SharePoint Solutions

Solution packages are the preferred mechanism for deploying WSS components. The solution package itself is a compressed CAB file with a .wsp extension, and it contains one or more WSS components along with any dependent files that need to be deployed on each front-end Web server.

A simple solution package might contain just the files needed to deploy a single feature. A more complex package could contain the files for multiple features, applications pages, Web Parts, list definitions, event handlers, and a site definition.

The WSS runtime provides a built-in installer component that runs on each front-end Web server and is responsible for uncompressing the files inside a solution package and properly installing its components. The WSS installer requires each solution package to carry additional metadata inside a file named manifest.xml. When the installer is called upon to deploy a solution package, it reads the metadata in manifest.xml to determine exactly which components and files from inside the CAB file need to be extracted and deployed.

Manifest.xml contains metadata to instruct the installer which files need to be extracted from the solution packages and copied into various WSS system directories. But beyond that, manifest.xml also carries metadata that tells the installer to perform other important deployment procedures, such as registering features with the WSS runtime, adding assembly DLLs to the Global Assembly Cache (GAC), and updating the web.config file with SafeControl entries required in Web Part deployment.