Hi Dan,
the issues you are referring are not directly related to the MI
interface, but to the modules implementing transports for it (like fifo,
unixsock, xmlrpc, etc).
so, the syntax part is managed by the transport modules and can be
different from transport to transport.
as yo said, for FIFO it is not an issue as it a stream like connection -
you read until the other party closes the connection.
we will consider this aspects when we will develop new module,
especially the one oriented on DATAGRAM communication.
regards,
bogdan
Dan Pascu wrote:
I do not know if this thing was already considered for the new management
interfaces, but I'd like to raise one issue the current FIFO/UNIX socket
interfaces have.
A command always ends with 2 LF characters, which is good as it allows
openser to know when one command ends and when the next starts.
However the replies sent by openser do not follow the same guidelines and
they only have 1 LF character after the last line in the reply. As a
result if the reply is bigger than the MTU for the transport in
discussion, the response will not be returned with a single read
operation. At this point it will be uncertain if there is more to come or
not. Since the MTU may be unknown, it is very difficult to figure out if
I should stop reading because I already have all the answer or I need to
keep reading because there is more.
Now on the FIFO interface this can be worked around, as one can read until
the reads return nothing (because openser will close the reply fifo after
it finishes sending). But the same is not true for the UNIX socket
interface given it is using SOCK_DGRAM and is never closed after a reply
is sent. But the FIFO interface has its own drawbacks (like the fifo may
block when being opened if there is none listening on the other end).
To avoid all these issues, I want to propose to change the communication
protocol to also end a reply with the same 2 LF characters, so it will be
easy to determine where a reply ends without having to worry about the
MTU of the transport layer, or the type of interface used (FIFO, UNIX
socket, ...)
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