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Saga Pattern Parallel Execution Evaluation

This project includes an example implementation of the Saga pattern using Camunda. The difference to the original Saga Pattern Realization With Camunda is the parallel execution of specific tasks instead of a sequential one.

Start the Application

  1. Run ./gradlew clean build

  2. Execute docker-compose up --no-start

  3. Execute docker-compose start mysql

  4. Execute docker-compose start travelservice

  5. Execute docker-compose up

  6. Requesting trip bookings is now possible. Either use curl commands, the provided TravelApplication.json insomnia file, which includes different trip booking requests, or access the Swagger UI of the different services:

Service
URL to Swagger UI
TravelService http://localhost:8090/swagger-ui.html
HotelService http://localhost:8081/swagger-ui.html
FlightService http://localhost:8082/swagger-ui.html

An example for such a request:

TravelRequest
{
    "duration":
    {
        "start":"2021-12-01",
        "end":"2021-12-12"
    },
    "start":
    {
        "country":"Scotland",
        "city":"Stirling"
    },
    "destination":
    {
        "country":"Sweden",
        "city":"Stockholm"
    },
    "travellerName": "Max Mustermann",
    "boardType":"breakfast",
    "customerId":"1"
}

To simulate a Saga that fails because no hotel or no flight is available, use one of the following Strings as destination country in the trip booking request: 

"Provoke hotel failure"

"Provoke flight failure"

Additionally, the Camunda Cockpit can be accessed via http://localhost:8090/ with the credentials:
Username: admin | Password: admin

The services also provide a health and an info endpoint that show some information about the system like that the DB is up and running. These endpoints can be accessed via:

Service
URL to health endpoint
URL to info endpoint
TravelService http://localhost:8090/api/travel/monitor/health http://localhost:8090/api/travel/monitor/info
HotelService http://localhost:8081/api/hotels/monitor/health http://localhost:8081/api/hotels/monitor/info
FlightService http://localhost:8082/api/flights/monitor/health http://localhost:8082/api/flights/monitor/info

If you are on Windows or Mac, you sometimes have to replace localhost with the default IP of your docker machine (use docker-machine ip default to get this default IP).

Stop the Application

To stop the application and remove the created containers, execute the following command: 

docker-compose down --remove-orphans

Parallel Execution of Tasks

The bookTrip, bookHotel and the bookFlight tasks, as well as the confirmHotel and the confirmTrip tasks, are now executed in parallel by using parallel gateways. Since the Camunda process engine is responsible for the invocation of the compensating transactions, this execution cannot be influenced.

Camunda_Implementations/Camunda_ParallelExec-Evaluation

Last update: 2022-02-15
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