MSDN Magazine - November 2008 - (Page 27)

Instantly Search Terabytes of Text is hosted on a different domain than the Web service. For example, Figure 6 shows that a Silverlight 2 application hosted on the Web server johnpapa.net can call a Web service also on johnpapa.net since they are on the same domain. However if the Silverlight 2 client hosted from johnpapa.net wants to call a Web service hosted on microsoft.com, Silverlight 2 checks to make sure the cross-domain policy file on microsoft.com exists and allows the call. For more information on Cross-Domain Policies, see my September 2008 column at msdn.microsoft.com/magazine/cc794260. In that column, I discuss the file formats and how the policies work. Whether the call is made to a WCF Web service, a REST-based service or any type of Web service, Silverlight 2 only allows crossdomain calls to occur if the target Web server allows the call through its cross-domain policy file. For example, the code you saw earlier string baseUri = "http://services.digg.com/stories/topic"; string topic = txtTopic.Text; string appKey = "http%3A%2F%2Fwww.microsoft.com"; int count = int.Parse(txtTopicCount.Text); string url = String.Format("{0}/{1}?appkey={2}&count={3}", baseUri, topic, appKey, count); WebClient svc = new WebClient(); svc.DownloadStringAsync(new Uri(url)); N dozens of indexed, unindexed, fielded data and full-text search options (including Unicode support for hundreds of international languages) N file parsers / converters for hit-highlighted display of all popular file types N Spider supports invokes the Digg Web services to access the most recent stories. Digg includes a cross-domain policy file using the Flash format at the location http://services.digg.com /crossdomain.xml. The contents of this Digg cross-domain file at the time of this writing are shown here: static and dynamic web data; highlights hits while displaying links, formatting and images intact New .NET Spider API h Spider Desktop wit h Spider Network wit CD/DVDs Publish for pider Web with S Win & .NET Engine for Linux Engine for New 64-bit Notice that the Digg cross-domain file allows calls from any domain. However, this could be restricted, just like the Twitter crossdomain file enforces restrictions. Notice the Twitter cross-domain file in the following: N API supports .NET, C++, Java, databases, etc. The Smart Choice for Text Retrieval® since 1991 N “Bottom line: dtSearch manages a terabyte of text in a single index and returns results in less than a second” – InfoWorld N “For combing through large amounts of data,” The cross-domain file for Twitter restricts calls to those that originate from the *.twitter.com domain. Your Silverlight 2 application likely is not hosted on the twitter.com domain, so a Silverlight client cannot make a Web service request to Twitter’s REST-based services directly. This is where a proxy service can help you out. For example, you could create a WCF Web service hosted on your domain that calls the Twitter.com Web services. The calls from your WCF services relay the information between the Silverlight application and Twitter. The WCF service running on the server does not suffer the cross-domain policy file restrictions as a Silverlight client does, so it can make the calls. Another option is to relay the calls through a service such as Popfly or Yahoo’s cloud services. T JOHN PAPA (johnpapa.net) is a Senior Consultant with ASPSOFT (aspsoft.com) and a baseball fan who spends summer nights rooting for the Yankees with his family. John, a C# MVP and INETA speaker, has authored several books and is now working on his latest, Data Access with Silverlight 2. He often speaks at conferences such as DevConnections and VSLive. msdnmagazine.com dtSearch “leads the market” – Network Computing N dtSearch “covers all data sources powerful Web-based engines” – eWEEK N dtSearch “searches at blazing speeds” – Computer Reseller News Test Center See www.dtsearch.com for hundreds more reviews, and hundreds of developer case studies Contact dtSearch for fully-functional evaluations 1-800-IT-FINDS • www.dtsearch.com November 2008 27 http://www.johnpapa.net http://www.johnpapa.net http://www.johnpapa.net http://www.microsoft.com http://www.microsoft.com http://msdn.microsoft.com/magazine/cc794260 http://services.digg.com/crossdomain.xml http://www.twitter.com http://www.twitter.com http://www.Twitter.com http://www.dtsearch.com http://www.johnpapa.net http://www.aspsoft.com http://www.dtsearch.com http://www.msdnmagazine.com

Table of Contents Feed for the Digital Edition of MSDN Magazine - November 2008

Contents MSDN Magazine - November 2008 Toolbox CLR Inside Out Data Points Cutting Edge Security Briefs Test Your Security IQ Agile SDL Access Control Utility Spotlight RIA Test Run Wicked Code Foundations Team System End Bracket

MSDN Magazine - November 2008

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