[Fix_#873] Rename output.from and output.to

ctk/features/data-flow.feature

@@ -44,7 +44,7 @@ Feature: Data Flow
         endpoint:
           uri: https://petstore.swagger.io/v2/pet/{petId} #simple interpolation, only possible with top level variables
       output:
-        from: .id #filters the output of the http call, using only the id of the returned object
+        as: .id #filters the output of the http call, using only the id of the returned object
     """
     And given the workflow input is:
     """yaml
@@ -74,15 +74,15 @@ Feature: Data Flow
                 endpoint:
                   uri: https://petstore.swagger.io/v2/pet/{petId} #simple interpolation, only possible with top level variables
               output:
-                from: .id
+                as: .id
           - getPetById2:
               call: http
               with:
                 method: get
                 endpoint:
                   uri: https://petstore.swagger.io/v2/pet/2
               output:
-                from: '{ ids: [ $input, .id ] }'
+                as: '{ ids: [ $input, .id ] }'
     """
     When the workflow is executed
     Then the workflow should complete with output:

dsl-reference.md

@@ -44,6 +44,7 @@
   + [Retry](#retry)
   + [Input](#input)
   + [Output](#output)
+  + [Export] (#export)
   + [Timeout](#timeout)
   + [Duration](#duration)
   + [HTTP Response](#http-response)
@@ -176,7 +177,7 @@ do:
       - getAvailablePets:
           call: getAvailablePets
           output:
-            from: "$input + { availablePets: [.[] | select(.category.name == "dog" and (.tags[] | .breed == $input.order.breed))] }"
+            as: "$input + { availablePets: [.[] | select(.category.name == "dog" and (.tags[] | .breed == $input.order.breed))] }"
       - submitMatchesByMail:
           call: http
           with:
@@ -234,6 +235,7 @@ The Serverless Workflow DSL defines a list of [tasks](#task) that **must be** su
 |:--|:---:|:---:|:---|
 | input | [`input`](#input) | `no` | An object used to customize the task's input and to document its schema, if any. |
 | output | [`output`](#output) | `no` | An object used to customize the task's output and to document its schema, if any. |
+| export | [`export`](#export) | `no` | An object used to customize the content of the workflow context. | 
 | timeout | [`timeout`](#timeout) | `no` | The configuration of the task's timeout, if any. |
 | then | [`flowDirective`](#flow-directive) | `no` | The flow directive to execute next.<br>*If not set, defaults to `continue`.* |
 
@@ -558,7 +560,7 @@ do:
           with:
             type: com.fake.petclinic.pets.checkup.completed.v2
       output:
-        to: '.pets + [{ "id": $pet.id }]'        
+        as: '.pets + [{ "id": $pet.id }]'        
 ```
 
 #### Listen
@@ -1416,6 +1418,33 @@ from:
 to: '.petList += [ . ]'
 ```
 
+### Export
+
+Certain task needs to set the workflow context to save the task output for later usage. Users set the content of the context through a runtime expression. The result of the expression is the new value of the context. The expression is evaluated against the existing context. 
+
+Optionally, the context might have an associated schema. 
+
+#### Properties
+
+| Property | Type | Required | Description |
+|----------|:----:|:--------:|-------------|
+| schema | [`schema`](#schema) | `no` | The [`schema`](#schema) used to describe and validate context.<br>*Included to handle the non frequent case in which the context has a known format.* |
+| as | `string`<br>`object` | `no` | A runtime expression, if any, used to export the output data to the context. |
+
+#### Examples
+
+Merge the task output into the current context. 
+
+```yaml
+as: '.+$output'
+```
+
+Replace the context with the task output. 
+
+```yaml
+as: $output
+```
+
 ### Schema
 
 Describes a data schema.

examples/accumulate-room-readings.yaml

@@ -17,15 +17,15 @@ do:
                     roomId:
                       from: .roomid
                   output:
-                    from: .data.reading
+                    as: .data.reading
                 - with:
                     source: https://my.home.com/sensor
                     type: my.home.sensors.humidity
                   correlate:
                     roomId:
                       from: .roomid
                   output:
-                    from: .data.reading
+                    as: .data.reading
           as: readings
       - logReading:
           for:

schema/workflow.yaml

@@ -816,13 +816,20 @@ $defs:
       schema:
         $ref: '#/$defs/schema'
         description: The schema used to describe and validate the output of the workflow or task.
-      from:
+      as:
         type: string
         description: A runtime expression, if any, used to mutate and/or filter the output of the workflow or task.
-      to:
-        type: string
-        description: A runtime expression, if any, used to output data to the current context.
     description: Configures the output of a workflow or task.
+  export:
+    type: object
+    properties:
+      schema:
+        $ref: '#/$defs/schema'
+        description: The schema used to describe and validate the workflow context.
+      as:
+        type: string
+        description: A runtime expression, if any, used to export the output data to the context.
+    description: Set the content of the context. 
   retryPolicy:
     type: object
     properties: