What is a process hierarchy?

Now-a-days all general purpose operating systems permit a user to create and destroy processes. A process can create several new processes during its time of execution.

The creating process is called the Parent Process and the new process is called Child Process.

There are different ways for creating a new process. These are as follows −

• Execution − The child process is executed by the parent process concurrently or it waits till all children get terminated.

• Sharing − The parent or child process shares all resources like memory or files or children process shares a subset of parent’s resources or parent and children process share no resource in common.

The reasons that parent process terminates the execution of one of its children are as follows −

• The child process has exceeded its usage of resources that have been allocated. Because of this there should be some mechanism which allows the parent process to inspect the state of its children process.

• The task that is assigned to the child process is no longer required.

Example

Consider a Business process to know about process hierarchy.

Step 1 − Business processes can become very complicated, making it difficult to model a large process with a single graphical model.

Step 2 − It makes no sense to condense an end-to-end mechanism like "order to cash" into a single graphical model that includes "article collection to shopping cart," "purchase order request," "money transfer," "packaging," and "logistics," among other things.

Step 3 − To break down large processes into smaller chunks, you'll need a process hierarchy. The "from abstract to real" theory is followed by a process hierarchy.

Step 4 − This indicates that it includes data on operations at various levels of granularity. As a result, knowledge about the abstract value chain or very basic method steps and their logical order can be obtained.

Step 5 − The levels of a process hierarchy, as well as the details included in these levels, determine the hierarchy.

Step 6 − It is critical to have a given knowledge base at each level; otherwise, process models would not be comparable later.

The model below depicts the process hierarchy model which includes examples for each level – there are six levels in all.