Simple example of applying Rx operators to an asynchronous Observable sequence.

simpleRxComposition.groovy

/**
 * Asynchronously calls 'customObservableNonBlocking' and defines 
 * a chain of operators to apply to the callback sequence.
 */
def simpleComposition() {
  // fetch an asynchronous Observable<String> 
  // that emits 75 Strings of 'anotherValue_#'
  customObservableNonBlocking()
    // skip the first 10
    .skip(10)
    // take the next 5
    .take(5)
    // transform each String with the provided function
    .map({ stringValue -> return stringValue + "_transformed"})
    // subscribe to the sequence and print each transformed String
    .subscribe({ println "onNext => " + it})
}

// output
onNext => anotherValue_10_transformed
onNext => anotherValue_11_transformed
onNext => anotherValue_12_transformed
onNext => anotherValue_13_transformed
onNext => anotherValue_14_transformed

line 14 could be simplified to

.map({ "$it_transformed" })