.TH megaco_transport 3erl "megaco 3.18.1" "Ericsson AB" "Erlang Module Definition"
.SH NAME
megaco_transport \- Megaco transport behaviour.
.SH DESCRIPTION
.LP
The following functions should be exported from a \fImegaco_transport\fR\& callback module:
.RS 2
.TP 2
*
\fBsend_message/2\fR\& [\fImandatory\fR\&]
.LP
.TP 2
*
\fBsend_message/3\fR\& [\fIoptional\fR\&]
.LP
.TP 2
*
\fBresend_message/2\fR\& [\fIoptional\fR\&]
.LP
.TP 2
*

.LP
.RE

.SH EXPORTS
.LP
.B
Module:send_message(Handle, Msg) -> ok | {cancel, Reason} | Error
.br
.B
Module:send_message(Handle, Msg, Resend) -> ok | {cancel, Reason} | Error
.br
.RS
.LP
Types:

.RS 3
Handle = term()
.br
Msg = binary() | iolist()
.br
Resend = boolean()
.br
Reason = term()
.br
Error = term()
.br
.RE
.RE
.RS
.LP
Send a megaco message\&.
.LP
If the function returns \fI{cancel, Reason}\fR\&, this means the transport module decided not to send the message\&. This is \fInot\fR\& an error\&. No error messages will be issued and no error counters incremented\&. What actions this will result in depends on what kind of message was sent\&.
.LP
In the case of requests, megaco will cancel the message in much the same way as if \fImegaco:cancel\fR\& had been called (after a successfull send)\&. The information will be propagated back to the user differently depending on how the request(s) where issued: For requests issued using \fBmegaco:call\fR\&, the info will be delivered in the return value\&. For requests issued using \fImegaco:cast\fR\& the info will be delivered via a call to the callback function \fBhandle_trans_reply\fR\&\&.
.LP
In the case of reply, megaco will cancel the reply and information of this will be returned to the user via a call to the callback function \fBhandle_trans_ack\fR\&\&.
.LP
The function \fIsend_message/3\fR\& will only be called if the \fBresend_indication\fR\& config option has been set to the value \fIflag\fR\&\&. The third argument, \fIResend\fR\& then indicates if the message send is a resend or not\&.
.RE

.LP
.B
Module:resend_message(Handle, Msg) -> ok | {cancel, Reason} | Error
.br
.RS
.LP
Types:

.RS 3
Handle = term()
.br
Msg = binary() | iolist()
.br
Reason = term()
.br
Error = term()
.br
.RE
.RE
.RS
.LP
Re-send a megaco message\&.
.LP
Note that this function will only be called if the user has set the \fBresend_indication\fR\& config option to \fItrue\fR\&\fIand\fR\& it is in fact a message resend\&. If not \fIboth\fR\& of these condition\&'s are meet, \fIsend_message\fR\& will be called\&.
.LP
If the function returns \fI{cancel, Reason}\fR\&, this means the transport module decided not to send the message\&. This is \fInot\fR\& an error\&. No error messages will be issued and no error counters incremented\&. What actions this will result in depends on what kind of message was sent\&.
.LP
In the case of requests, megaco will cancel the message in much the same way as if \fImegaco:cancel\fR\& had been called (after a successfull send)\&. The information will be propagated back to the user differently depending on how the request(s) where issued: For requests issued using \fBmegaco:call\fR\&, the info will be delivered in the return value\&. For requests issued using \fImegaco:cast\fR\& the info will be delivered via a call to the callback function \fBhandle_trans_reply\fR\&\&.
.LP
In the case of reply, megaco will cancel the reply and information of this will be returned to the user via a call to the callback function \fBhandle_trans_ack\fR\&\&.
.RE