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    16Jan, 2012
    Client Application Development

    Client Application Development

    Client applications are the closest to a traditional style of application in Windows-based programming. These are the types of applications that display windows or forms on the desktop, enabling a user to perform a task. Client applications include applications such as word processors and spreadsheets, as well as custom business applications such as data-entry tools, reporting tools, and so on. Client applications usually employ windows, menus, buttons, and other GUI elements, and they likely access local resources such as the file system and peripherals such as printers.
    Another kind of client application is the traditional ActiveX control (now replaced by the managed Windows Forms control) deployed over the Internet as a Web page. This application is much like other client applications: it is executed natively, has access to local resources, and includes graphical elements.
    In the past, developers created such applications using C/C++ in conjunction with the Microsoft Foundation Classes (MFC) or with a rapid application development (RAD) environment such as Microsoft® Visual Basic®. The .NET Framework incorporates aspects of these existing products into a single, consistent development environment that drastically simplifies the development of client applications.
    The Windows Forms classes contained in the .NET Framework are designed to be used for GUI development. You can easily create command windows, buttons, menus, toolbars, and other screen elements with the flexibility necessary to accommodate shifting business needs.
    For example, the .NET Framework provides simple properties to adjust visual attributes associated with forms. In some cases the underlying operating system does not support changing these attributes directly, and in these cases the .NET Framework automatically recreates the forms. This is one of many ways in which the .NET Framework integrates the developer interface, making coding simpler and more consistent.
    Unlike ActiveX controls, Windows Forms controls have semi-trusted access to a user’s computer. This means that binary or natively executing code can access some of the resources on the user’s system (such as GUI elements and limited file access) without being able to access or compromise other resources. Because of code access security, many applications that once needed to be installed on a user’s system can now be deployed through the Web. Your applications can implement the features of a local application while being deployed like a Web page.

    16Jan, 2012
    .NET Framework Class Library

    .NET Framework Class Library

    The .NET Framework class library is a collection of reusable types that tightly integrate with the common language runtime (CLR). The class library is object oriented, providing types from which your own managed code can derive functionality. This not only makes the .NET Framework types easy to use, but also reduces the time associated with learning new features of the .NET Framework. In addition, third-party components can integrate seamlessly with classes in the .NET Framework.
    For example, the .NET Framework collection classes implement a set of interfaces that you can use to develop your own collection classes. Your collection classes will blend seamlessly with the classes in the .NET Framework.
    As you would expect from an object-oriented class library, the .NET Framework types enable you to accomplish a range of common programming tasks, including tasks such as string management, data collection, database connectivity, and file access. In addition to these common tasks, the class library includes types that support a variety of specialized development scenarios. For example, you can use the .NET Framework to develop the following types of applications and services:

    • Console applications.
    • Windows GUI applications (Windows Forms).
    • ASP.NET applications.
    • XML Web services.
    • Windows services.

    For example, the Windows Forms classes are a comprehensive set of reusable types that vastly simplify Windows GUI development. If you write an ASP.NET Web Form application, you can use the Web Forms classes (System.Web).

    16Jan, 2012
    The Common Language Runtime

    The Common Language Runtime

    The common language runtime is the core component of the Microsoft .Net Framework and manages memory, thread execution, code execution, code safety verification, compilation, and other system services. These features are intrinsic to the managed code that runs on the common language runtime.
    With regards to security, managed components are awarded varying degrees of trust, depending on a number of factors that include their origin (such as the Internet, enterprise network, or local computer). This means that a managed component might or might not be able to perform file-access operations, registry-access operations, or other sensitive functions, even if it is being used in the same active application.
    The runtime enforces code access security (CAS). For example, users can trust that an executable embedded in a Web page can play an animation on the screen or sing a song, play a WAV or MP3 file but cannot access their personal data, file system, or internal network. The security features of the runtime thus enable legitimate Internet-deployed software to be exceptionally feature rich.
    The runtime also enforces code robustness by implementing a strict type-and-code-verification infrastructure called the common type system (CTS). The CTS ensures that all managed code is self-describing. The various Microsoft and third-party language compilers generate managed code that conforms to the CTS. This means that managed code can consume other managed types and instances, while strictly enforcing type fidelity and type safety.
    In addition, the managed environment of the runtime eliminates many common software issues. For example, the runtime automatically handles object layout and manages references to objects, releasing them when they are no longer being used. This automatic memory management resolves the two most common application errors, memory leaks and invalid memory references.
    The runtime also accelerates developer productivity. For example, programmers can write applications in their development language of choice, yet take full advantage of the runtime, the class library, and components written in other languages by other developers. Any compiler vendor who chooses to target the runtime can do so. Language compilers that target the .NET Framework make the features of the .NET Framework available to existing code written in that language, greatly easing the migration process for existing applications.
    While the runtime is designed for the software of the future, it also supports software of today and yesterday. Interoperability between managed and unmanaged code enables developers to continue to use necessary COM components and DLLs.
    The runtime is designed to enhance performance. Although the common language runtime provides many standard runtime services, managed code is never interpreted. A feature called just-in-time (JIT) compiling enables all managed code to run in the native machine language of the system on which it is executing. Meanwhile, the memory manager removes the possibilities of fragmented memory and increases memory locality-of-reference to further increase performance.
    Finally, the runtime can be hosted by high-performance, server-side applications, such as Microsoft® SQL Server™ and Internet Information Services (IIS). This infrastructure enables you to use managed code to write your business logic, while still enjoying the superior performance of the industry’s best enterprise servers that support runtime hosting.
     

    16Jan, 2012
    The .NET Framework

    The .NET Framework

    The Microsoft .NET Framework is an integral part of the Microsoft Windows Operating System components that supports building and running applications and XML Web services that take advantage of this new technology.
    The .NET Framework is designed to fulfill the following objectives:

    • To provide a consistent object-oriented programming environment where: 1) object code is stored and executed locally, 2) executed locally but Internet-distributed; or, 3) executed remotely.
    • To provide a code-execution environment that minimizes software deployment and versioning conflicts.
    • To provide a code-execution environment that promotes safe execution of code, including code created by an unknown or semi-trusted third party.
    • To provide a code-execution environment that eliminates the performance problems of scripted or interpreted environments.
    • To make the developer experience consistent across widely varying types of applications, such as Windows-based applications and Web-based applications.
    • To build all communication on industry standards to ensure that code based on the .NET Framework can integrate with any other code.

    The .NET Framework has two main components:

    1. The common language runtime; and,
    2. The .NET Framework class library.

    The common language runtime

    The common language runtime is the foundation of the .NET Framework. You can think of the runtime as an agent that manages code at execution time, providing core services such as memory management, thread management, and remoting, while also enforcing strict type safety and other forms of code accuracy that promote security and robustness. In fact, the concept of code management is a fundamental principle of the runtime. Code that targets the runtime is known as managed code, while code that does not target the runtime is known as unmanaged code. More about the Common Language Runtime at: http://www.daprose.com/?p=1267

    The .NET Framework class library

    The class library is the other main component of the .NET Framework, it is a comprehensive object-oriented collection of reusable types that you can use to develop applications ranging from traditional command-line or graphical user interface (GUI) applications to applications based on the latest innovations provided by the ASP.NET technology, such as Web Forms and XML Web services.
    The .NET Framework can be accessed by unmanaged components that load the common language runtime into their processes and initiate the execution of managed code, thereby creating a software environment that can exploit both managed and unmanaged features.

    The .NET Framework Runtime Hosts

    The .NET Framework not only provides several runtime hosts, but also supports the development of third-party runtime hosts. For example, ASP.NET hosts the runtime to provide a scalable, server-side environment for managed code. ASP.NET for example, works directly with the runtime to enable ASP.NET applications and XML Web services.
    The Microsoft Internet Explorer is an example of an unmanaged application that hosts the runtime (in the form of a MIME type extension). Using Internet Explorer to host the runtime enables you to embed managed components or Windows Forms controls in HTML documents. Hosting the runtime in this way makes managed mobile code similar to Microsoft ActiveX controls possible, but with significant improvements that only managed code can offer, such as semi-trusted execution and isolated file storage.
     

    15Nov, 2011
    Cannot join workstation to domain

    When you attempt to join a Windows 2000 domain from a computer running Windows NT 4.0 Workstation or Windows NT 4.0 Server, the following error message may be displayed:
    The machine account for this computer either does not exist or is unavailable.
    If the workstation or server you are attempting to join is a computer running Windows 2000 Professional or Windows 2000 Server, the following error message is displayed:
    Your computer could not be joined to the domain. You have exceeded the maximum number of computer accounts you are allowed to create in this domain. Contact your system administrator to have this limit reset or increased.
    NOTE: This error message only occurs if you have already joined 10 workstations to the domain.
    Windows 2000 grants the “Add workstations to domain” privilege to the Authenticated Users group by default. When this privilege is enabled, authenticated users can bypass the access control list (ACL) check for up to a predefined maximum value. To prevent misuse, the maximum number of machine accounts any authenticated user can join is 10 by default.
    To resolve this problem, use the appropriate method.
    Method 1: Pre-Create the User’s Computer Account

    1. From the Active Directory Users and Computers snap-in, right-click the container where the account resides.
    • Click New, and then click Computer.

     

    • In the Computer name box, type the name of the Windows 2000-based computer that you want to add to the domain.

     
    Make sure the computer’s name is also entered in the Computer name (pre-Windows 2000) box (this should occur automatically).

    • Click Change. Select the user or group that will be joining this computer to the domain, and then click OK.

     

    • If you want Windows NT 4.0 and previous operating systems to use this computer name object, click to select the Allow pre-Windows 2000 computers to use this account check box, and then click OK.

     
     
    Method 2: Grant the “Create Computer Objects” and “Delete Computer Objects” Access Control Entries (ACEs) to the User

    1. From the Active Directory Users and Computers snap-in, click Advanced Features on the View menu so that the Security tab is exposed when you click Properties.
    • Right-click the Computers container, and then click Properties.

     

    • On the Security tab, click Advanced.

     

    • On the Permissions tab, click Authenticated Users, and then click View/Edit.

     
    NOTE: If the Authenticated Users group is not listed, click Add and add it to the list of permission entries.

    • Make sure the This object and all child objects option is displayed in the Apply onto box.

     

    • From the Permissions box, click to select the Allow check box next to the Create Computer Objects and Delete Computer Objects ACEs, and then click OK.

     
     
    Method 3: Override the Default Limit of the Number of Computers an Authenticated User Can Join to a Domain
    You can override the default limit, using either of the following methods:

    • Use the Ldp (Ldp.exe) tool included in the Microsoft Windows 2000 Resource Kit.
    • Use an Active Directory Services Interface (ADSI) script to increase or decrease the value of the Active Directory ms-DS-MachineAccountQuota attribute. To do this:
      1. Install the Windows 2000 Support tools if they have not already been installed. To install these tools, run Setup.exe from the SupportTools folder on the Windows 2000 Server or the Windows 2000 Professional CD-ROM.

       

    • Run Adsiedit.msc as an administrator of the domain.
    • Expand the Domain NC node. This node contains an object that begins with “DC=” and reflects the correct domain name. Right-click this object, and then click Properties.
    • In the Select which properties to view box, click Both.
    • In the Select a property to view box, click ms-DS-MachineAccountQuota.
    • In the Edit Attribute box, type a number. This number represents the number of workstations that you want users to be able to maintain concurrently.
    • Click Set, and then click OK.