Flow engine usage

Integration description

There are quickstart test cases in test folder of sources. You can run or debug to learn the usage and principle.

Basic

See https://github.com/jd-opensource/jd-easyflow/blob/master/README.md

Spring

Inject FlowEngine and use as normal bean. Demo are as follows:

    @Bean
    public FlowEngine flowEngine() {
        FlowEngineImpl flowEngineImpl = new FlowEngineImpl();
        flowEngineImpl.setFlowPath("classpath*:flow/**/*.json");
        return flowEngineImpl;
    }

Invoke demo:

    @Autowired
    private FlowEngine flowEngine;

// java code...

    FlowParam param = new FlowParam(flowId, startNodeId, bizData);
    FlowResult result = flowEngine.execute(param);

Flow definition description

Overall description

First level	Second level	Third level	Name	Description
id			Flow ID	Global unique
name			Flow name
nodes			Node list
	id		Node ID	Unique in flow
	name		Node name
	action		Node action
		exp	Spel expression to execute
		createExp	Spel expression of creating NodeAction	return value should be NodeAction type
		flow	Subflow definition
		flowId	Subflow id
		startNodeId	Start node(s) of subflow
	post		Node post handler
listeners			Listener list
	createExp		Create expression of listener
filters			Filter list
nodePreHandlerFilters			Node PreHandler filter list
nodeFilters			Node filter list
nodePostHandlerFilters			Node PostHandler filter list
nodeActionFilters			Node action filter list
runner			Flow runner	Default is single thread executor
properties			Flow properties

'post' configuration

'post' has several configuration types as follows：

A、Fixed

1、{"to":XXX}，to XXX node

B、Conditional

2、{"when":XXX, "to":XXX}

3、{"conditions":[{"when":XXX, "to":XXX},{"when":XXX, "to":XXX}]}

'when' is expression lanaguage

'conditionType' is optional: exclusive/inclusive，default is exclusive.

'defaultTo' is also optional.

C、Create expression.

4、{"createExp":XXX}，execute when flow parsing. The result should be an implementation of NodePostHandler.

D、Expression

5、{"exp":XXX}，execute when flow running

'to' configuration

String:If it starts with '$', it is an index: $first, $last, $previous or $next, or else it is a fix node id. Integer: Node index List:String list or Integer list Map: "exp":"XXX"

You can see configuration example in test folder.

SPEL expression variables.

Varialbles when flow running

Name	Type	Description
context	FlowContext	Flow context
param	FlowParam	Flow param
bizParam	depend on invoker	param in FlowParam
paramData	Map	dataMap in FlowParam
result	FlowResult	Flow result
bizResult	depend on invoker	result in FlowResult
nodeContext	NodeContext	node context
actionResult	depend on implementation	Return value of NodeAction

Other

Usage of filter and listener

Filer and listener all are pointcut control manner.

Exception process

By default, Flow engine don't catch or wrap exception, it throws original exception of business code.

Key naming conversion.

All keys of flow engine have no ':", The customize keys can start with 'XXX:' or ':'. 'XXX' is namespace.