A channel type for sending and receiving messages. This channel type is primarily used for textual messages, but can also be used for formatted text, text with "attachments", or binary messages on some protocols.

Most of the methods and signals on this interface are deprecated, since they only support plain-text messages with limited metadata. See the mandatory Messages interface for the modern equivalents.

When a message is received, an identifier is assigned and a MessageReceived signal emitted, and the message is placed in a pending queue represented by the PendingMessages property. When the Handler for a channel has handled the message by showing it to the user (or equivalent), it should acknowledge the receipt of that message using the AcknowledgePendingMessages method, and the message will then be removed from the pending queue. Numeric identifiers for received messages may be reused over the lifetime of the channel.

Sending messages can be requested using the SendMessage method, which will return successfully when the message has been submitted for sending, or return an error with no signal emission if there is an immediate failure. If a message is submitted for sending but delivery of the message later fails, this is indicated by a delivery report, which is received in the same way as an incoming message.

Simple one-to-one chats (such as streams of private messages in XMPP or IRC) should be represented by a Text channel whose TargetHandleType is Handle_Type_Contact. The expected way to request such a channel is to set the ChannelType, TargetHandleType, and either TargetHandle or TargetID in a call to EnsureChannel.

Named chat rooms whose identity can be saved and used again later (IRC channels, Jabber MUCs) are expected to be represented by Text channels with Handle_Type_Room and the Group interface. In protocols where a chatroom can be used as a continuation of one or more one-to-one chats, these channels should also have the Conference interface.

Unnamed, transient chat rooms which cannot be rejoined by their unique identifier (e.g. a conversation on MSN which has, or once had, three or more participants) are expected to be represented by Text channels with Handle_Type_None (and hence TargetHandle 0), the Group interface, and optionally the Conference interface.

On protocols like MSN where a conversation with a user is actually just a nameless chat room starting with exactly two members, to which more members can be invited, the initial one-to-one conversation SHOULD be represented with Handle_Type_Contact. If a third participant joins or is invited, this SHOULD be represented by signalling a new Conference channel with the one-to-one channel in its InitialChannels, migrating the underlying protocol object from the one-to-one channel to the Conference channel, and creating a new protocol-level conversation if the one-to-one channel is re-used. See the Conference interface for more details.

If a channel of type Text is closed while it has pending messages, the connection manager MUST allow this, but SHOULD open a new channel to deliver those messages, signalling it as a new channel with the NewChannels signal. The new channel should resemble the old channel, but have Requested = FALSE regardless of its previous value; the InitiatorHandle and InitiatorID should correspond to the sender of one of the pending messages.

As a result, Text channels SHOULD implement Channel.Interface.Destroyable.