Each Relational Database Management System (RDBMS) exposes an Application Programming Interface (API) that developers can use to interoperate with the database.
OLE DB, ODBC, DB-LIB, JDBC, and SQLNCLI are all examples of data access providers. A data access provider encapsulates the complex logic implemented by the API for an RDBMS. A data access provider also exposes a common interface that allows application developers to write data access logic once and be able to interoperate with multiple RDBMSs. The fact is that, to be able to talk to a specific RDBMS, application development platforms require support from a data access provider.
With HTTP Endpoints, SQL Server 2005 provides an alternative to using a data access provider.
Since HTTP Endpoints are managed by the database administrator, he or she can carefully choose which stored procedures and user-defined functions to make available through the Endpoints, but any development platform can then connect and call those HTTP Endpoints.
The only requirement for an application to connect to an HTTP EndPoint is that the application be able to communicate through the HTTP communication protocol and that it be able to send requests conforming to the specific XML/SOAP format required by SQL Server 2005.
Programming platforms and languages with poor support for OLE DB or ODBC data access providers can take advantage of communicating with SQL Server 2005 through HTTP Endpoints.
Some examples of such platforms, languages, and new scenarios that HTTP Endpoints enable are: