From d9517333b1fc9697d4847df33d3b774f881a111b Mon Sep 17 00:00:00 2001
From: Nikolay Mahotkin <nmakhotkin@mirantis.com>
Date: Tue, 10 Feb 2015 19:45:08 +0300
Subject: [PATCH] Changing InlineYAQLEvaluator: treat only {yaql} as YAQL

 * Fixed unit tests
 * Fixed YAQL regexp
 * Now single expression keeps data type, e.g. {$.num}
   returns numerical data type instead of string.

Change-Id: I2a8d4a1c38b75ce667781ec49702aaf3253e5761
---
 mistral/expressions.py                        | 19 +++-----
 mistral/tests/resources/action_v2.yaml        |  4 +-
 .../resources/control_flow/direct_flow.yaml   |  2 +-
 .../control_flow/one_async_task.yaml          |  2 +-
 .../resources/control_flow/one_std_task.yaml  |  2 +-
 .../resources/control_flow/one_sync_task.yaml |  2 +-
 .../resources/control_flow/require_flow.yaml  |  6 +--
 .../task_with_diamond_dependencies.yaml       | 16 +++----
 .../data_flow/task_with_two_dependencies.yaml | 18 ++++----
 .../data_flow/three_subsequent_tasks.yaml     | 20 ++++----
 .../data_flow/two_dependent_tasks.yaml        | 12 ++---
 .../data_flow/two_subsequent_tasks.yaml       | 14 +++---
 .../resources/openstack/glance_actions.yaml   |  8 ++--
 .../resources/openstack/keystone_actions.yaml |  2 +-
 .../resources/openstack/nova_actions.yaml     | 14 +++---
 .../retry_task/delay_retry_task.yaml          |  2 +-
 .../resources/retry_task/retry_task.yaml      |  4 +-
 .../tests/resources/retry_task/sync_task.yaml |  4 +-
 .../tests/resources/retry_task/two_tasks.yaml |  4 +-
 .../test_direct_flow_all_keywords.yaml        | 10 ++--
 mistral/tests/resources/test_mixed_flow.yaml  | 12 ++---
 mistral/tests/resources/wb_v2.yaml            |  2 +-
 mistral/tests/resources/wf_v2.yaml            |  4 +-
 .../unit/engine/test_data_flow_module.py      |  4 +-
 .../unit/engine1/test_action_defaults.py      | 12 ++---
 .../tests/unit/engine1/test_adhoc_actions.py  |  6 +--
 mistral/tests/unit/engine1/test_commands.py   | 16 +++----
 mistral/tests/unit/engine1/test_dataflow.py   | 18 ++++----
 .../tests/unit/engine1/test_default_engine.py | 10 ++--
 .../tests/unit/engine1/test_environment.py    | 16 +++----
 .../unit/engine1/test_javascript_action.py    |  4 +-
 mistral/tests/unit/engine1/test_join.py       | 44 +++++++++---------
 mistral/tests/unit/engine1/test_noop_task.py  | 12 ++---
 mistral/tests/unit/engine1/test_policies.py   |  6 +--
 .../tests/unit/engine1/test_race_condition.py |  8 ++--
 .../unit/engine1/test_reverse_workflow.py     |  4 +-
 .../tests/unit/engine1/test_subworkflows.py   |  8 ++--
 mistral/tests/unit/engine1/test_with_items.py | 18 ++++----
 .../unit/services/test_workbook_service.py    | 12 ++---
 .../unit/services/test_workflow_service.py    | 10 ++--
 mistral/tests/unit/test_expressions.py        | 46 ++++++++++---------
 .../unit/workbook/v2/test_dsl_specs_v2.py     | 42 ++++++++---------
 .../unit/workflow/test_direct_workflow.py     |  6 +--
 .../tests/unit/workflow/test_with_items.py    |  6 +--
 mistral/workbook/base.py                      |  4 +-
 mistral/workbook/v2/tasks.py                  |  6 ++-
 mistral/workflow/with_items.py                |  4 +-
 47 files changed, 252 insertions(+), 253 deletions(-)

diff --git a/mistral/expressions.py b/mistral/expressions.py
index 376ffa859..e3d98f025 100644
--- a/mistral/expressions.py
+++ b/mistral/expressions.py
@@ -72,16 +72,15 @@ class YAQLEvaluator(Evaluator):
     @classmethod
     def is_expression(cls, s):
         # TODO(rakhmerov): It should be generalized since it may not be YAQL.
-        # If there is at least one dollar sign in the string,
-        # then treat the string as a YAQL expression.
-        return s and '$' in s
+        # Treat any string as a YAQL expression.
+        return isinstance(s, six.string_types)
 
 
 class InlineYAQLEvaluator(YAQLEvaluator):
     # This regular expression will look for multiple occurrences of YAQL
     # expressions in between curly braces (i.e. {any_symbols_except'}'})
     # within a string.
-    regex_yaql_expr = '(\{\.*[^\}]*\}*)'
+    regex_yaql_expr = '(\{[^\s][^}]*\})'
     find_expression_pattern = re.compile(regex_yaql_expr)
 
     @classmethod
@@ -93,19 +92,15 @@ class InlineYAQLEvaluator(YAQLEvaluator):
 
         result = expression
         found_expressions = cls.find_inline_expressions(expression)
-
         if found_expressions:
             for expr in found_expressions:
                 trim_expr = expr.strip("{}")
                 evaluated = super(InlineYAQLEvaluator,
                                   cls).evaluate(trim_expr, data_context)
-                result = result.replace(expr, str(evaluated))
-        else:
-            # If there is no inline YAQL expressions found, then
-            # pass the entire string to the parent YAQL evaluator.
-            if super(InlineYAQLEvaluator, cls).is_expression(expression):
-                return super(InlineYAQLEvaluator,
-                             cls).evaluate(expression, data_context)
+                if len(expression) == len(expr):
+                    result = evaluated
+                else:
+                    result = result.replace(expr, str(evaluated))
 
         LOG.debug("Inline YAQL expression result: %s" % result)
 
diff --git a/mistral/tests/resources/action_v2.yaml b/mistral/tests/resources/action_v2.yaml
index ccca02c4a..6ceaf685e 100644
--- a/mistral/tests/resources/action_v2.yaml
+++ b/mistral/tests/resources/action_v2.yaml
@@ -10,12 +10,12 @@ greeting:
   input:
     - name
   output:
-    string: $.output
+    string: "{$.output}"
 
 farewell:
   base: std.echo
   base-input:
     output: 'Bye!'
   output:
-    info: $.output
+    info: "{$.output}"
 
diff --git a/mistral/tests/resources/control_flow/direct_flow.yaml b/mistral/tests/resources/control_flow/direct_flow.yaml
index 80a66f312..afd014a61 100644
--- a/mistral/tests/resources/control_flow/direct_flow.yaml
+++ b/mistral/tests/resources/control_flow/direct_flow.yaml
@@ -4,7 +4,7 @@ Namespaces:
     base-parameters:
       method: GET
       headers:
-        X-Auth-Token: $.auth_token
+        X-Auth-Token: "{$.auth_token}"
 
     actions:
       async-action:
diff --git a/mistral/tests/resources/control_flow/one_async_task.yaml b/mistral/tests/resources/control_flow/one_async_task.yaml
index dd15c3728..25aa57a5e 100644
--- a/mistral/tests/resources/control_flow/one_async_task.yaml
+++ b/mistral/tests/resources/control_flow/one_async_task.yaml
@@ -4,7 +4,7 @@ Namespaces:
     base-parameters:
       method: GET
       headers:
-        X-Auth-Token: $.auth_token
+        X-Auth-Token: "{$.auth_token}"
 
     actions:
       create-vm:
diff --git a/mistral/tests/resources/control_flow/one_std_task.yaml b/mistral/tests/resources/control_flow/one_std_task.yaml
index c93a10e6a..073c3a95d 100644
--- a/mistral/tests/resources/control_flow/one_std_task.yaml
+++ b/mistral/tests/resources/control_flow/one_std_task.yaml
@@ -6,7 +6,7 @@ Namespaces:
         base-parameters:
           url: http://path_to_nova/url_for_create
         output:
-          vm_id: $.base_output.server_id
+          vm_id: "{$.base_output.server_id}"
 
 Workflow:
   tasks:
diff --git a/mistral/tests/resources/control_flow/one_sync_task.yaml b/mistral/tests/resources/control_flow/one_sync_task.yaml
index d93c3ded6..ec36ba8e4 100644
--- a/mistral/tests/resources/control_flow/one_sync_task.yaml
+++ b/mistral/tests/resources/control_flow/one_sync_task.yaml
@@ -9,7 +9,7 @@ Namespaces:
           - left
           - right
         output:
-          string: $.output
+          string: "{$.output}"
 
 Workflow:
   tasks:
diff --git a/mistral/tests/resources/control_flow/require_flow.yaml b/mistral/tests/resources/control_flow/require_flow.yaml
index 3d4df4f5b..e172e86d0 100644
--- a/mistral/tests/resources/control_flow/require_flow.yaml
+++ b/mistral/tests/resources/control_flow/require_flow.yaml
@@ -9,13 +9,13 @@ Namespaces:
           - left
           - right
         output:
-          string: $.output
+          string: "{$.output}"
       start:
         class: std.echo
         base-parameters:
           output: 'Starting...'
         output:
-          info: $.output
+          info: "{$.output}"
 
 Workflow:
   tasks:
@@ -31,4 +31,4 @@ Workflow:
       action: MyActions.concat
       parameters:
         left: Greetings
-        right: {$.string}
+        right: "{$.string}"
diff --git a/mistral/tests/resources/data_flow/task_with_diamond_dependencies.yaml b/mistral/tests/resources/data_flow/task_with_diamond_dependencies.yaml
index 8f15a5367..5d44c5cec 100644
--- a/mistral/tests/resources/data_flow/task_with_diamond_dependencies.yaml
+++ b/mistral/tests/resources/data_flow/task_with_diamond_dependencies.yaml
@@ -12,7 +12,7 @@ Namespaces:
           - left
           - right
         output:
-          string: $
+          string: "{$}"
 
 Workflow:
   #  context = {
@@ -31,28 +31,28 @@ Workflow:
     build_full_name:
       action: MyService.concat
       parameters:
-        left: $.person.first_name
-        right: $.person.last_name
+        left: "{$.person.first_name}"
+        right: "{$.person.last_name}"
       publish:
-        full_name: $.string
+        full_name: "{$.string}"
 
     build_greeting:
       requires: [build_full_name]
       action: MyService.concat
       parameters:
         left: Dear
-        right: $.full_name
+        right: "{$.full_name}"
       publish:
-        greeting: $.string
+        greeting: "{$.string}"
 
     build_address:
       requires: [build_full_name]
       action: MyService.concat
       parameters:
         left: To
-        right: $.full_name
+        right: "{$.full_name}"
       publish:
-        address: $.string
+        address: "{$.string}"
 
     send_greeting:
       requires: [build_address, build_greeting]
diff --git a/mistral/tests/resources/data_flow/task_with_two_dependencies.yaml b/mistral/tests/resources/data_flow/task_with_two_dependencies.yaml
index 337c8ad1a..0fa0a9dcc 100644
--- a/mistral/tests/resources/data_flow/task_with_two_dependencies.yaml
+++ b/mistral/tests/resources/data_flow/task_with_two_dependencies.yaml
@@ -12,14 +12,14 @@ Namespaces:
           - first_name
           - last_name
         output:
-          full_name: $
+          full_name: "{$}"
 
       build_greeting:
         class: std.echo
         base-parameters:
           output: Cheers!
         output:
-          greeting: $
+          greeting: "{$}"
 
       send_greeting:
         class: std.echo
@@ -29,7 +29,7 @@ Namespaces:
           - f_name
           - greet_msg
         output:
-          greeting_sent: $
+          greeting_sent: "{$}"
 
 Workflow:
   #  context = {
@@ -48,20 +48,20 @@ Workflow:
     build_full_name:
       action: MyService.build_full_name
       parameters:
-        first_name: $.person.first_name
-        last_name: $.person.last_name
+        first_name: "{$.person.first_name}"
+        last_name: "{$.person.last_name}"
       publish:
-        f_name: $.full_name
+        f_name: "{$.full_name}"
 
     build_greeting:
       requires: [build_full_name]
       action: MyService.build_greeting
       publish:
-        greet_msg: $.greeting
+        greet_msg: "{$.greeting}"
 
     send_greeting:
       requires: [build_full_name, build_greeting]
       action: MyService.send_greeting
       parameters:
-        f_name: $.f_name
-        greet_msg: $.greet_msg
+        f_name: "{$.f_name}"
+        greet_msg: "{$.greet_msg}"
diff --git a/mistral/tests/resources/data_flow/three_subsequent_tasks.yaml b/mistral/tests/resources/data_flow/three_subsequent_tasks.yaml
index c7a1874d4..d3b2e1ea6 100644
--- a/mistral/tests/resources/data_flow/three_subsequent_tasks.yaml
+++ b/mistral/tests/resources/data_flow/three_subsequent_tasks.yaml
@@ -12,7 +12,7 @@ Namespaces:
           - first_name
           - last_name
         output:
-          full_name: $
+          full_name: "{$}"
 
       build_greeting:
         class: std.echo
@@ -21,7 +21,7 @@ Namespaces:
         parameters:
           - full_name
         output:
-          greeting: $
+          greeting: "{$}"
 
       send_greeting:
         class: std.echo
@@ -30,7 +30,7 @@ Namespaces:
         parameters:
           - greeting
         output:
-          greeting_sent: $
+          greeting_sent: "{$}"
 
 
 Workflow:
@@ -50,23 +50,23 @@ Workflow:
     build_full_name:
       action: MyService.build_full_name
       parameters:
-        first_name: $.person.first_name
-        last_name: $.person.last_name
+        first_name: "{$.person.first_name}"
+        last_name: "{$.person.last_name}"
       publish:
-        f_name: $.full_name
+        f_name: "{$.full_name}"
       on-success: build_greeting
 
     build_greeting:
       action: MyService.build_greeting
       parameters:
-        full_name: $.f_name
+        full_name: "{$.f_name}"
       publish:
-        greet_msg: $.greeting
+        greet_msg: "{$.greeting}"
       on-success: send_greeting
 
     send_greeting:
       action: MyService.send_greeting
       parameters:
-        greeting: $.task.build_greeting.greeting
+        greeting: "{$.task.build_greeting.greeting}"
       publish:
-        sent: $.greeting_sent
+        sent: "{$.greeting_sent}"
diff --git a/mistral/tests/resources/data_flow/two_dependent_tasks.yaml b/mistral/tests/resources/data_flow/two_dependent_tasks.yaml
index d32c6ead6..a6d2e9c61 100644
--- a/mistral/tests/resources/data_flow/two_dependent_tasks.yaml
+++ b/mistral/tests/resources/data_flow/two_dependent_tasks.yaml
@@ -12,7 +12,7 @@ Namespaces:
           - first_name
           - last_name
         output:
-          full_name: $
+          full_name: "{$}"
 
       build_greeting:
         class: std.echo
@@ -21,7 +21,7 @@ Namespaces:
         parameters:
           - full_name
         output:
-          greeting: $
+          greeting: "{$}"
 
 
 Workflow:
@@ -41,13 +41,13 @@ Workflow:
     build_full_name:
       action: MyService.build_full_name
       parameters:
-        first_name: $.person.first_name
-        last_name: $.person.last_name
+        first_name: "{$.person.first_name}"
+        last_name: "{$.person.last_name}"
       publish:
-        f_name: $.full_name
+        f_name: "{$.full_name}"
 
     build_greeting:
       requires: [build_full_name]
       action: MyService.build_greeting
       parameters:
-        full_name: $.f_name
+        full_name: "{$.f_name}"
diff --git a/mistral/tests/resources/data_flow/two_subsequent_tasks.yaml b/mistral/tests/resources/data_flow/two_subsequent_tasks.yaml
index 3a7b99c9d..affcc241b 100644
--- a/mistral/tests/resources/data_flow/two_subsequent_tasks.yaml
+++ b/mistral/tests/resources/data_flow/two_subsequent_tasks.yaml
@@ -12,7 +12,7 @@ Namespaces:
           - first_name
           - last_name
         output:
-          full_name: $
+          full_name: "{$}"
 
       build_greeting:
         class: std.echo
@@ -22,7 +22,7 @@ Namespaces:
           - full_name
         output:
           greeting:
-            greet_message: $
+            greet_message: "{$}"
 
 
 Workflow:
@@ -42,15 +42,15 @@ Workflow:
     build_full_name:
       action: MyService.build_full_name
       parameters:
-        first_name: $.person.first_name
-        last_name: $.person.last_name
+        first_name: "{$.person.first_name}"
+        last_name: "{$.person.last_name}"
       publish:
-        f_name: $.full_name
+        f_name: "{$.full_name}"
       on-success: build_greeting
 
     build_greeting:
       action: MyService.build_greeting
       parameters:
-        full_name: $.f_name
+        full_name: "{$.f_name}"
       publish:
-        greet_msg: $.greeting
+        greet_msg: "{$.greeting}"
diff --git a/mistral/tests/resources/openstack/glance_actions.yaml b/mistral/tests/resources/openstack/glance_actions.yaml
index 724d66897..b1472f437 100644
--- a/mistral/tests/resources/openstack/glance_actions.yaml
+++ b/mistral/tests/resources/openstack/glance_actions.yaml
@@ -3,13 +3,13 @@ Workflow:
     image_list:
       action: glance.images_list
       publish:
-        image_id: $[0].id
+        image_id: "{$[0].id}"
       on-success: image_get
 
     image_get:
       action: glance.images_get
       parameters:
-        image_id: $.image_id
+        image_id: "{$.image_id}"
       publish:
-        image_id: $.id
-        image_name: $.name
\ No newline at end of file
+        image_id: "{$.id}"
+        image_name: "{$.name}"
\ No newline at end of file
diff --git a/mistral/tests/resources/openstack/keystone_actions.yaml b/mistral/tests/resources/openstack/keystone_actions.yaml
index 1189017de..8fb5b316f 100644
--- a/mistral/tests/resources/openstack/keystone_actions.yaml
+++ b/mistral/tests/resources/openstack/keystone_actions.yaml
@@ -3,4 +3,4 @@ Workflow:
     get_some_endpoint:
       action: keystone.service_catalog_get_data
       publish:
-        endpoint_url: $[0].endpoints[0].url
+        endpoint_url: "{$[0].endpoints[0].url}"
diff --git a/mistral/tests/resources/openstack/nova_actions.yaml b/mistral/tests/resources/openstack/nova_actions.yaml
index b0be48e70..b670f34ba 100644
--- a/mistral/tests/resources/openstack/nova_actions.yaml
+++ b/mistral/tests/resources/openstack/nova_actions.yaml
@@ -3,17 +3,17 @@ Workflow:
     server_create:
       action: nova.servers_create
       parameters:
-        name: $.server_name
-        image: $.image_ref
-        flavor: $.flavor_ref
+        name: "{$.server_name}"
+        image: "{$.image_ref}"
+        flavor: "{$.flavor_ref}"
       publish:
-        server_id: $.id
+        server_id: "{$.id}"
       on-success: check_server_exists
 
     check_server_exists:
       action: nova.servers_get
       parameters:
-        server: $.server_id
+        server: "{$.server_id}"
       publish:
         server_exists: True
       on-success:
@@ -25,7 +25,7 @@ Workflow:
         delay: 5
         count: 15
       parameters:
-        id: $.server_id
+        id: "{$.server_id}"
         status: 'ACTIVE'
       publish:
-        instance_id: $.id
+        instance_id: "{$.id}"
diff --git a/mistral/tests/resources/retry_task/delay_retry_task.yaml b/mistral/tests/resources/retry_task/delay_retry_task.yaml
index 350dbd653..6ccb3b8d4 100644
--- a/mistral/tests/resources/retry_task/delay_retry_task.yaml
+++ b/mistral/tests/resources/retry_task/delay_retry_task.yaml
@@ -7,7 +7,7 @@ Namespaces:
           url: http://path_to_service/action_url
           method: GET
         output:
-          output: $
+          output: "{$}"
 
 Workflow:
   tasks:
diff --git a/mistral/tests/resources/retry_task/retry_task.yaml b/mistral/tests/resources/retry_task/retry_task.yaml
index 0e248eb3f..10ca322a9 100644
--- a/mistral/tests/resources/retry_task/retry_task.yaml
+++ b/mistral/tests/resources/retry_task/retry_task.yaml
@@ -7,7 +7,7 @@ Namespaces:
           url: http://path_to_service/action_url
           method: GET
         output:
-          output: $
+          output: "{$}"
 
 Workflow:
   tasks:
@@ -16,4 +16,4 @@ Workflow:
       retry:
         count: 5
       publish:
-        rt_output: $.output
+        rt_output: "{$.output}"
diff --git a/mistral/tests/resources/retry_task/sync_task.yaml b/mistral/tests/resources/retry_task/sync_task.yaml
index 8ca213f3c..beeaf36c3 100644
--- a/mistral/tests/resources/retry_task/sync_task.yaml
+++ b/mistral/tests/resources/retry_task/sync_task.yaml
@@ -6,7 +6,7 @@ Namespaces:
         base-parameters:
           output: Cheers!
         output:
-          greeting: $
+          greeting: "{$}"
 
 Workflow:
   tasks:
@@ -15,4 +15,4 @@ Workflow:
       retry:
         count: 5
       publish:
-        st_output: $.greeting
\ No newline at end of file
+        st_output: "{$.greeting}"
\ No newline at end of file
diff --git a/mistral/tests/resources/retry_task/two_tasks.yaml b/mistral/tests/resources/retry_task/two_tasks.yaml
index d82b72de8..b00bdb573 100644
--- a/mistral/tests/resources/retry_task/two_tasks.yaml
+++ b/mistral/tests/resources/retry_task/two_tasks.yaml
@@ -7,14 +7,14 @@ Namespaces:
           url: http://path_to_service/action_url
           method: GET
         output:
-          output: $
+          output: "{$}"
 
 Workflow:
   tasks:
     no_retry_task:
       action: MyService.some-action
       publish:
-        n_rt_output: $.output
+        n_rt_output: "{$.output}"
       on-success: delay_retry_task
 
     delay_retry_task:
diff --git a/mistral/tests/resources/test_direct_flow_all_keywords.yaml b/mistral/tests/resources/test_direct_flow_all_keywords.yaml
index 7ea485f92..47a2a59a5 100644
--- a/mistral/tests/resources/test_direct_flow_all_keywords.yaml
+++ b/mistral/tests/resources/test_direct_flow_all_keywords.yaml
@@ -4,7 +4,7 @@ Namespaces:
     base-parameters:
       method: GET
       headers:
-        X-Auth-Token: $.auth_token
+        X-Auth-Token: "{$.auth_token}"
 
     actions:
       create-vm:
@@ -26,7 +26,7 @@ Namespaces:
           - left
           - right
         output:
-          string: $
+          string: "{$}"
 
 Workflow:
   tasks:
@@ -43,7 +43,7 @@ Workflow:
         left: workflow
         right: is
       publish:
-        result2: $.string 
+        result2: "{$.string}"
       on-finish: task3
 
     task3:
@@ -56,8 +56,8 @@ Workflow:
     task4:
       action: Echo.concat
       parameters:
-        left: $.result2
+        left: "{$.result2}"
         right: complete!
       publish:
-        result4: $.string
+        result4: "{$.string}"
 
diff --git a/mistral/tests/resources/test_mixed_flow.yaml b/mistral/tests/resources/test_mixed_flow.yaml
index 8e54838ef..8088888fd 100644
--- a/mistral/tests/resources/test_mixed_flow.yaml
+++ b/mistral/tests/resources/test_mixed_flow.yaml
@@ -9,7 +9,7 @@ Namespaces:
           - left
           - right
         output:
-          string: $
+          string: "{$}"
 
 Workflow:
   tasks:
@@ -19,22 +19,22 @@ Workflow:
         left: workflow
         right: is
       publish:
-        result1: $.string
+        result1: "{$.string}"
 
     task2:
       requires: [task1]
       action: MyService.concat
       parameters:
-        left: $.result1
+        left: "{$.result1}"
         right:  complete
       publish:
-        result2: $.string
+        result2: "{$.string}"
       on-success: task3
 
     task3:
       action: MyService.concat
       parameters:
-        left: $.result2
+        left: "{$.result2}"
         right: '!'
       publish:
-        result3: $.string
+        result3: "{$.string}"
diff --git a/mistral/tests/resources/wb_v2.yaml b/mistral/tests/resources/wb_v2.yaml
index c4640d214..a9ce8ae28 100644
--- a/mistral/tests/resources/wb_v2.yaml
+++ b/mistral/tests/resources/wb_v2.yaml
@@ -10,4 +10,4 @@ workflows:
       hello:
         action: std.echo output="Hello"
         publish:
-           result: {$.hello}
+           result: "{$.hello}"
diff --git a/mistral/tests/resources/wf_v2.yaml b/mistral/tests/resources/wf_v2.yaml
index c736cecba..c87fa13e1 100644
--- a/mistral/tests/resources/wf_v2.yaml
+++ b/mistral/tests/resources/wf_v2.yaml
@@ -10,7 +10,7 @@ wf:
       policies:
         wait-before: 1
       publish:
-        result: {$.hello}
+        result: "{$.hello}"
 
 wf1:
   type: reverse
@@ -21,7 +21,7 @@ wf1:
     addressee:
       action: std.echo output="John"
       publish:
-        name: $.adressee
+        name: "{$.adressee}"
 
     goodbye:
       action: std.echo output="{$.farewell}, {$.name}"
diff --git a/mistral/tests/unit/engine/test_data_flow_module.py b/mistral/tests/unit/engine/test_data_flow_module.py
index 314338f32..ffb60ddca 100644
--- a/mistral/tests/unit/engine/test_data_flow_module.py
+++ b/mistral/tests/unit/engine/test_data_flow_module.py
@@ -46,11 +46,11 @@ TASK = {
         'action': 'std.echo',
         'parameters': {
             'p1': 'My string',
-            'p2': '$.param3.param32',
+            'p2': '{$.param3.param32}',
             'p3': ''
         },
         'publish': {
-            'new_key11': '$.new_key1'
+            'new_key11': '{$.new_key1}'
         }
     },
     'in_context': CONTEXT
diff --git a/mistral/tests/unit/engine1/test_action_defaults.py b/mistral/tests/unit/engine1/test_action_defaults.py
index 04a9cb4f3..e08dae274 100644
--- a/mistral/tests/unit/engine1/test_action_defaults.py
+++ b/mistral/tests/unit/engine1/test_action_defaults.py
@@ -52,7 +52,7 @@ wf1:
     task1:
       action: std.http url="https://api.library.org/books"
       publish:
-        result: $
+        result: "{$}"
 """
 
 WORKFLOW2 = """
@@ -64,7 +64,7 @@ wf2:
     task1:
       action: std.http url="https://api.library.org/books" timeout=60
       publish:
-        result: $
+        result: "{$}"
 """
 
 WORKFLOW1_WITH_ITEMS = """
@@ -76,10 +76,10 @@ wf1_with_items:
     - links
   tasks:
     task1:
-      with-items: link in $.links
+      with-items: link in {$.links}
       action: std.http url={$.link}
       publish:
-        result: $
+        result: "{$}"
 """
 
 WORKFLOW2_WITH_ITEMS = """
@@ -91,10 +91,10 @@ wf2_with_items:
     - links
   tasks:
     task1:
-      with-items: link in $.links
+      with-items: link in {$.links}
       action: std.http url={$.link} timeout=60
       publish:
-        result: $
+        result: "{$}"
 """
 
 
diff --git a/mistral/tests/unit/engine1/test_adhoc_actions.py b/mistral/tests/unit/engine1/test_adhoc_actions.py
index ef39fc9ca..21ef2b5e3 100644
--- a/mistral/tests/unit/engine1/test_adhoc_actions.py
+++ b/mistral/tests/unit/engine1/test_adhoc_actions.py
@@ -49,14 +49,14 @@ workflows:
       - str1
       - str2
     output:
-      workflow_result: $.result # Access to execution context variables
-      concat_task_result: $.concat # Access to the same but via task name
+      workflow_result: "{$.result}" # Access to execution context variables
+      concat_task_result: "{$.concat}" # Access to the same but via task name
 
     tasks:
       concat:
         action: concat_twice s1={$.str1} s2={$.str2}
         publish:
-          result: $.concat
+          result: "{$.concat}"
 """
 
 
diff --git a/mistral/tests/unit/engine1/test_commands.py b/mistral/tests/unit/engine1/test_commands.py
index ccd9d4063..e94072ab9 100644
--- a/mistral/tests/unit/engine1/test_commands.py
+++ b/mistral/tests/unit/engine1/test_commands.py
@@ -43,9 +43,9 @@ workflows:
       task1:
         action: std.echo output='1'
         on-complete:
-          - fail: $.my_var = 1
-          - succeed: $.my_var = 2
-          - pause: $.my_var = 3
+          - fail: "{$.my_var = 1}"
+          - succeed: "{$.my_var = 2}"
+          - pause: "{$.my_var = 3}"
           - task2
 
       task2:
@@ -116,11 +116,11 @@ workflows:
 
     task-defaults:
       on-complete:
-        - fail: $.my_var = 1
-        - succeed: $.my_var = 2
-        - pause: $.my_var = 3
-        - rollback: $.my_var = 3
-        - task2: $.my_var = 4 # (Never happens in this test)
+        - fail: "{$.my_var = 1}"
+        - succeed: "{$.my_var = 2}"
+        - pause: "{$.my_var = 3}"
+        - rollback: "{$.my_var = 3}"
+        - task2: "{$.my_var = 4}" # (Never happens in this test)
 
     tasks:
       task1:
diff --git a/mistral/tests/unit/engine1/test_dataflow.py b/mistral/tests/unit/engine1/test_dataflow.py
index c25e8fd81..3d0ac4350 100644
--- a/mistral/tests/unit/engine1/test_dataflow.py
+++ b/mistral/tests/unit/engine1/test_dataflow.py
@@ -43,14 +43,14 @@ wf:
     task1:
       action: std.echo output="Hi"
       publish:
-        hi: $.task1
+        hi: "{$.task1}"
       on-success:
         - task2
 
     task2:
       action: std.echo output="Morpheus"
       publish:
-        to: $.task2
+        to: "{$.task2}"
       on-success:
         - task3
 
@@ -70,12 +70,12 @@ wf:
     task1:
       action: std.echo output=1
       publish:
-        var1: $.task1
+        var1: "{$.task1}"
 
     task2:
       action: std.echo output=2
       publish:
-        var2: $.task2
+        var2: "{$.task2}"
 """
 
 VAR_OVERWRITE_WF = """
@@ -89,21 +89,21 @@ wf:
     task1:
       action: std.echo output="Hi"
       publish:
-        greeting: $.task1
+        greeting: "{$.task1}"
       on-success:
         - task2
 
     task2:
       action: std.echo output="Yo"
       publish:
-        greeting: $.task2
+        greeting: "{$.task2}"
       on-success:
         - task3
 
     task3:
       action: std.echo output="Morpheus"
       publish:
-        to: $.task3
+        to: "{$.task3}"
       on-success:
         - task4
 
@@ -247,7 +247,7 @@ class DataFlowTest(test_base.BaseTest):
 
         publish = {
             'v': '{$.var}',
-            'e': '$.__env.ekey',
+            'e': '{$.__env.ekey}',
             'a': '{$.task1.akey}'
         }
 
@@ -279,7 +279,7 @@ class DataFlowTest(test_base.BaseTest):
 
         Expected to get action error.
         """
-        publish = {'foo': '$.akey'}
+        publish = {'foo': '{$.akey}'}
         action_output = 'error data'
 
         task_db = models.Task(name='task1')
diff --git a/mistral/tests/unit/engine1/test_default_engine.py b/mistral/tests/unit/engine1/test_default_engine.py
index 6d21a2501..d77ffc99a 100644
--- a/mistral/tests/unit/engine1/test_default_engine.py
+++ b/mistral/tests/unit/engine1/test_default_engine.py
@@ -54,7 +54,7 @@ workflows:
       task1:
         action: std.echo output="{$.param1}"
         publish:
-            result: $.task1
+            result: "{$.task1}"
 
       task2:
         action: std.echo output="{$.param2}"
@@ -139,7 +139,7 @@ class DefaultEngineTest(base.DbTestCase):
         self.assertDictEqual({'output': 'Hey'}, task_db.input)
 
     def test_start_workflow_with_adhoc_env(self):
-        wf_input = {'param1': '$.__env.key1', 'param2': '$.__env.key2'}
+        wf_input = {'param1': '{$.__env.key1}', 'param2': '{$.__env.key2}'}
         env = ENVIRONMENT['variables']
 
         # Start workflow.
@@ -157,7 +157,7 @@ class DefaultEngineTest(base.DbTestCase):
 
     @mock.patch.object(db_api, "get_environment", MOCK_ENVIRONMENT)
     def test_start_workflow_with_saved_env(self):
-        wf_input = {'param1': '$.__env.key1', 'param2': '$.__env.key2'}
+        wf_input = {'param1': '{$.__env.key1}', 'param2': '{$.__env.key2}'}
         env = ENVIRONMENT['variables']
 
         # Start workflow.
@@ -178,7 +178,7 @@ class DefaultEngineTest(base.DbTestCase):
         self.assertRaises(exc.NotFoundException,
                           self.engine.start_workflow,
                           'wb.wf1',
-                          {'param1': '$.__env.key1'},
+                          {'param1': '{$.__env.key1}'},
                           env='foo',
                           task_name='task2')
 
@@ -186,7 +186,7 @@ class DefaultEngineTest(base.DbTestCase):
         self.assertRaises(ValueError,
                           self.engine.start_workflow,
                           'wb.wf1',
-                          {'param1': '$.__env.key1'},
+                          {'param1': '{$.__env.key1}'},
                           env=True,
                           task_name='task2')
 
diff --git a/mistral/tests/unit/engine1/test_environment.py b/mistral/tests/unit/engine1/test_environment.py
index 8366fb0ba..969d756a7 100644
--- a/mistral/tests/unit/engine1/test_environment.py
+++ b/mistral/tests/unit/engine1/test_environment.py
@@ -46,34 +46,34 @@ workflows:
       - param2
 
     output:
-      final_result: $.final_result
+      final_result: "{$.final_result}"
 
     tasks:
       task1:
         action: std.echo output='{$.param1}'
-        target: $.__env.var1
+        target: "{$.__env.var1}"
         publish:
-          result1: $.task1
+          result1: "{$.task1}"
 
       task2:
         requires: [task1]
         action: std.echo output="'{$.result1} & {$.param2}'"
-        target: $.__env.var1
+        target: "{$.__env.var1}"
         publish:
-          final_result: $.task2
+          final_result: "{$.task2}"
 
   wf2:
     type: direct
 
     output:
-      slogan: $.slogan
+      slogan: "{$.slogan}"
 
     tasks:
       task1:
         workflow: wf1
         input:
-          param1: $.__env.var2
-          param2: $.__env.var3
+          param1: "{$.__env.var2}"
+          param2: "{$.__env.var3}"
           task_name: task2
         publish:
           slogan: "{$.task1.final_result} is a cool {$.__env.var4}!"
diff --git a/mistral/tests/unit/engine1/test_javascript_action.py b/mistral/tests/unit/engine1/test_javascript_action.py
index c867905a6..63c8ff691 100644
--- a/mistral/tests/unit/engine1/test_javascript_action.py
+++ b/mistral/tests/unit/engine1/test_javascript_action.py
@@ -53,10 +53,10 @@ workflows:
           # Skip this '$' sign until bug
           # https://bugs.launchpad.net/mistral/+bug/1415886 is resolved.
           # return $['num'] * 10
-          context: $
+          context: "{$}"
 
         publish:
-          result: $.task1
+          result: "{$.task1}"
 
 """
 
diff --git a/mistral/tests/unit/engine1/test_join.py b/mistral/tests/unit/engine1/test_join.py
index 15ff8f5dd..8e14ec822 100644
--- a/mistral/tests/unit/engine1/test_join.py
+++ b/mistral/tests/unit/engine1/test_join.py
@@ -33,20 +33,20 @@ wf:
   type: direct
 
   output:
-    result: $.result3
+    result: "{$.result3}"
 
   tasks:
     task1:
       action: std.echo output=1
       publish:
-        result1: $.task1
+        result1: "{$.task1}"
       on-complete:
         - task3
 
     task2:
       action: std.echo output=2
       publish:
-        result2: $.task2
+        result2: "{$.task2}"
       on-complete:
         - task3
 
@@ -54,7 +54,7 @@ wf:
       join: all
       action: std.echo output="{$.result1},{$.result2}"
       publish:
-        result3: $.task3
+        result3: "{$.task3}"
 """
 
 
@@ -66,13 +66,13 @@ wf:
   type: direct
 
   output:
-    result: $.result3
+    result: "{$.result3}"
 
   tasks:
     task1:
       action: std.echo output=1
       publish:
-        result1: $.task1
+        result1: "{$.task1}"
       on-complete:
         - task3
 
@@ -85,7 +85,7 @@ wf:
       join: all
       action: std.echo output="{$.result1}-{$.result1}"
       publish:
-        result3: $.task3
+        result3: "{$.task3}"
 """
 
 WF_FULL_JOIN_WITH_CONDITIONS = """
@@ -96,34 +96,34 @@ wf:
   type: direct
 
   output:
-    result: $.result4
+    result: "{$.result4}"
 
   tasks:
     task1:
       action: std.echo output=1
       publish:
-        result1: $.task1
+        result1: "{$.task1}"
       on-complete:
         - task3
 
     task2:
       action: std.echo output=2
       publish:
-        result2: $.task2
+        result2: "{$.task2}"
       on-complete:
-        - task3: $.result2 = 11111
-        - task4: $.result2 = 2
+        - task3: "{$.result2 = 11111}"
+        - task4: "{$.result2 = 2}"
 
     task3:
       join: all
       action: std.echo output="{$.result1}-{$.result1}"
       publish:
-        result3: $.task3
+        result3: "{$.task3}"
 
     task4:
       action: std.echo output=4
       publish:
-        result4: $.task4
+        result4: "{$.task4}"
 """
 
 WF_PARTIAL_JOIN = """
@@ -134,20 +134,20 @@ wf:
   type: direct
 
   output:
-    result: $.result4
+    result: "{$.result4}"
 
   tasks:
     task1:
       action: std.echo output=1
       publish:
-        result1: $.task1
+        result1: "{$.task1}"
       on-complete:
         - task4
 
     task2:
       action: std.echo output=2
       publish:
-        result2: $.task2
+        result2: "{$.task2}"
       on-complete:
         - task4
 
@@ -167,7 +167,7 @@ wf:
       join: 2
       action: std.echo output="{$.result1},{$.result2}"
       publish:
-        result4: $.task4
+        result4: "{$.task4}"
 """
 
 WF_PARTIAL_JOIN_TRIGGERS_ONCE = """
@@ -178,7 +178,7 @@ wf:
   type: direct
 
   output:
-    result: $.result4
+    result: "{$.result4}"
 
   tasks:
     task1:
@@ -213,7 +213,7 @@ wf:
       join: 2
       action: std.echo output="{$.result1},{$.result2},{$.result3},{$.result4}"
       publish:
-        result5: $.task5
+        result5: "{$.task5}"
 """
 
 WF_DISCRIMINATOR = """
@@ -224,7 +224,7 @@ wf:
   type: direct
 
   output:
-    result: $.result4
+    result: "{$.result4}"
 
   tasks:
     task1:
@@ -252,7 +252,7 @@ wf:
       join: one
       action: std.echo output="{$.result1},{$.result2},{$.result3}"
       publish:
-        result4: $.task4
+        result4: "{$.task4}"
 """
 
 
diff --git a/mistral/tests/unit/engine1/test_noop_task.py b/mistral/tests/unit/engine1/test_noop_task.py
index 072c1e00b..8cfa1d095 100644
--- a/mistral/tests/unit/engine1/test_noop_task.py
+++ b/mistral/tests/unit/engine1/test_noop_task.py
@@ -43,14 +43,14 @@ wf:
     task1:
       action: std.echo output={$.num1}
       publish:
-        result1: $.task1
+        result1: "{$.task1}"
       on-complete:
         - task3
 
     task2:
       action: std.echo output={$.num2}
       publish:
-        result2: $.task2
+        result2: "{$.task2}"
       on-complete:
         - task3
 
@@ -60,18 +60,18 @@ wf:
         task and serves just a decision point in the workflow.
       join: all
       on-complete:
-        - task4: $.num1 + $.num2 = 2
-        - task5: $.num1 + $.num2 = 3
+        - task4: "{$.num1 + $.num2 = 2}"
+        - task5: "{$.num1 + $.num2 = 3}"
 
     task4:
       action: std.echo output=4
       publish:
-        result4: $.task4
+        result4: "{$.task4}"
 
     task5:
       action: std.echo output=5
       publish:
-        result5: $.task5
+        result5: "{$.task5}"
 """
 
 
diff --git a/mistral/tests/unit/engine1/test_policies.py b/mistral/tests/unit/engine1/test_policies.py
index 2b5b61a35..2e6e0ec51 100644
--- a/mistral/tests/unit/engine1/test_policies.py
+++ b/mistral/tests/unit/engine1/test_policies.py
@@ -48,7 +48,7 @@ workflows:
           retry:
             count: 5
             delay: 10
-            break-on: $.my_val = 10
+            break-on: "{$.my_val = 10}"
 """
 
 
@@ -133,7 +133,7 @@ workflows:
           retry:
             count: 3
             delay: 1
-            break-on: $.my_val = 10
+            break-on: "{$.my_val = 10}"
 """
 
 
@@ -248,7 +248,7 @@ class PoliciesTest(base.EngineTestCase):
 
         self.assertIsInstance(p, policies.RetryPolicy)
         self.assertEqual(5, p.count)
-        self.assertEqual('$.my_val = 10', p.break_on)
+        self.assertEqual('{$.my_val = 10}', p.break_on)
 
         p = self._assert_single_item(arr, delay=7)
 
diff --git a/mistral/tests/unit/engine1/test_race_condition.py b/mistral/tests/unit/engine1/test_race_condition.py
index b85ac7b71..09838cc9b 100644
--- a/mistral/tests/unit/engine1/test_race_condition.py
+++ b/mistral/tests/unit/engine1/test_race_condition.py
@@ -43,13 +43,13 @@ wf:
     method. And we need to check that engine handles this situation.
 
   output:
-    result: $.result
+    result: "{$.result}"
 
   tasks:
     task1:
       action: std.block
       publish:
-        result: $.task1
+        result: "{$.task1}"
 """
 
 WF_SHORT_ACTION = """
@@ -73,13 +73,13 @@ wf:
     methods ends.
 
   output:
-    result: $.result
+    result: "{$.result}"
 
   tasks:
     task1:
       action: std.echo output=1
       publish:
-        result1: $.task1
+        result1: "{$.task1}"
 
     task2:
       action: std.block
diff --git a/mistral/tests/unit/engine1/test_reverse_workflow.py b/mistral/tests/unit/engine1/test_reverse_workflow.py
index 139a0cea9..227fb69ab 100644
--- a/mistral/tests/unit/engine1/test_reverse_workflow.py
+++ b/mistral/tests/unit/engine1/test_reverse_workflow.py
@@ -44,12 +44,12 @@ workflows:
       task1:
         action: std.echo output='{$.param1}'
         publish:
-          result1: $.task1
+          result1: "{$.task1}"
 
       task2:
         action: std.echo output="{$.result1} & {$.param2}"
         publish:
-          result2: $.task2
+          result2: "{$.task2}"
         requires: [task1]
 """
 
diff --git a/mistral/tests/unit/engine1/test_subworkflows.py b/mistral/tests/unit/engine1/test_subworkflows.py
index 9e7b50f72..9bacdbec6 100644
--- a/mistral/tests/unit/engine1/test_subworkflows.py
+++ b/mistral/tests/unit/engine1/test_subworkflows.py
@@ -44,24 +44,24 @@ workflows:
       - param1
       - param2
     output:
-      final_result: $.final_result
+      final_result: "{$.final_result}"
 
     tasks:
       task1:
         action: std.echo output='{$.param1}'
         publish:
-          result1: $.task1
+          result1: "{$.task1}"
 
       task2:
         action: std.echo output="'{$.param1} & {$.param2}'"
         publish:
-          final_result: $.task2
+          final_result: "{$.task2}"
         requires: [task1]
 
   wf2:
     type: direct
     output:
-      slogan: $.slogan
+      slogan: "{$.slogan}"
 
     tasks:
       task1:
diff --git a/mistral/tests/unit/engine1/test_with_items.py b/mistral/tests/unit/engine1/test_with_items.py
index 3ebcc7e5f..aca92f337 100644
--- a/mistral/tests/unit/engine1/test_with_items.py
+++ b/mistral/tests/unit/engine1/test_with_items.py
@@ -45,10 +45,10 @@ workflows:
 
     tasks:
       task1:
-        with-items: name_info in $.names_info
+        with-items: name_info in {$.names_info}
         action: std.echo output={$.name_info.name}
         publish:
-          result: $.task1
+          result: "{$.task1}"
 
 """
 
@@ -68,10 +68,10 @@ workflows:
 
     tasks:
       task1:
-        with-items: name_info in $.names_info
+        with-items: name_info in {$.names_info}
         action: std.echo output="{$.greeting}, {$.name_info.name}!"
         publish:
-          result: $.task1
+          result: "{$.task1}"
 """
 
 
@@ -92,11 +92,11 @@ workflows:
     tasks:
       task1:
         with-items:
-          - itemX in $.arrayI
-          - itemY in $.arrayJ
+          - itemX in {$.arrayI}
+          - itemY in {$.arrayJ}
         action: std.echo output="{$.itemX} {$.itemY}"
         publish:
-          result: $.task1
+          result: "{$.task1}"
 
 """
 
@@ -113,10 +113,10 @@ workflows:
       - links
     tasks:
       task1:
-        with-items: link in $.links
+        with-items: link in {$.links}
         action: std.mistral_http url={$.link}
         publish:
-          result: $.task1
+          result: "{$.task1}"
 """
 
 
diff --git a/mistral/tests/unit/services/test_workbook_service.py b/mistral/tests/unit/services/test_workbook_service.py
index 240c8f6bd..6b8d7efe7 100644
--- a/mistral/tests/unit/services/test_workbook_service.py
+++ b/mistral/tests/unit/services/test_workbook_service.py
@@ -46,18 +46,18 @@ workflows:
     input:
       - param1
     output:
-      result: $.result
+      result: "{$.result}"
 
     tasks:
       task1:
         action: std.echo output="{$.param1}"
         publish:
-          result: $
+          result: "{$}"
 
   wf2:
     type: direct
     output:
-      result: $.result
+      result: "{$.result}"
 
     tasks:
       task1:
@@ -83,7 +83,7 @@ workflows:
   wf1:
     type: direct
     output:
-      result: $.result
+      result: "{$.result}"
 
     tasks:
       task1:
@@ -96,13 +96,13 @@ workflows:
     input:
       - param1
     output:
-      result: $.result
+      result: "{$.result}"
 
     tasks:
       task1:
         action: std.echo output="{$.param1}"
         publish:
-          result: $
+          result: "{$}"
 """
 
 
diff --git a/mistral/tests/unit/services/test_workflow_service.py b/mistral/tests/unit/services/test_workflow_service.py
index da55afa26..f2a8d7fee 100644
--- a/mistral/tests/unit/services/test_workflow_service.py
+++ b/mistral/tests/unit/services/test_workflow_service.py
@@ -37,18 +37,18 @@ wf1:
   input:
     - param1
   output:
-    result: $.result
+    result: "{$.result}"
 
   tasks:
     task1:
       action: std.echo output="{$.param1}"
       publish:
-        result: $
+        result: "{$}"
 
 wf2:
   type: direct
   output:
-    result: $.result
+    result: "{$.result}"
 
   tasks:
     task1:
@@ -67,13 +67,13 @@ wf1:
     - param1
     - param2
   output:
-    result: $.result
+    result: "{$.result}"
 
   tasks:
     task1:
       action: std.echo output="{$.param1}{$.param2}"
       publish:
-        result: $
+        result: "{$}"
 """
 
 
diff --git a/mistral/tests/unit/test_expressions.py b/mistral/tests/unit/test_expressions.py
index b31f44f2e..965a7fac7 100644
--- a/mistral/tests/unit/test_expressions.py
+++ b/mistral/tests/unit/test_expressions.py
@@ -72,26 +72,28 @@ class YaqlEvaluatorTest(base.BaseTest):
 
     def test_function_length(self):
         # Lists.
-        self.assertEqual(0, expr.evaluate('$.length()', []))
-        self.assertEqual(3, expr.evaluate('$.length()', [1, 2, 3]))
-        self.assertEqual(2, expr.evaluate('$.length()', ['one', 'two']))
-        self.assertEqual(4, expr.evaluate(
+        self.assertEqual(0, self._evaluator.evaluate('$.length()', []))
+        self.assertEqual(3, self._evaluator.evaluate('$.length()', [1, 2, 3]))
+        self.assertEqual(
+            2, self._evaluator.evaluate('$.length()', ['one', 'two'])
+        )
+        self.assertEqual(4, self._evaluator.evaluate(
             '$.array.length()',
             {'array': ['1', '2', '3', '4']})
         )
 
         # Strings.
-        self.assertEqual(3, expr.evaluate('$.length()', '123'))
-        self.assertEqual(2, expr.evaluate('$.length()', '12'))
+        self.assertEqual(3, self._evaluator.evaluate('$.length()', '123'))
+        self.assertEqual(2, self._evaluator.evaluate('$.length()', '12'))
         self.assertEqual(
             4,
-            expr.evaluate('$.string.length()', {'string': '1234'})
+            self._evaluator.evaluate('$.string.length()', {'string': '1234'})
         )
 
         # Generators.
         self.assertEqual(
             2,
-            expr.evaluate(
+            self._evaluator.evaluate(
                 "$[$.state = 'active'].length()",
                 [
                     {'state': 'active'},
@@ -103,7 +105,7 @@ class YaqlEvaluatorTest(base.BaseTest):
 
         self.assertEqual(
             0,
-            expr.evaluate("$[$.state = 'active'].length()", [])
+            self._evaluator.evaluate("$[$.state = 'active'].length()", [])
         )
 
 
@@ -166,19 +168,19 @@ class ExpressionsTest(base.BaseTest):
         }
 
         test_cases = [
-            ('{$.a + $.b * $.c}', '7'),
-            ('{($.a + $.b) * $.c}', '9'),
-            ('{$.d and $.e}', 'False'),
-            ('{$.f > $.g}', 'True'),
-            ('{$.h.length() >= 5}', 'True'),
-            ('{$.h.length() >= $.b + $.c}', 'True'),
-            ('{100 in $.h}', 'False'),
-            ('{$.a in $.h}', 'True'),
-            ('{''OpenStack'' in $.i}', 'True'),
+            ('{$.a + $.b * $.c}', 7),
+            ('{($.a + $.b) * $.c}', 9),
+            ('{$.d and $.e}', False),
+            ('{$.f > $.g}', True),
+            ('{$.h.length() >= 5}', True),
+            ('{$.h.length() >= $.b + $.c}', True),
+            ('{100 in $.h}', False),
+            ('{$.a in $.h}', True),
+            ('{''OpenStack'' in $.i}', True),
             ('Hello, {$.j}!', 'Hello, World!'),
             ('{$.k} is {$.l}!', 'Mistral is awesome!'),
             ('This is {$.m}.', 'This is the way we roll.'),
-            ('{1 + 1 = 3}', 'False')
+            ('{1 + 1 = 3}', False)
         ]
 
         for expression, expected in test_cases:
@@ -190,7 +192,7 @@ class ExpressionsTest(base.BaseTest):
         task_spec_dict = {
             'parameters': {
                 'p1': 'My string',
-                'p2': '$.param2',
+                'p2': '{$.param2}',
                 'p3': ''
             },
             'publish': {
@@ -226,7 +228,7 @@ class ExpressionsTest(base.BaseTest):
         data = {
             "parameters": {
                 "parameter1": {
-                    "name1": "$.auth_token",
+                    "name1": "{$.auth_token}",
                     "name2": "val_name2"
                 },
                 "param2": [
@@ -235,7 +237,7 @@ class ExpressionsTest(base.BaseTest):
                     "/servers/{$.project_id}/bla"
                 ]
             },
-            "token": "$.auth_token"
+            "token": "{$.auth_token}"
         }
 
         applied = expr.evaluate_recursively(data, context)
diff --git a/mistral/tests/unit/workbook/v2/test_dsl_specs_v2.py b/mistral/tests/unit/workbook/v2/test_dsl_specs_v2.py
index dd4f47b06..4bee27dee 100644
--- a/mistral/tests/unit/workbook/v2/test_dsl_specs_v2.py
+++ b/mistral/tests/unit/workbook/v2/test_dsl_specs_v2.py
@@ -33,13 +33,13 @@ actions:
     base: std.echo
     base-input:
       output: Hello {$.name}!
-    output: $
+    output: "{$}"
 
   action2:
     description: This is a test ad-hoc action with base params
     tags: [test, v2]
     base: std.echo output="Echo output"
-    output: $
+    output: "{$}"
 
 workflows:
   wf1:
@@ -60,7 +60,7 @@ workflows:
           retry:
             count: 10
             delay: 30
-            break-on: $.my_val = 10
+            break-on: "{$.my_val = 10}"
           concurrency: 3
 
       task2:
@@ -76,9 +76,9 @@ workflows:
         retry:
           count: 10
           delay: 30
-          break-on: $.my_val = 10
+          break-on: "{$.my_val = 10}"
       on-error:
-        - fail: $.my_val = 0
+        - fail: "{$.my_val = 0}"
       on-success:
         - pause
       on-complete:
@@ -88,11 +88,11 @@ workflows:
       task3:
         workflow: wf1 name="John Doe" age=32 param1=null param2=false
         on-error:
-          - task4: $.my_val = 1
+          - task4: "{$.my_val = 1}"
         on-success:
-          - task5: $.my_val = 2
+          - task5: "{$.my_val = 2}"
         on-complete:
-          - task6: $.my_val = 3
+          - task6: "{$.my_val = 3}"
 
       task4:
         action: std.echo output="Task 4 echo"
@@ -104,7 +104,7 @@ workflows:
         action: std.echo output="Task 6 echo"
 
       task7:
-        with-items: vm_info in $.vms
+        with-items: vm_info in {$.vms}
         workflow: wf2 is_true=true object_list=[1, null, "str"] is_string="50"
         on-complete:
           - task9
@@ -112,9 +112,9 @@ workflows:
 
       task8:
         with-items:
-         - itemX in $.arrayI
-         - itemY in $.arrayJ
-        workflow: wf2 expr_list=["$.value", "{$.key}"] expr={$.value}
+         - itemX in {$.arrayI}
+         - itemY in {$.arrayJ}
+        workflow: wf2 expr_list=["{$.value}", "{$.key}"] expr={$.value}
         target: nova
         on-complete:
           - task9
@@ -216,7 +216,7 @@ class DSLv2ModelTest(base.BaseTest):
             action_spec.get_base_input()
         )
         self.assertListEqual([], action_spec.get_input())
-        self.assertEqual('$', action_spec.get_output())
+        self.assertEqual('{$}', action_spec.get_output())
 
         # Workflows.
 
@@ -255,7 +255,7 @@ class DSLv2ModelTest(base.BaseTest):
 
         self.assertEqual(10, retry_spec.get_count())
         self.assertEqual(30, retry_spec.get_delay())
-        self.assertEqual('$.my_val = 10', retry_spec.get_break_on())
+        self.assertEqual('{$.my_val = 10}', retry_spec.get_break_on())
 
         task2_spec = wf1_spec.get_tasks().get('task2')
 
@@ -280,7 +280,7 @@ class DSLv2ModelTest(base.BaseTest):
         task_defaults_spec = wf2_spec.get_task_defaults()
 
         self.assertListEqual(
-            [('fail', '$.my_val = 0')],
+            [('fail', '{$.my_val = 0}')],
             task_defaults_spec.get_on_error()
         )
         self.assertListEqual(
@@ -309,15 +309,15 @@ class DSLv2ModelTest(base.BaseTest):
             task3_spec.get_input()
         )
         self.assertListEqual(
-            [('task4', '$.my_val = 1')],
+            [('task4', '{$.my_val = 1}')],
             task3_spec.get_on_error()
         )
         self.assertListEqual(
-            [('task5', '$.my_val = 2')],
+            [('task5', '{$.my_val = 2}')],
             task3_spec.get_on_success()
         )
         self.assertListEqual(
-            [('task6', '$.my_val = 3')],
+            [('task6', '{$.my_val = 3}')],
             task3_spec.get_on_complete()
         )
 
@@ -333,20 +333,20 @@ class DSLv2ModelTest(base.BaseTest):
         )
 
         self.assertEqual(
-            {'vm_info': '$.vms'},
+            {'vm_info': '{$.vms}'},
             task7_spec.get_with_items()
         )
 
         task8_spec = wf2_spec.get_tasks().get('task8')
 
         self.assertEqual(
-            {"itemX": '$.arrayI', "itemY": '$.arrayJ'},
+            {"itemX": '{$.arrayI}', "itemY": '{$.arrayJ}'},
             task8_spec.get_with_items()
         )
 
         self.assertEqual(
             {
-                'expr_list': ['$.value', '{$.key}'],
+                'expr_list': ['{$.value}', '{$.key}'],
                 'expr': '{$.value}',
             },
             task8_spec.get_input()
diff --git a/mistral/tests/unit/workflow/test_direct_workflow.py b/mistral/tests/unit/workflow/test_direct_workflow.py
index 62d566b69..4a6ca137d 100644
--- a/mistral/tests/unit/workflow/test_direct_workflow.py
+++ b/mistral/tests/unit/workflow/test_direct_workflow.py
@@ -38,10 +38,10 @@ workflows:
       task1:
         action: std.echo output="Hey"
         publish:
-          res1: $.task1
+          res1: "{$.task1}"
         on-complete:
-          - task2: $.res1 = 'Hey'
-          - task3: $.res1 = 'Not Hey'
+          - task2: "{$.res1 = 'Hey'}"
+          - task3: "{$.res1 = 'Not Hey'}"
 
       task2:
         action: std.echo output="Hi"
diff --git a/mistral/tests/unit/workflow/test_with_items.py b/mistral/tests/unit/workflow/test_with_items.py
index e92abeefc..e8232fb49 100644
--- a/mistral/tests/unit/workflow/test_with_items.py
+++ b/mistral/tests/unit/workflow/test_with_items.py
@@ -27,10 +27,10 @@ TASK_DICT = {
     'version': '2.0',
     'action': 'std.echo',
     'with-items': [
-        'item in $.array'
+        'item in {$.array}'
     ],
     'input': {
-        'array': '$.my_array'
+        'array': '{$.my_array}'
     }
 }
 
@@ -45,7 +45,7 @@ TASK_DB = models.Task(
 class WithItemsCalculationsTest(base.BaseTest):
     def test_calculate_output_with_key(self):
         task_dict = TASK_DICT.copy()
-        task_dict['publish'] = {'result': '$.task1'}
+        task_dict['publish'] = {'result': '{$.task1}'}
 
         task_spec = tasks.TaskSpec(task_dict)
         raw_result = utils.TaskResult(data='output!')
diff --git a/mistral/workbook/base.py b/mistral/workbook/base.py
index a56a3aec3..5d7faf01f 100644
--- a/mistral/workbook/base.py
+++ b/mistral/workbook/base.py
@@ -22,7 +22,7 @@ from mistral import exceptions as exc
 
 CMD_PTRN = re.compile("^[\w\.]+[^=\s\"]*")
 
-_ALL_IN_BRACES = "\{[^}]*\}\s*"
+ALL_IN_BRACES = "\{[^}]*\}\s*"
 _ALL_IN_BRACKETS = "\[.*\]\s*"
 _ALL_IN_QUOTES = "\"[^\"]*\"\s*"
 _ALL_IN_APOSTROPHES = "'[^']*'\s*"
@@ -32,7 +32,7 @@ _FALSE = "false"
 _NULL = "null"
 
 ALL = (
-    _ALL_IN_QUOTES, _ALL_IN_APOSTROPHES, _ALL_IN_BRACES,
+    _ALL_IN_QUOTES, _ALL_IN_APOSTROPHES, ALL_IN_BRACES,
     _ALL_IN_BRACKETS, _TRUE, _FALSE, _NULL, _DIGITS
 )
 
diff --git a/mistral/workbook/v2/tasks.py b/mistral/workbook/v2/tasks.py
index c640ab0ac..458680b80 100644
--- a/mistral/workbook/v2/tasks.py
+++ b/mistral/workbook/v2/tasks.py
@@ -21,7 +21,9 @@ from mistral.workbook import base
 from mistral.workbook.v2 import task_policies
 
 
-WITH_ITEMS_PTRN = re.compile("\s*([\w\d_\-]+)\s*in\s*(\[.+\]|\$\..+)")
+WITH_ITEMS_PTRN = re.compile(
+    "\s*([\w\d_\-]+)\s*in\s*(\[.+\]|%s)" % base.ALL_IN_BRACES
+)
 
 
 class TaskSpec(base.BaseSpec):
@@ -111,7 +113,7 @@ class TaskSpec(base.BaseSpec):
 
             if not match:
                 msg = ("Wrong format of 'with-items' property. Please use "
-                       "format 'var in {[some, list] | $.array}: "
+                       "format 'var in {[some, list] | {$.array} }: "
                        "%s" % self._data)
                 raise exc.InvalidModelException(msg)
 
diff --git a/mistral/workflow/with_items.py b/mistral/workflow/with_items.py
index 599f4637a..dc9c4bb64 100644
--- a/mistral/workflow/with_items.py
+++ b/mistral/workflow/with_items.py
@@ -149,8 +149,8 @@ def calc_input(with_items_input):
     Example:
       DSL:
         with_items:
-          - itemX in $.arrayI
-          - itemY in $.arrayJ
+          - itemX in {$.arrayI}
+          - itemY in {$.arrayJ}
 
       Assume arrayI = [1, 2], arrayJ = ['a', 'b'].
       with_items_input = {