[OZAPRS] Programmatically Sending Data to APRS Server

[Peter Tyers]

I need some pointers here.

I'm trying to craft an interface between marine AIS data streams and APRS.
I can happily decode the AIS !AIVDM sentences and create the appropriate
tunnelling messages to go to an APRS server
BUT
Using Telnet I can get the APRS server to recognise the character streams I
manually send
However if I establish a TCP connection (3 way handshake occurs) and send a
stream of the same characters using a stream.Write the server doesn't
recognise the characters. I can read characters coming back from the server
although after the first header message "UI-View32 V2.03 APRS Server"
my reads timeout.

There's obviously something simple that I am missing.
Is there a header structure that the APRS server uses? I have trolled the
net but can find no reference to interfacing to APRS servers other than that
Telnet is used.
I can't see any Telnet NVT negotiation going on using MS Telnet client on a
network data analyser so assume that its not required.
I throw a data stream at the server and get a fairly consistent packet back
which I can't decode due to lack of knowledge re the APRS Server protocols.
Return packet is (in hex) 
90 2B 34 38 CD ED 00 0C 76 44 37 EE 08 00 45 00 00 28 0F F5 40 00 80 06 C9
6A C0 A8 50 1C C0 A8 50 03 05 A8 57 2A 78 67 C6 1F 11 54 67 71 50 10 FE 38
7C 0C 00 00 00 00 00 00 00 00
Of which 40 bytes are said to be the payload.

What am I missing?? 
Does Telnet wrap data streams in a header that I haven't implemented? I
can't find reference to this in the Telnet RFC documents but that doesn't
mean that it doesn't exist.

Has anyone got links they are prepared to share regarding interfacing to
(UIView) APRS Servers via TCP datastreams?


Thanks in advance
Peter Tyers
VK3KTS