and lister for possible rejections:

// Get the MultiUserChatManager
MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);

// Create a MultiUserChat using a XMPPConnection for a room
MultiUserChat muc2 = manager.getMultiUserChat("myroom@conference.jabber.org");

muc2.join("testbot2");
// User2 listens for invitation rejections
muc2.addInvitationRejectionListener(new InvitationRejectionListener() {
	public void invitationDeclined(String invitee, String reason) {
		// Do whatever you need here...
	}
});
// User2 invites user3 to join to the room
muc2.invite("user3@host.org/Smack", "Meet me in this excellent room");

In this example we can see how to listen for room invitations and decline invitations:

// User3 listens for MUC invitations
MultiUserChatManager.getInstanceFor(connection).addInvitationListener(new InvitationListener() {
	public void invitationReceived(XMPPConnection conn, String room, String inviter, String reason, String password) {
		// Reject the invitation
		MultiUserChat.decline(conn, room, inviter, "I'm busy right now");
	}
});

Discover MUC support

Description

A user may want to discover if one of the user's contacts supports the Multi- User Chat protocol.

Usage

In order to discover if one of the user's contacts supports MUC just send isServiceEnabled(String user) to the MultiUserChatManager class where user is a fully qualified XMPP ID, e.g. jdoe@example.com. You will receive a boolean indicating whether the user supports MUC or not.

Examples

In this example we can see how to discover support of MUC:

// Discover whether user3@host.org supports MUC or not
boolean supports = MultiUserChatManager.getInstanceFor(connection).isServiceEnabled("user3@host.org/Smack");

Discover joined rooms

Description

A user may also want to query a contact regarding which rooms the contact is in.

Usage

In order to get the rooms where a user is in just send getJoinedRooms(String user) to the MultiUserChatManager class where user is a fully qualified XMPP ID, e.g. jdoe@example.com. You will get an Iterator of Strings as an answer where each String represents a room name.

Examples

In this example we can see how to get the rooms where a user is in:

// Get the MultiUserChatManager
MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);

// Get the rooms where user3@host.org has joined
List<String> joinedRooms = manager.getJoinedRooms("user3@host.org/Smack");

Discover room information

Description

A user may need to discover information about a room without having to actually join the room. The server will provide information only for public rooms.

Usage

In order to discover information about a room just send getRoomInfo(String room) to the MultiUserChatManager class where room is the XMPP ID of the room, e.g. roomName@conference.myserver. You will get a RoomInfo object that contains the discovered room information.

Examples

In this example we can see how to discover information about a room:

// Get the MultiUserChatManager
MultiUserChatManager manager = MultiUserChatManager.getInstanceFor(connection);

// Discover information about the room roomName@conference.myserver
RoomInfo info = manager.getRoomInfo("roomName@conference.myserver");
System.out.println("Number of occupants:" + info.getOccupantsCount());
System.out.println("Room Subject:" + info.getSubject());

Start a private chat

Description

A room occupant may want to start a private chat with another room occupant even though they don't know the fully qualified XMPP ID (e.g. jdoe@example.com) of each other.

Usage

To create a private chat with another room occupant just send createPrivateChat(String participant) to the MultiUserChat that you used to join the room. The parameter participant is the occupant unique room JID (e.g. 'darkcave@macbeth.shakespeare.lit/Paul'). You will receive a regular Chat object that you can use to chat with the other room occupant.

Examples

In this example we can see how to start a private chat with another room occupant:

// Start a private chat with another participant
Chat chat = muc2.createPrivateChat("myroom@conference.jabber.org/johndoe");
chat.sendMessage("Hello there");

Manage changes on room subject

Description

A common feature of multi-user chat rooms is the ability to change the subject within the room. As a default, only users with a role of "moderator" are allowed to change the subject in a room. Although some rooms may be configured to allow a mere participant or even a visitor to change the subject.

Every time the room's subject is changed you may want to be notified of the modification. The new subject could be used to display an in-room message.

Usage

In order to modify the room's subject just send changeSubject(String subject) to the MultiUserChat that you used to join the room where subject is the new room's subject. On the other hand, if you want to be notified whenever the room's subject is modified you should add a SubjectUpdatedListener to the MultiUserChat by sending addSubjectUpdatedListener(SubjectUpdatedListener listener) to the MultiUserChat. Since the SubjectUpdatedListener is an interface, it is necessary to create a class that implements this interface.

Examples

In this example we can see how to change the room's subject and react whenever the room's subject is modified:

// An occupant wants to be notified every time the room's subject is changed
muc3.addSubjectUpdatedListener(new SubjectUpdatedListener() {
	public void subjectUpdated(String subject, String from) {
		....
	}
});
// A room's owner changes the room's subject
muc2.changeSubject("New Subject");

Manage role modifications

Description

There are four defined roles that an occupant can have:

1. Moderator
2. Participant
3. Visitor
4. None (the absence of a role)

These roles are temporary in that they do not persist across a user's visits to the room and can change during the course of an occupant's visit to the room.

A moderator is the most powerful occupant within the context of the room, and can to some extent manage other occupants' roles in the room. A participant has fewer privileges than a moderator, although he or she always has the right to speak. A visitor is a more restricted role within the context of a moderated room, since visitors are not allowed to send messages to all occupants.

Roles are granted, revoked, and maintained based on the occupant's room nickname or full JID. Whenever an occupant's role is changed Smack will trigger specific events.

Usage

In order to grant voice (i.e. make someone a participant) just send the message grantVoice(String nickname) to MultiUserChat. Use revokeVoice(String nickname) to revoke the occupant's voice (i.e. make the occupant a visitor).

In order to grant moderator privileges to a participant or visitor just send the message grantModerator(String nickname) to MultiUserChat. Use revokeModerator(String nickname) to revoke the moderator privilege from the occupant thus making the occupant a participant.

Smack allows you to listen for role modification events. If you are interested in listening role modification events of any occupant then use the listener ParticipantStatusListener. But if you are interested in listening for your own role modification events, use the listener UserStatusListener. Both listeners should be added to the MultiUserChat by using addParticipantStatusListener(ParticipantStatusListener listener) or addUserStatusListener(UserStatusListener listener) respectively. These listeners include several notification events but you may be interested in just a few of them. Smack provides default implementations for these listeners avoiding you to implement all the interfaces' methods. The default implementations are DefaultUserStatusListener and DefaultParticipantStatusListener. Below you will find the sent messages to the listeners whenever an occupant's role has changed.

These are the triggered events when the role has been upgraded:

Old	New	Events
None	Visitor	--
Visitor	Participant	voiceGranted
Participant	Moderator	moderatorGranted
None	Participant	voiceGranted
None	Moderator	voiceGranted + moderatorGranted
Visitor	Moderator	voiceGranted + moderatorGranted

These are the triggered events when the role has been downgraded:

Old	New	Events
Moderator	Participant	moderatorRevoked
Participant	Visitor	voiceRevoked
Visitor	None	kicked
Moderator	Visitor	voiceRevoked + moderatorRevoked
Moderator	None	kicked
Participant	None	kicked

Examples

In this example we can see how to grant voice to a visitor and listen for the notification events:

// User1 creates a room
muc = manager.getMultiUserChat("myroom@conference.jabber.org");
muc.create("testbot");
// User1 (which is the room owner) configures the room as a moderated room
Form form = muc.getConfigurationForm();
Form answerForm = form.createAnswerForm();
answerForm.setAnswer("muc#roomconfig_moderatedroom", "1");
muc.sendConfigurationForm(answerForm);

// User2 joins the new room (as a visitor)
MultiUserChat muc2 = manager2.getMultiUserChat("myroom@conference.jabber.org");
muc2.join("testbot2");
// User2 will listen for his own "voice" notification events
muc2.addUserStatusListener(new DefaultUserStatusListener() {
	public void voiceGranted() {
		super.voiceGranted();
		...
	}
	public void voiceRevoked() {
		super.voiceRevoked();
		...
	}
});

// User3 joins the new room (as a visitor)
MultiUserChat muc3 = manager3.getMultiUserChat("myroom@conference.jabber.org");
muc3.join("testbot3");
// User3 will lister for other occupants "voice" notification events
muc3.addParticipantStatusListener(new DefaultParticipantStatusListener() {
	public void voiceGranted(String participant) {
		super.voiceGranted(participant);
		...
	}
	public void voiceRevoked(String participant) {
		super.voiceRevoked(participant);
		...
	}
});

// The room's owner grants voice to user2
muc.grantVoice("testbot2");

Manage affiliation modifications

Description

There are five defined affiliations that a user can have in relation to a room:

1. Owner
2. Admin
3. Member
4. Outcast
5. None (the absence of an affiliation)

These affiliations are semi-permanent in that they persist across a user's visits to the room and are not affected by happenings in the room. Affiliations are granted, revoked, and maintained based on the user's bare JID.

If a user without a defined affiliation enters a room, the user's affiliation is defined as "none"; however, this affiliation does not persist across visits.

Owners and admins are by definition immune from certain actions. Specifically, an owner or admin cannot be kicked from a room and cannot be banned from a room. An admin must first lose his or her affiliation (i.e., have an affiliation of "none" or "member") before such actions could be performed on them.

The member affiliation provides a way for a room owner or admin to specify a "whitelist" of users who are allowed to enter a members-only room. When a member enters a members-only room, his or her affiliation does not change, no matter what his or her role is. The member affiliation also provides a way for users to effectively register with an open room and thus be permanently associated with that room in some way (one result may be that the user's nickname is reserved in the room).

An outcast is a user who has been banned from a room and who is not allowed to enter the room. Whenever a user's affiliation is changed Smack will trigger specific events.

Usage

In order to grant membership to a room, administrator privileges or owner priveliges just send grantMembership(String jid), grantAdmin(String jid) or grantOwnership(String jid) to MultiUserChat respectively. Use revokeMembership(String jid), revokeAdmin(String jid) or revokeOwnership(String jid) to revoke the membership to a room, administrator privileges or owner priveliges respectively.

In order to ban a user from the room just send the message banUser(String jid, String reason) to MultiUserChat.

Smack allows you to listen for affiliation modification events. If you are interested in listening affiliation modification events of any user then use the listener ParticipantStatusListener. But if you are interested in listening for your own affiliation modification events, use the listener UserStatusListener. Both listeners should be added to the MultiUserChat by using addParticipantStatusListener(ParticipantStatusListener listener) or addUserStatusListener(UserStatusListener listener) respectively. These listeners include several notification events but you may be interested in just a few of them. Smack provides default implementations for these listeners avoiding you to implement all the interfaces' methods. The default implementations are DefaultUserStatusListener and DefaultParticipantStatusListener. Below you will find the sent messages to the listeners whenever a user's affiliation has changed.

These are the triggered events when the affiliation has been upgraded:

Old	New	Events
None	Member	membershipGranted
Member	Admin	membershipRevoked + adminGranted
Admin	Owner	adminRevoked + ownershipGranted
None	Admin	adminGranted
None	Owner	ownershipGranted
Member	Owner	membershipRevoked + ownershipGranted

These are the triggered events when the affiliation has been downgraded:

Old	New	Events
Owner	Admin	ownershipRevoked + adminGranted
Admin	Member	adminRevoked + membershipGranted
Member	None	membershipRevoked
Owner	Member	ownershipRevoked + membershipGranted
Owner	None	ownershipRevoked
Admin	None	adminRevoked
Anyone	Outcast	banned

Examples

In this example we can see how to grant admin privileges to a user and listen for the notification events:

// User1 creates a room
muc = manager.getMultiUserChat("myroom@conference.jabber.org");
muc.create("testbot");
// User1 (which is the room owner) configures the room as a moderated room
Form form = muc.getConfigurationForm();
Form answerForm = form.createAnswerForm();
answerForm.setAnswer("muc#roomconfig_moderatedroom", "1");
muc.sendConfigurationForm(answerForm);

// User2 joins the new room (as a visitor)
MultiUserChat muc2 = manager2.getMultiUserChat("myroom@conference.jabber.org");
muc2.join("testbot2");
// User2 will listen for his own admin privileges
muc2.addUserStatusListener(new DefaultUserStatusListener() {
	public void membershipRevoked() {
		super.membershipRevoked();
		...
	}
	public void adminGranted() {
		super.adminGranted();
		...
	}
});

// User3 joins the new room (as a visitor)
MultiUserChat muc3 = manager3.getMultiUserChat("myroom@conference.jabber.org");
muc3.join("testbot3");
// User3 will lister for other users admin privileges
muc3.addParticipantStatusListener(new DefaultParticipantStatusListener() {
	public void membershipRevoked(String participant) {
		super.membershipRevoked(participant);
		...
	}
	public void adminGranted(String participant) {
		super.adminGranted(participant);
		...
	}
});
// The room's owner grants admin privileges to user2
muc.grantAdmin("user2@jabber.org");