Wrox Professional Web Parts and Custom Controls with ASP.NET 2.0 phần 6 potx

The LicenseProvider is passed a number of parameters:

❑ context: This object provides information about the environment that the control is executing in.

The UsageMode property in this object, for instance, allows you to check whether the control is

in design or run time mode.

❑ type: The datatype of the control.

❑ instance: A reference to the control.

❑ allowExceptions: When set to True, it indicates that a LicenseException is to be thrown if

licensing fails.

Now that your license and license provider are built, you need to attach the license provider to your

custom control. Follow these steps:

1. Add the LicenseProviderAttribute to your class declaration and pass the attribute a reference to

your license provider. This Visual Basic 2005 example uses the license provider created in the

previous section:

<LicenseProvider(GetType(MyLicensingProvider)), _

ToolboxData(“<{0}:MyControl1 runat=server></{0}:MyControl1>”)> _

Public Class MyControl

In C#:

[LicenseProvider(typeof(MyLicensingProvider))]

[ToolboxData(“<{0}:MyControl1 runat=server></{0}:MyControl1>”)]

public class MyControl

{

2. In your control’s constructor, your control should call the Validate method of the LicenseManager

object (the LicenseManager automatically references the LicenseProvider referenced by the

attribute on the class). If the licensing fails, a LicenseException error is raised, terminating the

control’s processing. This Visual Basic 2005 code demonstrates how the Validate method is used:

Dim lic As System.ComponentModel.License

Public Sub New()

lic = LicenseManager.Validate(GetType(MyControl), Me)

End Sub

In C#:

public class MyControl

{

System.ComponentModel.License lic;

public MyControl()

{

lic = LicenseManager.Validate(typeof(MyControl), this);

}

}

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3. In the Dispose method of your control, call the Dispose method of any license that you retrieved

in your control’s constructor and haven’t already disposed:

Public Overloads Overrides Sub Dispose()

If lic IsNot Nothing Then

lic.Dispose()

lic = Nothing

End If

End Sub

In C#:

public override void Dispose()

{

if(lic != null)

{

lic.Dispose();

lic = null;

}

}

In Step 2, instead of using the Validate method, you can call the IsValid method, passing the type of the

custom control. The IsValid method doesn’t throw an exception but returns False if licensing fails. This is

a Visual Basic 2005 example of the IsValid property:

Public Sub New()

If LicenseManager.IsValid(GetType(CustomControl1)) = False Then

Throw New System.Exception(“Licensing failed.”)

End If

End Sub

In C#:

public MyControl()

{

if(LicenseManager.IsValid(GetType(CustomControl1)) == false)

{

throw new System.Exception(“Licensing failed.”);

}

}

The LicenseManager object that you call from your control is created for you automatically, and handles

calling the GetLicense method of your License provider either through the LicenseManager’s Validate or

IsValid method.

This is just the bare bones of implementing licensing. You can have your License object check the licensing

source (a text file, a Web Service) for any set of conditions. You might specify usage counts in your

licensing, or list which functions on the control are to be enabled. In your license provider, you can add

additional methods or properties that interact with the license object to check for these conditions. Finally,

in your custom control, you can call these methods and properties to determine what your control is

allowed to do.

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Rather than writing your own licensing provider, you can use the LicFileLicenseProvider, which is part

of the .NET framework. You can create a licensing provider by inheriting from LicFileLicenseProvider

and implementing only the functions that you want to override. If you have worked with licensing in

COM applications, you’ll find that the LicFileLicenseProvider supports the same functionality as

ActiveX licensing.

Managing the Personalization Subsystem

When you deploy your Web Parts they will take advantage of the membership subsystem that is part of

ASP.NET. The membership subsystem is automatically activated and a membership data store is set up

in SQL Server Express the first time you add a WebPartManager to a Web page in Visual Studio 2005.

However, to take full advantage of personalization, you need to provide a method for users to identify

themselves so that the personalizations that users make are applied to them.

In addition, ASP.NET provides a mechanism for you to control where your personalization data is stored

and allows you to switch between data stores from within your code. As you’ll see, there are many

aspects of personalization that you can control from your code. You can even set up your page so that

changes made by one user (the system administrator, for instance) are applied to all users.

This all boils down to these three topics:

❑ Allowing users to identify themselves to the application

❑ Setting up personalization providers

❑ Managing personalization for your page

Identifying the User

ASP.NET 2.0 comes with a set of login controls that you can add to a Web page to create a login page.

The key component is the Login control, which adds text boxes for entering the username and password,

a button for logging in, and a checkbox for setting up a cookie that will let the user be remembered by

the login process. Using these controls allows a user to log on to the site with a specific identity and be

assigned the customizations that he has made.

In order for users to log on to the membership system, you need to set up those user identities for the

site. You can add new users to your site from Visual Studio 2005 with these simple steps:

1. Select ASP.NET Configuration from the Website menu.

2. When the Web site administration page is displayed (see Figure 7-11), click the Security tab.

3. Click the Create user link to display the Create User form.

If your Web site is using Windows authentication, you won’t be able to create users and the Create

User link won’t appear. To stop using Windows authentication, click the Select authentication type

link (see Figure 7-12), and then select the From the Internet option and click Done.

4. Enter the information required by the form and click the Create User button to create the user.

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Figure 7-11

Figure 7-12

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In most cases, you probably already have a list of users with usernames and passwords stored in some

datastore (such as a database or Active Directory repository). In these situations, it makes more sense to

create code that will read users from your datastore and add them to your site’s membership system.

To create a user from your code, you can use the CreateUser method of the Membership object. This

method can accept a number of parameters that set the user’s name, password, e-mail address, and

other items required on the Create User page of the administration pages. Some of the CreateUser

methods accept a MembershipCreateStatus object while others do not. If you use one of the methods

that doesn’t accept a MembershipCreateStatus object, if the user isn’t successfully created, a

MembershipCreateUserException error is raised. On the other hand, if you use one of the methods

that does accept a MembershipCreateStatus object, no error is thrown if the user isn’t successfully

created. Instead, the MembershipCreateStatus object passed as a parameter is updated with the result

from attempting to create the user.

The following Visual Basic 2005 code uses one of the versions of the CreateUser methods that accepts a

MembershipCreateStatus object. After calling the CreateUser method, the code tests the Membership￾CreateStatus’s value using one of the MembershipCreateStatus enumerated values to see if the attempt

to create a user succeeded.

Dim nu As System.Web.Security.MembershipUser

Dim stat As System.Web.Security.MembershipCreateStatus

nu = System.Web.Security.Membership.CreateUser(“PeterVogel”, “CMingus”, _

“[email protected]”, “Who is a bassist”, “Charlie”, True, stat)

If stat <> MembershipCreateStatus.Success Then

Me.txtError.Text = “User creation failed.”

End If

In C#:

System.Web.Security.MembershipUser nu;

System.Web.Security.MembershipCreateStatus stat;

nu = System.Web.Security.Membership.CreateUser(“PeterVogel”, “CMingus”,

“[email protected]”, “Who is a bassist”, “Charlie”, true, out stat);

if (stat != MembershipCreateStatus.Success){

this.txtError.Text = “User creation failed.”;

}

While administering your users from Visual Studio 2005 makes sense for your test site, you will want to

use a more sophisticated tool on your production Web site. You can:

❑ Add the ASP.NET user creation controls to your pages to give you (or your users) the ability to

create users.

❑ Administer users with the Web administration pages for your Web site by selecting ASP.NET

Configuration from the Website menu from within Visual Studio 2005. From outside Visual

Studio 2005 or on a deployed site, use http:/hostname/sitename/WebAdmin.axd.

❑ Build user management pages with the Membership objects.

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