The subject is a little misleading, but I couldn’t remember what the datacard that I’ve borrowed from Vlad is called.
I’m connecting to the Internet from home via a T-Mobile PCCard, which uses some fangled 3g technology to give me a 1.8Mbps Interweb connection. Latency is a little higher than with conventional ‘broadband’, but the overall feel is good.
The big issue I have is with images… T-Mobile made a blanket decision to enable image compression by default. This means that I get garbled crappy images which are a pain in the backside.
After a little reading about I discovered that you could use a force reload (Shift+Ctrl+R in Firefox) to get the full-res samples. Yet more reading and I discovered that some people were setting a custom User Agent (appending “Blazer/4.0”) to fool the transparent proxy server into thinking the browser was incapable of page compression (although I don’t fully understand how this would help with inline JPEG compression, but anyway). Unfortunately this neat little trick didn’t work to me.
This got me thinking… if I can use my browser to force the proxy to send me a full-res image then it must be doing something special. A trip over to livehttpheaders.mozdev.org/, a new Firefox plugin and restart later and I was able to observe the HTTP headers that Firefox was sending to the server.
I quickly spotted that the following two extra headers were being sent on a force reload:
Pragma: no-cache
Cache-Control: no-cache
So it looked as though the Pragma and Cache-Control force the proxy to send me the real deal. Now, time for another plugin, this time
Modify Headers which I configured to be active at all times (“Always on”) and to send the exact two headers I mentioned in the last paragraph.
Modify Headers is a neat little plugin that allows the user to send any custom headers in a reasonably fine-grained way. But for me, I wanted the headers active for all requests.
The result? It was good… all of the pictures were now pretty. Of course, this isn’t without its drawbacks… all requests bypass the cache, which means I’ll be pulling more data down, but in exchange for the good images I guess I don’t have much other choice.
I’ve not played around much yet, but I’m sure there will be other issues. I’m a little curious as to how a regular page refresh is different to a forced page refresh… from what I’ve read there are a bunch of odd little things that go on, mostly historical.
But for now, I’m a happy bunny :)