Updated GroupComponent helper:

 - Added support for async components (via config and callback in handler's params)
 - Matching inputs by group name is disabled by default, because it conflicts with other grouping conventions

spec/Helpers.coffee

@@ -97,7 +97,7 @@ describe 'Component traits', ->
         chai.expect(data).to.deep.equal src[groups[0]]
         out.send data
         # done() if groups[0] is 333
-      , ['x', 'y', 'z'], 'point'
+      , ['x', 'y', 'z'], 'point', {group: true}
 
       groups = []
       count = 0
@@ -142,7 +142,7 @@ describe 'Component traits', ->
       z.send 789
       z.disconnect()
 
-    it 'should process inputs for different groups independently', (done) ->
+    it 'should process inputs for different groups independently with group: true', (done) ->
       src =
         1: {x: 1, y: 2, z: 3}
         2: {x: 4, y: 5, z: 6}
@@ -162,7 +162,7 @@ describe 'Component traits', ->
 
       helpers.GroupComponent c, (data, groups, out) ->
         out.send {x: data.x, y: data.y, z: data.z}
-      , ['x', 'y', 'z'], 'point'
+      , ['x', 'y', 'z'], 'point', {group: true}
 
       groups = []
 
@@ -190,3 +190,38 @@ describe 'Component traits', ->
         input.send src[tuple[0]][tuple[1]]
         input.endGroup()
         input.disconnect()
+
+    it 'should support asynchronous handlers', (done) ->
+      point =
+        x: 123
+        y: 456
+        z: 789
+
+      helpers.GroupComponent c, (data, groups, out, callback) ->
+        setTimeout ->
+          out.send {x: data.x, y: data.y, z: data.z}
+          callback()
+        , 100
+      , ['x', 'y', 'z'], 'point', {async: true, group: true}
+
+      p.removeAllListeners()
+      counter = 0
+      p.on 'begingroup', (grp) ->
+        counter++
+      p.on 'endgroup', ->
+        counter--
+      p.once 'data', (data) ->
+        chai.expect(data).to.deep.equal point
+      p.once 'disconnect', ->
+        chai.expect(counter).to.equal 0
+        done()
+
+      x.beginGroup 'async'
+      y.beginGroup 'async'
+      z.beginGroup 'async'
+      x.send point.x
+      y.send point.y
+      z.send point.z
+      x.endGroup()
+      y.endGroup()
+      z.endGroup()

src/lib/Helpers.coffee

@@ -28,6 +28,10 @@ exports.MapComponent = (component, func, config) ->
 exports.GroupComponent = (component, func, inPorts='in', outPort='out', config={}) ->
   unless Object.prototype.toString.call(inPorts) is '[object Array]'
     inPorts = [inPorts]
+  # For async func
+  config.async = false unless 'async' of config
+  # Group requests by group ID
+  config.group = false unless 'group' of config
 
   for name in inPorts
     unless component.inPorts[name]
@@ -48,15 +52,27 @@ exports.GroupComponent = (component, func, inPorts='in', outPort='out', config={
           when 'begingroup'
             inPort.groups.push payload
           when 'data'
-            key = inPort.groups.toString()
+            key = if config.group then inPort.groups.toString() else ''
             groupedData[key] = {} unless key of groupedData
             groupedData[key][port] = payload
             # Flush the data if the tuple is complete
             if Object.keys(groupedData[key]).length is inPorts.length
-              out.beginGroup group for group in inPort.groups
-              func groupedData[key], inPort.groups, out
-              out.endGroup() for group in inPort.groups
-              out.disconnect()
-              delete groupedData[key]
+              groups = inPort.groups
+              out.beginGroup group for group in groups
+              if config.async
+                grps = groups.slice(0)
+                func groupedData[key], groups, out, (err) ->
+                  if err
+                    component.error err, groups
+                    # For use with MultiError trait
+                    component.fail if typeof component.fail is 'function'
+                  out.endGroup() for group in grps
+                  out.disconnect()
+                  delete groupedData[key]
+              else
+                func groupedData[key], inPort.groups, out
+                out.endGroup() for group in inPort.groups
+                out.disconnect()
+                delete groupedData[key]
           when 'endgroup'
             inPort.groups.pop()