[OpenLayers-Users] WMSFeatureInfo not working on Firefox on Ubuntu 12.04

[Phil Scadden]

I am no expert on this but have battled royally with the problem getting 
OL application working off a USB.

Why need a proxy?

Well because usually you have your application (especially the host 
page) on one server and geoserver somewhere else. Since the browsers started
tightening up security on XHR, the restriction has been that XHR request 
need to reference an item in same directory as your OL page or in a 
subdirectory of that. Obviously mapserver/geoserver will be somewhere 
else. What OL needs to do is switch its http requests through a proxy. 
In my system, I have
proxy.jsp in my main directory, with proxyhost pointing to it. So 
instead of GET to http://myserver, it generates 
proxy.jsp?url=http://mygeoserver
Proxy.jsp checks the URL to see if it is one my allowed hosts, opens the 
url, fetches data and pipes back to OL.

This is different from using a web proxy in your lab network configuration.

Using cgi is another way implement the proxy.

Its my understanding, that any OL function implemented to use a callback 
is going to go through XHR, so to use those you must have 
OpenLayers.proxyhost configured.

Somethings can be implemented without the proxy (especially WFS) by 
using script protocol. Script injection is another way avoid cross-site 
restrictions, but it depends on server able to wrap response (json) in a 
callback function.



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