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.. _apex-myFirstExample:
HowTo: My First Policy
**********************
.. contents::
:depth: 3
Introduction
^^^^^^^^^^^^
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.. container:: paragraph
Consider a scenario where a supermarket chain called
*HyperM* controls how it sells items in a policy-based
manner. Each time an item is processed by *HyperM*'s
point-of-sale (PoS) system an event is generated and
published about that item of stock being sold. This
event can then be used to update stock levels, etc..
.. container:: paragraph
*HyperM* want to extend this approach to allow some
checks to be performed before the sale can be
completed. This can be achieved by requesting a
policy-controlled decision as each item is processed
by for sale by each PoS system. The decision process
is integrated with *HyperM*'s other IT systems that
manage stock control, sourcing and purchasing,
personnel systems, etc.
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In this document we will show how APEX and APEX
Policies can be used to achieve this, starting with a
simple policy, building up to more complicated policy
that demonstrates the features of APEX.
Data Models
^^^^^^^^^^^
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.. container:: sect2
.. rubric:: Sales Input Event
:name: sales_input_event
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Each time a PoS system processes a sales item an
event with the following format is emitted:
.. table:: Table 1. Sale Input Event
+----------------------+----------------------+-----------------------+
| Event | Fields | Description |
+======================+======================+=======================+
| SALE_INPUT | time, sale_ID, | Event indicating a |
| | amount, item_ID, | sale of an item is |
| | quantity, | occurring |
| | assistant_ID, | |
| | branch_ID, notes, …​ | |
+----------------------+----------------------+-----------------------+
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In each ``SALE_INPUT`` event the ``sale_ID`` field
is a unique ID generated by the PoS system. A
timestamp for the event is stored in the ``time``
field. The ``amount`` field refers to the value of
the item(s) to be sold (in cents). The ``item_ID``
field is a unique identifier for each item type,
and can be used to retrieve more information about
the item from *HyperM*'s stock control system. The
``quantity`` field refers to the quantity of the
item to be sold. The ``assistant_ID`` field is a
unique identifier for the PoS operator, and can be
used to retrieve more information about the
operator from the *HyperM*'s personnel system.
Since *HyperM* has many branches the ``branch_ID``
identifies the shop. The ``notes`` field contains
arbitrary notes about the sale.
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.. rubric:: Sales Decision Event
:name: sales_decision_event
.. container:: paragraph
After a ``SALE_INPUT`` event is emitted by the PoS
system *HyperM*'s policy-based controlled sales
checking system emits a Sale Authorization Event
indicating whether the sale is authorized or
denied. The PoS system can then listen for this
event before continuing with the sale.
.. table:: Table 2. Sale Authorisation Event
+----------------------+----------------------+-----------------------+
| Event | Fields | Description |
+======================+======================+=======================+
| SALE_AUTH | sale_ID, time, | Event indicating a |
| | authorized, amount, | sale of an item is |
| | item_ID, quantity, | authorized or denied |
| | assistant_ID, | |
| | branch_ID, notes, | |
| | message…​ | |
+----------------------+----------------------+-----------------------+
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In each ``SALE_AUTH`` event the ``sale_ID`` field
is copied from the ``SALE_INPUT`` event that
trigger the decision request. The ``SALE_AUTH``
event is also timestamped using the ``time`` field,
and a field called ``authorised`` is set to
``true`` or ``false`` depending on whether the sale
is authorized or denied. The ``message`` field
carries an optional message about why a sale was
not authorized. The other fields from the
``SALE_INPUT`` event are also included for
completeness.
.. container:: sect2
.. rubric:: Stock Control: Items
:name: stock_control_items
.. container:: paragraph
*HyperM* maintains information about each item for
sale in a database table called ``ITEMS``.
.. table:: Table 3. Items Database
+----------------------+----------------------+-----------------------+
| Table | Fields | Description |
+======================+======================+=======================+
| ITEMS | item_ID, | Database table |
| | description, | describing each item |
| | cost_price, barcode, | for sale |
| | supplier_ID, | |
| | category, …​ | |
+----------------------+----------------------+-----------------------+
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The database table ``ITEMS`` has a row for each
items that *HyperM* sells. Each item is identified
by an ``item_ID`` value. The ``description`` field
stores a description of the item. The cost price of
the item is given in ``cost_price``. The barcode of
the item is encoded in ``barcode``, while the item
supplier is identified by ``supplier_ID``. Items
may also be classified into categories using the
``category`` field. Useful categories might
include: ``soft drinks``, ``alcoholic drinks``,
``cigarettes``, ``knives``, ``confectionery``,
``bakery``, ``fruit&vegetables``, ``meat``, etc..
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.. rubric:: Personnel System: Assistants
:name: personnel_system_assistants
.. table:: Table 4. Assistants Database
+----------------------+----------------------+-----------------------+
| Table | Fields | Description |
+======================+======================+=======================+
| ASSISTANTS | assistant_ID, | Database table |
| | surname, firstname, | describing each |
| | middlename, age, | *HyperM* sales |
| | grade, phone_number, | assistant |
| | …​ | |
+----------------------+----------------------+-----------------------+
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The database table ``ASSISTANTS`` has a row for
each sales assistant employed by *HyperM*. Each
assistant is identified by an ``assistant_ID``
value, with their name given in the ``firstname``,
``middlename`` and ``surname`` fields. The
assistant’s age in years is given in ``age``, while
their phone number is contained in the
``phone_number`` field. The assistant’s grade is
encoded in ``grade``. Useful values for ``grade``
might include: ``trainee``, ``operator``,
``supervisor``, etc..
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.. rubric:: Locations: Branches
:name: locations_branches
.. table:: Table 5. Branches Database
+----------------------+----------------------+-----------------------+
| Table | Fields | Description |
+======================+======================+=======================+
| BRANCHES | branch_ID, | Database table |
| | branch_Name, | describing each |
| | category, street, | *HyperM* branch |
| | city, country, | |
| | postcode, …​ | |
+----------------------+----------------------+-----------------------+
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*HyperM* operates a number of branches. Each branch
is described in the ``BRANCHES`` database table.
Each branch is identified by a ``branch_ID``, with
a branch name given in ``branch_Name``. The address
for the branch is encoded in ``street``, ``city``,
``country`` and ``postcode``. The branch category
is given in the ``category`` field. Useful values
for ``category`` might include: ``Small``,
``Large``, ``Super``, ``Hyper``, etc..
Policy Step 1
^^^^^^^^^^^^^
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.. rubric:: Scenario
:name: scenario
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For the first version of our policy, let’s start
with something simple. Let us assume that there
exists some restriction that alcohol products
cannot be sold before 11:30am. In this section we
will go through the necessary steps to define a
policy that can enforce this for *HyperM*.
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- Alcohol cannot be sold before 11:30am...
New Policy Model
----------------
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.. rubric:: Create the an new empty Policy Model ``MyFirstPolicyModel``
:name: create_the_an_new_empty_policy_model_code_myfirstpolicymodel_code
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Since an organisation like *HyperM* may have many
policies covering many different domains, policies should
be grouped into policy sets. In order to edit or deploy a
policy, or policy set, the definition of the policy(ies)
and all required events, tasks, states, etc., are grouped
together into a 'Policy Model'. An organization might
define many Policy Models, each containing a different
set of policies.
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So the first step is to create a new empty Policy Model
called ``MyFirstPolicyModel``. Using the APEX Policy
Editor, click on the 'File' menus and select 'New'. Then
define our new policy model called
``MyFirstPolicyModel``. Use the 'Generate UUID' button to
create a new unique ID for the policy model, and fill in
a description for the policy model. Press the ``Submit``
button to save your changes.
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|File > New to create a new Policy Model|
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|Create a new Policy Model|
Events
------
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.. rubric:: Create the input event ``SALE_INPUT`` and the
output event ``SALE_AUTH``
:name: create_the_input_event_code_sale_input_code_and_the_output_event_code_sale_auth_code
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Using the APEX Policy Editor, click on the 'Events' tab.
In the 'Events' pane, right click and select 'New':
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|Right click to create a new event|
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Create a new event type called ``SALE_INPUT``. Use the
'Generate UUID' button to create a new unique ID for the
event type, and fill in a description for the event. Add
a namespace, e.g. ``com.hyperm``. We can add hard-coded
strings for the ``Source`` and ``Target``, e.g. ``POS``
and ``APEX``. At this stage we will not add any parameter
fields, we will leave this until later. Use the
``Submit`` button to create the event.
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|Fill in the necessary information for the
'SALE_INPUT' event and click 'Submit'|
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Repeat the same steps for a new event type called
``SALE_AUTH``. Just use ``APEX`` as source and ``POS`` as
target, since this is the output event coming from APEX
going to the sales point.
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Before we can add parameter fields to an event we must
first define APEX Context Item Schemas that can be used
by those fields.
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To create new item schemas, click on the 'Context Item
Schemas' tab. In that 'Context Item Schemas' pane, right
click and select 'Create new ContextSchema'.
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|Right click to create a new Item Schema|
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Create item schemas with the following characteristics,
each with its own unique UUID:
.. table:: Table 1. Item Schemas
+-----------------+-----------------+-----------------+-----------------+
| Name | Schema Flavour | Schema | Description |
| | | Definition | |
+=================+=================+=================+=================+
| timestamp_type | Java | java.lang.Long | A type for |
| | | | ``time`` values |
+-----------------+-----------------+-----------------+-----------------+
| sale_ID_type | Java | java.lang.Long | A type for |
| | | | ``sale_ID`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
| price_type | Java | java.lang.Long | A type for |
| | | | ``amo |
| | | | unt``/``price`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
| item_ID_type | Java | java.lang.Long | A type for |
| | | | ``item_ID`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
| as | Java | java.lang.Long | A type for |
| sistant_ID_type | | | ` |
| | | | `assistant_ID`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
| quantity_type | Java | ja | A type for |
| | | va.lang.Integer | ``quantity`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
| branch_ID_type | Java | java.lang.Long | A type for |
| | | | ``branch_ID`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
| notes_type | Java | j | A type for |
| | | ava.lang.String | ``notes`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
| authorised_type | Java | ja | A type for |
| | | va.lang.Boolean | ``authorised`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
| message_type | Java | j | A type for |
| | | ava.lang.String | ``message`` |
| | | | values |
+-----------------+-----------------+-----------------+-----------------+
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|Create a new Item Schema|
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The item schemas can now be seen on the 'Context Item
Schemas' tab, and can be updated at any time by
right-clicking on the item schemas on the 'Context Item
Schemas' tab. Now we can go back to the event definitions
for ``SALE_INPUT`` and ``SALE_AUTH`` and add some
parameter fields.
.. TIP::
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APEX natively supports schema definitions in ``Java`` and ``Avro``.
``Java`` schema definitions are simply the name of a Java Class. There are some restrictions:
.. container:: ulist
- the class must be instantiatable, i.e. not an Java interface or abstract class
- primitive types are not supported, i.e. use ``java.lang.Integer`` instead of ``int``, etc.
- it must be possible to find the class, i.e. the class must be contained in the Java classpath.
.. container:: paragraph
``Avro`` schema definitions can be any valid `Avro <https://avro.apac
he.org/docs/current/spec.html>`__ schema. For events using fields defined with
Avro schemas, any incoming event containing that field must contain a value that conforms to the Avro schema.
.. container:: paragraph
Click on the 'Events' tab, then right click the
``SALE_INPUT`` row and select 'Edit Event
:literal:`SALE_INPUT’. To add a new event parameter use the 'Add Event Parameter' button at the bottom of the screen. For the `SALE_INPUT`
event add the following event parameters:
.. table:: Table 2. Event Parameter Fields for the ``SALE_INPUT`` Event
+----------------------+----------------------+-----------------------+
| Parameter Name | Parameter Type | Optional |
+======================+======================+=======================+
| time | timestamp_type | no |
+----------------------+----------------------+-----------------------+
| sale_ID | sale_ID_type | no |
+----------------------+----------------------+-----------------------+
| amount | price_type | no |
+----------------------+----------------------+-----------------------+
| item_ID | item_ID_type | no |
+----------------------+----------------------+-----------------------+
| quantity | quantity_type | no |
+----------------------+----------------------+-----------------------+
| assistant_ID | assistant_ID_type | no |
+----------------------+----------------------+-----------------------+
| branch_ID | branch_ID_type | no |
+----------------------+----------------------+-----------------------+
| notes | notes_type | *yes* |
+----------------------+----------------------+-----------------------+
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Remember to click the 'Submit' button at the bottom of
the event definition pane.
.. TIP::
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Parameter fields can be *optional* in events. If a parameter is not marked as
*optional* then by default it is *mandatory*, so it must appear in any input event
passed to APEX. If an *optional* field is not set for an output event then value
will be set to ``null``.
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|Add new event parameters to an event|
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Select the ``SALE_AUTH`` event and add the following
event parameters:
.. table:: Table 3. Event Parameter Fields for the ``SALE_AUTH`` Event
+----------------------+----------------------+-----------------------+
| Parameter Name | Parameter Type | no |
+======================+======================+=======================+
| sale_ID | sale_ID_type | no |
+----------------------+----------------------+-----------------------+
| time | timestamp_type | no |
+----------------------+----------------------+-----------------------+
| authorised | authorised_type | no |
+----------------------+----------------------+-----------------------+
| message | message_type | *yes* |
+----------------------+----------------------+-----------------------+
| amount | price_type | no |
+----------------------+----------------------+-----------------------+
| item_ID | item_ID_type | no |
+----------------------+----------------------+-----------------------+
| assistant_ID | assistant_ID_type | no |
+----------------------+----------------------+-----------------------+
| quantity | quantity_type | no |
+----------------------+----------------------+-----------------------+
| branch_ID | branch_ID_type | no |
+----------------------+----------------------+-----------------------+
| notes | notes_type | *yes* |
+----------------------+----------------------+-----------------------+
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Remember to click the 'Submit' button at the bottom of
the event definition pane.
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The events for our policy are now defined.
New Policy
----------
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.. container:: sect1
.. rubric:: Create a new Policy and add the *"No Booze
before 11:30"* check
:name: create_a_new_policy_and_add_the_em_no_booze_before_11_30_em_check
.. container:: paragraph
APEX policies are defined using a state-machine model.
Each policy comprises one or more *states* that can be
individually executed. Where there is more than one
*state* the states are chained together to form a
`Directed Acyclic Graph
(DAG) <https://en.wikipedia.org/wiki/Directed_acyclic_graph>`__
of states. A *state* is triggered by passing it a single
input (or 'trigger') event and once executed each state
then emits an output event. For each *state* the logic
for the *state* is embedded in one or more *tasks*. Each
*task* contains specific *task logic* that is executed by
the APEX execution environment each time the *task* is
invoked. Where there is more than one *task* in a *state*
then the *state* also defines some *task selection logic*
to select an appropriate task each time the *state* is
executed.
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Therefore, to create a new policy we must first define
one or more tasks.
.. container:: paragraph
To create a new Task click on the 'Tasks' tab. In the
'Tasks' pane, right click and select 'Create new Task'.
Create a new Task called ``MorningBoozeCheck``. Use the
'Generate UUID' button to create a new unique ID for the
task, and fill in a description for the task.
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|Right click to create a new task|
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Tasks are configured with a set of *input fields* and a
set of *output fields*. To add new input/output fields
for a task use the 'Add Task Input Field' and 'Add Task
Output Field' button. The list of input and out fields to
add for the ``MorningBoozeCheck`` task are given below.
The input fields are drawn from the parameters in the
state’s input event, and the task’s output fields are
used to populate the state’s output event. The task’s
input and output fields must be a subset of the event
parameters defined for the input and output events for
any state that uses that task. (You may have noticed that
the input and output fields for the ``MorningBoozeCheck``
task have the exact same names and reuse the item schemas
that we used for the parameters in the ``SALE_INPUT`` and
``SALE_AUTH`` events respectively).
.. table:: Table 1. Input fields for ``MorningBoozeCheck`` task
+-----------------------------------+-----------------------------------+
| Parameter Name | Parameter Type |
+===================================+===================================+
| time | timestamp_type |
+-----------------------------------+-----------------------------------+
| sale_ID | sale_ID_type |
+-----------------------------------+-----------------------------------+
| amount | price_type |
+-----------------------------------+-----------------------------------+
| item_ID | item_ID_type |
+-----------------------------------+-----------------------------------+
| quantity | quantity_type |
+-----------------------------------+-----------------------------------+
| assistant_ID | assistant_ID_type |
+-----------------------------------+-----------------------------------+
| branch_ID | branch_ID_type |
+-----------------------------------+-----------------------------------+
| notes | notes_type |
+-----------------------------------+-----------------------------------+
.. table:: Table 2. Output fields for ``MorningBoozeCheck`` task
+-----------------------------------+-----------------------------------+
| Parameter Name | Parameter Type |
+===================================+===================================+
| sale_ID | sale_ID_type |
+-----------------------------------+-----------------------------------+
| time | timestamp_type |
+-----------------------------------+-----------------------------------+
| authorised | authorised_type |
+-----------------------------------+-----------------------------------+
| message | message_type |
+-----------------------------------+-----------------------------------+
| amount | price_type |
+-----------------------------------+-----------------------------------+
| item_ID | item_ID_type |
+-----------------------------------+-----------------------------------+
| assistant_ID | assistant_ID_type |
+-----------------------------------+-----------------------------------+
| quantity | quantity_type |
+-----------------------------------+-----------------------------------+
| branch_ID | branch_ID_type |
+-----------------------------------+-----------------------------------+
| notes | notes_type |
+-----------------------------------+-----------------------------------+
.. container:: imageblock
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|Add input and out fields for the task|
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Each task must include some 'Task Logic' that implements
the behaviour for the task. Task logic can be defined in
a number of different ways using a choice of languages.
For this task we will author the logic using the
Java-like scripting language called
```MVEL`` <https://en.wikipedia.org/wiki/MVEL>`__.
.. container:: paragraph
For simplicity use the code for the task logic here(|taskLogicMvel_link|).
Paste the script text into the 'Task Logic' box, and use
"MVEL" as the 'Task Logic Type / Flavour'.
.. container:: paragraph
This logic assumes that all items with ``item_ID``
between 1000 and 2000 contain alcohol, which is not very
realistic, but we will see a better approach for this
later. It also uses the standard ``Java`` time utilities
to check if the current time is between ``00:00:00 GMT``
and ``11:30:00 GMT``. For a detailed guide to how to
write your own logic in
```JavaScript`` <https://en.wikipedia.org/wiki/JavaScript>`__,
```MVEL`` <https://en.wikipedia.org/wiki/MVEL>`__ or one
of the other supported languages please refer to APEX
Programmers Guide.
.. container:: imageblock
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|Add task logic the task|
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An alternative version of the same logic is available in
JavaScript(|taskLogicJS_link|). Just use "JAVASCRIPT" as the 'Task Logic Type
/ Flavour' instead.
.. container:: paragraph
The task definition is now complete so click the 'Submit'
button to save the task. The task can now be seen on the
'Tasks' tab, and can be updated at any time by
right-clicking on the task on the 'Task' tab. Now that we
have created our task, we can can create a policy that
uses that task.
.. container:: paragraph
To create a new Policy click on the 'Policies' tab. In
the 'Policies' pane, right click and select 'Create new
Policy':
.. container:: paragraph
Create a new Policy called ``MyFirstPolicy``. Use the
'Generate UUID' button to create a new unique ID for the
policy, and fill in a description for the policy. Use
'FREEFORM' as the 'Policy Flavour'.
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Each policy must have at least one state. Since this is
'freeform' policy we can add as many states as we wish.
Let’s start with one state. Add a new state called
``BoozeAuthDecide`` to this ``MyFirstPolicy`` policy
using the 'Add new State' button after filling in the
name of our new state.
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|Create a new policy|
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Each state must uses one input event type. For this new
state select the ``SALE_INPUT`` event as the input event.
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Each policy must define a 'First State' and a 'Policy
Trigger Event'. The 'Policy Trigger Event' is the input
event for the policy as a whole. This event is then
passed to the first state in the chain of states in the
policy, therefore the 'Policy Trigger Event' will be the
input event for the first state. Each policy can only
have one 'First State'. For our ``MyFirstPolicy`` policy,
select ``BoozeAuthDecide`` as the 'First State'. This
will automatically select ``SALE_INPUT`` as the 'Policy
Trigger Event' for our policy.
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|Create a state|
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In this case we will create a reference the pre-existing
``MorningBoozeCheck`` task that we defined above using
the 'Add New Task' button. Select the
``MorningBoozeCheck`` task, and use the name of the task
as the 'Local Name' for the task.
.. container:: paragraph
in the case where a state references more than one task,
a 'Default Task' must be selected for the state and some
logic ('Task Selection Logic') must be specified to
select the appropriate task at execution time. Since our
new state ``BoozeAuthDecide`` only has one task the
default task is automatically selected and no 'Task
Selection Logic' is required.
.. NOTE::
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In a 'Policy' 'State' a 'State Output Mapping' has 3 roles: 1) Select which 'State'
should be executed next, 2) Select the type of the state’s 'Outgoing Event', and
3) Populate the state’s 'Outgoing Event'. This is how states are chained together
to form a (`Directed Acyclic Graph (DAG) <https://en.wikipedia.org/wiki/Directed_acyclic_graph>`__)
of states. The final state(s) of a policy are those that do not select any 'next'
state. Since a 'State' can only accept a single type of event, the type of the
event emitted by a previous 'State' must match the incoming event type of the next
'State'. This is also how the last state(s) in a policy can emit events of
different types. The 'State Output Mapping' is also responsible for taking the
fields that are output by the task executed in the state and populating the
state’s output populating the state’s output event before it is emitted.
Each 'Task' referenced in 'State' must have a defined 'Output Mapping' to take the output of the task, select an 'Outgoing Event' type for the state, populate the state's outgoing event, and then select the next state to be executed (if any).
There are 2 basic types of output mappings:
.. container:: olist arabic
#. **Direct Output Mappings** have a single value for 'Next State' and a single value for 'State Output Event'. The outgoing event for the state is automatically created, any outgoing event parameters that were present in the incoming event are copied into the outgoing event, then any task output fields that have the same name and type as parameters in the outgoing event are automatically copied into the outgoing event.
#. **Logic-Based State Output Mappings / Finalizers** have some logic defined that dynamically selects and creates the 'State Outgoing Event', manages the population of the outgoing event parameters (perhaps changing or adding to the outputs from the task), and then dynamically selects the next state to be executed (if any).
.. container:: paragraph
Each task reference must also have an associated 'Output
State Mapping' so we need an 'Output State Mapping' for
the ``BoozeAuthDecide`` state to use when the
``MorningBoozeCheck`` task is executed. The simplest type
of output mapping is a 'Direct Output Mapping'.
.. container:: paragraph
Create a new 'Direct Output Mapping' for the state called
``MorningBoozeCheck_Output_Direct`` using the 'Add New
Direct State Output Mapping' button. Select ``SALE_AUTH``
as the output event and select ``None`` for the next
state value. We can then select this output mapping for
use when the the ``MorningBoozeCheck`` task is executed.
Since there is only state, and only one task for that
state, this output mapping ensures that the
``BoozeAuthDecide`` state is the only state executed and
the state (and the policy) can only emit events of type
``SALE_AUTH``. (You may remember that the output fields
for the ``MorningBoozeCheck`` task have the exact same
names and reuse the item schemas that we used for the
parameters in ``SALE_AUTH`` event. The
``MorningBoozeCheck_Output_Direct`` direct output mapping
can now automatically copy the values from the
``MorningBoozeCheck`` task directly into outgoing
``SALE_AUTH`` events.)
.. container:: imageblock
.. container:: content
|Add a Task and Output Mapping|
.. container:: paragraph
Click the 'Submit' button to complete the definition of
our ``MyFirstPolicy`` policy. The policy
``MyFirstPolicy`` can now be seen in the list of policies
on the 'Policies' tab, and can be updated at any time by
right-clicking on the policy on the 'Policies' tab.
.. container:: paragraph
The ``MyFirstPolicyModel``, including our
``MyFirstPolicy`` policy can now be checked for errors.
Click on the 'Model' menu and select 'Validate'. The
model should validate without any 'Warning' or 'Error'
messages. If you see any 'Error' or 'Warning' messages,
carefully read the message as a hint to find where you
might have made a mistake when defining some aspect of
your policy model.
.. container:: imageblock
.. container:: content
|Validate the policy model for error using the 'Model'
> 'Validate' menu item|
.. container:: paragraph
Congratulations, you have now completed your first APEX
policy. The policy model containing our new policy can
now be exported from the editor and saved. Click on the
'File' menu and select 'Download' to save the policy
model in JSON format. The exported policy model is then
available in the directory you selected, for instance
``$APEX_HOME/examples/models/MyFirstPolicy/1/MyFirstPolicyModel_0.0.1.json``.
The exported policy can now be loaded into the APEX
Policy Engine, or can be re-loaded and edited by the APEX
Policy Editor.
.. container:: imageblock
.. container:: content
|Download the completed policy model using the 'File'
> 'Download' menu item|
Test The Policy
---------------
.. container:: sectionbody
.. container:: sect1
.. rubric:: Test Policy Step 1
:name: test_policy_step_1
.. container:: paragraph
To start a new APEX Engine you can use the following
|policy1_configuration|. In a full APEX installation you can find
this configuration in
``$APEX_HOME/examples/config/MyFirstPolicy/1/MyFirstPolicyConfigStdin2StdoutJsonEvent.json``.
This configuration expects incoming events to be in
``JSON`` format and to be passed into the APEX Engine
from ``stdin``, and result events will be printed in
``JSON`` format to ``stdout``. This configuration loads
the policy model stored in the file
'MyFirstPolicyModel_0.0.1.json' as exported from the APEX
Editor. Note, you may need to edit this file to provide
the full path to wherever you stored the exported policy
model file.
.. container:: paragraph
To test the policy try paste the following events into
the console as the APEX engine executes:
.. list-table:: Title
:widths: 25 40 35
:header-rows: 1
* - Input Event (JSON)
- Output Event (JSON)
- comment
* - .. literalinclude:: events/1/EventIn_NonBoozeItem_101309GMT.json
:language: JSON
- .. literalinclude:: events/1/EventOut_NonBoozeItem_101309GMT.json
:language: JSON
- .. container:: paragraph
Request to buy a non-alcoholic item (item_ID=5123) at 10:13:09 on Tuesday, 10 January 2017.
Sale is authorized.
* - .. literalinclude:: events/1/EventIn_BoozeItem_084106GMT.json
:language: JSON
- .. literalinclude:: events/1/EventOut_BoozeItem_084106GMT.json
:language: JSON
- .. container:: paragraph
Request to buy alcohol item (`item_ID=1249`) at 08:41:06 on Monday, 02 January 2017.
Sale is not authorized.
* - .. literalinclude:: events/1/EventIn_BoozeItem_201713GMT.json
:language: JSON
- .. literalinclude:: events/1/EventOut_BoozeItem_201713GMT.json
:language: JSON
- .. container:: paragraph
Request to buy alcohol (`item_ID=1943`) at 20:17:13 on Tuesday, 20 December 2016.
Sale is authorized.
CLI Editor File
---------------
.. container:: sectionbody
.. container:: sect1
.. rubric:: Policy 1 in CLI Editor
:name: policy_1_in_cli_editor
.. container:: paragraph
An equivalent version of the ``MyFirstPolicyModel``
policy model can again be generated using the APEX CLI
editor. A sample APEX CLI script is shown below:
.. container:: ulist
- |policy1ModelMvel_link|
- |policy1ModelJs_link|
Policy Step 2
^^^^^^^^^^^^^
.. container:: sectionbody
.. container:: sect1
.. rubric:: Scenario
:name: scenario_policy2
.. container:: paragraph
*HyperM* have just opened a new branch in a
different country, but that country has different
rules about when alcohol can be sold! In this
section we will go through the necessary steps to
extend our policy to enforce this for *HyperM*.
.. container:: ulist
- In some branches alcohol cannot be sold before
1pm, and not at all on Sundays.
.. container:: paragraph
Although there are a number of ways to accomplish
this the easiest approach for us is to define
another task and then select which task is
appropriate at runtime depending on the branch
identifier in the incoming event.
Extend Policy Model
-------------------
.. container:: sectionbody
.. container:: sect2
.. rubric:: Extend the Policy with the new Scenario
:name: extend_the_policy_with_the_new_scenario
.. container:: paragraph
To create a new Task click on the 'Tasks' tab. In the
'Tasks' pane, right click and select 'Create new Task':
.. container:: paragraph
Create a new Task called ``MorningBoozeCheckAlt1``. Use
the 'Generate UUID' button to create a new unique ID for
the task, and fill in a description for the task. Select
the same input and output fields that we used earlier
when we defined the ``MorningBoozeCheck`` task earlier.
.. table:: Table 1. Input fields for ``MorningBoozeCheckAlt1`` task
+-----------------------------------+-----------------------------------+
| Parameter Name | Parameter Type |
+===================================+===================================+
| time | timestamp_type |
+-----------------------------------+-----------------------------------+
| sale_ID | sale_ID_type |
+-----------------------------------+-----------------------------------+
| amount | price_type |
+-----------------------------------+-----------------------------------+
| item_ID | item_ID_type |
+-----------------------------------+-----------------------------------+
| quantity | quantity_type |
+-----------------------------------+-----------------------------------+
| assistant_ID | assistant_ID_type |
+-----------------------------------+-----------------------------------+
| branch_ID | branch_ID_type |
+-----------------------------------+-----------------------------------+
| notes | notes_type |
+-----------------------------------+-----------------------------------+
.. table:: Table 2. Output fields for ``MorningBoozeCheckAlt1`` task
+-----------------------------------+-----------------------------------+
| Parameter Name | Parameter Type |
+===================================+===================================+
| sale_ID | sale_ID_type |
+-----------------------------------+-----------------------------------+
| time | timestamp_type |
+-----------------------------------+-----------------------------------+
| authorised | authorised_type |
+-----------------------------------+-----------------------------------+
| message | message_type |
+-----------------------------------+-----------------------------------+
| amount | price_type |
+-----------------------------------+-----------------------------------+
| item_ID | item_ID_type |
+-----------------------------------+-----------------------------------+
| assistant_ID | assistant_ID_type |
+-----------------------------------+-----------------------------------+
| quantity | quantity_type |
+-----------------------------------+-----------------------------------+
| branch_ID | branch_ID_type |
+-----------------------------------+-----------------------------------+
| notes | notes_type |
+-----------------------------------+-----------------------------------+
.. container:: paragraph
This task also requires some 'Task Logic' to implement
the new behaviour for this task.
.. container:: paragraph
For simplicity use the following code for the task logic (|policy2_taskLogic_link|).
It again assumes that all items with ``item_ID`` between
1000 and 2000 contain alcohol. We again use the standard
``Java`` time utilities to check if the current time is
between ``00:00:00 CET`` and ``13:00:00 CET`` or if it is
``Sunday``.
.. container:: paragraph
For this task we will again author the logic using the
```MVEL`` <https://en.wikipedia.org/wiki/MVEL>`__
scripting language. Sample task logic code (specified in
```MVEL`` <https://en.wikipedia.org/wiki/MVEL>`__) is
given below. For a detailed guide to how to write your
own logic in
```JavaScript`` <https://en.wikipedia.org/wiki/JavaScript>`__,
```MVEL`` <https://en.wikipedia.org/wiki/MVEL>`__ or one
of the other supported languages please refer to APEX
Programmers Guide.
.. container:: imageblock
.. container:: content
|Create a new alternative task
\`MorningBoozeCheckAlt1\`|
.. container:: paragraph
The task definition is now complete so click the 'Submit'
button to save the task. Now that we have created our
task, we can can add this task to the single pre-existing
state (``BoozeAuthDecide``) in our policy.
.. container:: paragraph
To edit the ``BoozeAuthDecide`` state in our policy click
on the 'Policies' tab. In the 'Policies' pane, right
click on our ``MyFirstPolicy`` policy and select 'Edit'.
Navigate to the ``BoozeAuthDecide`` state in the 'states'
section at the bottom of the policy definition pane.
.. container:: imageblock
.. container:: content
|Right click to edit a policy|
.. container:: paragraph
To add our new task ``MorningBoozeCheckAlt1``, scroll
down to the ``BoozeAuthDecide`` state in the 'States'
section. In the 'State Tasks' section for
``BoozeAuthDecide`` use the 'Add new task' button. Select
our new ``MorningBoozeCheckAlt1`` task, and use the name
of the task as the 'Local Name' for the task. The
``MorningBoozeCheckAlt1`` task can reuse the same
``MorningBoozeCheck_Output_Direct`` 'Direct State Output
Mapping' that we used for the ``MorningBoozeCheck`` task.
(Recall that the role of the 'State Output Mapping' is to
select the output event for the state, and select the
next state to be executed. These both remain the same as
before.)
.. container:: paragraph
Since our state has more than one task we must define
some logic to determine which task should be used each
time the state is executed. This *task selection logic*
is defined in the state definition. For our
``BoozeAuthDecide`` state we want the choice of which
task to use to be based on the ``branch_ID`` from which
the ``SALE_INPUT`` event originated. For simplicity sake
let us assume that branches with ``branch_ID`` between
``0`` and ``999`` should use the ``MorningBoozeCheck``
task, and the branches with with ``branch_ID`` between
``1000`` and ``1999`` should use the
``MorningBoozeCheckAlt1`` task.
.. container:: paragraph
This time, for variety, we will author the task selection
logic using the
```JavaScript`` <https://en.wikipedia.org/wiki/JavaScript>`__
scripting language. Sample task selection logic code
is given here (|policy2_taskSelectionLogic_link|). Paste the script text into the 'Task
Selection Logic' box, and use "JAVASCRIPT" as the 'Task
Selection Logic Type / Flavour'. It is necessary to mark
one of the tasks as the 'Default Task' so that the task
selection logic always has a fallback default option in
cases where a particular task cannot be selected. In this
case the ``MorningBoozeCheck`` task can be the default
task.
.. container:: imageblock
.. container:: content
|State definition with 2 Tasks and Task Selection
Logic|
.. container:: paragraph
When complete don’t forget to click the 'Submit' button
at the bottom of 'Policies' pane for our
``MyFirstPolicy`` policy after updating the
``BoozeAuthDecide`` state.
.. container:: paragraph
Congratulations, you have now completed the second step
towards your first APEX policy. The policy model
containing our new policy can again be validated and
exported from the editor and saved as shown in Step 1.
.. container:: paragraph
The exported policy model is then available in the
directory you selected, as
`MyFirstPolicyModel_0.0.1.json <files/mfp-files/2/MyFirstPolicyModel_0.0.1.json>`__.
The exported policy can now be loaded into the APEX
Policy Engine, or can be re-loaded and edited by the APEX
Policy Editor.
Test The Policy
---------------
.. container:: sectionbody
.. container:: sect2
.. rubric:: Test Policy Step 2
:name: test_policy_step_2
.. container:: paragraph
To start a new APEX Engine you can use the following
|policy2_configuration_link|. In a full APEX installation you can find
this configuration in
``$APEX_HOME/examples/config/MyFirstPolicy/2/MyFirstPolicyConfigStdin2StdoutJsonEvent.json``.
Note, this has changed from the configuration file in
Step 1 to enable the ``JAVASCRIPT`` executor for our new
'Task Selection Logic'.
.. container:: paragraph
To test the policy try paste the following events into
the console as the APEX engine executes. Note, all tests
from Step 1 will still work perfectly since none of those
events originate from a branch with ``branch_ID`` between
``1000`` and ``2000``. The 'Task Selection Logic' will
therefore pick the ``MorningBoozeCheck`` task as
expected, and will therefore give the same results.
.. list-table:: Table 1. Inputs and Outputs when testing *My First Policy*
:widths: 25 40 35
:header-rows: 1
* - Input Event (JSON)
- Output Event (JSON)
- comment
* - .. literalinclude:: events/1/EventIn_BoozeItem_084106GMT.json
:language: JSON
- .. literalinclude:: events/1/EventOut_BoozeItem_084106GMT.json
:language: JSON
- .. container:: paragraph
Request to buy alcohol item (`item_ID=1249`) at 08:41:06 GMT on Monday, 02 January 2017.
Sale is not authorized. Uses the `MorningBoozeCheck` task.
* - .. literalinclude:: events/2/EventIn_BoozeItem_101433CET_thurs.json
:language: JSON
- .. literalinclude:: events/2/EventOut_BoozeItem_101433CET_thurs.json
:language: JSON
- .. container:: paragraph
Request to buy alcohol (`item_ID=1047`) at 10:14:33 on Thursday, 22 December 2016.
Sale is not authorized. Uses the `MorningBoozeCheckAlt1` task.
* - .. literalinclude:: events/2/EventIn_BoozeItem_171937CET_sun.json
:language: JSON
- .. literalinclude:: events/2/EventOut_BoozeItem_171937CET_sun.json
:language: JSON
- .. container:: paragraph
Request to buy alcohol (`item_ID=1443`) at 17:19:37 on Sunday, 18 December 2016.
Sale is not authorized. Uses the `MorningBoozeCheckAlt1` task.
* - .. literalinclude:: events/2/EventIn_NonBoozeItem_111309CET_mon.json
:language: JSON
- .. literalinclude:: events/2/EventOut_NonBoozeItem_111309CET_mon.json
:language: JSON
- .. container:: paragraph
Request to buy non-alcoholic item (`item_ID=5321`) at 11:13:09 on Monday, 2 January 2017.
Sale is authorized. Uses the `MorningBoozeCheckAlt1` task.
CLI Editor File
---------------
.. container:: sectionbody
.. container:: sect2
.. rubric:: Policy 2 in CLI Editor
:name: policy_2_in_cli_editor
.. container:: paragraph
An equivalent version of the ``MyFirstPolicyModel``
policy model can again be generated using the APEX CLI
editor. A sample APEX CLI script is shown below:
.. container:: ulist
- |policy2_Model_link|
.. container::
:name: footer-text
2.3.0-SNAPSHOT
Last updated 2020-04-03 16:04:24 IST
.. |File > New to create a new Policy Model| image:: images/mfp/MyFirstPolicy_P1_newPolicyModel1.png
.. |Create a new Policy Model| image:: images/mfp/MyFirstPolicy_P1_newPolicyModel2.png
.. |ONAP| image:: ../../../images/logos.png
:class: builtBy
:target: http://www.onap.org/
.. |Right click to create a new event| image:: images/mfp/MyFirstPolicy_P1_newEvent1.png
.. |Fill in the necessary information for the 'SALE_INPUT' event and click 'Submit'| image:: images/mfp/MyFirstPolicy_P1_newEvent2.png
.. |Right click to create a new Item Schema| image:: images/mfp/MyFirstPolicy_P1_newItemSchema1.png
.. |Create a new Item Schema| image:: images/mfp/MyFirstPolicy_P1_newItemSchema2.png
.. |Add new event parameters to an event| image:: images/mfp/MyFirstPolicy_P1_newEvent3.png
.. |Right click to create a new task| image:: images/mfp/MyFirstPolicy_P1_newTask1.png
.. |Add input and out fields for the task| image:: images/mfp/MyFirstPolicy_P1_newTask2.png
.. |Add task logic the task| image:: images/mfp/MyFirstPolicy_P1_newTask3.png
.. |Create a new policy| image:: images/mfp/MyFirstPolicy_P1_newPolicy1.png
.. |Create a state| image:: images/mfp/MyFirstPolicy_P1_newState1.png
.. |Add a Task and Output Mapping| image:: images/mfp/MyFirstPolicy_P1_newState2.png
.. |Validate the policy model for error using the 'Model' > 'Validate' menu item| image:: images/mfp/MyFirstPolicy_P1_validatePolicyModel.png
.. |Download the completed policy model using the 'File' > 'Download' menu item| image:: images/mfp/MyFirstPolicy_P1_exportPolicyModel1.png
.. |Create a new alternative task `MorningBoozeCheckAlt1`| image:: images/mfp/MyFirstPolicy_P2_newTask1.png
.. |Right click to edit a policy| image:: images/mfp/MyFirstPolicy_P2_editPolicy1.png
.. |State definition with 2 Tasks and Task Selection Logic| image:: images/mfp/MyFirstPolicy_P2_editState1.png
.. |taskLogicMvel_link| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/models/MyFirstPolicy/1/MorningBoozeCheck.mvel" target="_blank">Task Logic: MorningBoozeCheck.mvel</a>
.. |taskLogicJs_link| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/models/MyFirstPolicy/1/MorningBoozeCheck.js" target="_blank">Task Logic: MorningBoozeCheck.js</a>
.. |policy1_configuration| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/config/MyFirstPolicy/1/MyFirstPolicyConfigStdin2StdoutJsonEvent.json" target="_blank">configuration</a>
.. |policy1ModelMvel_link| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/models/MyFirstPolicy/1/MyFirstPolicyModelMvel_0.0.1.apex" target="_blank">APEX CLI Editor code for Policy 1 using .Mvel Task Logic</a>
.. |policy1ModelJs_link| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/models/MyFirstPolicy/1/MyFirstPolicyModelJavascript_0.0.1.apex" target="_blank">APEX CLI Editor code for Policy 1 using .Js Task Logic</a>
.. |policy2_taskLogic_link| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/models/MyFirstPolicy/2/MorningBoozeCheckAlt1.mvel" target="_blank">`MorningBoozeCheckAlt1` task logic (`MVEL`)</a>
.. |policy2_taskSelectionLogic_link| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/models/MyFirstPolicy/2/MyFirstPolicy_BoozeAuthDecideTSL.js" target="_blank">`BoozeAuthDecide` task selection logic (`JavaScript`)</a>
.. |policy2_configuration_link| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/config/MyFirstPolicy/2/MyFirstPolicyConfigStdin2StdoutJsonEvent.json" target="_blank">configuration</a>
.. |policy2_Model_link| raw:: html
<a href="https://github.com/onap/policy-apex-pdp/tree/master/examples/examples-myfirstpolicy/src/main/resources/examples/models/MyFirstPolicy/2/MyFirstPolicyModel_0.0.1.apex" target="_blank">APEX CLI Editor code for Policy 2</a>