role.md

##Caller and Worker

Next: Background Worker Pool

Below is a flow when you initiate a task and receive reports in Dingo.

The key to scaling dividing a big procedure into smaller ones, and making each one of them isolated from each other. For a function in #golang, we can devide it into three parts:

//         passing arguments      receiving return values
//                |                          |
//                v                          v
//       ---------------------   --------------------------
func Foo(count int, msg string) (composed string, err error) {  // |
    return fmt.Sprintf("%v:%v", msg, count), nil                // |<- execution
}                                                               // |

• Passing Arguments
• Execution
• Receiving Return Values
• Example

###Passing Arguments There are 3 roles related to this part:

• Caller: the one who...
  • composes arguments into dingo.Task
  • marshall it into []byte
  • sends to brokers
• Broker: the one who dispatching tasks
• Worker: the one who
  • consumes []byte from brokers
  • unmarshall it into dingo.Task

###Execution Only Worker relates this part. Upon receiving tasks, Worker should find corresponding functions according to the names of tasks, and execute it.

###Receiving Return Values After execution:

• Worker:
  • compose return values into dingo.Report
  • marshall it into []byte
  • send it to Store.
• Caller:
  • poll from Store
  • unmarshall []byte to dingo.Report
  • dispatch it to the right channel.

###Example There are runnable examples on GoDoc(Caller and Worker) based on our AMQP adaptor.