Service Tasks

In this tutorial, we will focus on how to implement service tasks. A service task is a category of task that is automatically executed by the process engine and that are usually used in situations such as:

• communication with third party systems;
• evaluation of complex condition expressions (see tutorial Gateways);
• updating domain entities;
• etc

Service tasks are useful for many other situations and you will find when you should use them when you start to design your processes.

Let’s change the Travel Plan Process to include a service task Integrate Airline Company, Hotel, Rent Car Company that aims at integrating with third party systems at the end of the process:

To configure this task, click on the wrench icon and then select the type Service Task

Then configure the delegate on the property tab as follow:

• Implementation: Delegate Expression
• Delegate Expression: ${integrateThirdPartyDelegate}

Now create a java delegate class IntegrateThirdPartyDelegate that implements the interface org.camunda.bpm.engine.delegate.JavaDelegate.

package com.mycompany.myapp.delegate;

import com.mycompany.myapp.service.AirlineService;
import com.mycompany.myapp.service.HotelService;
import com.mycompany.myapp.service.RentCarService;
import com.mycompany.myapp.service.dto.TravelPlanProcessDTO;
import org.camunda.bpm.engine.delegate.DelegateExecution;
import org.camunda.bpm.engine.delegate.JavaDelegate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class IntegrateThirdPartyDelegate implements JavaDelegate {

    @Autowired
    AirlineService airlineService;

    @Autowired
    HotelService hotelService;

    @Autowired
    RentCarService rentCarService;

    @Override
    public void execute(DelegateExecution delegateExecution) throws Exception {
        TravelPlanProcessDTO travelPlanProcess = (TravelPlanProcessDTO) delegateExecution.getVariable("processInstance");

        //Confirming the flight
        airlineService.confirmFlight(travelPlanProcess.getTravelPlan().getAirlineTicketNumber());

        //Confirming the hotel booking
        hotelService.confirmReservation(travelPlanProcess.getTravelPlan().getHotelBookingNumber());

        //Confirming the car booking
        rentCarService.confirmReservation(travelPlanProcess.getTravelPlan().getCarBookingNumber());
    }
}

The class AirlineService is a Spring component that implements the communication with the airline company system:

package com.mycompany.myapp.service;

import org.springframework.stereotype.Component;

@Component
public class AirlineService {

    public void confirmFlight(String airlineTicketNumber) {
        System.out.println("AirlineService: ###########################################");
        System.out.println("AirlineService: ###########################################");
        System.out.println("AirlineService: ###########################################");
        System.out.println("AirlineService:        CONFIRMING FLIGHT " + airlineTicketNumber);
        System.out.println("AirlineService:        FLIGHT " + airlineTicketNumber + " CONFIRMED");
        System.out.println("AirlineService: ###########################################");
        System.out.println("AirlineService: ###########################################");
        System.out.println("AirlineService: ###########################################\n\n\n");
    }
}

The class HotelService is a Spring component that implements the communication with the hotel reservation system:

package com.mycompany.myapp.service;

import org.springframework.stereotype.Component;

@Component
public class HotelService {
    public void confirmReservation(String hotelBookingNumber) {
        System.out.println("HotelService: ###########################################");
        System.out.println("HotelService: ###########################################");
        System.out.println("HotelService: ###########################################");
        System.out.println("HotelService:        CONFIRMING BOOKING HOTEL " + hotelBookingNumber);
        System.out.println("HotelService:        BOOKING HOTEL " + hotelBookingNumber + " CONFIRMED");
        System.out.println("HotelService: ###########################################");
        System.out.println("HotelService: ###########################################");
        System.out.println("HotelService: ###########################################\n\n\n");
    }
}

The class RentCarService is a Spring component that implements the communication with the rental car company reservation system:

package com.mycompany.myapp.service;

import org.springframework.stereotype.Component;

@Component
public class RentCarService {
    public void confirmReservation(String carBookingNumber) {
        System.out.println("RentCarService: ###########################################");
        System.out.println("RentCarService: ###########################################");
        System.out.println("RentCarService: ###########################################");
        System.out.println("RentCarService:        CONFIRMING BOOKING CAR " + carBookingNumber);
        System.out.println("RentCarService:        BOOKING CAR " + carBookingNumber + " CONFIRMED");
        System.out.println("RentCarService: ###########################################");
        System.out.println("RentCarService: ###########################################");
        System.out.println("RentCarService: ###########################################\n\n\n");
    }
}

The Travel Plan Process now has a Service Task called Integrate Airline Company, Hotel, Rent Car Company that is automatically executed at the end of the process.

Note: You can checkout the tag part3-handling-service-task from the TravelPlan repository on Github to get the BPMN file src/main/resources/TravelPlanProcess.bpmn, the delegate IntegrateThirdPartyDelegate, and the classes AirlineService, HotelService, and RentCarService used in this step. git checkout part3-handling-service-task.

That’s it for today.
I hope this tutorial was helpful to you and you can implement processes with service tasks.

Comming soon!