If, as an ASP.NET developer, you haven't used embedded resources, you're missing out big.
How many times have you had to deploy or maintain a site, only to have one or more of your images going missing, javascripts being modified by rogue web admins, or wrestling with the ASPNET securities monster?
If the answer's more than one, or even if it's zero, you need to think about embedding your site's resources at some point. The basic idea is that you embed your sites resources (ie, javascript, images, EULAs or whatever you have) into a seperate class library. When a resource is then requested by the user, the web server then pulls the requested resource out of the dll rather than the filesystem.
The nice part is it's pretty simple to do. There are really just 2 main parts - get the resources into the dll, get the resouces out of the dll.
Firstly you need to create a new class library that's referenced by your web project. Be sure to give it a default namespace, something like <Company>.<Project>.Resources is a good start.
Add to it your resources
Next, select all your resources, go to their property page (F4), and set their build action to "Embedded Resource". This means that when you go to compile your DLL, your "Embedded resource" files will be stored inside it.
The next step is an easy one to forget. Although the resources have been embedded, you need to mark them to be accessable as a web resource. To do this you need to open up your Properties\AssemblyInfo.cs and add the following line for each one of your resources:
[assembly: WebResource("Company.Project.Resources.Images.Login.background.gif", "image/gif")]
The file reference is made up of Namespace.Folder(s).filename.ext
Compile your project to produce the dll. I highly recommend Lutz Roeder's .NET Reflector - a functional and free dll browser, essential to any .NET dev's toolkit. You can use this to see
- if your files are being embedded in the dll, and
- what their manifest names are
To get the resources out of the dll, you need to use the method call:
Page.ClientScript.GetWebResourceUrl(typeof(Language), "Company.Project.Resources.Images.Login.background.gif");
For simplicity sake in my site, I've created a public static class to do this stuff for me, and also take out the repetitiveness of having to supply the same namespace all the time:
public static class Global
{
public static string GetResource(Page currentPage, string resourceName)
{
string resNamespace = typeof(Language).Namespace;
return currentPage.ClientScript.GetWebResourceUrl(typeof(Language), resNamespace + "." + resourceName);
}
}
In the above examples, Language is simply a class that i've compiled into the Resources dll. It's necessary so that reflections can locate the assembly that contains your resources. This method will return a string that looks something like this:
WebResource.axd?d=rLxM_e-hNRgcxNZLXGjctTk29lCIdmt5WI7DIzX8eu0chQcXvXKMdywK0qPrNmD7OWHAxEdM_Bgznu_OY1JLU413x9VqlXs-NmZ294HGH8E1&t=633300286780182866
So for instance to display the background image, in your HTML you'd use:
<img src="<%=Global.GetResource(Page, "Images.Login.background.gif") %>" alt="Login Background" />
And there you have it, your images should then be read through your dll and viewable through your web browser. You can do the same with your javascripts, or really any other static file. You can then deploy websites which don't have a whole heap of images that can go missing. But a word of warning - because you're embedding all these things into a single dll, it gets fully loaded into memory. Making it too big will impact the performance of your website.
For this reason, here's a quick list of DOs and DONTs:
DO
- Embed frequently used resources
- Embed javascripts etc that you don't want sneaky web admins to modify
- Files that tend to remain static throughout the life of your server
DONT
- Embed big media (ie: video, audio, swf's, streaming data)
- Embed files which are rarely accessed
- Embed files which need to be writable
posted @ Thursday, November 08, 2007 8:02 AM