The sheduler within Integration Server is sufficient for many things. For more robust scheduling, one will want to consider something like AutoSys Job Management or Maestor Job Scheduler.
These are far more sophisticated that the IS scheduler in that they can run missed jobs (e.g. say you have a job scheduled for 12pm but the IS happened to be down at that time–the 12pm task will not be run); they can manage job dependencies (e.g. job 2 runs only after job 1 is finished); and they provide better tracking.
How these schedulers invoke services on IS varies based on the scheduler and on how you want the scheduler and IS to interface. One approach is to use the http post capabilities of the scheduler to invoke a service on IS. You’ll want to define an interface so that the scheduler can detect success and failure of the service.
#Integration-Server-and-ESB#webMethods#Flow-and-Java-services