With SOAP Web services, you can create higher-level APIs of your own directly in the Force.com platform and invoke them from your own programs outside of Force. Your custom SOAP services can bundle a series of related queries or updates into a single call, providing an atomic unit of work and reducing network traffic and API call consumption.
Custom SOAP services run with administrative rights by default, granting your Apex code access to all data in the organization.
One way to understand the value of Apex SOAP Web services is to first examine limitations in the Enterprise API. The Enterprise API is a direct representation of the objects in your database as SOAP message types, with methods to ...