Need to reduce overhead on a round-trip message/response

[kpturner]

Hello Alessandro,

Your answer has me a bit worried that I have messed something up. I am not testing locally as such. The client is obviously running on my PC, and Lightstreamer is running on a very powerful IBMi partition (JDK 7). It is on the same subnet (so not over the internet).

I am effectively having to use Lighstreamer to emulate a XHR request for comparison purposes. I know this is not what it is usually meant for, but my benchmarking includes this test.

I am effectively creating a connection, a subscription (DISTINCT) and a listener on the subscription. I then send a querystring using sendMessage and my data adapter passes this to an RPG program (via a data queue) that generate about 20000 bytes of static HTML with embedded script etc. This is passed back to the client using smartUpdate, and when onItemUpdate fires on my listener, some script uses jQuery to replace some elements of the DOM with the HTML etc received.

It works - so good. However, if I cache the response in the data adapter so that subsequent calls completely omit the RPG call and just sends back the previous response, I still get a round trip averaging around 150-170ms. I am sending a tiny querystring of about 200 bytes and returning about 20000 bytes. Why does it take so long? My timer starts when the sendMessage() is called, and stops when onItemUpdate() fires - so the fiddling around with the response is omitted from the timer completely.

My metadataadapter and dataadapter are fairly trivial. I could include the code if it helps, but I don't want to clutter up the thread yet unless you think it is necessary. I am hoping I have a big mistake there that explains it.

Even my simple echo server takes about 120ms to echo a message back.