Silverlight: Some HttpWebRequest Headers don't work

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Parents: Talk to your kids about Linux. Before somebody else does. -- XKCD

I saw a couple of posts where people were attempting to make GET or POST requests to some service (which, if not same-domain, had the required crossdomain.xml or clientaccesspolicy.xml file) and this service required BASIC authentication credentials.

Normally, you would add an "Authorization" header with the value "Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==" where the gobblydegook after the word BASIC is username:password converted to a Base64 string.  That's standard W3C Header protocol.

Unfortunately, even though there is sample code illustrating this from Karen Corby here, it does not work (she does not actually add an Authorization header, just illustrates how to add a header). It turns out that the "Authorization" header is on the "restricted list". See here for a complete listing.  So, if you have been trying to do this, or any similar header that is on the restricted list, you'll only get strange exceptions that make no sense at all, and  you can give up and look for a workaround.

Obviously, the easy workaround is to have your own proxy page or service that would accept the requisite username and password on the querystring (encrypted if desired, or as form post fields) and your server-side code  would make the full framework HttpWebRequest  -- where we do not have such restrictions, and pass the results back to the Silverlight app.  An annoyance to be sure, but "it is what it is".  Here is an article I recently put together that provides an interesting workaround.

Peter has been active on the C# and other MS newsgroups, has had samples at gotdotnet.com (now codegallery.com) that have been downloaded over 56,000 times, and has written numerous articles for eggheadcafe.com, for which he is a co-founder, and MSDNAA sites. He has also been a technical reviewer on books from Prentice Hall, Manning and other publishers. Peter was a Microsoft MVP for 10 years. Peter was born and raised in New York City, and after a stint as a jazz musician playing contrabass with the Robert Hunt Trio, migrated to sunny Florida, where he was hired as a rookie Financial Consultant at Merrill Lynch in Orlando, specializing in Corporate Services. It was at Merrill that Peter realized computers and technology were his forte. He spent his last few years at Merrill developing real – time computerized trading and and stock charting program using advanced technical analysis indicators, some of which are his own inventions. In 1997, he moved on to architect and serve as lead developer on a number of innovative web-based and middleware solutions for the healthcare and financial services industry.

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