Chapter 4. Example application using a fallback function with the circuit breaker add-on

...

// Import the circuit breaker add-on
const Opossum = require('@redhat/opossum');

...

// Create a new circuit breaker instance and pass the
// remote nameService as its first parameter
const circuit = new Opossum(nameService, circuitOptions);

// Define a fallback function that will be called when
// the remote nameService fails
function fallback(result) {
    console.log('This is the fallback function', result);
}

// Use the circuit breaker's fallback method to add the
// fallback function to the circuit breaker instance
circuit.fallback(fallback);

...

// Greeting API
app.get('/api/greeting', (request, response) => {
  // Use the circuit breaker’s fire method to execute the call
  // to the name service
  circuit.fire(`${nameServiceHost}/api/name`).then(name => {
    response.send({ content: `Hello, ${name}`, time: new Date() });
  }).catch(console.error);
});

...

...

// Import the circuit breaker add-on
const Opossum = require('@redhat/opossum');

...

// Create a new circuit breaker instance and pass the
// remote nameService as its first parameter
const circuit = new Opossum(nameService, circuitOptions);

// Define a fallback function that will be called when
// the remote nameService fails
function fallback(result) {
    console.log('This is the fallback function', result);
}

// Use the circuit breaker's fallback method to add the
// fallback function to the circuit breaker instance
circuit.fallback(fallback);

...

// Greeting API
app.get('/api/greeting', (request, response) => {
  // Use the circuit breaker’s fire method to execute the call
  // to the name service
  circuit.fire(`${nameServiceHost}/api/name`).then(name => {
    response.send({ content: `Hello, ${name}`, time: new Date() });
  }).catch(console.error);
});

...