Reach host DB2 through CoreIQ, on z/OS and on IBM i

A converted program's embedded SQL can now run against real host DB2 through OL CoreIQ, without a JDBC driver or a direct route to the database. Both DB2 for z/OS and DB2 for i are reachable: the engine follows the endpoint the connection points at, so an IBM i host is configured exactly like a mainframe one.

CoreIQ opens a connection per statement, which changes what the program needs to be told. The application's schema is carried into every statement rather than set once for the session, because a SET CURRENT SCHEMA cannot survive a connection that closes — without it, DB2 resolves an unqualified table against the mainframe user id and answers SQLCODE -204. Host variables travel with each statement, and only real table names are qualified, never text that merely looks like one inside a string literal.

Testing a connection asks the endpoint for its schema list rather than running a statement against it, so a connection can be proved before any program uses it, and the check covers the URL, the credentials, the host and the engine together. Because each statement commits as it runs, a play session against CoreIQ writes to the real database and a program's rollback cannot undo it.