Chapter 27. External Procedures




An external procedure is an operating system file or program that can be called from within Oracle.



External procedures can be called anywhere a native PL/SQL procedure or function is called. The external procedure has a “wrapper” PL/SQL unit around it that calls the proper OS code. It can be used in situations where the programmer has implemented a program in a language other than PL/SQL but wishes to call it from within PL/SQL.



The statements are:

  1. False. Interprocess communication using external procedures requires much less complexity than using database pipes. With pipes, the programmer must set up a listener process that picks the messages off the pipe and acts on them. With external procedures, the program is executed directly on behalf of the user.

  2. False. With external procedures, communication is bidirectional. The programmer can pass information to an external procedure, and the external program can pass information back.

  3. True. With the appropriate pragmas (assuming that the PL/SQL wrapper is inside a package), calls to external procedures can be used anywhere PL/SQL stored functions can be used—for example, in SQL statements, in assignments, etc.

  4. True. The most common and well-supported language for external procedures is C (mostly because this is what Oracle is written in). The code for an external procedure can be written in any language that can be compiled into a C-callable format.

  5. False. External procedures ...

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