ASP.NET Tips and Tricks

ASP.NET 2.0 ArchitectureCh, Ch, Ch, Ch, Ch, Changes…ASP.NET took on the most changes in .NET 2.0Web site are no longer projects!We now work with web sites as a collection of “dynamically compiled” web files.Previously, all code-behinds and miscellaneous class files compiled into one big .DLLThis made web page updates painful!

ASP.NET 2.0 ArchitectureNow, each web page is a miniature .DLL file.Updating a web site now involves merely replacing the old file with the new oneDoesn’t matter if it’s the .ASPX or the code-behind fileEven class files can be added. They are also dynamically compiled when used.When used with deployment, will strip source code out.

aspnet_compiler.exeWait!Isn’t putting your source code on the web server a bad idea? Isn’t that why ASP files were hacked so easily?aspnet_compiler.exe fixes this problem!This utility can pre-compile your entire web site and create all necessary .DLLs for deployment.How did Microsoft suggest pre-compiling ASP.NET 1.1 sites? Easy – just visit every web page with your web browser… Not a real answer.

aspnet_compiler.exeThis utility can also be used to deploy a website from a working folder to a virtual directory.It can also be used to compile in place.It will pre-compile the site in the process.

Where are the files?Where are the .DLLs?Depends on where they are deployed!C:WindowsMicrosoft.NETFrameworkv2.0.50727Temporary ASP.NET FilesNavigate here to find the DLLsOpen the source code (*.cs or *.vb) files to see the control declarations and the added event handlersOpen the a page’s DLL using ILDASM.exe

When are the DLLs recompiled?Many reasons…When they’re explicitly compiled using aspnet_compiler.exeWhen a web site is compiled explicitly from Visual StudioWhen a file changes (ASPX or code-behind) on the web siteOnly the changed code is recompiled.Restarting the web server does not throw away the DLL’s.

ASP.NET 1.1 ArchitectureUML of page hierarchyMost ASP.NET developersdon’t know this pattern!The ASPX file inherits thecontrols declared in the code-behind file.Page_Default_Default_ASPX

ASP.NET 2.0 ArchitectureSlightly different!ASP.NET takes advantage of .NET 2.0 partial classes!Page_Default_DefaultHidden file. Automatically generated.Contains control declarations and event handler assignments._Default_ASPX

So… do you like it?This architecture cleaned up the Code-Behind file (now called CodeFile).No control declarationsNo event handling codeMy Opinions: I miss the control declarations – what did I name that DataGrid control?Now I use thisa lot.C#: How do I create a Page_PreInit() event handler?

ASP.NET SnippetsDownload from www.MNDeveloper.comGives C# developers access to event handlers for ASPX, MASTER, ASCX, ASMX, and ASAX files.Follow installation instructions carefully!If you can’t see the Snippets Manager, change your VS settings to General Development Settings.

ASP.NET Handlers and ModulesThe old days of C++/MFC web programming…ISAPI Extensions – called directly within the Querystring from the browserEbay is still doing this today: http://search.ebay.com/search/search.dll?from=R40&satitle=frogger&category0=ISAPI Filters – ran on IIS investigating, modifying and even shutting down requests and responses passing through IISUnmanaged ISAPI Still the fastest way to program the webATL Server anyone? (What’s that?)

ASP.NET Handlers and ModulesISAPI Extensions = HandlersCalled directly in URLOffer capability of custom file extensionsISAPI Filters = ModulesOften used for securityNot a good choice for modifying output (limited)Can stop a Request or Response in its tracks!Used extensively by ASP.NET for security, caching, session variables, etc.

ASP.NET Handlers and ModulesIf you’re writing ASP.NET apps today, you’re already using Handlers and Modules!All Handlers and Modules are registered in the root “web.config” file for .NET 2.0, located at: C:WindowsMicrosoft.NETFrameworkv2.0.50727CONFIGThey are in the machine.config file in .NET 1.1Let’s look at them now…

ASP.NET HandlersThe easiest way to create you own handler is to add an ASHX file to your web site.It is pre-registered to automatically pass the request into the ASHX file.Here’s some starting code.<%@ WebHandler Language="C#" Class="Handler" %>using System;using System.Web;public class Handler : IHttpHandler { public void ProcessRequest (HttpContext context) {context.Response.ContentType = "text/plain";context.Response.Write("Hello World"); } public boolIsReusable { get { return false; }}}

ASP.NET HandlersASHX files were not officially supported in VS 2003. (A bit of a mystery at the time)With access to the HttpContext, you can create any kind of response that you want.The IsReusable property will instruct ASP.NET whether to hold the DLL in memory for additional requests.Can be much fast than ASPX files – no control tree to file through!

ASP.NET HandlersWant your own file extension? Register it with IIS and ASP.NET.Register with ASP.NET in web.config at root, web site, virtual directory or folder level.ASP.NET 2.0 also requires that specify the <buildProviders> section for the new file extension.What actually gets sent back to the client is up to you. You return data HTML your Handler code.

ASP.NET ModulesPerfect for implementing your own securityPlug right into the Http pipeline.Warning: a badly written module can affect performanceConsider other uses for modules:Tracking/Counting requestsRedirecting requests to different pagesBlacklisting troublesome IP addresses

ASP.NET Custom ControlsWhy bother? Power!!!Create your own control that emits whatever HTML/JavaScript you’d like.Create a composite control that contains several controls.Create a utility control without a UI that performs under the coversInherit from an existing web control and make it your own.

ASP.NET Custom ControlsYou will inherits from the System.Web.UI.WebControls.WebControl class.If no user interface needed, consider inheriting from WebControl’s parent class – Control.Visual Studio project template will get you started.It’s all about the attributes… See example.Can be programmed to support AutoPostBack.Override CreateChildControls() to create composite control containing multiple web server controls.

ASP.NET Custom ControlsWeb Site must have reference to DLL containing custom control(s)When part of a VS solution, compiling adds control to Toolbox automatically! (new in VS 2005)Dragging the control onto the form automatically registers it on the ASPX, ASCX, MASTER fileAssembly level attribute can set Register prefix:[assembly: TagPrefix(“MyControls”, “myc”)]

SqlCacheDependency ObjectASP.NET Caching has been around as long as .NET has been aroundCache objectOutputCachingThe Cache object can have dependencies placed on time, a file, a directory or another Cache object.If a file changed or a Cache changed, the initial Cache is flushed.Good coding practice ensured our objects were always populated.

SqlCacheDependency ObjectFile dependency is cute, real world demands database dependency!Hacks were abound in the .NET 1.1 world.Table triggers and extended stored procedures were writing to the file system or calling custom handlers(Rightfully) scared DB Adminshated these.Microsoft created the SqlDependency object to address this need.Custom Dependencies can now be created using CacheDependency class, which is no longer sealed!When data in a database table changes, throw away the cached data.

SqlCacheDependency ObjectWhat is this supported with?Sql Server 7.0, Sql Server 2000 and MSDE, Sql Server 2005 (Std, Express, Enterprise, etc.)Sql Server 2005 is the only database that automatically makes external notifications if a table has changed.We can make it work with the older versions as well (with a little more work).Ultimately, we want to throw away our cached data when someone INSERTs, UPDATEs or DELETEs data in a given table.

Sql Server 2005 SetupNone! It’s built in already!Just create a SqlCacheDependency object with a SqlCommand instance.Sql 7.0 and 2000?Let’s see how to set those up…

SqlCacheDependency ObjectFor Sql Server 7.0/2000, two primary steps are needed to create a SqlCacheDependency on a database table.Run the aspnet_regsql.exe against the database.This adds a tracking table called (huge frickin’ name) “AspNet_SqlCacheTablesForChangeNotification” and numerous triggers and stored procedures.Run the aspnet_regsql.exe against the table you are monitoring.This adds a trigger to that particular table and an entry to the table we just created (above).

Setting up our DatabaseUse the aspnet_regsql.exe utility against the database.aspnet_regsql.exe –S (local) –U username –P password –d pubs –edS = Server nameU, P = Username and passwordd = database nameed = enable database for SQL Dependency Caching

Setting up TableUse the aspnet_regsql.exe utility against the table.aspnet_regsql.exe –S (local) –U username –P password –d pubs –et –t authorset = enable table for SQL Dependency Cachingt = table name

Final Piece: web.config<system.web> <caching> <sqlCacheDependency enabled=“true” pollTime=“1000” > <databases> <add name=“pubs” connectionStringName=“LocalPubs” /> </databases> </sqlCacheDependency> </caching></system.web>pollTime is in milliseconds connectionStringName has been predefined in connectionStringssection.This isn’t needed for Sql Server 2005!

Using Our SqlCacheDependencySqlCacheDependency constructor, Two versions:Sql 7.0 and Sql 2000:SqlCacheDependencydep = new SqlCacheDependency(“pubs”, “authors”);Sql 2005:SqlCacheDependencydep = new SqlCacheDependency(myCommandObj);

Performance?Sql Server 2005 will always perform faster than 7.0 and 2000 implementationsBuilt into the Sql Server 2005 runtimeNo polling necessaryCreating/modifying Sql 7.0/2000 tables requires admin rights to perform. Not all developers have those.

My Book RecommendationsMSPress Programming Microsoft ASP.NET 2.0Core Reference (Dino Esposito)Advanced Topics (Dino Esposito)MSPressDeveloping More-Secure Microsoft ASP.NET 2.0 Applications (Dominick Baier)Wrox ASP.NET 2.0 MVP Hacks and Tips (David Yack, et. al)Wrox Web Parts and Custom Controls with ASP.NET 2.0 (Peter Vogel)