The Service Application Framework replaces the Shared Services Provider in SharePoint Server 2007. The Service Application Framework model is much more flexible than the Shared Services Provider model. Service applications can be consumed by a single server farm or shared across farms, allowing for centralized sharing of your IT investments. Service Application Framework applications are easily scaled out for load balancing high-demand service applications.
Service developers are now able to focus on the business logic of their applications through the use of the Service Application Framework. The Framework also makes it easy to implement details such as writing code to configure a server that is running IIS, installing a Secure Sockets Layer (SSL) certificate, creating a virtual directory, managing credentials for a pool of application users, managing and caching distributed settings, tracking and load balancing endpoints, and also performing many back-up and restore tasks.
Services can now plug their management user interface (UI) in to the SharePoint Service Management page to provide a common experience for administrators. All services can now benefit from common SharePoint administration tools, such as Upgrade, Backup/Restore, and Account management. Administrators can also use this common UI to manage, start, stop, group, associate, federate, and back up services.
In addition, not only can service developers create their own administrative pages to manage their service, but they can also host these pages by using SharePoint Central Administration. Services can also be configured to have their own additional specialized administrative roles.
Management of Service Application Framework applications can be performed through either the Central Administration UI or Windows PowerShell.
The WCF service model deals with communication between client and service. The SharePoint service model deals with deployment, management, and discovery of services in a server farm. The Service Application Framework is ideal for deploying, managing, and discovering WCF service clients and applications.
SharePoint Service Applications are typically hosted on multiple servers and are invoked from a service client application that is running on a front-end web server. Service Application proxy method invocations must be routed from the front end web server to the appropriate application server by using a load balancing tool.
Normally, SharePoint Foundation administrators tend to configure load balancing solutions for the front-end web servers; it is not normally expected that there will be calls between the front-end web servers and application server to require an additional external load balancer. SharePoint provides a simple round-robin load balancer implementation that is handled in the SPRoundRobinServiceLoadBalancer class, which can be either replaced or enhanced by third-party developers as needed. Service application proxies can use the built-in round-robin load balancer to route requests to the appropriate back-end service application.
The claims-based identity model for SharePoint Foundation is built upon the Windows Identity Foundation (WIF). This new identity model includes features, such as authentication of users across both Windows-based and non–Windows-based systems, multiple authentication types, stronger real-time authentication, a wider set of principal types, and delegation of user identity between applications.
When claims-aware applications are built, the user presents an identity to the application as a set of claims. One claim could be a user’s name and another claim could be the user’s email address; the idea being that an external identity system is set up to give the application all of the information it needs to know about the user.