Using Alf with Cameo Simulation Toolkit - Part 2: Modeling

No Magic World Symposium, Allen TX
Ed Seidewitz
Model Driven Solutions, Inc. ● http://www.modeldriven.com
ed-s@modeldriven.com ● @Seidewitz
http://slideshare.net/seidewitz
Copyright © 2018 Ed Seidewitz
Using the Alf Action Language
with Cameo Simulation Toolkit
Part 2 – Modeling

About me
Ed Seidewitz
Chief Technology Officier, Model Driven Solutions, Inc.
ed-s@modeldriven.com ● @seidewitz
• 30 years experience as a project manager,
architect, developer and modeler
• Involved with UML since version 0.8
• Developer of fUML and Alf Reference
Implementations and MagicDraw Alf Plugin
• Chair of the OMG fUML and Alf Revision Task
Forces; member of the UML Revision Task Force

Goals
Part 1 – Basics (Sunday)
• Learn the basics of the Alf action language for Executable UML.
• Use the Alf Plugin for MagicDraw.
• Practice using Alf with Cameo Simulation Toolkit.
Part 2 – Modeling (Today)
• Model simulations using the Alf action language.
• Use Alf in class and state machine models in MagicDraw.
• Creating and run simulations using Alf with Cameo Simulation
Toolkit.

Prerequisites (for Part 2)
• Participant
– Basic knowledge of class, activity and state machine modeling
using MagicDraw
– Some experience with model execution using Cameo Simulation
Toolkit
– Introductory understanding of using Alf in CST (e.g., from Part 1 of
this tutorial)
• System (for hands-on exercises)
– MagicDraw 18.5
– Cameo Simulation Toolkit 18.5sp3
– Alf plugin 18.5
Install MagicDraw, CST and Alf Plugin on line or from USB stick

5
Installing the Alf plugin
Plugin documentation is available at:
https://docs.nomagic.com/display/ALFP185/Alf+plugin
Under Plugins
(commercial),
download / install the
Alf plugin v18.5.
Select Help ► Resource/Plugin
Manager to open the Resource/
Plugin Manager window.
 A new version will be
available for the 19.0
release.
Or click here to install
from USB stick.

Class Models

Object creation and property access
order = new Order();
order.product = aProduct;
order.quantity = aQuantity;
order.amount = aQuantity * aProduct.price;
Create a new Order.
Set the properties
of the new order.
aCustomer.orders->add(order);
totalAmount =
aCustomer.orders.amount->
reduce RealFunctions::'+' ?? 0.0;
Add the new order to
an existing customer.
Navigate associations to
compute total amount.
 A reduce expression “inserts” a binary
function into the elements of a sequence.
 Properties must be public
to be accessible.
A property access

Operations and methods
this.product = product;
this.quantity = quantity;
return this.quantity * this.product.price;
this.orders->add(order);
return this.orders.getAmount()->
reduce RealFunctions::'+' ?? 0.0;
 The behavior that implements an operation
is called its method.
An operation call

Operation invocations
order = new Order(aQuantity, aProduct);
amount = order.getAmount();
aCustomer.addOrder(order);
totalAmount = aCustomer.getTotalAmount();
A constructor can be used to create an
object with initialization.
A constructor operation
has the standard Create
stereotype applied.
 Operation calls are synchronous invocations.
The caller waits until the operation method
execution completes.

Hands On
Address Book

Create the Address Book project
In the Alf folder,
select the Alf
template.
Under Other,
select Project
from Template.
Select File ► New Project to
open the project creation window.
Create an Address
Book project.

Create the Address Book class model
Make sure these Entry
attributes are public.
Give this association
end a multiplicity of *.

Are you using SysML?
 CST and Alf assume the use
of the UML primitive types.
But SysML provides primitive
value types that are different
than the UML primitive types.
Value properties have to
have value types, so String
here is the SysML type.
Remove the ValueProperty
stereotype and change the type to
the UML primitive type.
✗
✗
 This is resolved in v19.0 for
both CST and Alf.

Create Address Book and Entry operations
Create a constructor operation in
the usual way, and then apply
the standard Create stereotype.

Create the Entry constructor method
Right click on the Entry
operation and select
Create Method ►
Behavior to open this
selection window.
Choose either
Activity or
Opaque Behavior.
Enter code in the Alf
editor window to
initialize an Entry.

Create Address Book operation methods
Create methods for
the AddressBook
operations, and then
enter the Alf code
shown for them.
 A select expression is used to filter
a sequence based on a condition.
The index [1] ensures that at most
one value is selected.
 This expression will return either a
single value or null, as required by
the return multiplicity of 0..1.
 The constructor
operation is used when
creating an instance of
the Entry class.
 The braces { } are
required in if statement
clauses in Alf.

Test the Address Book model
Create an
AddressBookTest
activity with the
Alf code below.
 The ?? (null-coalescing) operator is
used here because get has return
multiplicity 0..1 and the + operator
requires argument multiplicity 1..1.
Run the activity
and see if it works!

State Machine Models

Classifier behaviors
A signal reception declares
the ability of instances of a
class to handle a signal.
A state machine can be
attached to a class as a
classifier behavior.
The state machine reacts to
signals that are sent to
instances of its context class.

Transition and state behaviors
Alf can be used to define
transition and state behaviors
in state machines.

Signal sending
fan = new Fan();
fan.TurnOn();
fan.TurnOff();
A signal send has a similar syntax to
operation calls, but referencing a
signal reception, rather than an
operation.
The state machine starts running
when an object is created.
 A signal can only be sent using Alf
to an object whose class has a
reception declared for the signal.
 Signal sends are asynchronous
invocations. The sender continues
immediately after the signal is sent.

Hands On
Heating Simulation

Create the Heating Simulation project
In the Alf folder,
select the Alf
template.
Under Other,
select Project
from Template.
Select File ► New Project to
open the project creation window.
Create a Heating
Simulation project.

Create the model package structure

Create Environment and House classes
Create three signals...
…and use them to declare
signal receptions.
Make this attribute
public.
Make this association
composite.
Make this operation
private.
Give both association
ends names.

Create the Environment state machine

Add triggers to transitions

Create opaque behavior
Under Effect, set the
Behavior Type to
Opaque Behavior.

Add Alf code
 A signal is sent by invoking the
signal reception on the target
object.
Click on the transition to enter
code for its effect behavior in
the Alf editor window.
Create an opaque
behavior and add Alf code
for this transition, too.

Create the House state machine

Create the cool method
Right click on the cool operation
and select Create Method ►
Behavior to open the Behavior
selection window.
Enter the Alf code in
the Alf editor window.
Choose either
Activity or
Opaque Behavior.
 The braces { } are
required in if statement
clauses in Alf.

Coming in v19.0!
Access event data
in transition and
state behaviors.

Create an instance model
Add a link for the Environment-
House composite association.
Be sure to create
slots for both ends.
Right click on the
Environment instance and
select Simulation ► Run
to execute the model.

Add a Heater class
Add new signals.
Add new reception.
Add new operation.
Make this
attribute public.
Make this
association
composite.
Add new attribute.

Update the House state machine
Add a new transition
triggered by the Heat
signal with Alf code to
call the heat operation.
Create a method behavior
for the heat operation.

Create the Heater state machine

Update the instance model
Add a Heater instance and
a link of the House-Heater
composite association.
Right click on the
to execute the model again.

Add a Thermostat class
Make this
association
composite.
Add a new attribute.
This
association is
not composite.

Update the Heater state machine
Use the isOn attribute
to record which state
the Heater is in.
 There is no built-in way in
Alf to determine what state
a state machine is in.

Create the monitor method

Are you using SysML?
Alf currently cannot be
used to send a signal
via a specified port.
 To be resolved through
further integration of
Alf with composite
structure semantics.

Update the House state machine
Double click on the running
state (as a whole) to open
its specification window.
Under Entry, set the
Behavior Type to
Opaque Behavior.
Click on just the entry behavior
line and enter code in the Alf
editor window.

Update the instance model
Add a Thermostat instance
and links to the House and
Heater instances.
Right click on the
to execute the model again.

Using Alf with Cameo Simulation Toolkit - Part 2: Modeling

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