Yiyi Sun - Programming Blog

Web Service Description: RSD and RDF

Most popular blog servers/engines such as WordPress, Drupal, Neclues and etc. are using RDS (Really Simple Discovery) to help client software like WB Editor to find the services that can be used to retrieve, modified and delete the blog posts.

Those blog servers/engines are also generating RDF (Resource Description Framework) for each blog post to give more information about the post, e.g. track back url. But not enough. I am looking for,

• RDF extension that describes the blog service API lisk WSDL dose for SOAP, so that WB Editor can generate dynamically proxies to the service.
• RDF extension that describes which HTML elements can WB Editor extract data from and then send to the blog service.

Here are some interesting references:

• http://msdn2.microsoft.com/en-us/library/xxb0bsdh(vs.80).aspx
• http://en.wikipedia.org/wiki/Semantic_Web
• http://en.wikipedia.org/wiki/Screen_scraping
• http://simile.mit.edu/wiki/Piggy_Bank
• http://simile.mit.edu/wiki/Solvent

Add comment May 6th, 2007

About

Add comment October 18th, 2006

Created a CAB workspace that has VS 2005 style Tabs

2 comments August 17th, 2006

SharePoint Windows Authentication

In IE: open “Tools | Internet Options -> Security”, add the SharePoint sites in “trusted sites”

In firefox: open firefox browse to about:config find “network.automatic-ntlm-auth.trused-uris” modify the value and enter in SharePoint intranet sites that you must pass your username and password to. For some site i connect to i also had to add values to: “network.negotiate-auth.delegation-uris” “network.negotiate-auth.trusted-uris”

1 comment July 20th, 2006

Unit Test : MVP vs PM

Smart Client Software Factory team is recommending the “Model View Presenter” pattern. They have created Guidance Package for using this pattern.

From my experience, the “Presentation Model” pattern is better. When I asked if SC-SF can also include Guidance Package for PM, it looks like people may think MVP is more suitable for unit tests than PM. Read this thread.

To me, PM is even easier for unit testing, because it is less coupled.

I have refactored the CAB Smart Part Quick Start project to use MVP and PM patterns and have also created unit test projects for comparison.

Source Code:

• SmartPartQuickStart_MVP.zip
• SmartPartQuickStart_MVP.Test.zip
• SmartPartQuickStart_PM.zip
• SmartPartQuickStart_PM.Test.zip

They can be added to the CAB Smart Part Quick Start solution.

Add comment June 14th, 2006

Refactor CAB Smart Part Quick Start Project to ” Model View Presenter”

In my previous post, I refactored CAB Smart Part Quick Start project to use Presentation Model. This time I refactored the project to use Model View Presenter. Note: the Presenter class is borrowed from Smart Client Software Factory, SC-SF.

Download: Source for PM,  Source for MVP

They can be added to Smart Part QuickStart Solution for comparison.

The difference is that in MVP the presenter uses the interfaces to push data into the views. That presenter refers to views. In PM, views pull data from the presentation model.  Views refer to pm via interface. The pm implements the interfaces. Personally,

I prefer PM to MVP. I successfully used the PM pattern in several projects.

My thougths are, 

What esstentially MVP and PM do is to take the state and behavior of the presentation out of view. The views are dumb. They do nothing other than data binding and bypass user inputs.

But in MVP, although it splits one “autonomous View” into two parts, actually presenter and view are logically one thing, physically two class. When adding a new view, a new presenter is required.

In PM, it is a decoupled structure. Presentation model has no idea about view(s). It just holds the state and raise events. Adding new views needs no changes to the PM. View can also choose to connect different presentation model.

The Smart Client Software Factory recommand MVP over PM, “The rationale behind MVP as implemented in SC-SF is to encourage unit testing …” Read this thread.

So, I created two projects for the two patterns. Next I will try to unit tests for them to see.

Add comment May 19th, 2006

Refactor CAB Smart Part Quick Start Project to “Presentation Model”

Composite UI Application Block (CAB) is really a powerful framework for smart client applications. It comes with samples implementing the Model View Control (MVC) pattern and the Model View Presenter (MVP) pattern. There is actually a third pattern called Presentation Model. See the pictures from http://jgoodies.com/articles/patterns-and-binding.pdf.

As described in Martin Fowler’s article (MVP, PM), the presenter in MVP has no state and the views need to provide interface allow presenter to manipulate them. The Presentation Model holds and synchronizes the state, but no need to create view interfaces.

Choice between MVP and PM, as per Martin Fowler’s article:

Compare to MVC or MVP, I prefer using the Presentation Model, because it has a centralized place to store state/data and centralized event source to notify views to update themselves. The CAB’s Event Broker is perfect for notification. So I modified the Smart Part Quick Start Project to become the ”Presentation Model” pattern.  Here is the Source code.

What have I done?

1. Refactor to extract interface ICustomerListView and ICustomerDetailView from the views*. 
2. Added CustomerPresentationModel class that implements the above two interfaces. 
3. Define the CustomerPresentationModel class as Service. **
4. Inject the CustomerPresentationModel instances into views using service dependency injection. ***
5. Published events CustomerSelected events CustomerCommentsSelected from the CustomerPresentationModel class.
6. Subscribed the above events in BrowseCustomerWorkItem and ViewCustomerWorkItem

* Extract interface from the views sound very much similar to MVP, isn’t it? The difference is that in MVP, the presenter uses the interfaces to push data into the views, means that presenter refers to views. In PM, the controller implements the interface. The views pull data from the controller, means that views refer to controller. The “refer to” is a very good case of using depedency injection.

**

[Service]
public class CustomerPresentationModel: ICustomerDetailView, ICustomerListView
{
}

***
public partial class CustomerListView : TitledSmartPart
{
    private ICustomerListView controller = null;

    [ServiceDependency(Required = true, Type = typeof(CustomerPresentationModel))]
    public ICustomerListView Controller
    {
        set { controller = value; }
    }
    ….
}

Tags: smart client Composite UI Application Block MVC Model View Presenter Presentation Model injection

1 comment May 15th, 2006

P&P OB CAB EntLib

继续 VSLive Toronto 的后续故事。 上次记录了 SQL/e，这次是关于 Daniel Cazzulino çš„发言 《Microsoft p&p ObjectBuilder》。听完这个演讲发现最近周围的事情还都发生了些关联。

首先是日前买了本书 《Head Up Design Patterns》。它的第一章就以一个引人入胜的故事介绍了设计模式的 Strategy Pattern。这个模式的好处多多，但是负作用是会产生了很多相互关联的类。如何按照合理地创建这些类，并把它们组和起来。这就引出了另外一个话题 Inversion of Control / Dependency Injection。

这几天帮女儿复习准备乐理考试，还碰到了 Interval Inversion / Triad Inversion，搞得我就很头昏。Dependency Injection å¥½åƒè¿˜å¥½ç†è§£äº›ã€‚

Daniel Cazzulino 讲的 ObjectBuilder å°±æ˜¯ä¸€ä¸ªå…·æœ‰ dependency injection 功能的轻量级对象容器*。 ObjectBuilder æ˜¯ ï¼­ï¼³ patterns & practices Composite UI Application Block ä»¥åŠ Enterprise Library 的核心部分。

这就又引到了 CAB - Composite UI Application Block。也是不久前 WB Editor 3.0 的设计已经开始了。鉴于 2.0 版本中 RAD 流毒太深**，决定应该采用个好的系统结构，正在犹豫，是否用这篇 Implement a Microsoft Word-like Object Model for Your .NET Framework Application 文章介绍的方法呢，还是用 CAB。

经过聆听 Daniel Cazzulino 的讲解，不但了解了 OB 的功能，还了解了其内部的一些机制。因此决定进一步学习了一下 CAB Hands on Lab。于是得到结论就是 WB Editor 3.0 将采用 CAB。

Daniel Cazzulino 还讲了个有用的内容，Guidance Automation Toolkit / GAT，值得再用一篇笔记介绍。
* 轻量级对象容器和 ** RAD 流毒也可以讲些故事。

Tags: VSLive ObjectBuilder Strategy Pattern Inversion of Control Dependency Injection Composite UI Application Block CAB RAD

1 comment May 14th, 2006

Optimistic concurrency

During the WB Editor 2.5 testing, we found an interesting concurrency control issue. In this version, we allowed multiple program instance for ease of cross posting.

Now in multiple instance windows, user can setup blog server accounts differently. Which one is the winner?

“Last one wins” was disapproved by QA.

Maybe we need optimistic concurrency. I this case user will receive a dialog saying “another instance has modified the settings”, do you want to overwrite or discard or reload?

Another option is concurrency control with change notifications. Using FileSystemWatcher to detect changes of configuration file, but what should happen next in UI?

Tgas: WB Editor concurrency control Last one wins optimistic change notifications multiple instance blog cross posting FileSystemWatcher 

Add comment May 10th, 2006

SQL/e

在 VSLive Toronto 上见到两个人物，Steve Lasker å’Œ Daniel Cazzulino

Steve Lasker 介绍了使用 SQL Server Everywhere 的 Occasionally Connected Systems。 SQL Server Everywhere(SQL/e) 何须人也？原来2-4年前做 Pocket PC 程序就相识，那时它叫 SQL Server CE，后来又叫 SQL Server Mobile。 Visual Studio 2005 带的 SQL Server Mobile 被限制只能运行在 Tablet PC 上。SQL/e 就是解除了这个限制的版本。SQL/e 因此能运行在台式 Windows 上。

SQL/e 计划在 2006年下半年发布。 Steve 演示了目前如何在 VS 2005 中试验开发的和可以通过 ClickOnce 安装的办法。

这就解决了一个版本 WB Editor çš„数据库选择问题。 本来正在犹豫是否应该用 SQL Server 2005 Express (SQL/x)。这个家伙 55M，还需要 Admin 用户权限才能安装。 比较  SQL/x å’Œ SQL/e，SQL/e 才 1.4M。看来SQL/e 更加适合 WB Editor 3.0。

Daniel Cazzulino 讲的内容也很有用，将会在下一篇笔记内介绍。

Add comment May 8th, 2006

CurrentVersion - Explorer - SharedTaskScheduler

An icon in the system tray kept poping up a notification saying “Your computer is infected! …”. If clicked the message, it opens the browser and connects to spywarequake.com.

Scanned with Windows Defender and Windows Live Safety Center, they could not find anything …

Finally used the old Spy tool to catch that popup’s class name is “ballon window”. Then searched DLL to find out suprox.dll. In the registry:

[HKEY_CLASSES_ROOT\CLSID\{AC1B4DA2-12FA-31F2-1A7D-CD2B14E6AD4E}\InProcServer32]
@=”C:\WINDOWS\system32\suprox.dll”
“ThreadingModel”=”Apartment” 

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\Explorer\SharedTaskScheduler]
“{AC1B4DA2-12FA-31F2-1A7D-CD2B14E6AD4E}”=”USB Mouse Driver”

SharedTaskScheduler!, a new place to watch out.

Tags: system tray spyware malware  spy tool clsid popup SharedTaskScheduler Your computer is infected

1 comment April 15th, 2006

SharePoint / ASP.NET with Windows Authentication in Intranet

Server Side

1. IIS Configuration - Directory Security Tab of Site / Virtual Root Properties

• Disable anonymous access
• Enable ONLY Integrated Windows Authentication

2. Web.config

  <authentication mode=”Windows” />
    <authorization>
      <deny users=”?” />
    </authorization>
  <identity impersonate=”true” />

3. NTFS Security Tab of the physical folder

• Add allowed user / user group

Client Side (IE)

• Add the server IP / Machine name / domain name to Intranet Sites
• Bypass proxy for the server if proxy server causing problem
• IE Security Setting, select “Automatic logon only in Intranet zone”

Add comment March 7th, 2006

把图片存到 Flickr

Flickr 是免费的图片发布和分享网站。最近被收购到 yahoo 旗下。

把图片存在 Flickr 然后连接到自己的 blog 中 是个很不错的做法。

WB Editor 2 已经支持直接上传图片到 Flickr 了。另外还会有一个插件，来管理和检索图片。

1 comment December 10th, 2005

与 Biztalk 搏斗

开发个 Biztalk 系统真是颇费周折。记下一些经验备用。

1. Error about enlisting DTC.
Solution:
1) Turn off the RPC security on your Windows Server 2003 computers.
http://support.microsoft.com/default.aspx?scid=kb;en-us;839187
2) Turn off DTC authentication.
http://support.microsoft.com/default.aspx?scid=kb;en-us;884623
Error Messages:
Failed to execute SQL Statement. Please ensure that the supplied syntax is correct. An error occurred while enlisting in a distributed transaction.

2. Unable to deploy early bindings… Access is denied.
Solution: Add user id / group to Biztalk Admin group and SSO admin group
Error Messages:
[Microsoft.BizTalk.Deployment.DeploymentException] Unable to deploy early bindings.
[Microsoft.BizTalk.Deployment.Binding.BindingException] Failed updating binding information.
BindingException: Could not store transport type data for Primary Transport of Send Port ‘xxSendPort’ to config store. Access is denied.[Microsoft.BizTalk.ExplorerOM.BtsException] Could not store transport type data for Primary Transport of Send Port ‘xxSendPort’ to config store. Access is denied.

3. Event Log is full of ENTSSO events?
Solution: C:Program FilesCommon FilesEnterprise Single Sign-Onssoconfig -backupsecret mybackup.bak
Error Messages:
The master secret has not been backed up. If you lose the master secret all the information stored in the SSO system will be lost permanently and your systems may fail to work correctly. Please use the SSO admin tools to back up your master secret.

4. Cannot deploy without strong name
Solution: Assign strong name from within the BizTalk project’s properties window.
Error Messages:
[Microsoft.BizTalk.Deployment.DeploymentException] Unable to install the “….dll” assembly into the Global Assembly Cache. Exception: A strongly-named assembly is required.
[Microsoft.BizTalk.Gac.GacException] A strongly-named assembly is required.

5. Cannot Access Schema Based Message’s Property in the Expression Editor
Solution: Open the XSD, right click the property name, select Promote | Show Promotions ..
Promote the properties to be distinguished.

November 18th, 2005

late-bound data binding 的妙处

搞定 支持 aspx 语法的 Template 引擎 后即开始编写 template以及试验从 windows forms 程序传递数据。在我的设计标准中，数据结构 Custom Object 有先于 DataSet，一般尽量避免 late-bound data binding：
< %# DataBinder.Eval(Container, "DataItem.Title") %>
而是建议 bind to cutom object：
< %# ((WBEditor.Post) Container.DataItem).Title %>‘>

asp.net web 系统是应该这么做的，但是用在 Template 引擎 中有个问题：asp.net host 固定要到 bin 目录下去找包含 WBEditor.Post 类定义的 DLL。从程序发布 (depolyment) 的观点来看，不是很舒服的结构。这种情况下 late-bound data binding 就很有用了。它不要依赖于 DLL，而是在 run-time 通过 reflection 去取值。

有趣的是 DataBinder.Eval 不仅仅能对付 Container.DataItem，还能用在 object 上。< %# DataBinder.Eval(Post, "CreatedDate", "d") %>

1 comment March 28th, 2005

支持 aspx 语法的 Template 引擎

最近需要一个 .NET 下的 Template 引擎来支持自定义网页模版。一般如 Velocity(java), Smarty(php) 等 Template 引擎都自带一套语法。而 CodeSmith 的概念是用 ASPX 语法。这个概念卖点不仅仅在于能直接用已经熟悉了的ASPX 语法，还在于能嵌入 inline code，并且能用 server control，例如 DataGrid DataList 和 Repeater。Template 本身可以用 WebMatrix 来编辑。所以是很酷的设计。

在 m3rlin 中找到了 hosting the ASP.NET runtime 的办法，包括创建新的 AppDomain 和 通过 HttpContext 传递数据等等。这样我有了能用在 windows forms 程序中的支持 ASPX 语法的 Template 引擎。

ps. Template 引擎通常可以用来做代码生成工具的核心。

1 comment March 28th, 2005

HTML 语法加亮编辑器

终于为下一版的 WB Editor 搞定了HTML 语法加亮编辑器。

老的编辑器的原理同这篇文章。它实现了实时染色的功能 (highlight on the fly)，但是一篇文章新载入时，全文染色效率极差 (feel it’s being choked)。

想了很多办法试图分页，但不成功。于是开始分析 SharpDevelop 的编辑器和 JSource 的编辑器的代码。发现如果自己从头做工程量巨大。接着向 SharpDevelop 开发者询价，得到个目前无法支付的价格。

回头再想，全文染色慢的主要原因就是用 SelectionStart 和 SelectionLength 两个属性来操作。甚至根据 Syntax colorizing with Speller engine using TOM and CSAPI 一文，用了 TOM 接口也没有改观。

再研究，能不能直接生成 rtf，终于发现 Delphi 的文章 Automatic Syntax Highlighting Using a RichEdit Control 介绍了 rtf 的格式以及 Syntax Highlighting With RichEdit 一文给出了生成 HTML 语法加亮 rtf 的办法。

用我现成的 HTML Tokenizer 接上去一试效果很好，200 多K 的HTML 加亮没有延迟的感觉。准备升级 WB Editor 2 了。

Add comment March 24th, 2005

OleDbCommand.Parameters

折腾了两天，才发现 OLE DB .NET 不支持 named parameters。

The SQL Server .NET data provider (SqlClient) supports named parameters. Therefore, when you use the SqlCommand object, you do not have add the parameters in any particular order, but the parameters must have the correct name. In this case, you must add the at sign (@) prefix to the parameter names.

Alternatively, the OLE DB .NET data provider does not support named parameters. Therefore, when you use the OleDbCommand object, you must add the parameters in the correct order (which is the same order that is defined at the backend stored procedure). In this case, you do not need to add the “@” prefix to the parameter names, and the parameter names do not have to match those that are defined at the stored procedure.

From: http://support.microsoft.com/kb/310071/EN-US/

另：Microsoft Support 开始用 URL Re-Write 技术了

Add comment March 18th, 2005

.NET 下制作 Shareware 的关键技术探讨二：非对称加密

前文描述了.NET 为 Shareware 程序开发提供了许可证检测机制，使得开发者可以集中精力到如何验证许可证。

把一个信息经由不可信任的途径传达给接受者的时候，就需要进行加密。对于信息接受者来说，则需要确认信息的来源是来自正确的，就需要进行数字签名。Shareware 程序拥有者要告诉远在用户机器上的自己的程序用户有权使用这么个信息，是要加密的。因为你不想让其他人知道这个信息是如何表达的，更不能让人家如法炮制出相同的信息。

.NET 提供了加密和数字签名等现在用在网络安全方面的技术用到 Shareware 上是绝对好的。下面是用 .NET RSACryptoServiceProvider 的一个办法。

RSA 是一种非对称加密技术 Asymmetric Cryptography，即加密用的密码和解密用的密码是分开，相互不能推演的。如果知道了解密用的密码，无法知道加密用的密码。这比对称加密安全性好，因为 Shareware 总是需要一个密码用来解注册码，用对称加密的情况下，如果被人从程序中分析到了解密的密码，有可能复制注册机。而用非对称加密，即使解密的密码泄漏，也无法做出注册机。

1、生成和保存密码

创建个新的 RSACryptoServiceProvider 对象，.NET 就随机生成了密码。
RSACryptoServiceProvider 对象可以把密码输出成 xml。

RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
Console.WriteLine(rsa.ToXmlString(true));

这个 xml 是要好好保存起来的秘密。其中包含了用来做注册机的加密用的 private key 和 将来在程序中用来解密的用 public key。

<RSAKeyValue>
  <Modulus>…</Modulus>
  <Exponent>…</Exponent>
  <P>…</P>
  <Q>…</Q>
  <DP>…</DP>
  <DQ>…</DQ>
  <InverseQ>…</InverseQ>
  <D>…</D>
</RSAKeyValue>

2、注册机

根据上面的密码 xml，可以这样生成注册机所需要的 RSACryptoServiceProvider 对象。然后用数字签名的办法生成注册码。

SignData 是做数字签名。它与单纯的加密解密有区别。

如果要变成注册码是这样一句话：某人于某时某地购买了我的软件。单纯的加密后的解密你会看到这句原话(从内存里什么地方挖出来)。而用数字签名办法，解密后看不到原话，而是一个单向计算出来的 Hash 值。所以对所传送的信息多了一层保护。RSACryptoServiceProvider 提供了直接的生成数字签名和验证数字签名的方法。

private static byte[]CreateKey()
{
    byte[] digestInput = fileEncoding.GetBytes(GetRegistrationInfo());
    RSACryptoServiceProvider RSAalg= new RSACryptoServiceProvider();
    RSAalg.ImportParameters(GetPrivateKeyParam()); 
    return RSAalg.SignData(digestInput, new SHA1CryptoServiceProvider());
}

private static string GetRegistrationInfo()
{
    return GetValue(“NAME”)+GetValue(“PURCHASE_TIME”)+GetValue(“FROM”);
}

private static RSAParametersGetPrivateKeyParam()
{
    RSAParameters param = new RSAParameters(); 
    param.D= Convert.FromBase64String(“…”); 
    param.DP = Convert.FromBase64String(“…”);
    param.DQ = Convert.FromBase64String(“…”); 
    param.Q = Convert.FromBase64String(“…”); 
    param.P = Convert.FromBase64String(“…”); 
    param.Exponent= Convert.FromBase64String(“…”); 
    param.Modulus= Convert.FromBase64String(“…”); 
    param.InverseQ= Convert.FromBase64String(“…”); 
    return param;
}

从 XML 中生成 private key 来制作数字签名，需要用到全部参数：D, DP, DQ, P, Q, Exponent, Modulus, InverseQ.

3、验证数字签名

在 Shareware 程序中，从密码 xml 文件生成验证数字签名所需要的 SACryptoServiceProvider 对象，然后请用户输入他的名字、以及购买软件的时间地点。组成一个句子：某人于某时某地购买了我的软件，用 SACryptoServiceProvider 验证一下它的数字签名是否符合注册机生成注册码。

private static bool VerifyKey(byte[]digestInput, byte[] signed)
{ 
    RSACryptoServiceProviderRSAalg = new RSACryptoServiceProvider();
    RSAalg.ImportParameters(GetPublicKeyParam()); 
    return RSAalg.VerifyData(digestInput, new SHA1CryptoServiceProvider(),signed);
}

private static RSAParametersGetPublicKeyParam()
{ 
    RSAParameters param = new RSAParameters();
    param.Exponent = Convert.FromBase64String(“…”);
    param.Modulus = Convert.FromBase64String(“…”); 
    return param;
}

从 XML 中生成 public key 来验证数字签名，只要用两个参数：Exponent, Modulus. 别人即使从你散发出去的程序本身破解得到了public key，没有其它多大用处。

当然，破解不仅仅是要得到密码。如果来个暴力破解，把你的程序反编译出来，把你的 public key 换成他的，与他自己的注册机配合的，那你不就被抢劫一空了，或者反编译出来删掉前文所述的 LicenseProvdier，或者 …….，还有很多办法。

.NET 提供的许可证监测机制，非对称加密是否能真正发挥，还得看程序本身的加扰程度。下一篇文章介绍。

Tags: shareware asymmetric cryptography rsa private key public key

Add comment March 16th, 2005

.NET 下制作 Shareware 的关键技术探讨一：Licensing

制作 Shareware 有三个关键点：

• 如何保护对象(程序)，在创建对象的时候检测许可证 (License)。
• 加密/解密 用户信息和注册信息。
• 程序加扰 (obfuscate) 或者程序加密，反破解。

.NET 为前两者提供了基本支持，非常方便。这里先说检测许可证。许可证可以有通用注册码、验证用户名的注册码、验证用户机器的注册码等形式。当用户花钱购买了 Shareware 程序，Shareware 程序拥有者就会发送注册码给用户。(Share-It æœ‰åœ¨çº¿æ³¨å†Œç ç”ŸæˆåŠŸèƒ½ï¼Œä¸€æ”¶åˆ°é’±ç«‹å³è‡ªåŠ¨ç”Ÿæˆæ³¨å†Œç )。

Shareware 程序运行时要检测和验证用户是否具有有效的注册码，以决定用户是否能执行程序。

.NET 下的程序都是面向对象的，所以 .NET 在对象的创建机制上，提供了许可证检测的一个接口，Shareware 程序开发可以在此基础上加入自己的注册码验证算法。

.NET Licensing 一文介绍了许可证检测的办法：

[LicenseProviderAttribute(typeof(LicFileLicenseProvider))]
public class LicensedClass : IDisposable
{
    private License license = null;
    public LicensedClass()
    {
        license = LicenseManager.Validate(typeof(LicensedClass), this);
        Console.WriteLine(“Hello from the licensed class.”);
    }
    public void Dispose() 
    {
        if (license != null) 
        {
            license.Dispose();
            license = null;
        }
    }
}

有了这么个结构，程序开发可以把检测许可证交由 .NET 完成，而自己集中精力设计如何验证注册码。把上面的 LicFileLicenseProvider 换成自己的 Custom LicenseProvider。比如，不读文件而去读注册表，见：CodeGuru: Licensed Applications using the .NET Framework 。我的一些文章收藏 (RSS格式) 。

不论是从文件或者从注册表得到注册码，它包含了户是否可以运行程序的信息，而且它一定是只能 Shareware 程序拥有者说了算。因此这个信息是必须加密的。

.NET 提供了非对称加密 (Asymmetric Cryptography) 工具可以用来处理注册码。下一篇文章里继续介绍。

Add comment March 3rd, 2005