diff --git a/core/task.go b/core/task.go
index c78d684db..1a018cb5a 100644
--- a/core/task.go
+++ b/core/task.go
@@ -22,6 +22,7 @@ package core
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"time"
@@ -157,6 +158,7 @@ type TaskErrors interface {
 
 type TaskCreationRequest struct {
 	Name        string            `json:"name"`
+	Version     int               `json:"version"`
 	Deadline    string            `json:"deadline"`
 	Workflow    *wmap.WorkflowMap `json:"workflow"`
 	Schedule    Schedule          `json:"schedule"`
@@ -164,6 +166,48 @@ type TaskCreationRequest struct {
 	MaxFailures int               `json:"max-failures"`
 }
 
+func (tr *TaskCreationRequest) UnmarshalJSON(data []byte) error {
+	t := make(map[string]json.RawMessage)
+	if err := json.Unmarshal(data, &t); err != nil {
+		return err
+	}
+	for k, v := range t {
+		switch k {
+		case "name":
+			if err := json.Unmarshal(v, &(tr.Name)); err != nil {
+				return fmt.Errorf("%v (while parsing 'name')", err)
+			}
+		case "deadline":
+			if err := json.Unmarshal(v, &(tr.Deadline)); err != nil {
+				return fmt.Errorf("%v (while parsing 'deadline')", err)
+			}
+		case "workflow":
+			if err := json.Unmarshal(v, &(tr.Workflow)); err != nil {
+				return err
+			}
+		case "schedule":
+			if err := json.Unmarshal(v, &(tr.Schedule)); err != nil {
+				return err
+			}
+		case "start":
+			if err := json.Unmarshal(v, &(tr.Start)); err != nil {
+				return fmt.Errorf("%v (while parsing 'start')", err)
+			}
+		case "max-failures":
+			if err := json.Unmarshal(v, &(tr.MaxFailures)); err != nil {
+				return fmt.Errorf("%v (while parsing 'max-failures')", err)
+			}
+		case "version":
+			if err := json.Unmarshal(v, &(tr.Version)); err != nil {
+				return fmt.Errorf("%v (while parsing 'version')", err)
+			}
+		default:
+			return fmt.Errorf("Unrecognized key '%v' in task creation request", k)
+		}
+	}
+	return nil
+}
+
 // Function used to create a task according to content (1st parameter)
 // . Content can be retrieved from a configuration file or a HTTP REST request body
 // . Mode is used to specify if the created task should start right away or not
diff --git a/scheduler/wmap/wmap.go b/scheduler/wmap/wmap.go
index 0d150d1a4..cd10958fe 100644
--- a/scheduler/wmap/wmap.go
+++ b/scheduler/wmap/wmap.go
@@ -133,6 +133,24 @@ type WorkflowMap struct {
 	CollectNode *CollectWorkflowMapNode `json:"collect"yaml:"collect"`
 }
 
+func (w *WorkflowMap) UnmarshalJSON(data []byte) error {
+	t := make(map[string]json.RawMessage)
+	if err := json.Unmarshal(data, &t); err != nil {
+		return err
+	}
+	for k, v := range t {
+		switch k {
+		case "collect":
+			if err := json.Unmarshal(v, &w.CollectNode); err != nil {
+				return err
+			}
+		default:
+			return fmt.Errorf("Unrecognized key '%v' in workflow of task.", k)
+		}
+	}
+	return nil
+}
+
 func NewWorkflowMap() *WorkflowMap {
 	w := &WorkflowMap{}
 	c := &CollectWorkflowMapNode{
@@ -159,6 +177,40 @@ type CollectWorkflowMapNode struct {
 	PublishNodes []PublishWorkflowMapNode          `json:"publish,omitempty"yaml:"publish"`
 }
 
+func (cw *CollectWorkflowMapNode) UnmarshalJSON(data []byte) error {
+	t := make(map[string]json.RawMessage)
+	if err := json.Unmarshal(data, &t); err != nil {
+		return err
+	}
+	for k, v := range t {
+		switch k {
+		case "metrics":
+			if err := json.Unmarshal(v, &cw.Metrics); err != nil {
+				return err
+			}
+		case "config":
+			if err := json.Unmarshal(v, &cw.Config); err != nil {
+				return fmt.Errorf("%v (while parsing 'config')", err)
+			}
+		case "tags":
+			if err := json.Unmarshal(v, &cw.Tags); err != nil {
+				return fmt.Errorf("%v (while parsing 'tags')", err)
+			}
+		case "process":
+			if err := json.Unmarshal(v, &cw.ProcessNodes); err != nil {
+				return err
+			}
+		case "publish":
+			if err := json.Unmarshal(v, &cw.PublishNodes); err != nil {
+				return err
+			}
+		default:
+			return fmt.Errorf("Unrecognized key '%v' in collect workflow of task.", k)
+		}
+	}
+	return nil
+}
+
 func (c *CollectWorkflowMapNode) GetMetrics() []Metric {
 	metrics := make([]Metric, len(c.Metrics))
 	i := 0
@@ -240,6 +292,45 @@ type ProcessWorkflowMapNode struct {
 	Target string                 `json:"target"yaml:"target"`
 }
 
+func (pw *ProcessWorkflowMapNode) UnmarshalJSON(data []byte) error {
+	t := make(map[string]json.RawMessage)
+	if err := json.Unmarshal(data, &t); err != nil {
+		return err
+	}
+	for k, v := range t {
+		switch k {
+		case "plugin_name":
+			if err := json.Unmarshal(v, &pw.Name); err != nil {
+				return fmt.Errorf("%v (while parsing 'plugin_name')", err)
+			}
+		case "plugin_version":
+			if err := json.Unmarshal(v, &pw.Version); err != nil {
+				return fmt.Errorf("%v (while parsing 'plugin_version')", err)
+			}
+		case "process":
+			if err := json.Unmarshal(v, &pw.ProcessNodes); err != nil {
+				return err
+			}
+		case "publish":
+			if err := json.Unmarshal(v, &pw.PublishNodes); err != nil {
+				return err
+			}
+		case "config":
+			if err := json.Unmarshal(v, &pw.Config); err != nil {
+				return fmt.Errorf("%v (while parsing 'config')", err)
+			}
+		case "target":
+			if err := json.Unmarshal(v, &pw.Target); err != nil {
+				return fmt.Errorf("%v (while parsing 'target')", err)
+			}
+		default:
+			return fmt.Errorf("Unrecognized key '%v' in process workflow of task.", k)
+		}
+	}
+	return nil
+
+}
+
 func NewProcessNode(name string, version int) *ProcessWorkflowMapNode {
 	p := &ProcessWorkflowMapNode{
 		Name:    name,
@@ -282,6 +373,36 @@ type PublishWorkflowMapNode struct {
 	Target string                 `json:"target"yaml:"target"`
 }
 
+func (pw *PublishWorkflowMapNode) UnmarshalJSON(data []byte) error {
+	t := make(map[string]json.RawMessage)
+	if err := json.Unmarshal(data, &t); err != nil {
+		return err
+	}
+	for k, v := range t {
+		switch k {
+		case "plugin_name":
+			if err := json.Unmarshal(v, &pw.Name); err != nil {
+				return fmt.Errorf("%v (while parsing 'plugin_name')", err)
+			}
+		case "plugin_version":
+			if err := json.Unmarshal(v, &pw.Version); err != nil {
+				return fmt.Errorf("%v (while parsing 'plugin_version')", err)
+			}
+		case "config":
+			if err := json.Unmarshal(v, &pw.Config); err != nil {
+				return fmt.Errorf("%v (while parsing 'config')", err)
+			}
+		case "target":
+			if err := json.Unmarshal(v, &pw.Target); err != nil {
+				return fmt.Errorf("%v (while parsing 'target')", err)
+			}
+		default:
+			return fmt.Errorf("Unrecognized key '%v' in publish workflow of task.", k)
+		}
+	}
+	return nil
+}
+
 func NewPublishNode(name string, version int) *PublishWorkflowMapNode {
 	p := &PublishWorkflowMapNode{
 		Name:    name,
@@ -308,6 +429,24 @@ type metricInfo struct {
 	Version_ int `json:"version"yaml:"version"`
 }
 
+func (m *metricInfo) UnmarshalJSON(data []byte) error {
+	t := make(map[string]json.RawMessage)
+	if err := json.Unmarshal(data, &t); err != nil {
+		return err
+	}
+	for k, v := range t {
+		switch k {
+		case "version":
+			if err := json.Unmarshal(v, &m.Version_); err != nil {
+				return fmt.Errorf("%v (while parsing 'version')", err)
+			}
+		default:
+			return fmt.Errorf("Unrecognized key '%v' in metrics in collect workflow of task", k)
+		}
+	}
+	return nil
+}
+
 type Metric struct {
 	namespace []string
 	version   int