NIWeek 2011: Beyond State Machines / Building Modular Applications in LabVIEW (JKI)
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Justin GoeresSenior Engineer & Product Marketing ManagerJKI
PUSHING THE LIMITS OF LABVIEW
Beyond State Machines:Building Modular Applications in LabVIEW Using Public & Private Events
Monday, August 8, 11
1. Vote with your feet.
2. Please turn on your smartphones.
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Rules
@JustinGoeres is going Beyond State Machines at #niweek!
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Let’s Get This Straight
User Events are a very easy-to-use feature with a lot of cool functionality.They form the basis of JKI’s primary application frameworks & templates.If we could get a couple things fixed/added to LabVIEW, we could do even better.
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
A Public & Private Events Framework
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Agenda
What is it?
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Agenda
What is it?How does it work?
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Agenda
What is it?How does it work?What’s it good for?
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Agenda
What is it?How does it work?What’s it good for?What’s it bad at?
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Agenda
What is it?How does it work?What’s it good for?What’s it bad at?How can you use it in your projects?
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
What is it?
A “module” has: Statefulness / private data Asynchronous process(es) Public API Public Events
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Key Benefits
Module knows nothing about who’s consuming the data it producesLightweight & easy to useCompatible with by-ref and by-val architectures
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Client Code is Simple
Start Process & register for Public
EventsInvoke Public API
as neededExit Modulewhen done
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
How Does it Work?
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Process VI & Public Events
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Process VI & Public Events
Shift register for private module data(“State”)
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Process VI & Public Events
Shift register for private module data(“State”)
Generate a “Public Event” when “something happens”
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public Events: Sending Information OUT
Process VI generates a Public Event...
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public Events: Sending Information OUT
Process VI generates a Public Event...
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public Events: Sending Information OUT
Process VI generates a Public Event...
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public Events: Sending Information OUT
Process VI generates a Public Event...
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public Events: Sending Information OUT
Process VI generates a Public Event...
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public Events: Sending Information OUT
Process VI generates a Public Event...
...which is received by any other Event Structure that’s registered for
it.
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public Events: One to Many
Process VI generates a Public Event...
...that can be received by any number of consumers!
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
The Public API
Public API VIs...
...generate Private Events...
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
The Public API
Public API VIs...
...generate Private Events...
...that are handled by the asynchronous Process VI
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public API / Private Events
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public API / Private Events
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public API / Private Events
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public API / Private Events
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Monday, August 8, 11
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public API / Private Events
Only our Process VI can receive thisPRIVATE event
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public API / Private Events
Process VI registers for“Private Events” at initialization
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Public API / Private Events
When the Process VI receives a Private Event, it responds
appropriately.
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Putting it All Together
Client code invokes Public API
Client code registers for Public
Events
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Putting it All Together
Start Process & register for Public
EventsInvoke Public API
as neededExit Modulewhen done
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MainApp
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Everything is a Module
AnalogInput
MotorController
LeakDetection
EKGAnalysis
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MainApp
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Everything is a Module
AnalogInput
MotorController
LeakDetection
EKGAnalysis
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Monday, August 8, 11
MainApp
PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Everything is a Module
AnalogInput
MotorController
LeakDetection
EKGAnalysis
MainApp UI
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Extensions & Tweaks
Use with by-value & by-ref objectsCommunity & Protected EventsDynamically unregister / reregisterSynchronous communication
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Things That Suck
Most annoying bug ever. Fixed in LV2011!No Event queue management or introspectionNo Notifier-like behavior (“ignore previous”)
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
Take Home Point
User Events are a very easy-to-use feature with a lot of cool functionality.They form the basis of JKI’s primary application frameworks & templates.If we could get a couple things fixed/added to LabVIEW, we could do even better.
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PUSHING THE LIMITS OF LABVIEW | JKI CONFIDENTIAL
The End!
Discussion!
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