I'm writing a mobile application and I'm having difficulty downloading lengthy files from a Yahoo! server that periodically (about every three minutes) aborts the download. The mobile application successfully downloads lengthy files from other servers via the same slow data connection. A dump of the HTTP header from the Yahoo! server is
D/AsyncDownloadFile( 694): header fields: {p3p=[policyref="http://info.yahoo.co m/w3c/p3p.xml", CP="CAO DSP COR CUR ADM DEV TAI PSA PSD IVAi IVDi CONi TELo OTPi OUR DELi SAMi OTRi UNRi PUBi IND PHY ONL UNI PUR FIN COM NAV INT DEM CNT STA PO L HEA PRE LOC GOV"], content-type=[application/octet-stream], connection=[close] , last-modified=[Fri, 06 Aug 2010 14:47:50 GMT], content-length=[2000000], age=[ 0], server=[YTS/1.17.13], accept-ranges=[bytes], date=[Sat, 07 Aug 2010 18:53:02 GMT]}
which shows it defines connection=[close]. A different (non Yahoo!) server defines connection=[keep-alive] and my mobile application successfully downloads from it. So I have a few questions:
What is causing the Yahoo! server to periodically abort the downloads? What can I do to avoid the periodic aborting or what can I do to resume an aborted download? Are requests for byte ranges considered when the server defines connection=[close]?
Things I've read:
- description of persistent connections,
- description of byte range requests
Things I've tried:
- I've tried setting the http header "Connection" field to "keep-alive" but the Yahoo! server response was a header "Connection" field set to "close".
- I've tried resuming the connection as described in this question. Even though the HTTP header from the Yahoo! server shows that it supports byte range requests and the content range responses appear correct (e.g., content-range=[bytes 387924-1999999/2000000]), the resumed transfers incorrectly resume at the file start. I'm wondering if that is due to the connection=[close] setting.
Because the subject of HTTP headers is rather new to me, any suggestions or warnings about common pitfalls are welcome.
[UPDATE] I received a reply from Yahoo! tech support saying that byte range is not supported: "Yahoo! Web Hosting does not support Accept-range header since we work with a pool of servers and each request potentially reaches a different server. You will see connection=[close] in the response header indicating this." The remaining question is whether or not the periodic download abortions can be avoided. (I tried requesting Connection="keep-alive" but that was ignored.)