I really want to know what the XAP file on Windows Phone 7 is; how important it is; and how I can create it. Could you help me?
XAP is the application package - it is the distributable unit that allows you to install the application on a device (or emulator). Basically, it is a ZIP file with a different extension. If you change XAP to ZIP, you'll be able to read its contents fairly easy.
The XAP file format was inherited from standard Silverlight, and since WP7 is built around the same fundamental core, the file format remained unchanged.
Here is a pretty good description of what it does (remember, that even though it talks about Silverlight, the same main idea applies to WP7):
http://beyondrelational.com/blogs/dinesh/archive/2010/08/18/what-is-xap-file.aspx
In addition to Dennis' excellent post, one other thing about a XAP file - it's a ZIP file - so if you want to look inside one, then just rename it to .zip and then open it using a normal ZIP browser (e.g Windows explorer)
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We use the .NET resource manager to localize our Silverlight application and want to embed the satellite assemblies for the german language ("de") into the XAP file. Therefor, we set the neutral language to "en" and added "de" to the list of supported languages in the csproj file. This works fine, when we build the project locally. If we build the Silverlight solution with MSBuild (TFS), Silverlight will try to fetch the satellite assemblies with HTTP requests from /ClientBin/de/*.dll instead of taking those files embeded into the XAP (which do exist). Because the webserver returns 404 error codes for the non existent files, Silverlight crashes with an initialization error.
It turned out that if we remove a custom TFS build activity manipulating the assembly info code files, the Silverlight applications works as expected. Strangely, after re-enabling the activity the compiled XAP application still works (verified for two different build definitions working on seperate branches). The custom activity manipulates the assembly attributes AssemblyConfiguration, AssemblyCompany, AssemblyProduct, AssemblyCopyright, AssemblyTrademark, AssemblyVersion, and AssemblyFileVersion.
Some additional hints:
The custom activity will change the assembly info files before any compilation is done
Compiling the manipulated sources with Visual Studio will build a working XAP
The content of the XAP files (working and not working) is equal (nearly same sizes, no difference in manifest file)
The resource manager is instantiated using ResourceManager("Resource", Assembly.GetExecutingAssembly())
My questions are:
Why does Silverlight try to fetch those satellite assemblies from /ClientBin/de/ instead of just using those in the XAP file?
What kind of attribute in the assembly info file could cause such a behavior?
Why does re-enabling the versioning activity not break the XAP again?
And here's the solution: We use a tool named "Total Commander" for editing a file in the generated XAP to adjust the URL the (generic) client connects to. Since we added the localization dlls, editing the XAP with the Total Commander will lead to the behavior described above. If we manipulate the XAP with WinRAR or the internal Windows archive manager, all works as expected.
Edit: After comparing the XAP files we found, that Total Commander uses the backslash (\) to seperate directories, whereas WinRAR and the Silverlight Tools use slashes (/). It seems that we discovered a hidden Silverlight feature here ;-)
I created a customized version of the Silverlight Player. After building/compiling, the .XAP which gets pushed out, it ends up being over 700KB.
I'm not too sure why it's doing this because I'm not adding any new resources. All my changes have all been in the code.
Is there any way to reduce the file size?
You are probably including DLLs you did not intend to. The Copy Local option for DLL references you add is True by default.
A XAP file is just a ZIP file with a different extension so the first thing to do is unzip it and take a look at what is included.
You can use a better Zip program to recompress the XAP file, but that will only gain you another 10%-20% at best.
If it turns out you are really just concerned about initial load time vs. total load time you can load an initial (small) bootstrapper to update the display while loading subsequent modules dynamically (look at PRISM and MEF).
You can check the "Reduce XAP size by using application library caching" option.
By default any system dlls that your application uses will be included in the XAP file. By checking this option they are downloaded as separate zip files.
This won't reduce the total size of the files that your application downloads, but will mean that when you publish an update your users won't have to download all the system dlls again - they'll already have these in their local cache.
This option is primarily used in applications that are split across several XAP files to ensure that only one copy of the system dlls are downloaded for the whole application.
I'm working on a WinForms C# 3.0 / .NET 3.5 project involving building some canned reports. One of the requirements of the project is to export to PDF format, and currently doing so to disk is working just fine. The question was raised, however, if it's possible to export the file to a stream and open it directly in the native viewer on the client, skipping entirely writing it to disk. I know that this is somewhat possible with ASP.Net through the use of Response.Write() headers and the like, but I need to try to do this with standard WinForms/WPF, and I've exhausted my own ideas for it. Anybody have any insight on how it might be done, if it's possible at all? Or does the file have to be written to disk first, then opened separately?
I think it is important that you ask yourself what you accomplish if you bypass the file system. Writing to a the standard temporary folder is a perfectly acceptable solution. This is typically how browsers let you view media files and pdfs. I would concentrate on writing a nice cleanup function, that removes the temporary file after it has been create. Also what would be the purpose of exporting to PDF if you are not saving the file?
Under Unix / Linux you could have made a named pipe in the file system. This make sense if you have a huge media stream that you want to buffer between applications. In the PDF case you win very little.
Export to a temporary folder. It is Ok.
You will need to write the PDF to a temp directory.
The only way to display a PDF from an in-memory stream is to embed a third-party PDF viewer control
I have started coding an FTP client application (for fun). I’m trying to represent remotely hosted files with icons. For example, let’s say I’m browsing the root folder of an FTP server (/) and want to display the Backup.zip file with the icon association from that client operating system. On some systems, this may be the windows compression icon and other operating systems this may be WinZip or WinRAR icons.
I have the client browsing local files with the SHGetFileInfo() function. This works great with files that are local, however, this function requires the physical file in order to retrieve the associated icon. So, this will not work with remotely hosted files. I have found some samples of loading icons given a file extension, and this is really where the question comes in... What would be the best strategy to get icons associated to remote files?
Go to the registry every time and look up extension to icon associations
Create 1 byte files with each extension and use the SHGetFileInfo() function for remote files (using local 1 byte files as association for remote files)
Other strategies???
What would a professional software company creating an FTP client do?
Thank you for your time.
-Jessy Houle
I suggest that you don't go to the registry every time: go if you need to, but if you've already been for a given filetype then remember/cache that result (within your program) and reuse it.
Use the procedure here from a previous Stack Overflow question on the same idea and uses the registry instead of an actual file.
How can I get the filetype icon that Windows Explorer shows?
I don't quite understand how Silverlight code works within the browser. Are the assemblies downloaded to the client machine? Is there any chance of the code getting decompiled using Reflector or some similar tool? If so, what options does one have to protect the code? Do .net obfuscators work with Silverlight?
Whenever you are in a web browser, all client side code is downloaded to the machine and can be examined by the user. This goes for Javascript, Flash, and Silverlight.
If you have proprietary code that absolutely must be hidden then you need to put it on the server and expose an API that the clients can call to show information to the user.
To view a Silverlight application the client download a .xap file that contains the dll and one configuration xml and optional resources. The dll contains compiled c# code that runs in a Silverlight runtime in client machine. Silverlight runtime is basically a subset of complete .net runtime. So the point is user gets the code in dll and then can use tools to get original source code. So at most you can do is obfuscation. Still for very critical code that should not be the option. You can use some other way (WCF or other webservices to hide some part of your code may be) if it shouts your need.
If you want to see just how easy it is to look at the code in a silverlight app just run SilverlightSpylink text by FirstFloor. As long as your have .NET Reflector installed you will be able to see (as you interact with the app) all the source code including the xaml files.
Since the code does get downloaded to the client (and even trying to prevent it with pragma no-cache won't work since they can hit the URL) you will need to protect your code by keeping important logic on the server.
If your afraid some one will steal your intellectual property and that law is not enough, Then you will need to obfuscate your code. But I would not call that protection per say but a deterrent to the casual reverse engineer.
Putting a pragma -No Cache- will prevent the .xap from being stored on the machine, instead it will be streamed by the Silverlight plugin. Without the pragma the .xap file is stored in the temp internet files.
Putting the application on a page on https will further protect the transmition of the .xap
If possible require authentication to view the web page / .xap file (thanks Joel)
Emrah,
Yes obfuscation is possible for SL application.
Yes, Silverlight xap files are nothing but zip files with your assemblies in them, so they do need protection via obfuscation. Give Crypto Obfuscator a try - it directly obfuscates xap files, it can also obfuscate XAML files in your assemblies by renaming class references, stripping comments, whitespace, newlines, etc