Apress Introducing dot NET 4 0 with Visual Studio 2010_5 pot

Installation A number of Visual Studio 2010 project templates such as ASP.NET MVC 2 and ASP.NET web application projects include the Microsoft AJAX libraries out of the box.. Adding Mic

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CHAPTER 10 ASP.NET

One-Click Publishing

One-click publishing uses IIS remote management services to allow you to publish your application to a remote server with one click One-click publishing only deploys files that have changed, so is very

efficient To use one-click publishing, you will need a hoster that supports One Click (at the time of

writing Discount ASP or OrcsWeb) or, if deploying to your own server, to have IIS remote management services enabled (http://technet.microsoft.com/en-us/library/cc731771(WS.10).aspx) One Click is

also only available for projects in the VS2010 format

Before we can use one-click publishing we need to configure a number of settings Right-click on

your project and select the Publish option You will see a screen similar to Figure 10.4

Figure 10-4 One-click publishing profile settings

Fill in the details as shown (using MSDeploy Publish as the Publish Method) and click Close Once these details are completed, you can publish your application by selecting the Publish Profile you want

to use from the drop-down menu (top left-hand side of the VS2010 screen) and clicking the Publish

button (Figure 10-5) Note if this tool bar is not showing, right-click on the toolbar and select Web One Click Publish VS2010 allows a single project to contain up to 50 different one click publishing profiles

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Figure 10-5 Initiating one-click publishing

ViewState

ViewState is the mechanism by which ASP.NET stores the state of controls on a web form This

information is held in a hidden form value called VIEWSTATE Depending on the page’s content,

ViewState can get pretty large, and is often unnecessary for controls that don’t change such as labels ASP.NET 4.0 gives you the ability for controls to inherit ViewState settings from parent controls by using the new ViewStateMode property This makes it very easy to efficiently set ViewStateMode on a large number of controls

ViewStateMode has three settings

• Enabled (ViewState used)

• Disabled (ViewState not used)

• Inherit (ViewStateMode is inherited from parent control)

The following example shows how to make lbl1 Label inherit pnlParent's ViewStateMode

<asp:Panel ID=”pnlParent” runat=server ViewStateMode=Disabled>

<asp:Label ID="lbl1" Text="text" ViewStateMode=Inherit runat="server" />

</asp:Panel>

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CHAPTER 10 ASP.NET

ClientIDMode

A long-term irritation in ASP.NET is the lack of control you have over the ID property of rendered

controls For example, take the following HTML that is rendered from a few simple controls that are

nested inside a Master page:

</div>

Most of the time, ASP.NET’s automatic ID generation features work pretty well, but in some

situations, say, when working with Master pages or writing client script, you need a finer level of control ASP.NET 4.0 gives you this control with the new ClientIDMode

ClientIDMode has four settings

• AutoID: Works as per previous ASP.NET releases

• Static: Allows you to specify the ID that is used Warning: you can obviously generate duplicate client IDs, so it is up to you to ensure your ID is unique or face client-side script hell (well,

probably an annoying JavaScript error, anyway)

• Predictable: Used in conjunction with RowClientIdSuffix property to generate incrementing IDs for repeating controls such as DataGrid and Repeater, for example, myrow1, myrow2, myrow3

• Inherit: Controls uses the same ClientIDMode as its parent control (default)

ClientIdMode can be set at control, page, and application level

• To set on an individual control:

<asp:Label ID="lblTest" runat="server" Text="Test" ClientIdMode=”Inherit”></asp:Label>

Response.Redirect() is a frequently used method that redirects the current request to another URL At

an HTTP level Response.Redirect() issues a temporary redirect (HTTP 302) message to the user’s

browser ASP.NET 4.0 now offers a new Response.RedirectPermanent() method that issues a

permanently moved (HTTP 301) message (http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html) Why bother? HTTP 301 is mainly used to tell search engines that they should save the new page

location in their indexes rather than the old location This saves an unnecessary trip to the server

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Meta-MetaDescription will act as properties so make sure you append rather than overwrite when using them

As well as creating simple one-to-one mapping URLs, it is useful to be able to pass in parameters to routes For example most shops sell a number of different types of products so you could create URLs such as myshop.com/cats or myshop.com/dogs (note selling cats and dogs online is probably a bad idea)

To create these type of routes enclose the value that will change inside curly brackets:

System.Web.Routing.RouteTable.Routes.MapPageRoute(

"myProductGroupRoute", "{groups}", "~/default.aspx?id=123"

);

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CHAPTER 10 ASP.NET

Routing parameters can then be retrieved with the following syntax:

string searchTerm=Page.RouteData.Values["group"];

Sometimes it can also be useful to retrieve the URL that will be generated for a specific route to

create hyperlinks or redirect the user; this can be done with the GetRouteUrl() method:

Page.GetRouteUrl("myProductGroupRoute", new { group = "brandNew" })

HTML Encoding

All web developers should be aware that it is important to HTML encode values that are output to

prevent XSS attacks (particularly if you have received them from the user) ASP.NET 4.0 offers a new

markup syntax that uses the colon character to tell ASP.NET to HTML encode the expression:

<%: "<script>alert('I wont be run');</script>" %>

When ASP.NET parses this it does the following:

<%: new HtmlString("<script>alert('I will now be run');</script>") %>

Custom Request Validation

It is now possible to override the default request validators by inheriting from the

System.Web.Util.RequestValidator class and overriding the method IsValidRequestString() You must then specify the custom validator in the httpRuntime section in Web.config:

Custom Encoders

If you feel that ASP.NET’s existing page encoders are insufficient then you can now create your own by inheriting from System.Web.Util.HttpEncoder class and specifying the new encoder in the encoderType attribute of httpRuntime, for example:

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242

URL and Query String Length

Previously ASP.NET limited accepted URLs to a maximum of 260 characters (an NTFS constraint) ASP.NET 4.0 allows you to extend (or limit) the URL and query string maximum length To modify these settings change the maxRequestPathLength and maxQueryStringLength properties (in the httpRuntime section) in Web.config:

Valid URL Characters

Previous versions of ASP.NET limit accepted URLs to a specific set of characters The following

characters were considered invalid in a URL: <, >, & You can use the new requestPathInvalidChars property to specify invalid characters (such as the above) The below example makes a,b,c invalid in requests (which isn’t too useful but demonstrates the feature):

NOTE The Microsoft documentation states that ASP.NET 4.0 will reject paths with characters in ASCII range 0x00 to 0x1F (RFC 2396)

Accessibility and Standards

Accessibility and standards, whether you like it or not, are becoming increasingly important Microsoft is aware of this and has introduced a number of changes

controlRenderingCompatibilityVersion

The pages section in Web.config contains a new controlRenderingCompatibilityVersion property that determines how controls are rendered by default The controlRenderingCompatibilityVersion property can be set to 3.5 or 4.0

<system.web>

</system.web>

Setting controlRenderingCompatibilityVersion to 3.5 will ensure ASP.NET renders as in ASP.NET 3.5

If however you set controlRenderingCompatibilityVersion to 4.0 then Microsoft say that the following will occur:

• The xhtmlConformance property will be set to Strict and controls will be rendered

according to XHTML 1.0 Strict markup

• Disabled controls will not have invalid styles rendered

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CHAPTER 10 ASP.NET

• Hidden fields that have div elements around them will now be styled in a manner

that will not interfere with user-defined CSS rules

• Menu controls are now rendered using unordered list (UL) tags (fantastic)

• Validation controls will not use inline styles

• Previously some controls such as Image rendered the property border="0"; this will no

In ASP.NET 4.0, however, all these controls support a new RenderOuterTable property that if set to

false will use a div instead

CheckBoxList and RadioButtonList

CheckBoxList and RadioButtonList benefit from a the new property RepeatLayout RepeatLayout has four modes: UnorderedList, OrderedList, Flow, and Table, allowing you fine control over how they are

rendered

ASP.NET Menu control

The ASP.NET Menu control now renders menu items using unordered list elements Keyboard support for the menu has also been improved so once an ASP.NET menu receives focus the user can navigate

through menu items using the arrow keys

Browser Capability Files

Browser capability files are used to determine how best to render content for individual browsers and

are held in XML format If you feel the need you can create your own browser provider by deriving from the HttpCapabilitiesProvider class

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244

Further Control Enhancements

There are a number of control enhancements, and a couple of miscellaneous new controls as well

ASP.NET 4.0 resolves this problem with the new EnablePersistedSelection property If

EnablePersistedSelection is set to True, then row selection is maintained using the datakey of each item

Another welcome change is that the declaration of ListViews has been much simplified The following code shows how a ListView control had to be declared previously:

<asp:ListView ID="lstView" runat="server">

ASP.NET 4.0 allows you to do the following:

<asp:ListView ID="ListView1" runat="server">

CompareValidator

The CompareValidator now supports the comparison of Time and DateTime values

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CHAPTER 10 ASP.NET

Query Extender

Query extender is a new control that aims to make the filtering of data easier by providing a declarative query syntax that you can link to the Entity or LinqDataSource controls

Browser capability files

Browser capability files are to determine how best to render content for individual browsers and are held

in XML format If you feel the need (perhaps to override the rendering capabilities for iPhones, for

example) you can create your own browser provider by deriving from the HttpCapabilitiesProvider

class

Auto-Start Web Applications

Some ASP.NET applications perform a lot of startup work (usually in Global.asax’s Application_Load() method) For example, preloading or caching data ASP.NET 4.0 introduces a new feature called auto-

start that enables you to define code to be run as soon as your application is installed (or the app pool is recycled) Until this startup work has completed ASP.NET will prevent access to the application

Not all applications will be able to benefit from this facility through as they must

• Be running on Windows Server 2008 R2 and IIS 7.5

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246

Compress Session State

It is generally a good rule to avoid storing anything in session unless absolutely necessary but if you must ASP.NET 4.0 allows you to compress session state Session state compression cannot be used by an in-process session so is only applicable if your application is using state or SQL Server To compress session simply set the compressionEnabled property to true in Web.config:

ASP.NET 4.0 gives you the option to create and utilize custom cache providers The cache provider can

be set at an application, control, and even individual request level (by overriding the

GetOutputCacheProviderName() method) offering very fine grained control

To create your own cache provider you must inherit from System.Web.Caching.OutputCacheProvider

System.Runtime.Caching

In previous versions of NET, caching functionality was contained in the System.Web assembly To enable easier integration for non-web clients, Microsoft has created the new System.Runtime.Caching assembly System.Runtime.Caching contains abstract classes for creating your own cache provider, and a new class called MemoryCache MemoryCache can be used by non-web clients and offers simple in memory caching functionality Microsoft say that the internal implementation of MemoryCache is very similar to ASP.NET’s cache

The following example shows how to utilize MemoryCache to store a string for an hour (note you can also create watchers to invalidate the cache if an item changes and add them to the policy.ChangeMonitors property):

ObjectCache cache = MemoryCache.Default;

string testData = cache["someData"] as string;

if (testData == null)

{

CacheItemPolicy policy = new CacheItemPolicy();

policy.AbsoluteExpiration = new DateTimeOffset(DateTime.Now.AddHours(1));

cache.Set("someData", "some test data", policy);

}

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CHAPTER 10 ASP.NET

Resource Monitoring

Some web servers run many applications within one app pool If issues occur on an individual site, it can

be difficult for an administrator to determine which particular application is having difficulties ASP.NET 4.0 introduces additional performance counters allowing you to monitor individual applications CPU

and memory usage

To utilize this, you must add the appDomainResourceMonitoring setting to Aspnet.config

(Aspnet.config is located where the NET framework is installed: C:\Windows\Microsoft.NET\

• Managed Processor Time

• Managed Memory Used

Figure 10-6 New perf counters for ASP.NET

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changes to Web.config to include them

Figure 10-7 A simple ASP.NET chart

To add a chart to your web page simply drag the Chart control from the toolbox or add a reference to System.Web.DataVisualization and the Register directive below (note this may be slightly different for the final release of VS2010):

<%@ Register Assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"

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CHAPTER 10 ASP.NET

The following code binds a series of random points to the chart:

Random r = new Random();

Series series = new Series("Line");

Dynamic Data Framework

It is worth noting that the Dynamic Data Framework has a number of additions in VS2010/ASP.NET 4.0

I will not be covering these but for interested readers please refer to: http://www.asp.net/dynamicdata

Conclusion

ASP.NET 4.0 fixes some long-term omissions and bugs and looks likely to continue to be a popular

method of developing web applications Alternative approaches such as ASP.NET MVC (Chapter 13) are gaining ground (due in part to their easy testability), so it will be interesting to see if this remains the

case in years to come

Tiêu đề	Apress Introducing dot NET 4 0 with Visual Studio 2010
Trường học	University of Example
Chuyên ngành	Computer Science
Thể loại	Textbook
Năm xuất bản	2010
Thành phố	New York

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Số trang	45
Dung lượng	1,61 MB