Fighting with Ethernet library, finally got something running stable, but why??

Projects Programming
1

hi,

so i have been developing a sketch that works as an ethernet client and posts some data to a WSGI apache server that stors it in a MySQL database...

for the last few weeks (feels like months) i have been fighting with the stability of the sketch (as it seems many others have as well).

normally i could post to my server for an unpredictable amount of time then the sketch would just freeze!! uggh..

however last night i made a seemingly minor change and eureka! its been stable all night. even at 3 http requests per second!!

so heres what i did:

Problematic code:

      client.println(outBuffer);
      client.println("Host: www.arduino.cc");
      client.println("User-Agent: arduino-ethernet");
      client.println("Connection: close");
      client.println();

Seemingly ok code:

      #define httpHeader "\nHost: www.arduino.cc\nUser-Agent: arduino-ethernet\nConnection: close\n"
      strcat(outBuffer,httpHeader);
      client.println(outBuffer);

so why the dramatic difference?? anyone got any ideas? im not 100% confident that i fixed anything but so far my tests are promising. also as a note, i am using the Seedstudio Ethernet Shield V1.0 with the Wiznet 5100 on an Arduino mega 2560.

thanks.

2

Each client.println() statement causes a new packet to be sent. Given that you were sending multiple packets, and are now sending one, I rather expect that more of the current packets are getting through in the correct order (since it's rather hard to get one packet out of order).

3

If you want it to work fast, use client.write rather than client println. It will need an extra "\n" tho.

      #define httpHeader "\nHost: www.arduino.cc\nUser-Agent: arduino-ethernet\nConnection: close\n\n"
      strcat(outBuffer,httpHeader);
      client.write(outBuffer);
4

Thanks for the explanation and suggestion.

I have updated "print" to "write" and all seems to be running great!!

now its time to go re-flash all the machines :smiley:

Thanks again!!!!!!