Re: Nuts and Bolts of a hub-app protocol

["Michael McSharry" <mcs101main@xxxxxxx>]

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MessageMy mistake on the network being used.  All received traffic on the
A=
pp is on 127.0.0.1 and none on 192.168.0.200.  This is per Patrick's
descri=
ption and things appear to be working as expected.  I do get a few data
arr=
ivals with a message length of 0.  Dont know what it is from, but does not
=
appear to be a problem.  I have two test apps running the same code with
th=
e only difference being the port.  On one I have no null data arrival
count=
s and the other I get a few.
----- Original Message -----=20
From: Michael McSharry=20
To: xAP_developer@xxxxxxx=20
Sent: Sunday, October 10, 2004 9:25 AM
Subject: Re: [xAP_developer] Nuts and Bolts of a hub-app protocol


I've tried two hubs.  In the case of the xap-hub.exe from your site it st=
arts with what looks to be using eth0: address 0.0.0.0 on port 3639.  I
nev=
er see any message traffic when this hub is running.  I also cannot start
a=
nother hub since 3639 has been claimed.  I also tried to look on your site
=
for any configuration information, but the site appears to be down.

I am able to get the hub functionality with Stuart's V1.2.1.5 GUI Hub.  I=
n my test application I have two sockets open for listening.  One at
127.0.=
0.1 and the other at 192.168.0.200.  This test app produces heartbeats and
=
a normal message.  I see all my traffic on 192.168.0.200.  I do see the
tra=
ffic from other apps on 192.168.0.200 routed through the hub onto
192.168.0=
.200:36768 back to my test app.  It does appear  that 127.0.0.1 is not
bein=
g used.
----- Original Message -----=20
From: Patrick Lidstone (Personal e-mail)=20
To: xAP_developer@xxxxxxx=20
Sent: Sunday, October 10, 2004 5:56 AM
Subject: RE: [xAP_developer] Nuts and Bolts of a hub-app protocol


Michael,
Who's hub are you using, and which version? There are some subtle diffe=
rences between the flavours...
What you have described is basically correct: at startup, a connecting =
app should send a heartbeat to the hub on port 3639, indicating which port
=
it is using for incoming messages. The port the application chooses should
=
be an unused (udp) port in the ephemeral port range (although some early
xa=
p apps just allocated sequentially from 3639 onwards). Once the heartbeat
h=
as been received, the hub should broadcast on
127.0.0.1:<allocated_port>. E=
arly versions of some hubs incorrectly used the real ip address instead,
al=
though the principle was the same. Rebroadcast on the allocated port by
the=
hub will continue until at least twice the hearbeat timeout interval, spec=
ified in the original heartbeat message from the app to the hub, has
expire=
d.
HTH
Patrick