Building a Picture Frame, Part 3: Connect a Windows Embedded CE Device to Web Services

2. Building a Picture Frame, Part 3: Connect a Windows Embedded CE Device to Web Services Douglas Boling President Boling Consulting Inc. WEM202

3. Speaker • Douglas Boling • Author – Programming Microsoft Windows CE • 4th Edition • Trainer – Classes on Windows CE App Development Windows CE OAL Development .NET Compact Framework • Consultant – Work with companies to help their Windows CE application and platform development efforts

4. Agenda • Introduction to Web Services • Implementing a Web Service Client • Understanding RSS Feeds • Connecting the Picture Frame

5. Agenda • Introduction to Web Services • What is a web service • Desktop/Server support • Tools to write web service clients • Implementing a Web Service Client • Understanding RSS Feeds • Connecting the Picture Frame

6. What is a Web Service? • Web services are ‘programmatic’ web sites • Using the web w/o “screen scraping” • RPC protocol using port 80 • Uses “SOAP” • Simple Object Access Protocol • All data transmitted as strings

7. Desktop/Server Support • Server side • Microsoft support via ASP • Simple to implement with ASP .NET • Client side • Simple to implement via .NET framework • Native clients implemented with ATL

8. Tools To write Web Service Clients • Visual Studio provides support • Server side • Client side • .NET commonly used for both sides • Native implementations can work • Client – ATL sample today • Server – Mike Hall example on CE http://blogs.msdn.com/mikehall/archive/2007/10/10/building-xml-web-services-for-windows-embedded-ce-6-0.aspx

9. Writing a Web Service • Simple, with ASP.NET • First example… • Add two numbers • VS 2005/2008 caution • Defaults to Local Development Server • Services can’t be seen by CE devices/emulators • IIS configuration difficult!

10. Agenda • Introduction to Web Services • Implementing a Web Service Client • Native • Managed • Understanding RSS Feeds • Connecting the Picture Frame

11. Native Web Service Client • Start with a simple device application • Add ATL support • Allow single threads in MTA • Increase stack size

12. Native Web Service Client • Add Web Reference • Include webref.h in stdafx.h • Create web client class • Call method

13. A Managed Web Service Client • Simple .NET Windows Forms App • Add web reference • “New up” the web reference object • Call methods

14. demo Web Services Douglas Boling President Boling Consulting Inc.

15. Agenda • Introduction to Web Services • Implementing a Web Service Client • Understanding RSS Feeds • Connecting the Picture Frame

16. Project • Create a picture frame that connects to web • Change of plans… • Use RSS instead of Web Service

17. New Project • Web based pictures at FrameIt.Com • Part of Windows Live Services • Use RSS feed to query pictures • Download and display pictures

18. RSS – “Really Simple Syndication” • Web feed format for frequently updated content • XML document describes feed content • Many readers available • We’re going to write a trivial one here

19. Example RSS XML Feed <?xmlversion="1.0"encoding="utf-8"?> <rssversion="2.0“ xmlns:frameit="http://www.frameit.live.com/firss/" xmlns:media="http://search.yahoo.com/mrss/"> <channel> <ttl>287</ttl> <title>DemoCollection</title> <link>http://frameit.live.com</link> <generator>http://frameit.live.com</generator> <lastBuildDate>Tue, 12 May 2009 13:14:49 -0700 </lastBuildDate> <pubDate>Tue, 12 May 2009 14:27:19 -0700</pubDate> <description></description> <item>…</item> <item>…</item> <item>…</item> </channel>

20. Example RSS XML Item <item> <frameit:sourceIcon>xxxxx</frameit:sourceIcon> <frameit:sourceCategory>Custom</frameit:sourceCategory> <frameit:sourceName>Windows Live Photos </frameit:sourceName> <title>Paris</title> <link>http://0mxaeg.blu.live/…/DSCN0360.JPG</link> <category>Paris</category> <guidisPermaLink="true"> http://0mxaeg.blu.live/…/DSCN0360.JPG</guid>

21. Example RSS XML Item (2) <description><![CDATA[ <imgsrc= "http://0mxaeg.blu.live/…/DSCN0360.JPG“ /><br/>]]></description> <pubDate>Mon, 30 Mar 2009 17:30:42 -0700</pubDate> <enclosuretype="image/jpeg“ url="http://0mxaeg.blu.live/…/DSCN0360.JPG" /> <media:contenttype="image/jpeg" url="http://0mxaeg.blu.live/…/DSCN0360.JPG" /> </item>

22. Agenda • Introduction to Web Services • Implementing a Web Service Client • Understanding RSS Feeds • Connecting the Picture Frame • Native • Managed

23. Tasks of Native Application • Connect to RSS feed • Download XML describing feed • Parse XML • Download images

24. Connecting UsingWinINet • WinINet library provides higher level access to web • APIs for • Initialize the library • Connect to server • Download file

25. Initializing WinINet • To initializeWinINet call InternetOpen • Parameters: • Agent String to indicate client type • Access type Indicates proxy or direct connect • Proxy Name Name of proxy server • Flags

26. Connecting to a Server • To connect to a server, use InternetConnect • Parameters: • lpszServerNameName of server • nServerPort Port to connect • lpszUserNameOptional user name • lpszPasswordOptional password • dwService HTTP or FTP • A few others…

27. Reading A File • Use the following functions • HttpOpenRequest • HttpAddRequestHeaders • HttpSendRequest • If successful, loop on • HttpQueryInfo • InternetQueryDataAvailable • InternetReadFile

28. demo Native Picture Frame RSS Reader Code Douglas Boling President Boling Consulting Inc.

29. Picture Frame in Managed Code • Managed code much simpler than native • Use WebRequest class to read data • Use XMLReader to parse the RSS XML • Use PictureBox to display image

30. Download A File // Compose the request WebRequest request=WebRequest.Create ("http://parisfeed.frameit.com"); WebResponse response = request.GetResponse(); StreamReadersr = new StreamReader(response.GetResponseStream()); stringstrXMLFeed = sr.ReadToEnd(); response.Close(); // Write the string into a file StreamWritersw = newStreamWriter(strXMLFile); sw.Write(strXMLFeed); sw.Close();

31. Parse The Feed XmlTextReader reader = newXmlTextReader(strFilename); while (reader.Read()) { switch (reader.NodeType) { caseXmlNodeType.Element: if (reader.Name == "enclosure“) { if (reader.AttributeCount > 0) { strURL = reader.GetAttribute("url"); if (null != strURL) ar.Add(strURL); } break; } }

32. demo Managed Frame RSS Reader Code Douglas Boling President Boling Consulting Inc.

33. Summary • Web services client support available in Windows Embedded CE • Managed much easier than native • RSS feeds aren’t that difficult • Again… Managed much easier than native

34. question & answer dboling@bolingconsulting.com

35. Windows Embedded Resources Website: www.windowsembedded.com Social Channels:  blogs.msdn.com/mikehall blogs.msdn.com/obloch Technical Resources: http://msdn.microsoft.com/embedded Tools evaluations: www.windowsembedded.com/downloads

36. Resources • www.microsoft.com/teched Sessions On-Demand & Community • www.microsoft.com/learning • Microsoft Certification & Training Resources • http://microsoft.com/technet • Resources for IT Professionals • http://microsoft.com/msdn Resources for Developers www.microsoft.com/learning Microsoft Certification and Training Resources

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