How to Visualize Activiti Workflow Progress in Real-Time with Spring Boot

This article demonstrates how to view the current workflow progress in real time by extending a previous tutorial on integrating the Activiti workflow engine with Spring Boot.

Adding methods to HolidayService

<code>/**
 * Query historic process instance
 * @param instanceId Instance ID
 * @return HistoricProcessInstance
 */
public HistoricProcessInstance queryHistory(String instanceId) {
    return historyService.createHistoricProcessInstanceQuery()
                         .processInstanceId(instanceId)
                         .singleResult();
}

/**
 * Get historic activity instance query by instance ID
 * @param instanceId Instance ID
 * @return HistoricActivityInstanceQuery
 */
public HistoricActivityInstanceQuery getHistoryActivity(String instanceId) {
    return historyService.createHistoricActivityInstanceQuery()
                         .processInstanceId(instanceId);
}
</code>

Configure process diagram generator bean

<code>@Configuration
public class ActivitiConfig {

    @Bean
    @ConditionalOnMissingBean
    public ProcessDiagramGenerator processDiagramGenerator() {
        return new DefaultProcessDiagramGenerator();
    }
}
</code>

Utility to obtain highlighted flows

<code>public class ActivitiUtils {

    /**
     * Get highlighted flows (lines) that have been traversed
     */
    public static List<String> getHighLightedFlows(BpmnModel bpmnModel,
                                                   ProcessDefinitionEntity processDefinitionEntity,
                                                   List<HistoricActivityInstance> historicActivityInstances) {
        List<String> highFlows = new ArrayList<>();
        if (historicActivityInstances == null || historicActivityInstances.isEmpty()) {
            return highFlows;
        }
        // ... (logic omitted for brevity)
        return highFlows;
    }

    private static FlowNode getNextFlowNode(BpmnModel bpmnModel,
                                            List<HistoricActivityInstance> historicActivityInstances,
                                            int i,
                                            HistoricActivityInstance activityImpl_) {
        // ... (logic omitted for brevity)
    }
}
</code>

Controller for displaying the process diagram

<code>@RestController
@RequestMapping("/view")
public class ProcessViewController {

    private static Logger logger = LoggerFactory.getLogger(ProcessViewController.class);

    @Resource
    private HolidayService holidayService;
    @Resource
    private RepositoryService repositoryService;
    @Resource
    private ProcessDiagramGenerator processDiagramGenerator;

    @ResponseBody
    @GetMapping("/image")
    public void showImg(String instanceId, HttpServletResponse response) throws Exception {
        response.setContentType("text/html;charset=utf-8");
        if (StringUtils.isEmpty(instanceId)) {
            response.getWriter().write("error");
            return;
        }
        HistoricProcessInstance processInstance = holidayService.queryHistory(instanceId);
        if (processInstance == null) {
            logger.error("Process instance ID:{} not found!", instanceId);
            response.getWriter().write("error instance not exists");
            return;
        }
        BpmnModel bpmnModel = repositoryService.getBpmnModel(processInstance.getProcessDefinitionId());
        HistoricActivityInstanceQuery historyInstanceQuery = holidayService.getHistoryActivity(instanceId);
        List<HistoricActivityInstance> historicActivityInstanceList = historyInstanceQuery
                .orderByHistoricActivityInstanceStartTime().asc().list();
        if (historicActivityInstanceList == null || historicActivityInstanceList.isEmpty()) {
            logger.error("Process instance ID: {}, no historic nodes!", instanceId);
            outputImg(response, bpmnModel, null, null);
            return;
        }
        List<String> executedActivityIdList = historicActivityInstanceList.stream()
                .map(item -> item.getActivityId())
                .collect(Collectors.toList());
        ProcessDefinitionEntity processDefinition = (ProcessDefinitionEntity) ((RepositoryServiceImpl) repositoryService)
                .getDeployedProcessDefinition(processInstance.getProcessDefinitionId());
        List<String> flowIds = ActivitiUtils.getHighLightedFlows(bpmnModel, processDefinition, historicActivityInstanceList);
        outputImg(response, bpmnModel, flowIds, executedActivityIdList);
    }

    private void outputImg(HttpServletResponse response, BpmnModel bpmnModel,
                           List<String> flowIds, List<String> executedActivityIdList) {
        InputStream imageStream = null;
        try {
            imageStream = processDiagramGenerator.generateDiagram(bpmnModel,
                    executedActivityIdList, flowIds, "宋体", "微软雅黑", "黑体", true, "png");
            byte[] buffer = new byte[10 * 1024];
            int len;
            while ((len = imageStream.read(buffer)) != -1) {
                response.getOutputStream().write(buffer, 0, len);
            }
            response.getOutputStream().flush();
        } catch (Exception e) {
            logger.error("Process diagram output error!", e);
        } finally {
            if (imageStream != null) {
                try { imageStream.close(); } catch (IOException e) { e.printStackTrace(); }
            }
        }
    }
}
</code>

Testing steps

Start a new holiday process: /holidays/start?processDefinitionId=holiday:1:...&userId=10000

List tasks for the user to obtain the instance ID: /holidays/tasks?userId=10000

View the current process diagram: /view/image?instanceId=...

Proceed to the next step: /holidays/apply?days=3&mgr=10001&explain=ill&instanceId=...

View the updated diagram again.