Java- Spring State Machine
What is Spring State Machine?
Never Heard of it. What is it? is it some kind of state management thing Spring Framework does?
Now, What is the Simple State Machine?
Umm... Something related to concepts of the Finite state machine that we have learned in our college days.
Bingo!!
Yes its similar to the finite state machine or we can say that it uses concepts of the Finite State machine.
Now let me put some light on FSM.
What is FSM?
It is an abstract machine that can be in exactly one of a finite number of states at any given time.
According to Wiki: https://en.wikipedia.org/wiki/Finite-state_machine
Stop Guessing, Hold the Nerve,
Its a machine that works on the principle "System will be at in any of the finite no. of states".
The FSM can change from one state to another in response to some external inputs; the change from one state to another is called a transition.
The system will change its state from one state to another on getting any Event.
Example:
A toggle Switch can be in any of the two states either ON or OFF.
It cannot go into any other states as it is defined for these Two states only.
The same Principle goes with Spring State Machine, as Spring State Machine is a framework for application developers to use state machine concepts with Spring applications.
When to use:
A typical Spring state Machine has:
In Spring State Machine you create your application around States, Your system will follow Event-State approach, in which each Event is Linked with Source State and Destination State.
For Example:
If you fire an event named: View
Source State named: Saved_state will change to
Destination State named: Viewing_state
A Quick Glimpse:
1.Actions:
Actions are the ones which really glues state machine state changes with a user’s own code. The state machine can execute an action on various changes and steps in a state machine like entering or exiting a state, or be doing a state transition.
2.Regions
Regions which are also called as orthogonal regions are usually viewed as exclusive-OR operation applied to states. The concept of a region in terms of a state machine is usually a little difficult to understand but things get a little simpler with a simple example.
3.Transitions
A transition is a relationship between a source state and a target state. A switch from a state to another is a state transition caused by a trigger.
4. Hierarchical states
Hierarchical states allow defining some level of abstraction is a sense how java developer would define a class structure with abstract classes.
5.Guard Conditions
Guard conditions are expressions which evaluate either to TRUE or FALSE based on extended state variables and event parameters. Guards are used with actions and transitions to dynamically choose if a particular action or transition should be executed. Aspects of guards, event parameters and extended state variables are simply to make state machine design much more simple.
6.Pseudo States
PseudoState is a special type of state which usually introduces higher level logic into a state machine by either giving a state a special meaning like initial state. The state machine can then internally react to these states by doing various actions available in UML state machine concepts.
So that's how we use Spring State Machine to simplify complex project problems. For More Info related to Spring State Machine check this out:
https://github.com/rahulmehtawd/SpringStateMachine
(This is a simple example to illustrate Spring State Machine using Gradle, SpringBoot, and Redis)
Thanks.
Rahul Mehta
What is Spring State Machine?
Never Heard of it. What is it? is it some kind of state management thing Spring Framework does?
Let's Find out!
Now, What is the Simple State Machine?
Umm... Something related to concepts of the Finite state machine that we have learned in our college days.
Bingo!!
Yes its similar to the finite state machine or we can say that it uses concepts of the Finite State machine.
Now let me put some light on FSM.
What is FSM?
It is an abstract machine that can be in exactly one of a finite number of states at any given time.
According to Wiki: https://en.wikipedia.org/wiki/Finite-state_machine
Stop Guessing, Hold the Nerve,
Its a machine that works on the principle "System will be at in any of the finite no. of states".
The FSM can change from one state to another in response to some external inputs; the change from one state to another is called a transition.
The system will change its state from one state to another on getting any Event.
Example:
A toggle Switch can be in any of the two states either ON or OFF.
It cannot go into any other states as it is defined for these Two states only.
The same Principle goes with Spring State Machine, as Spring State Machine is a framework for application developers to use state machine concepts with Spring applications.
When to use:
- The application or part of its structure can be represented as states.
- You want to split complex logic into smaller manageable tasks.
- The application is already suffering concurrency issues with i.e. something happening asynchronously.
When projects get large and your Business Rules getting complicated day by day and you are very frequent to change the system you can use Spring State machine.
You need your system to take any new requirements without changing much in existing functionality
you can use SSM.
What it does?
It replaces the old-fashioned IF-ELSE ladder with STATE-EVENT architecture. It creates the whole system around States and Events so that you can have concrete point after firing an event which state you left and current state as well.
- Easy to use flat one level state machine for simple use cases.
- Hierarchical state machine structure to ease complex state configuration.
- State machine regions to provide even more complex state configurations.
- Usage of triggers, transitions, guards, and actions.
- Typesafe configuration adapter.
- State machine event listeners.
- Spring IOC integration to associate beans with a state machine.
 |
| Spring State Machine |
A typical Spring state Machine has:
- States
- Pseudo States
- Guard Conditions
- Events
- Transitions
- Actions
- Hierarchical State Machines
- Regions
In Spring State Machine you create your application around States, Your system will follow Event-State approach, in which each Event is Linked with Source State and Destination State.
For Example:
 |
| State Transition |
If you fire an event named: View
Source State named: Saved_state will change to
Destination State named: Viewing_state
A Quick Glimpse:
1.Actions:
Actions are the ones which really glues state machine state changes with a user’s own code. The state machine can execute an action on various changes and steps in a state machine like entering or exiting a state, or be doing a state transition.
2.Regions
Regions which are also called as orthogonal regions are usually viewed as exclusive-OR operation applied to states. The concept of a region in terms of a state machine is usually a little difficult to understand but things get a little simpler with a simple example.
3.Transitions
A transition is a relationship between a source state and a target state. A switch from a state to another is a state transition caused by a trigger.
4. Hierarchical states
Hierarchical states allow defining some level of abstraction is a sense how java developer would define a class structure with abstract classes.
5.Guard Conditions
Guard conditions are expressions which evaluate either to TRUE or FALSE based on extended state variables and event parameters. Guards are used with actions and transitions to dynamically choose if a particular action or transition should be executed. Aspects of guards, event parameters and extended state variables are simply to make state machine design much more simple.
6.Pseudo States
PseudoState is a special type of state which usually introduces higher level logic into a state machine by either giving a state a special meaning like initial state. The state machine can then internally react to these states by doing various actions available in UML state machine concepts.
So that's how we use Spring State Machine to simplify complex project problems. For More Info related to Spring State Machine check this out:
https://github.com/rahulmehtawd/SpringStateMachine
(This is a simple example to illustrate Spring State Machine using Gradle, SpringBoot, and Redis)
Thanks.
Rahul Mehta
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