Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Exercises: Scenarios
List of Exercises for this Module
Exercise 1:
Exercise 2:
Exercise 3:
Exercise 4:
Exercise 5:
Exercise 6:
Exercise 7:
Exercise 8:
Create a New Scenario .............................................................................................................3
Define States ............................................................................................................................5
Define Scenario Variables........................................................................................................6
Add Block Instances to the Scenario .......................................................................................8
Link Scenario Variables and Block Parameters .....................................................................10
Compose Rules ......................................................................................................................13
Run the Project .......................................................................................................................21
Link Blocks Together .............................................................................................................22
Objective
In this exercise, you will learn how to use the Event Modeler tool to create a
simple Apama Scenario for the Off Market Limit Order.
Prerequisites
You must have installed the current release of Apama and completed the
previous lab exercise: Import Apama Projects.
Start Apama Studio, if it is not already started.
Overview of
All Steps
1. Start with the provided Limit_Lab_2 project.
2. In the Event Modeler, create a new scenario and call it
OffMarketLimitOrder.
3. Define three new states: Buy, Sell, and Wait until finished.
4. Define the following scenario variables:
 Input – Symbol (text, immutable), Side (choice, immutable) Price
(number), Qty (integer number)

Output – Final Qty, Final Price, Bid, Ask, MD Counter, Status

Private – OrderId
5. Add instances of two blocks:

OMS block – An Order Management system block that allows you to
submit orders to buy and sell stock

Market Data block – A block that simulates an event stream from a
stock market data feed. It contains two operations that let you subscribe
and unsubscribe from the simulated event stream.
continued on next page
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Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Basic Steps
(continued)
Module: Developing Apama Scenarios
in Event Modeler
6. Link scenario variables to block output feeds:

Final Qty and Final Price to the OMS qtyExecuted and
priceExecuted

Bid and Ask to the corresponding Market Data feeds
Link block parameters to the corresponding scenario variables:

Market Data: Symbol

OMS: OrderId, symbol, side, price, qty
7. Compose the rules for each state as follows:

Start (a processing state) – Subscribe to the Market Data block and
check the price of a particular stock. Then determine what type of order
to process – an order to buy the stock or an order to sell it.

Buy (a processing state) – When the ask price is less than or equal to the
input Price (from the UI), submit a BUY order to the Order Management
System (OMS), and wait for the order to fill.

Sell (a processing state) – When the ask price is greater than or equal to
the input Price (from the UI), submit a SELL order to the OMS, and wait
for the order to fill.

Wait unit finished (a wait state) – When the OMS has finished
processing the order, the order is filled, so then unsubscribe from market
data and enter the end state.
Compose a global rule that ensures the bid and ask price parameters are
flowing through from the Market_Data_Block. Use the MD Counter scenario
variable to count the number of Market Data updates coming from the
Market Data block.
8. Run the project and create an instance of the scenario in the Scenario
Browser view.
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Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Detailed Steps
Exercise 1: Create a New Scenario
Prepare
the Project
1. In Apama Studio, select File > Import to import the Limit_Lab_2 project
(provided by your instructor). This project is the same as the
Limit_Lab_1_Complete project, except:


Does not include the monitors/OffMarketLimitOrder.mon file
Includes block catalogs and a function catalog
2. Add the scenario bundle to the project:
a) Select Project > Properties from the Apama Studio menu.
b) In the Properties dialog, select MonitorScript Build Path and select the
Bundles tab.
c) Click Add.
d) In the Add Bundle Instance dialog, select the Scenario Service and click
OK twice.
Apama Studio adds a Bundles folder and a bundle_instance_files folder to
your project. The Scenario Service bundle includes two monitor files:


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ScenarioService.mon - Contains the shared event definitions that are
generic across all scenarios.
ScenarioDeleterSupport.mon - Provides event definitions for deleting
scenario instances.
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Create a
new
scenario
Module: Developing Apama Scenarios
in Event Modeler
To create a new scenario:
1. In the Limit_Lab_2 project, select the Scenarios folder, then click New
Scenario:
2. In the New Scenario dialog, type OffMarketLimitOrder for the filename.
3. Click Finish. The Event Modeler opens with the two default states already
created: start and end.
Through these exercises, you will create rules that cause the start state to
subscribe to the Market Data block and check the price of a particular stock.
It will then determine what type of order to process – an order to buy the
stock or an order to sell it. The start state will use blocks that you need to
add to the scenario before you can define the start state rules.
The end state is a default state that indicates a scenario instance has finished
processing.
4. Drag the end state so it is further down in the States panel.
Page 4 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Exercise 2: Define States
Define three You will add the following additional states to the Off MarketLimitOrder
scenario template:
new states

Buy (an action state) – When the ask price is less than or equal to the input
Price (from the UI), submit a BUY order to the Order Management System
(OMS), and wait for the order to fill.

Sell (an action state) – When the ask price is greater than or equal to the input
Price
(from the UI), submit a SELL order to the OMS, and wait for the order to fill.

Wait unit finished (a wait state) – When the OMS has finished processing
the order, the order is filled, so then unsubscribe to market data and enter the
end state
To define these three new states:
1. At the top of the States panel, click the plus sign
to create a new state.
2. Double-click the New State 1 label and rename it Buy.
3. Create another new state and rename it Sell.
4. Create another state and rename it Wait until finished.
5. Drag the new states so they are between the start and end states.
6. Select File > Save Scenario.
Page 5 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Exercise 3: Define Scenario Variables
Define
scenario
variables
To define scenario variables:
Scenario variables can be used by any of the states or rules in the scenario.
1. In the Scenario Variables panel, click on the green box.
2. Type Symbol in the name column and check the input box.
3. Double-click on the green box to open the Properties dialog.
4. Specify the Type as Text and Immutable, then click OK..
5. In the Scenario Variables panel, click in the value column for Symbol, then type
PRGS.
6. To define the next variable, click on the next green box, and type Side in the name
column.
7. Check the input box.
8. Double-click on the green box to open the Properties dialog, then specify the
Type as Choice and Immutable.
9. Click the Constraints tab, add BUY and SELL as Choices, then click OK to exit
the Properties dialog.
10. Double-click in the Value area and select SELL for the initial value.
continued on next page
Page 6 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
11. Create the following additional variables:
Define
scenario
Variable
Input/Output
variables
Name
(continued)
Type
Constraint
Price
Input
Number, Mutable
Qty
Input
Number, Mutable
Whole Number
Final Qty
Output
Number, Mutable
Whole Number
Final Price
Output
Number, Mutable
Bid
Output
Number, Mutable
Ask
Output
Number, Mutable
Status
Output
Text, Mutable
MD counter
Output
Number, Mutable
OrderId
Neither(private)
Number, Mutable
Mixed case
Whole number
12. Select File > Save Scenario.
Your scenario should now include the following variables:
Page 7 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Exercise 4: Add Block Instances to the Scenario
Objectives
In this exercise, you will add two pre-existing blocks of MonitorScript code and
a predefined function to the simple Apama Scenario application you created in
the previous exercise.
Description
of Blocks
The two blocks that you will add are:
Basic steps

OMS block – An Order Management system block that allows you to
submit orders to buy and sell stock

Market Data block – A block that simulates an event stream from a stock
market data feed. It contains two operations that let you subscribe and
unsubscribe from the simulated event stream.
When you add a block to a scenario, you are specifying that each instance of
that scenario should create an instance of that block running within the
scenario.
To use a block in a scenario, you must select it in the Event Modeler Catalogs
panel and add an instance to your scenario. You can add more than one instance
of the same block to a scenario.
Add the
Market Data
and Order
Management
System
blocks
To add instances of the Market Data block (code that simulates an event data
stream) and Order Management System block (process orders) :
1. In the title bar of the Event Modeler Catalogs panel (at the bottom of Event
Modeler), click the down arrow
and select the Limit_Lab_2 blocks
catalog.
2. In the Catalogs panel, select the Market Data block.
continued on next page
Page 8 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Add blocks
(continued)
Module: Developing Apama Scenarios
in Event Modeler
3. Click the icon
farthest to the right in the Catalogs title bar. An
instance of the Market Data block is added to your scenario. The Event
Modeler displays the block instance in the Blocks panel and calls it
Market_Data_Block 1. (If you were to add another instance, it would be
named Market_Data_Block 2.)
4. Repeat Steps 2 and 3 for the Order Management System block.
When you are done, the Blocks panel should look like this:
Page 9 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Exercise 5: Link Scenario Variables and
Block Parameters
Objective
In this exercise, you link the scenario’s variables to the output parameters of the
two code blocks.
Attaching a scenario variable to a block parameter provides greater flexibility
because it allows the scenario itself to be parameterized.Whenever the block
outputs an event on the given feed, the variable is automatically updated
Link scenario
variables to
block output
feeds
To link scenario variables to output feeds:
1. In the Event Modeler’s Scenario Variables panel, right-click in the value
column of the Bid variable.
2. From the pop-up menu, select Market_Data_Block_1 >
best bid and ask > bid :
3. Right-click in the value column of the Ask variable, then select
Market_Data_Block_1 > best bid and ask > ask.
4. Set the values of the following variables for interaction with the Order
Management System block:
Name
Final Qty
Final Price
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Value
qtyExecuted output feed from the OMS block
priceExecuted output feed from the OMS block
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Link block
parameters
to scenario
variables
Module: Developing Apama Scenarios
in Event Modeler
Whenever the variable’s value is modified, the block’s parameter is automatically
updated.
To link the value of a block parameter to the value of a scenario variable:
1. In the Blocks panel, right-click in the value field of the Market_Data_Block 1
symbol parameter and select Symbol from the pop-up menu. This
automatically passes the value of the scenario's Symbol variable into the block,
which causes the block to listen for events about Progress Software stock:
2. In the Blocks panel, right-click in the value field of the following
OMS _Block_1 block parameters to select the corresponding scenario
variable from the pop-up menu:
OMS Block Parameter
orderId
symbol
side
price
qty
Value = Scenario Variable
OrderID
Symbol
Side
Price
Qty
Note that the Type block parameter does not need to be set. It is of type
choice.
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Apama Fundamentals Course
Link block
parameters
and scenario
variables
Page 12 of 22
Module: Developing Apama Scenarios
in Event Modeler
When you have completed linking blocks and scenario variables, the Scenario and
Blocks Panels should look like this:
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Exercise 6: Compose Rules
Objective
In this exercise, you will learn how to compose local rules for each of the four
states (start, Buy, Sell, Wait until finished). You will also learn to define a global
rule that applies to all states
Overview of You will compose the following three rules in the start state:
 Subscribe to the Market_Data_Block, and continue to evaluate the next rule in
start state
the state
rules
Compose
rules for
the start
state

If the Side is set to BUY in the running scenario instance, move to the Buy
state

If the Side is set to SELL, move to the Sell state
To subscribe to market data:
1. In the Event Modeler States panel, select the start state.
2. In the Local Rules panel, click the plus sign to add a new rule, then click the
Up arrow button until the new rule is the first one at the top of the Local
Rules panel.
3. Double-click on the name New Rule, then change it to Subscribe to external
services.
4. In the When row, right-click condition and select true from the pop-up
menu.
5. In the Then row, click the grey circle next to continue to add an action
statement.
Note: If you create more than one by mistake, you can delete the extra one by
right-clicking on the grey circle.
6. Right-click action-statement and select Market Data Block 1 > subscribe.
When you are done, the new rule should look like this:
7. Select File > Save Scenario.
continued on next page
Page 13 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Compose
rules for
the start
state
(continued)
Module: Developing Apama Scenarios
in Event Modeler
To create a rule for moving to the Buy state:
1. In the Local Rules panel, click the plus sign to add a new rule. Use the Up or
Down arrow buttons, if necessary, so that the new rule comes after the
Subscribe to external services rule.
2. Change the name from New Rule to Order to BUY.
3. In the When row, right-click condition and select choice variable compared
with choice expression.
You want to compare the value of the Side scenario variable with a text
expression you specify (“BUY”). When the result is true, Apama executes the
action defined in this rule. When the result is false, Apama moves on to
evaluate the When statement in the next local rule.
4. Right-click on choice variable and select Side.
5. Right-click on compared with and select is equal to.
6. Right-click choice expression and select BUY.
7. In the Then row, add an action statement by clicking the grey button next to
the continue statement:
8. Right-click action-statement and select text variable = text expression.
9. Right-click text variable and select Status.
10. Right-click text expression and select Enter textual value and type:
Executing Buy order.
11. Right-click continue and select Move to state [Buy]. A transition arrow
immediately appears in the States pane going from the start state to the Buy
state.
12. Select File >Save.
13. To create a rule for moving to the Sell state, repeat the Steps 1-11 above,
replacing “buy” with “sell”.
14. Select File >Save.
continued on next page
Page 14 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Compose
rules for
the start
state
(continued)
Here are the three local rules in the start state:
Compose a
rule for the
Buy state
In the Buy state, when the ask price is less than or equal to the input Price (from
the UI), submit a BUY order to the OMS system, and wait for the order to fill.
To compose a rule in the buy state:
1. Click the Buy state.
2. In the Local Rules panel, click the plus sign to create a new rule.
3. Change the name of the rule to Wait for price.
4. To define the condition part of the rule:
a) Right-click ‘condition’ and select ‘number expression’ ‘compared
with’ ‘number expression’.
You want to compare the asking price from the market feed with the value
of the Price variable in the scenario. You want to wait to place an order to
buy until the asking price is less than or equal to the scenario price.
b) Right-click the first ‘number expression’ and select ‘number block
field’, then ‘best bid and ask’, and then ‘ask’.
c) Right-click ‘compared with’ and select is less than or equal to.
d) Right-click the last ‘number expression’ and select ‘number scenario
variable’, and then Price.
continued on next page
Page 15 of 22
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Apama Fundamentals Course
Compose a
rule for the
Buy state
(continued)
5.
Module: Developing Apama Scenarios
in Event Modeler
To define the action part of the rule:
a) Click the gray circle next to continue three times to add three action
statements.
b) Right-click the first action statement and select ‘number variable’ =
‘number expression’.
c) Right-click ‘number variable’ and select OrderId.
d) Right-click ‘number expression’ and select Limit_Lab_2functions >
GET_UNIQUE_ID().
e) Right-click the second action statement and select OMS_Block_1 >
submitOrder.
f) Right-click the third action statement and select ‘text variable’ = ‘text
expression’.
g) Right-click ‘text variable’ and select Status.
h) Right-click text expression, select Enter textual value, and type
Submitted BUY order to OMS block.
i) Right-click continue and select Wait until finished.
6. Select File >Save.
Here is the local rule in the Buy state:
Page 16 of 22
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Apama Fundamentals Course
Compose a
rule for the
Sell state
Module: Developing Apama Scenarios
in Event Modeler
In the Sell State, when the ask price is greater than or equal to the input Price
(from the UI), submit a SELL order to the OMS system, and wait for the order to
fill.
To compose a rule in the sell state:
In the Sell State, when the bid price ≥ input Price (from the UI), submit a SELL
order to the OMS system, and wait for order to fill.
To compose a rule in the sell state:
1. Copy the Wait for Price rule from the Buy state and paste it into the Sell
state.
2. In the When row, right-click “ask” and select “Market_Date_Block_1, best
bid and ask, and then bid.
3. Right-click is less than or equal to and select is greater than or equal to.
4. In the Then row, in the third action statement, right-click text expression,
select Enter textual data, and change BUY to SELL.
5. Select File > Save Scenario.
You should now have one rule in the sell state:
Page 17 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Compose a
rule for the
Wait until
finished
state
Module: Developing Apama Scenarios
in Event Modeler
In the Wait until finished state, when the OMS Block has finished processing
the order, the order is filled so unsubscribe to market data and enter the end state.
To compose the local rule for the Wait until finished state:
1. Select the Wait until finished state
2. In the Local Rules panel, click the plus sign to add a new rule.
3. Type Wait until… as the rule name.
4. Right-click condition and select condition block field > OrderUpdate
>finished.
5. Create two action statements.
6. Right-click the first action statement and select ‘text variable’ = ‘text
expression’.
7. Right-click ‘text variable’ and select Status.
8. Right-click ‘text expression’, select Enter textual value, and type Order
executed.
9. Right-click the second action statement and select Market_Data_Block_1
and unsubscribe.
10. Right-click continue and select end.
Here is the local rule in the Wait until finished state:
Page 18 of 22
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Apama Fundamentals Course
Compose a
global rule
Module: Developing Apama Scenarios
in Event Modeler
A global rule is evaluated before any of the local (state-specific) rules.
The purpose of this rule is to ensure that the bid and ask price parameters are
flowing through from the Market_Data_Block.
The MD Counter is the scenario variable that counts the number of Market Data
updates coming from the Market Data block.
To define the global rule:
1. In the Global Rules panel, click the plus sign.
2. For the rule name, enter Market Data counter to track # of updates.
3. Right-click ‘condition’, then select ‘variable changes’.
4. Right-click ‘variable’, select Market_Data_Block_1 > best bid and ask.
5. Create one action statement.
6. Right-click action statement then select ‘number variable’ = ‘number
expression”.
7. Right-click ‘number variable’ then select MD Counter.
8. Right-click ‘number expression’ then select […] ‘operator’ ‘number
expression’.
9. Right-click the first ‘number expression’ and select number scenario
variable and MD Counter.
10. Right-click ‘operator’ and select +.
11. Right-click the last ‘number expression’, select Enter numeric value and
type 1.
Here is the global rule:
Page 19 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
When you are done, your completed scenario should look like this:
Page 20 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Exercise 7: Run the Project
Run the
project
To run the project and create instances of the scenario:
1. In Apama Studio’s Launch Control Panel, click the Run button to start the
project. Apama Studio loads the project and opens the Apama Studio
Scenario Browser view.
2. Expand the localhost node in the left panel in the Scenario Browser and
select the OffMarketLimitOrder scenario.
3. At the top of the Scenario Browser view, click the plus button (+) to create
an instance of the OffMarketLimitOrder scenario.
4. In the Add Scenario Instance dialog, next to Side, double-click in the Value
field and select BUY.
5. Tab to Price, type 10. Click OK.
6. In the Scenario Browser, expand the OffMarketLimitOrder node, select
the new scenario, and observe the values of the scenario variables.
7. In the Workbench Project View, right-click the
events/marketevents.evt file and select Apama Runtime > Send
Events.
Observe the updates to the output in the Scenario Browser.
You can experiment by creating multiple scenario instances and changing the
values of the variables to see what happens.
8. To stop the project, click the Stop button in the Launch Control Panel.
Page 21 of 22
Copyright © 2009 Progress Software Corporation
Apama Fundamentals Course
Module: Developing Apama Scenarios
in Event Modeler
Exercise 8: Link Blocks Together
Objective
In this exercise, you will link two blocks together: the Market Data block and a
standard Data Distribution Calculator.
The Data Distribution block calculates running data distribution statistics from the
input data stream. In this example, you’ll use it to calculate the mean of the bid
data coming from the Market Data block.
To practice linking two blocks together:
Steps for
Linking Blocks 1. Add the Data Distribution Calculator block to your scenario.
Hint: It is a standard, General Analytics block.
Together
2. Open the block wiring panel:
3. Move the Market Data and the Data Distribution Calculator blocks so that
they are next to each other, with the Market Data block first (on the left).
4. Click and hold the black semi-circle on the Market Data block. This
represents the output feed of the Market Data block.
5. Drag a line from there to the input feed semi-circle(on the left) of the
calculator block.
The Configure Block Wiring dialog appears. In this dialog box, you need to
pick the proper input/output feeds from the two provided drop-down lists.
6. Map the Market Data block’s bid field to the calculator’s value field.
7. Back in the Event Modeler’s main window, edit the appropriate scenario rule
in the Start state to start the Data Distribution Calculator block.
8. Edit the appropriate scenario rule in the Wait Until Finished state to stop the
Data Distribution Calculator block.
9. Add a new scenario output variable called Bid Mean and sets its value to the
mean from the statistics output feed of the Data Distribution Calculator
block.
10. Save your updates to the scenario.
11. Run the project and view the output in the Scenario Browser view of Apama
Studio.
Page 22 of 22
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