The login (if any) associated with a session determines how the EclipseLink runtime connects to the project's data source.
A login includes details of data source access, such as authentication, use of connection pools, and use of external transaction controllers. A
Login owns a data source platform.
A data source platform includes options specific to a particular data source including binding, use of native SQL, use of batch writing, and sequencing.
For projects that do not persist to a data source, a login is not required. For projects that do persist to a data source, a login is always required.
You can use a login in a variety of roles. A login's role determines where and how you create it. The login role you choose depends on the type of project you are creating and how you intend to use the login.
There is a session login type for each project type that persists to a data source.
Note that there is no XML login. EclipseLink XML projects are used for nonpersistent, in-memory object to XML data transformation and consequently there is no data source to log in to.
If you are creating a project that accesses a relational database, you must configure the project with a
DatabaseLogin. Your choice of
DatabasePlatform further customizes your project for a particular type of database.