What is ile in as400

Whenever you call one program from another using the CALL operation, you are dynamically binding those programs. This type of binding is static, in that the objects are bound together and the relationship between those bound objects remains consistent. Procedures also known as subprocedures are the smallest component of static binding. Create and use the service program Bind by reference. It is the best overall performer in this case, because the code is copied right into the program at compile time.

In that case it is better to go for bind by reference. The reason is that it is slower to call a main program that refer to a service program. Subroutines have their limitations, two of which are:. That is, any variable or constant or indicator that I use in a subroutine may be used anywhere else in the program--in the main calculations, in any subroutine, in output specs.

This can lead to undesirable side effects. I have never had to worry about the performance of subprocedures, but in a heavily used program, performance may become an issue. Using subroutines instead of subprocedures may make a difference.

Static binding is much faster at run time than dynamic binding. Dynamic binding may not be the best term to describe a dynamic program call; it's used here as a contrast between the OPM program call model and the ILE procedure call model. Need to amplify this; maybe in the bind by reference and bind by copy sections above.

What is binding? Start by thinking of it as parameter binding. Since OPM parms are passed by reference, that means that the called program needs to know the addresses that the caller uses to store the parm values.

In essence, the called program modifies memory within the calling program's address space. It is more than just parameters Like maybe the addresses of the procedures themselves I don't know this for certain, but it seems logical to me that this would be the way you'd want to do it.

Most parameters in ILE are also passed by reference. Unless the "value" keyword is used Essentially all this entails is passing a pointer to the variable for the parameter -- to the called program. The called program then puts its variable in the same area of memory, which means that anything that's changed is changed for both programs. When called by value, the programs each have different areas of memory for their variables, but the byte values are copied from the caller's area of memory to the called's area.

In my current understanding, binding is the act of finding all of the procedures that are called except for dynamic calls, of course and putting either a copy of the called module into the program i. What is the difference between a dynamic program call and a static procedure call? With dynamic binding, the "connection" between the two programs happens at the moment the CALL operation is executed.

Between finding the program in the library list, verifying authority, opening the files and initialising the variables, this can be a long process several tenths of seconds. With static binding, almost all of the work aside from variable initialisation and file opens takes place at compile time.

This makes a static call fast. There is one other type of procedure call; calling a procedure in a service program. The difference is that the calling program does not know where the procedure code is until run time.

When the program is executed, the system performs a process called activation, when it goes out and finds the service programs conntaing the procedures your program calls.

This process of activating a service program happens once during a particular job see activation group , and is similar to the amount of time the system takes to walk the library list looking for a program the first time it is called dynamically. This text wants some cleanup. What difference does it make to the programmer? Service programs are very much like a library of commonly used procedures. If you don't currently program with many CALLs, you'll need to get used to the idea of local variables, and accessing them via parameters.

What is the advantage of static binding? We can finally break up our large programs into smaller, easier to read and maintain units without a performance penalty. What is the disadvantage of static binding? When you create a module, which is bound into many different program objects, it can become difficult to maintain, because when you make changes to it, you have to re-create all of the programs that use that module. You also need to determine which modules are used by a program every time you compile it which can make it difficult when you need to recompile things "en-masse".

This is bind by copy. Is there a happy medium between the speed of bound modules and the ease of maintenance of dynamic calls? Yes, Service Programs. Instead of writing reusable code as modules and then binding those modules to create programs, you can instead bind your reusable code into a service program. Then, when you create programs, you bind to that service program. The service program is a separate object on disk, and therefore, is a bit slower than a bound call -- but you can change a service program without having to recompile all the programs its bound to, as you would with a module.

This is bind by reference. What is binder language?