External routines enable the communication between the Oracle database and the programs, which are written in non-database language such as C, C++, Java, or COBOL. The fact is not new that Oracle has emerged as a compatible database manager for application clients. But from the programming and development perspective, every language has its own special features and utilities. Before UTL_MAIL and UTL_SMTP came to the rescue, there was no option for sending an e-mail in Oracle. In some situations, a special logic written on the client side is required to be used on the server side too. The idea is to resolve the situations where a non-PL/SQL program has to be invoked from PL/SQL. To confront such situations, Oracle introduced external routines in its eighth release (Oracle 8) to bridge the gap between the database and non-PL/SQL programs. This chapter covers the external procedures and its implementation in the following topics:
Understanding external...