{"id":7635,"date":"2022-02-21T04:05:08","date_gmt":"2022-02-21T04:05:08","guid":{"rendered":"http:\/\/fastbitlab.com\/?p=7635"},"modified":"2023-10-12T16:48:40","modified_gmt":"2023-10-12T11:18:40","slug":"hierarchical-state-machineshsms-hsms","status":"publish","type":"post","link":"https:\/\/fastbitlab.com\/blog\/hierarchical-state-machineshsms-hsms\/","title":{"rendered":"FSM Lecture 45- Hierarchical State Machines(HSMs)"},"content":{"rendered":"
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Hierarchical State Machines(HSMs)<\/strong><\/span><\/h1>\n
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This article teaches about HSMs, which stands for Hierarchical state machines.<\/span><\/p>\n

In the previous article, we used the Flat state machine(FSM) approach for our project. A flat state machine means there were no composite states. You don\u2019t see any state embedded within another state. The state machine diagram had a couple of states interconnected by a couple of arrows here. So those are nothing but the external transition, and the state machine diagram looks messy, as shown in Figure 1. <\/span><\/p>\n

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Figure 1. State machine diagram<\/span><\/figcaption><\/figure>\n

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For this exercise, there were just five states. So, it was quite manageable. But when you want to introduce more features to your application, you could be introducing more states. And when you introduce more states, obviously there will be many transitions among the states, more Guard conditions, so drawing your state machine gets complicated. <\/span><\/p>\n

When the complexity of the state machine diagram increases, it becomes too tedious to maintain, visualize, and troubleshoot. That’s why it would be better to explore what are hierarchical state machines used to tackle this problem. <\/span><\/p>\n

HSMs will greatly reduce the complexity introduced by the Flat state machine approach.<\/span> <\/span><\/span><\/p>\n

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Disadvantages of using a Flat state machine<\/span><\/span><\/p>\n