saga-spring-demo

Booking Demo

This demo simulates a booking application including three services:

• booking
• car
• hotel

Prerequisites

You will need:

1. JDK 1.8
2. Maven 3.x
3. Docker
4. Docker compose
5. alpha server

Running Demo

You can run the demo using either docker compose or executable files.

via docker compose

1. run the following command to create docker images in saga project root folder.

   mvn clean install -DskipTests -Pdocker -Pdemo
   

2. Enter the saga spring demo directory and give permissions to script

   cd ./saga-demo/saga-spring-demo
   chmod +x saga-demo.sh
   

3. start the whole application up(including alpha server and three demo services)

   ./saga-demo.sh up
   

   Note: If you prefer to use MySQL as alpha's backend database, you need to try the following steps instead:

   1. add dependency of mysql-connector-java in alpha/alpha-server/pom.xml

          <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
          </dependency>

   2. re-generate saga's docker images in saga project root folder

      mvn package -DskipTests -Pdocker -Pdemo

   3. start application up in saga-demo/booking with the following command

      cd ./saga-demo/saga-spring-demo
      ./saga-demo.sh up-mysql
      

   Note: If you want start alpha server and demon services separately, you can try the following steps:

   1. start alpha server

          ./saga-demo.sh up-alpha

      start alpha server with performance monitor and grafana

          ./saga-demo.sh up-alpha-perf

   2. when alpha server started completely, then start the demo services

          ./saga-demo.sh up-demo

4. stop application

   ./saga-demo.sh down
   

via executable files

1. run the following command to generate executable alpha server jar in alpha/alpha-server/target/saga/alpha-server-${saga_version}-exec.jar.

   mvn clean package -DskipTests -Pdemo
   

2. follow the instructions in the How to run section in User Guide to run postgreSQL and alpha server.

3. start application up

   1. start hotel service. The executable jar file should be in saga-demo/booking/hotel/target/saga.

   java -Dserver.port=8081 -Dalpha.cluster.address=${alpha_address}:8080 -jar hotel-${saga_version}-exec.jar

   2. start car service. The executable jar file should be in saga-demo/booking/car/target/saga.

   java -Dserver.port=8082 -Dalpha.cluster.address=${alpha_address}:8080 -jar car-${saga_version}-exec.jar

   3. start booking service. The executable jar file should be in saga-demo/booking/booking/target/saga.

   java -Dserver.port=8083 -Dalpha.cluster.address=${alpha_address}:8080 -Dcar.service.address=${host_address}:8082 -Dhotel.service.address=${host_address}:8081  -jar booking-${saga_version}-exec.jar

User Requests by command line tools

1. Booking 2 rooms and 2 cars, this booking will be OK.

curl -X POST http://${host_address}:8083/booking/test/2/2

If everything is OK, "test booking 2 rooms and 2 cars OK" will be returned and it means everything is OK

Check the hotel booking status with

curl http://${host_address}:8081/bookings

The hotel booking result is: [{"id":1,"name":"test","amount":2,"confirmed":true,"cancelled":false}] "cancelled":false means this booking is finished and confirmed status is true.

Check the car booking status with

curl http://${host_address}:8082/bookings

the card booking result is: [{"id":1,"name":"test","amount":2,"confirmed":true,"cancelled":false}] "confirmed":true,"cancelled":false means everything is OK too.

2. Booking 3 rooms and 2 cars, this booking will cause the hotel order failed and trigger the compensate operation with car booking.

curl -X POST http://${host_address}:8083/booking/test/3/2

Error message will returned because the room count is more than 2: {"timestamp":"2019-01-22T08:41:57.251+0000","status":500,"error":"Internal Server Error","message":"500 null","path":"/booking/test/3/2"}

Check the hotel booking status with

curl http://${host_address}:8081/bookings

There is no more records because the room booking was failed.

Check the car booking status with

curl http://${host_address}:8082/bookings

The second car booking will be marked with cancel:true: [{"id":1,"name":"test","amount":2,"confirmed":true,"cancelled":false}, {"id":2,"name":"test","amount":2,"confirmed":false,"cancelled":true}]

User Requests by html page

Open a browser with URL http://127.0.0.1:8083, You will get a html page. You can use this page to invoke test cases, and then get results.

Note transactions and compensations implemented by services must be idempotent.

Debugging

To debug the services of the demo, just add debug parameter to JVM through the environment field in docker-compose configs. Let's take alpha-server as an example:

alpha:
  image: "alpha-server:${TAG}"
  environment:
    - JAVA_OPTS=-Dspring.profiles.active=prd -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005
  ports:
    - "6006:5005"
...

We append the debug parameter -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005 to the JAVA_OPTS environment variable, the Java process inside the container will listen on port 5005. With the port forwarding rule 6006:5005, when alpha-server is ready, we can connect to port 6006 on the host and start debugging alpha-server.

If you're using IntelliJ, open the saga project, create a new debug configuration with template 'Remote', fill "Host" and "Port" input with "localhost" and "6006", then select "alpha" in the drop-down list of "Use classpath of module". When alpha-server is running, hit shift+f9 to debug the remote application.