workflow之sdk-java

一、workflow是什么？

workflow是为了完成一些预定的目的，根据一组规则，而制定的一系列步骤。对于一个开发者来说，workflow则是将复杂的业务规则以及控制流程以图形化的方法声明出来，组成一个高度可视化的图形环境。（来自百度百科 https://blog.csdn.net/scwulian/article/details/20543049）

二、sdk-java

https://github.com/serverlessworkflow/sdk-java

build projects:

To build project and run tests locally:

git clone https://github.com/serverlessworkflow/sdk-java.git
mvn clean install

Maven projects:

a) Add the following repository to your pom.xml section:repositories

    oss.sonatype.org-snapshot
    http://oss.sonatype.org/content/repositories/snapshots
    
        false
    
    
        true
    

b) Add the following dependencies to your pom.xml section:dependencies

    io.serverlessworkflow
    serverlessworkflow-api
    5.0.0-SNAPSHOT



    io.serverlessworkflow
    serverlessworkflow-spi
    5.0.0-SNAPSHOT



    io.serverlessworkflow
    serverlessworkflow-validation
    5.0.0-SNAPSHOT



    io.serverlessworkflow
    serverlessworkflow-diagram
    5.0.0-SNAPSHOT



    io.serverlessworkflow
    serverlessworkflow-util
    5.0.0-SNAPSHOT

这里使用的是5.0的依赖，所以JDK要11及以上

三、How to Use

You can create a Workflow instance from JSON/YAML source:

Let's say you have a simple YAML based workflow definition:

我们准备一个yaml文件, test.yaml, 放到resources目录下

id: greeting
version: '1.0'
name: Greeting Workflow
start: Greet
description: Greet Someone
functions:
  - name: greetingFunction
    operation: file://myapis/greetingapis.json#greeting
states:
- name: Greet
  type: operation
  actions:
  - functionRef:
      refName: greetingFunction
      arguments:
        name: "${ .greet.name }"
    actionDataFilter:
      results: "${ .payload.greeting }"
  stateDataFilter:
    output: "${ .greeting }"
  end: true

准备个 WorkFlowerTest.java

package com.liufei.demo;

import io.serverlessworkflow.api.Workflow;
import io.serverlessworkflow.api.interfaces.State;
import io.serverlessworkflow.api.interfaces.WorkflowDiagram;
import io.serverlessworkflow.diagram.WorkflowDiagramImpl;
import io.serverlessworkflow.utils.WorkflowUtils;
import org.junit.jupiter.api.Test;
import org.springframework.core.io.ClassPathResource;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;

public class WorkFlowerTest {


    @Test
    public void test() throws IOException {
        ClassPathResource classPathResource = new ClassPathResource("test.yaml");
        InputStream inputStream = classPathResource.getInputStream();
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
        String source = readFileAsString(inputStreamReader);
        try {
            Workflow workflow = Workflow.fromSource(source);
            WorkflowDiagram workflowDiagram = new WorkflowDiagramImpl();
            workflowDiagram.setWorkflow(workflow).showLegend(true);

            String diagramSVG = workflowDiagram.getSvgDiagram();
            System.out.println("结果：" + diagramSVG);

            State startingState = WorkflowUtils.getStartingState(workflow);
            System.out.println("状态：" + startingState.getName());

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public String readFileAsString(Reader reader) {
        try {
            StringBuilder fileData = new StringBuilder(1000);
            char[] buf = new char[1024];
            int numRead;
            while ((numRead = reader.read(buf)) != -1) {
                String readData = String.valueOf(buf, 0, numRead);
                fileData.append(readData);
                buf = new char[1024];
            }
            reader.close();
            return fileData.toString();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

结果返回的是个svg文件的内容：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

我们创建一个test.svg文件，然后将内容copy过去，使用浏览器打开

这个意思是说电脑上没有安装 Graphviz。所以生成的svg文件内容不完整。

手动安装下:
https://graphviz.org/download/

安装完成之后，打开cmd开下版本：dot -version

然后再重新运行下上面的java程序。重新生成svg内容

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

可以看到一个流程图就出来了。

四、其他语言

https://github.com/serverlessworkflow/specification

五：相关资料

PlantUML简述： https://plantuml.com/zh/