Difference between Job Scheduling and Job Sequencing.

Difference between Job Scheduling and Job Sequencing

Introduction

According to technopedia.com, Job Scheduling is the process of allocating system resources to many different tasks by an operating system (OS). Britannica.com​  has the same definition as technopedia.com. According to (Dr. John Onunga and Renu Shah 2003) K.I.E books 1 Page 156, Job scheduling involves preparing, scheduling and monitoring jobs for continuous processing by the computer system.

They explain the functions carried out at job scheduling as:

1. Controlling the loading and running of programs
2. Communicating directly with users and/or the operator
3. Dealing with user commands to organise files and run programs

S.Mburu and G.Chemwa (2004) Longhorn book 1 page 83 describe job scheduling as to allocating each job waiting for execution  processor time at each given interval.

Sequencing vs Scheduling

• Job scheduling can only handle one task at a time, therefore, the operating system has to determine which task will be processed first and makes sure that the one that is currently processed is closely monitored to.
• Job sequencing is as a result of the operating system keeping a list of jobs or tasks currently being run and clocks them in and out of the processor.
• Sequencing Is done to order of tasks in a chain
• Scheduling is done When (at what time) a certain task happens.Decides on time.
• Sequencing actually leads to optimization where you decide which order is to be taken first based on algorithm designed for the optimisation considering different constraint for cost and other parameters like capacity,Transportation lanes etc.
• ​Once the sequencing is done then based on scheduling parameters like finite scheduling or infinite schedule the orders are scheduled or executed based on time.

Conclusion

It's now clear to us that job sequencing is all about planning i.e. a list of tasks is laid at the register and arranged in the sequence at which they will be executed, allocated execution time and when to be executed and the method of execution e.g. First Come, First Serve. Job scheduling is a bit different and comes after sequencing has been done, it describes what time a task will be executed to enable other waiting tasks to be stacked in the queue.

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