45 sec delay when publishing VI on web via WLAN connection.

[RunnerBoy]

The resource consuming part of my application reads four analog channels from USB-device 6008, at samplerate 500 Hz and buffer 50 in a while loop. The plots are displayed a splitscreen graph. The 2 GHz lap-top PC is connected to a WLAN (802.11 b). The remote lap-top running Runtime Engine and IE is connected to the same WLAN.

I have tested two scenarios:

1) Open VI and starting web-server. Then calling the VI using IE on client. Then start running the VI on server
=> Everyting runs fine with 0,5 seconds delay in viewing the plots.

2) Open VI, running VI's and running web-server. Then calling the running VI using IE on client.
=> I experience a 45 sec (Yes,fourthyfive sec) delay in the transmission of the analogue graph data. Serial data from the same VI, transmitted via the same WLAN is however updated imediately (1 sec delay).

I have tested this on two different WLAN's
 - a dedicated WLAN network in hospital.
 - a WLAN hot spot in a hotel.
The result was the same

Is this delay caused by the WLAN, the web-server, LV or my poor programming skills?

Regards Runnerboy

[rolfk]

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@RunnerBoy wrote:
Is this delay caused by the WLAN, the web-server, LV or my poor programming skills?

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It's a DNS name lookup issue. The most simple workaround is to actually make sure you have added a DNS name entry for your server on the client computer in the <system dir>/drivers/etc/lmhosts file and the same for the client computer in the server computer. A more involved fix would be to setup a proper DNS name server.

You could also aproach the server computer through its IP adress from the client (http://111.111.111.111/) instead of its computer name but then you still need to either add the client computer name to the server computer lmhosts or add an INI key to the server INI file of your web server application. Not exactly sure about the exact INI settings but it is about disabling reverse DNS lookup in the web-server when a new connection requests arrives.

Rolf Kalbermatter