rsocket-loadbalancing-example

An example of load-balancing requests across multiple RSocket services.

In this example the hello-client load balances requests for 10 hello messages across two instances of the hello-service.

Building the Example

Run the following command to build the example:

./gradlew clean build

Running the Example:

Follow the steps below to run the example:

1. Run the following command to start an instance of the hello-service on port 7000:

    ./gradlew :hello-service:run --args="hello-service1 7000"
   

   If successful, you will see the following in the terminal:

   > Task :hello-service:run
   [main] INFO example.hello.service.HelloService - RSocket server 'hello-service1' started on port: 7000
   

2. In a new terminal, run the following command to start a second instance of the hello-service on port 7001:

    ./gradlew :hello-service:run --args="hello-service2 7001"
   

   If successful, you will see the following in the terminal:

    > Task :hello-service:run
    [main] INFO example.hello.service.HelloService - RSocket server 'hello-service2' started on port: 7001
   

3. Next, in a new terminal run the following command to start the hello-client and request 10 hello messages for Bob load balanced across the two service instances:

   ./gradlew :hello-client:run --args="Bob localhost:7000,localhost:7001"
   

   If successful, you will see that the requests were load balanced across both hello-service instances in the terminal:

   > Task :hello-client:run
   [main] INFO example.hello.client.HelloClient - Connected to hello-service at 'localhost:7000'
   [main] INFO example.hello.client.HelloClient - Connected to hello-service at 'localhost:7001'
   [parallel-3] INFO example.hello.client.HelloClient - Sending Request 1
   [reactor-tcp-nio-1] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service1
   [parallel-4] INFO example.hello.client.HelloClient - Sending Request 2
   [reactor-tcp-nio-2] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service2
   [parallel-5] INFO example.hello.client.HelloClient - Sending Request 3
   [reactor-tcp-nio-2] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service2
   [parallel-6] INFO example.hello.client.HelloClient - Sending Request 4
   [reactor-tcp-nio-1] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service1
   [parallel-7] INFO example.hello.client.HelloClient - Sending Request 5
   [reactor-tcp-nio-1] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service1
   [parallel-8] INFO example.hello.client.HelloClient - Sending Request 6
   [reactor-tcp-nio-1] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service1
   [parallel-1] INFO example.hello.client.HelloClient - Sending Request 7
   [reactor-tcp-nio-2] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service2
   [parallel-2] INFO example.hello.client.HelloClient - Sending Request 8
   [reactor-tcp-nio-1] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service1
   [parallel-3] INFO example.hello.client.HelloClient - Sending Request 9
   [reactor-tcp-nio-2] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service2
   [parallel-4] INFO example.hello.client.HelloClient - Sending Request 10
   [reactor-tcp-nio-2] INFO example.hello.client.HelloClient - Response: Hello, Bob! from hello-service2
   [reactor-tcp-nio-2] INFO example.hello.client.HelloClient - Done
   

   Notice that the requests are not evenly distributed amongst the service instances. This is because the load balancer uses intelligent routing to direct traffic to the least latent instance.

License

MIT License

Copyright (c) 2020 Greg Whitaker

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.