silverlight - How to set http header If-Modified-Since on a WebRequest in Windows Phone 7? -

trying set 'if-modified-since' header in wp7:

request.headers[httprequestheader.ifmodifiedsince] = datestring;

gives error:

this header must modified appropriate property.

which means property .ismodifiedsince should used on request class, described in msdn: http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.ifmodifiedsince.aspx

but property not exist in silverlight i.e. wp7.

has been able set header http request on windows phone 7?

thank you!

you can use string httprequestheader.ifmodifiedsince represents:

request.headers["if-modified-since"] = datestring;

i've had number of other headers wp7 doesn't expose helper methods setting.

update
based on remarks @ http://msdn.microsoft.com/en-us/library/8y7x3zz2(v=vs.95).aspx appear not possible set header in wp7.

as alternative create own proxy server handle caching app.

Sohocode