Approaching the minimal request & response payload sizes.

Request Bytes Sent: 192
POST http://gpstrackerhttpheaders.cloudapp.net/posV3.aspx HTTP/1.1
x-Pos: 5C-86-4A-00-3F-63 20130126054537 T -43.00000 172.00000 12.2 4.08 1 83
Content-Length: 0
Connection: Keep-Alive
Host: gpstrackerhttpheaders.cloudapp.net


Response Bytes Received:113
HTTP/1.1 200 OK
Cache-Control: private
x-UpdMin: 30
Date: Sat, 26 Jan 2013 05:45:37 GMT
Content-Length: 0


10 requests to gpstrackerhttpheaders.cloudapp.net
944,969,1246,1043,1282,948,940,968,980,968
Average 1029 mSec

10 requests to IP Address
692,696,691,702,693,684,691,692,689,693
Average 692 mSec

Removing anymore headers from the request or response could break could HTTP break compatibility.

I went back and timed a V1 request & response to see what impact the reduction in payload size was…

10 requests to gpstrackerhttpheaders.cloudapp.net
2534,1457,1426,1571,1453,1462,1516,1422,1416,1421
Average 1569 mSec

10 requests to IP Address
1222,1200,1221,1238,1210,1266,1199,1235,1218,1230,1215
Average 1345 mSec

V1 573 bytes – 1569mSec & 1345 mSec
V2 480 bytes
V3 376 bytes
V4 305 bytes – 1029 mSec & 692 mSec

Most probably another 20 or 30 bytes could be saved by removing the ‘-‘ from the MAC address, shorter url, fixed width fields with no delimiter, removing the keep alive etc.

During my testing the NMEA stack was quite unstable it would fail with buffer overflows and overruns. The HTTP client requests are blocking and sharing the main execution thread meant the NMEA stack was unable to keep up.