Foreach State - adding sequential exec option and batchSize for paral… (#441)

* Foreach State - adding sequential exec option and batchSize for parallel exec option

Signed-off-by: Tihomir Surdilovic <[email protected]>

* updated roadmap

Signed-off-by: Tihomir Surdilovic <[email protected]>

* Update specification.md

Co-authored-by: Ricardo Zanini <[email protected]>

* Update specification.md

Co-authored-by: Ricardo Zanini <[email protected]>

* Update specification.md

Co-authored-by: Ricardo Zanini <[email protected]>

Co-authored-by: Ricardo Zanini <[email protected]>

Author: tsurdilo

roadmap/README.md

@@ -43,8 +43,7 @@ _Status description:_
 | ✔️| Rename Delay state to Sleep state | [spec doc](../specification.md) |
 | ✔️| Added 'sleep' property to action definition | [spec doc](../specification.md) |
 | ✔️| Added Rate Limiting extension | [spec doc](../specification.md) |
-| ✏️ | AsyncAPI operation support |  |
-| ✏️ | OData function definition support |  |
+| ✔️| Update ForEach state - adding sequential exec option and batch size for parallel option | [spec doc](../specification.md) |
 | ✏️ | Update to retries - state specific rather than error specific |  |
 | ✏️ | Add batching and sync option for Foreach state |  |
 | 🚩 | Workflow invocation bindings |  |
@@ -57,7 +56,6 @@ _Status description:_
 | 🚩 | Start discussions on Serverless Workflow Technology Compatibility Kit (TCK) |  |
 | ✏️ | Specification primer | [google doc](https://docs.google.com/document/d/11rD3Azj63G2Si0VpokSpr-1ib3mFRFHSwN6tJb-0LQM/edit#heading=h.paewfy83tetm) continued in [wiki](https://github.com/serverlessworkflow/specification/wiki) |
 
-
 ## <a name="v06"></a> v0.6
 
 | Status | Description | Comments |

schema/workflow.json

@@ -1447,14 +1447,14 @@
           "type": "string",
           "description": "Name of the iteration parameter that can be referenced in actions/workflow. For each parallel iteration, this param should contain an unique element of the inputCollection array"
         },
-        "max": {
+        "batchSize": {
           "type": [
             "number",
             "string"
           ],
           "minimum": 0,
           "minLength": 0,
-          "description": "Specifies how upper bound on how many iterations may run in parallel"
+          "description": "Specifies how many iterations may run in parallel at the same time. Used if 'mode' property is set to 'parallel' (default)"
         },
         "actions": {
           "type": "array",
@@ -1505,6 +1505,15 @@
           "default": false,
           "description": "If true, this state is used to compensate another state. Default is false"
         },
+        "mode": {
+          "type": "string",
+          "enum": [
+            "sequential",
+            "parallel"
+          ],
+          "description": "Specifies how iterations are to be performed (sequentially or in parallel)",
+          "default": "parallel"
+        },
         "metadata": {
           "$ref": "common.json#/definitions/metadata"
         }

specification.md

@@ -2788,7 +2788,8 @@ The `timeouts` property can be used to define state specific timeout settings. I
 | inputCollection | Workflow expression selecting an array element of the states data | string | yes |
 | outputCollection | Workflow expression specifying an array element of the states data to add the results of each iteration | string | no |
 | iterationParam | Name of the iteration parameter that can be referenced in actions/workflow. For each parallel iteration, this param should contain an unique element of the inputCollection array | string | yes |
-| max | Specifies how upper bound on how many iterations may run in parallel | string or number | no |
+| batchSize | Specifies how many iterations may run in parallel at the same time. Used if `mode` property is set to `parallel` (default). If not specified, its value should be the size of the `inputCollection` | string or number | no |
+| mode | Specifies how iterations are to be performed (sequentially or in parallel). Default is `parallel` | string  | no |
 | [actions](#Action-Definition) | Actions to be executed for each of the elements of inputCollection | array | yes |
 | [timeouts](#Workflow-Timeouts) | State specific timeout settings | object | no |
 | [stateDataFilter](#State-data-filters) | State data filter definition | object | no |
@@ -2854,10 +2855,18 @@ actions:
 
 ForEach states can be used to execute [actions](#Action-Definition) for each element of a data set.
 
-Each iteration of the ForEach state should be executed in parallel.
+Each iteration of the ForEach state is by default executed in parallel by default.
+However, executing iterations sequentially is also possible by setting the value of the `mode` property to
+`sequential`.
 
-You can use the `max` property to set the upper bound on how many iterations may run in parallel. The default
-of the `max` property is zero, which places no limit on number of parallel executions.
+The `mode` property defines if iterations should be done sequentially or in parallel. By default 
+(if `mode` is not specified) iterations should be done in parallel.
+
+If the default `parallel` iteration mode is used, the `batchSize` property to the number of iterations (batch) 
+that can be executed at a time. To give an example, if the number of iterations is 55 and `batchSize`
+is set to `10`, 10 iterations are to be executed at a time, meaning that the state would execute 10 iterations in parallel,
+then execute the next batch of 10 iterations. After 5 such executions, the remaining 5 iterations are to be executed in the last batch.
+The batch size value must be greater than 1. If not specified, its value should be the size of the `inputCollection` (all iterations).
 
 The `inputCollection` property is a workflow expression which selects an array in the states data. All iterations
 are performed against data elements of this array. If this array does not exist, the runtime should throw