README.adoc

Vert.x Circuit Breaker examples

Here you will find examples demonstrating Vert.x Circuit Breaker.

Vert.x Circuit Breaker is an implementation of the Circuit Breaker pattern for Vert.x.

It keeps track of the number of failures and open the circuit when a threshold is reached. Optionally, a fallback is executed.

Supported failures are:

  • failures reported by your code

  • exception thrown by your code

  • uncompleted futures (timeout)

Operations guarded by a circuit breaker are intended to by non-blocking and asynchronous in order to benefits from the Vert.x execution model.

To use the circuit breaker you need to:

  • Create a circuit breaker, with the configuration you want (timeout, number of failure before opening the circuit)

  • Execute some code using the breaker

Client example

  • Creates a circuit breaker which

    • can fail 5 times before opening the circuit

    • consider a failure if the operation does not succeed in time

    • time spent in open state before attempting to re-try is 5 seconds

    • call the fallback method on failures

  • The execute method sends a request to localhost at port 8080

  • The fallback is called whenever the circuit is open

To run this example you need to:

  1. start or not the server (if not started, the circuit breaker will invoke the fallback)

  2. start the client

To start the server, run the Server.java class from your IDE or call:

vertx run src/main/java/io/vertx/example/circuit/breaker/Server.java

To start the client, run the Client.java class from your IDE or call:

# java version
vertx run src/main/java/io/vertx/example/circuit/breaker/Client.java

# groovy version
vertx run src/main/groovy/io/vertx/example/circuit/breaker/client.groovy

# javascript version
vertx run src/main/js/io/vertx/example/circuit/breaker/client.js