AIX

Hi,

I want to know the Difference between services and process...
is services having many processes

A "process" is one (or several, see below) string(s) of executable (processor-)instructions with its own environment. This environment is called "process-environment" and consists of memory segments, contents of environment variables, an entry in the process table and maybe other kernel tables and so on.

Notice the difference to the similar "thread", which is also one such string of executable instructions, but without an environment of its own. One or several threads combine to make for a process. How many such threads comprise a process is a matter of how the underlying program is written.

Also notice, that "process" means a single instance of a program. A "program" (a file containing executable instructions) can be started several times. Each time a separate process is created which just happens to contain the same instructions as the other (so-called) "instances" (=processes) of the program.

Processes may or may not constitute "services". A "service" is a process which carries out a specific task and is reachable via a certain network port address. For instance, the "telnet" service, which is a process (telnetd) listening to a certain port (usually 23) for incoming requests. Another example would be the listener of an Oracle database, which propagates the "Oracle service" a system can offer to the world.

Such services can be single-threaded or multi-threaded processes, but what makes them services is their function, not the way they are programmed.

I hope this helps.

bakunin