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
pre			Flow pre handler	string or object type
	createExp		EL creating pre handler	the return type should be FlowPreHandler type
nodes			Node list	array type
	id		Node ID	Unique in flow
	name		Node name
	start		start node flag	boolean type
	properties		node properties	object type
	pre		node pre handler
		createExp	EL creating pre handler	the return type should by NodePreHandler type
		exp	EL to execute
	type		pre handler type	multiCheck/inclusiveCheck
	preNodes		pre nodes list
	action		Node action	string or object type
		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
		createExp	EL creating post handler	the return type should be NodePostHanlder type
		exp	EL to execute
		other config	see description bellow about post
post			Flow post handler	string or object type
	createExp		EL creating post handler	the return type should be FlowPostHandler type
listeners			Listener list
	createExp		Create expression of listener
filters			Filter list
nodeFilters			Node filter list
nodePreHandlerFilters			Node PreHandler filter list
nodeActionFilters			Node action filter list
nodePostHandlerFilters			Node PostHandler filter list
flowPreHandlerFilters			Flow PostHandler filter list
flowPostHandlerFilters			Flow PostHandler filter list
runner			Flow runner	Default is single thread executor
properties			Flow properties
parseListeners			Flow parse listener list
logFlag			true/false, log flag

'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.