State machine definitions

Point of Smalldb is to make application logic easier to specify. This means it must be easy to define state machines. There are three ways of defining a state machine:

1. PHP Class inherited from Smalldb::StateMachine::AbstractMachine.
2. JSON file
3. JSON file + GraphML file (obsolete)

Since transition implementations require some PHP code anyway, there is no way to remove assigned PHP class completely (at least not for now). However, in common case it is not practical to define state machine in PHP code. Easier way is to use graphical editors like yEd to create GraphML file describing the state machine.

To make state machine diagram easy to create using existing tools, it is possible to "include" a GraphML file into JSON file. The GraphML file is parsed and converted into internal structure which is equivalent to the structure of the JSON file, then both files are merged together. If some option is defined in both files, value from JSON file is used, so it is easy to overcome imperfections of used editor.

See also

Examples of state machine definitions are in the doc/examples/statemachine/ directory.

State Machine Options

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State Options

label : Human readable name of the state.

color : Color of the state in diagrams.

group : Group to which state belongs. Used only in diagrams.

Action and Transition Options

label : Human readable name of the transition.

color : Color of the arrow and its label in diagrams.

weight : Weight of arrow in diagrams. Heavier arrows should be shorter.

pre_check_methods : List of method names executed just before transition invocation. If : exception is thrown or false returned, the transition will not be : invoked. Arguments: ref, transition name, args.

post_transition_methods : List of method names invoked after successful transition. : Arguments: ref, transition name, args, return value.

Properties Options

Properties options are passed with no processing to DUF and other related libraries which uses such metadata. State machine itself does not use most of the properties.

is_pk : These properties are used as primary key (FlupdoMachine).

column_encoding : Property is encoded/decoded to/from specified format before it is : stored in/loaded from database (FlupdoMachine).