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(as stable API)

The type for a channel representing an authentication step with the server. The actual authentication functionality is implemented by the additional interface named in AuthenticationMethod, such as Channel.Interface.SASLAuthentication.

Future authentication steps also supported by this channel type might include solving a captcha and/or agreeing to an EULA or terms-of-use document; each of these would be represented by a channel with this type, but a different AuthenticationMethod.

Channels of this type will normally be be signalled and dispatched while the Connection owning them is in the CONNECTING state. They MAY also appear on a Connection in the CONNECTED state, for instance if periodic re-authentication is required.

Normally, only one channel of this type will exist on a given Connection; if there is more than one, the handler must complete authentication with each of them in turn.

Channels of this type cannot be requested with methods such as CreateChannel. They always have Requested = False, TargetHandleType = None and TargetHandle = 0.

While it is CONNECTING, the Connection MUST NOT proceed with connection, or signal StatusChanged to the CONNECTED state, until each channel of this type has either been accepted as having a positive result (for instance, on SASL channels this is done with the AcceptSASL method), or closed with the Close method.

ServerAuthentication channels normally represent the client authenticating itself to the server, but can also be used for the server to authenticate itself to the client (i.e. prove that it is in fact the desired server and not an imposter). Until the authentication handler has confirmed this, connection should not continue.

If a channel of this type is closed with the Close method before authentication has succeeded, this indicates that the Handler has given up its attempts to authenticate or that no Handler is available.

If this occurs, the connection manager MAY attempt to continue connection (for instance, performing SASL authentication by using any credentials passed to RequestConnection, for instance from the Account.Parameters). If this fails or has already been tried, the Connection will disconnect.

In particular, the ChannelDispatcher will close the channel if it cannot find a handler.

When the connection is done with the channel and it is no longer needed, it is left open until either the connection state turns to DISCONNECTED or the handler closes the channel. The channel SHOULD NOT close itself once finished with.

This property defines the method used for the authentication step represented by this channel, which MUST be one of this channel's Interfaces.

The initially-defined interface that can be used here is Channel.Interface.SASLAuthentication.