Application Server Role

Application Server is an expanded server role in the Windows Server® 2008 operating system. The new version of Application Server provides an integrated environment for deploying and running custom, server-based business applications. These applications respond to requests that arrive over the network from remote client computers or from other applications. Typically, applications that are deployed and run on Application Server take advantage of one or more of the following:
• Internet Information Services (IIS) (the Hypertext Transfer Protocol (HTTP) server that is built into Windows Server)
• Microsoft® .NET Framework versions 3.0 and 2.0. (If you have applications that are built with the .NET Framework 3.5, you can download and install the .NET Framework 3.5 onto the operating system.)
• COM+
• Message Queuing
• Web services that are built with Windows Communication Foundation (WCF)
We recommend that you use the Application Server role when Windows Server 2008 runs applications that depend on role services or features that are part of the integrated Application Server role and that you select during the installation process. An example might be a specific configuration of Microsoft BizTalk® Server that uses a set of role services or features that are part of the Application Server environment.
Typically, the Application Server role is recommended when you are deploying a business application that was developed within your organization (or developed by an independent software vendor (ISV) for your organization) and when the developer has indicated that specific role services are required. For example, your organization may have an order-processing application that accesses customer records that are stored in a database. The application accesses the customer information through a set of WCF Web services. In this case, you can configure one Windows Server 2008 computer as an application server, and you can install the database on the same computer or on a different computer.
Not every server application benefits from the installation of the Application Server role. For example, the Application Server role is not necessary to support Microsoft Exchange Server or Microsoft SQL Server on Windows Server 2008.
To determine if the Application Server role is useful for running your organization’s business applications, have your administrators work closely with the application’s developers to understand the requirements of the application, for example, whether it uses the .NET Framework 3.0 or COM+ components.
What does Application Server do?
Application Server provides the following:
• A runtime that supports effective deployment and management of high-performance server-based business applications. These applications are able to service requests from remote client systems, including Web browsers connecting from the public Internet or from a corporate network or intranet, and remote computer systems that may send requests as messages.
• The .NET Framework 3.0, which provides developers with a simplified programming model for connected server applications. Developers can use the built-in .NET Framework libraries for many application functions, including input/output (I/O), numerical and text processing, database access, XML processing, transaction control, workflow, and Web services. For system administrators, the .NET Framework provides a secure and high-performance execution runtime for server-based applications, as well as a simplified application configuration and deployment environment.
• Windows Server 2008 installation by means of a new, user-friendly Add Roles Wizard that helps you choose the role services and features that are necessary to run your applications. The Add Roles Wizard automatically installs all features that are necessary for a given role service and makes it easier for you to set up and provision a computer as an application server for your business applications.
Who will be interested in this role?
This information about the Application Server role is primarily for information technology (IT) professionals who are responsible for deploying and maintaining an organization’s line-of-business (LOB) applications. LOB applications are typically developed in your organization or for your organization.
An application server environment consists of one or more servers running Windows Server 2008 that are configured with the Application Server role. This includes servers that do the following:
• Host applications that are built with the .NET Framework 3.0
• Host applications that are built to use COM+, Message Queuing, Web services, and distributed transactions
• Connect to an intranet or to the Internet to exchange information
• Host applications that expose or consume Web services
• Host applications that expose Web pages
• Interoperate with other remote systems running on disparate platforms and operating systems
An extended Application Server environment can also include the following:
• Domain-joined client computers and their users
• Computers that are used primarily for management of the application servers
• Infrastructure servers that run resources, such as Active Directory Domain Services (AD DS) or other Lightweight Directory Access Protocol (LDAP) repositories, Certificate Services, security gateways, process servers, integration servers, application or data gateways, or databases
What new functionality does this role provide?
The new, expanded version of the Application Server role is installed through the Add Roles Wizard in Server Manager. Administrators who have LOB applications that are built with the .NET Framework 3.0 may discover that setting up a hosting environment for these applications is simpler with this server role. The Add Roles Wizard guides the administrator through the process of selecting the role services or supporting features that are available in this role and may be necessary to run specific LOB applications.
Application Server Foundation
Application Server Foundation is the group of technologies that are installed by default when you install the Application Server role. Essentially, Application Server Foundation is the .NET Framework 3.0. (If you have applications that are built with the .NET Framework 3.5, you can download and install the .NET Framework 3.5 onto the operating system.)
Windows Server 2008 includes the .NET Framework 2.0, regardless of any server role that is installed. The .NET Framework 2.0 contains the Common Language Runtime (CLR), which provides a code-execution environment that promotes safe execution of code, simplified code deployment, and support for interoperability of multiple languages, as well as extensive libraries for building applications.
The key components of Application Server Foundation are installed as a set of code libraries and .NET assemblies. The following are the key components of Application Server Foundation:
• Windows Communication Foundation (WCF)
• Windows Workflow Foundation (WF)
• Windows Presentation Foundation (WPF)
WCF is the Microsoft unified programming model for building connected applications that use Web services to communicate with each other. These applications are also known as service-oriented applications (SOA), and they are becoming increasingly more important for business. Developers can use WCF to build SOA applications that employ secure, reliable, transacted Web services that communicate across platforms and interoperate with existing systems and applications in your organization.
WCF enables developers to compose or combine the various technologies that are available today for building distributed applications (COM+ and .NET Enterprise services, Message Queuing, .NET Remoting, ASP.NET Web Services, and Web Services Enhancements (WSE)) in ways that make sense for your organization’s business needs and computing environment.
WF is the programming model and engine for building workflow-enabled applications quickly on Windows Server 2008. A workflow is a set of activities that describe a real-world process, such as an order-purchasing process. A workflow is commonly described and viewed graphically—something like a flowchart. The description of the workflow is often called “the model.” Work items pass through the workflow model from start to finish.
Work items or activities within the model can be executed by people or by systems or computers. While it is possible to describe a workflow in traditional programming languages as a series of steps and conditions, for more complex workflows or workflows that support simpler revisions, designing the workflow graphically and storing that design as a model is typically much more appropriate and flexible.
WF supports system workflow and human workflow across a variety of scenarios, including the following:
• Workflow in LOB applications
• The sequential flow of screens, pages, and dialog boxes as presented to the user in response to the user’s interaction with the user interface (UI)
• Document-centric workflow, for example, the processing of a purchase order or a medical record
• Human workflow interaction, such as sending e-mail to a business client and receiving e-mail from the client
• Composite workflow for SOA
• Business-rule-driven workflow, for example: “On a Monday at 17:00, send an update catalogue request to business partners.”
• Workflow for systems management
What works differently?
Although there is an Application Server role in Windows Server 2003, the new, expanded Application Server role that is available in Windows Server 2008 is not simply an upgrade from the application server configuration tool that is included in Windows Server 2003 or an earlier operating system. Because the role functionality is completely new, administrators should be aware that there is no migration path for the Application Server configuration tool from Windows Server 2003 or earlier operating systems.
How do I resolve these issues?
If you upgrade your server to Windows Server 2008 from Windows Server 2003 or an earlier operating system, and you want to use the capabilities of the Application Server role, you must reinstall the Application Server role by using the Add Roles Wizard in Server Manager. As long as you configure Windows Server 2008 with the correct application services by using the Add Roles Wizard in Server Manager, you can easily move your applications from Windows Server 2003 to Windows Server 2008.
When should I use the Application Server role?
If the server-based LOB applications that you need to deploy and manage require one or more of the following technologies: Microsoft .NET Framework 3.0, Message Queuing, COM+, or distributed transactions, consider configuring your server in the Application Server role.

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**Article reprint with permission**