Afrous Core

Overview

To accomplish easy manipulation of asynchronous operations in Ajax-style applications, Afrous introduced the notion of declarative process configuration in process cordination.

Afrous Core JavaScript engine deals with pre-defined operation objects with same interface. We call them Unit Action.

Unit Action is encapsulated and accessible only via its input and output. The output is notified by callback function when the action operation has finished, but process developers shouldn't know which was synchronous or asynchronous.

Unit Action becomes an instance when included in process definition, which we call it Action Instance, or simply Action. Action input can be explicit static values or references which are mapped to other action's output.

All evaluation order of Actions are determined by the engine, considering the dependencies of inputs and outputs between the Actions, not in procedual manner.

Class Diagram

Process Config Element Reference

Process

Property Name	Data Type	Description
name	String	The name of process
requires	Hash<String, String>	The pair of package namespace and its script URL which should be loaded before process evaluation
params	Object[]	The array of process parameters
output	String	Definition of the process output value. Action output and parameter values can be refered by "${ ... }" notation
actions	Object[]	The array of action definitions

Parameter

Property Name	Data Type	Description
name	String	Name of the parameter
type	String	Data type of the parameter. Acceptable data type is String, Integer, Float and array form of those types.
default	String	Default value of the parameter if not specified.

Action

Property Name	Data Type	Description
name	String	Name of the action
type	String	The type name of Unit Action. Should be fully qualified name including package.
inputs	Hash<String,String>	Values assigned to the action's input. Action output and parameter values can be refered by "${ ... }" notation.
innerProcess	Object	(Option) Inner process definition. Some unit actions (e.g. "iterate") require this.

Sample Process Configuration

  var config = {
    name : "process1",
    params : [ 
      { name : 'username', type : 'string', 'default' : 'stomita' },
      { name : 'count', type : 'integer', 'default' : 5 }
    ],
    output : "${networkPosts}",
    actions : [
      { name : "delnetwork",
        type : "Ajax.Jsonp",
        inputs : { 
          "url" : "http://del.icio.us/feeds/json/network/${username}"
        }
      }
      ,
      { name : "networkPosts",
        type : "Array.Iterate",
        inputs : { 
          "array" : "${delnetwork}"
        },
        innerProcess : {
          output : "${posts}",
          actions : [
            { name : "posts",
              type : "Ajax.Jsonp",
              inputs : { 
                "url" : "http://del.icio.us/feeds/json/${element}"
              }
            }
          ]
        }
      }
    ] 
  }

Sample JavaScript

<script type="text/javascript" src="http://sandbox.afrous.com/js/afrous/afrous-core.js"></script>
<script type="text/javascript" src="http://sandbox.afrous.com/js/afrous/afrous-package.js"></script>
<script type="text/javascript">
var config = { ... };  // afrous config in JSON
var procdef = new afrous.ProcessDef(config);
var proc = new afrous.ProcessInstance(procdef);
proc.start({
  onSuccess : function(result) {  ...  } // write handler to handle process output
  onFailure : function(error) { ...  }
});
</script>

Comment by meco007, Oct 07, 2008

How to write the handler to handle process output?