SEA Side
Software Engineering Annotations
•AAnnotation 9 :
AOP
One hour presentation to inform you of new
techniques and practices in software development.
Professor Sara Stoecklin
Director of Software Engineering- Panama City
Florida State University – Computer Science
[email protected]
[email protected]
850-522-2091
850-522-2023 Ex 182
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Dr. Sara Stoecklin
Florida State University
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Adaptive Oriented Programming
• MIT Technology Review
– January/February 2001 issue defined ten
emerging areas of technology that will
soon have a PROFOUND impact on the
economy and on how we live and work.
– They listed as one of those ten areas
“adaptive programming”.
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Adaptive Oriented Programming
• Alias
– Adaptive Oriented Programming
(Northwestern University)
– Subject Oriented Programming (IBM)
– Aspect Oriented Programming (XEROX)
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Adaptive Oriented Programming
• Definition
– A technique for creating robustness to
changes in a particular aspect of a
system, program, or software
component.
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Adaptive Oriented Programming
• Concept
– Design software iteratively, identifying
those things that will become necessary
to change at later dates.
– Build abstractions for these changes so
that changes during maintenance will be
necessary only in parts of the system.
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Adaptive Oriented Programming
• Concept
– Software is written in a manner that
allows the programmer to work at a
higher level of abstractions than the
normal executable code.
– It can be implemented as meta
programming.
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Adaptive Oriented Programming
• Concept
– Adaptive Programming is an extension
of OO software development where
relationships between functions and data
are flexible or loosely coupled.
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Aspect Oriented Programming
Agenda
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Why Aspect Oriented Programming?
What are Aspects?
What is a cross-cutting with Aspects?
How AOP tackle a software problem?
Examples.
Conclusions
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Aspect Oriented Programming
Why Aspect Oriented Programming?
• A typical process model.
–
–
–
–
Divide system into small units of functionality.
Write code for each functional unit.
Have the units collaborate to form the system.
Design decisions are tangled, business rules are
tangled.
– Results in tangled code.
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Aspect Oriented Programming
Why Aspect Oriented Programming --Contd.
– Hard to manage, maintain and expand.
– OO and Procedural languages have a few
points in common, functional decomposition
into procedure/function/object.
– Called GP(Generalized Procedure Languages).
– The Tangling problem is not solved by GPs.
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Aspect Oriented Programming
What is a Cross Cutting with Aspects?
SOFTWARE
PROJECT
Units of functionality or procedure (components)
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Aspect Oriented Programming
What is a Cross Cut?
Cross cut
SOFTWARE
PROJECT
Units of functionality or procedure
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Aspect Oriented Programming
What is an Aspect?
Cross cut
• It’s not a unit of system’s
functional decomposition.
• It’s a property that effect
the performance of the
components in the system.
e.g. synchronization,
memory access patterns etc.
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Aspect Oriented Programming
How AOP addresses the problem.
• A new technique called AOP.
• Aspects and concerns can be dealt with in a
relatively new way.
• Provides appropriate isolation between the
components and the aspects.
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Aspect Oriented Programming
Proposed Solution
• AOP is a step ahead in this direction of
separation of concern.
– Allows to write a separate code block for a
design decision instead of spreading it all over.
– Aspect Oriented Languages
– AspectJ (core functionality),
– Cool(synchronization) and
– Ridl( distribution concerns).
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Aspect Oriented Programming
An Example
Suppose you have an
order entry system and
one use case allows you
to create and cancel
orders.
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Aspect Oriented Programming
Order Entry System
• Let’s assume we have the following
simplified Order class as our base
object:
• public class Order {
• int orderID;
• public void placeOrder() {
• public void cancelOrder() {
• }
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Aspect Oriented Programming
Order Entry System
• Suppose we now need to add
authorization checks for the persons
entering and canceling orders.
• Suppose also we would like to check in
particular if the requester has access
rights to the methods placeOrder() and
cancelOrder().
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Aspect Oriented Programming
Order Entry System
• If we have written this in an OO
architecture with something like EJB.
Then we are stuck with the strict OO
implementation of EJB.
• EJB separates the services from the
business objects BUT now we want to
add a service to the already written C/S
service (i.e EJB services) and
messaging provided in both Java and 20
Aspect Oriented Programming
Order Entry System
• Thus this access to user
procedures may be an
ASPECT of C/S systems.
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Aspect Oriented Programming
The Difference
• In OO, components are glued together with
bits of code using create this object, create
that object, etc.
• A transaction processing goes something along
these lines: log this method to a file for
debugging, run a security check, start a
transaction, open a database connection,
remember to catch exceptions or Win32®
structured exceptions and validate parameters.
• Thus this code is duplicated across transactions
for transaction and session management.
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Aspect Oriented Programming
The Difference
• In the realm of AOP, these aspects
need to be programmed
separately.
• Aspects associated with
components often use metadata
such as the session management
aspect or data management aspect
or transaction management aspect.
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Aspect Oriented Programming
The Difference
• The runtime uses the metadata to
compose the stack of aspects,
typically occurs at object creation
time.
• Thus the correct class is created
according to the aspect technique
(CICS like transaction management)
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Aspect Oriented Programming
What are some main uses?
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Aspect Oriented Programming
What are some main uses?
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Aspect Oriented Programming
What are some main uses?
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Aspect Oriented Programming
Related work
• Mehmet Aksit et al. at university of Twente
developed composition filters,object model.
– Component language is OOP.
– Aspects used to synchronization and
communication.
• Calton Pu et. Al. at Oregon Graduate institute, OS
kernels. Components are typical OS kernels,
aspects are optimizations based on invariants.
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Aspect Oriented Programming
Related work
• Karl Lieberherr et al at north eastern university
trying to make OOP more reusable by introducing
aspects to control cross cutting issues.
• Joe Yoder has made progress Reflection and Metaobject Proposals
• Subjective Programming introduced by IBM
• Other Engineering Disciplines
– Mechanical engineers use static, dynamic and thermal
models as these models cross cut each other.
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Aspect Oriented Programming
Conclusions
• Components are properties of a system for which
implementation can be easily encapsulated in a
procedure/function/object.
• Aspects are properties for which implementation
can’t be encapsulated.
• Aspects cross-cut in systems implementation.
• AOP is needed for clean abstraction and
composition of both components and aspects.
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Aspect Oriented Programming
Conclusions
• AOP is different from other languages as it
provides separate languages for component and
aspects.
• Also provides different abstraction and
composition mechanisms.
• Aspect weaver is used to co-ordinate them.
• These systems are proven to be easier to develop
and maintain and being more efficient too.
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Aspect Oriented Programming