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Informatics 122 Software Design II. Lecture 10 André van der Hoek & Alex Baker Duplication of course material for any commercial purpose without the explicit written permission of the professor is prohibited. February 21, 2009 – 18:05:18. - PowerPoint PPT Presentation
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(c) 2009 University of California, Irvine – André van der Hoek 1February 21, 2009 – 18:05:18
Informatics 122Software Design II
Lecture 10
André van der Hoek & Alex Baker
Duplication of course material for any commercial purpose without the explicit written permission of the professor is prohibited.
(c) 2009 University of California, Irvine – André van der Hoek 2February 21, 2009 – 18:05:18
Today’s Lecture
Component reuse Assignment 5
(c) 2009 University of California, Irvine – André van der Hoek 3February 21, 2009 – 18:05:18
A Critical Design Tradeoff
build(and thus design)
buy or get for free(and thus fit into a design)
(c) 2009 University of California, Irvine – André van der Hoek 4February 21, 2009 – 18:05:18
A Critical Design Tradeoff: Benefits
build(and thus design)
buy or get for free(and thus fit into a design)
full controlfull understandingflexibilitycompetitive advantage
can be instantaneousexternal support
quality
(c) 2009 University of California, Irvine – André van der Hoek 5February 21, 2009 – 18:05:18
A Critical Design Tradeoff: Drawbacks
build(and thus design)
buy or get for free(and thus fit into a design)
timecostmaintenancestandards
licensinglack of customizability
obsolescenceurgent bugs
evaluation cost
(c) 2009 University of California, Irvine – André van der Hoek 6February 21, 2009 – 18:05:18
A Critical Design Tradeoff
build(and thus design)
buy or get for free(and thus fit into a design)
timecostmaintenancestandards
licensinglack of customizability
obsolescenceurgent bugs
evaluation cost
full controlfull understandingflexibilitycompetitive advantage
can be instantaneousexternal support
quality
(c) 2009 University of California, Irvine – André van der Hoek 7February 21, 2009 – 18:05:18
Our Focus Today
build(and thus design)
buy or get for free(and thus fit into a design)
timecostmaintenancestandards
licensinglack of customizability
obsolescenceurgent bugs
evaluation cost
full controlfull understandingflexibilitycompetitive advantage
can be instantaneousexternal support
quality
(c) 2009 University of California, Irvine – André van der Hoek 8February 21, 2009 – 18:05:18
A New Kind of Design Decision
Less fine control More learning and using and applying
Similar to recovery
(c) 2009 University of California, Irvine – André van der Hoek 9February 21, 2009 – 18:05:18
Architectural Mismatch
Architectural mismatch stems from mismatched assumptions a reusable component makes about the system structure of which it is to be part
Components– functionality– interfaces– behavior– control model
Connectors– protocols– data model
System topology Construction
– dependencies– initialization
Difficult to predict a-priori
(c) 2009 University of California, Irvine – André van der Hoek 10February 21, 2009 – 18:05:18
Architectural Mismatch
Architectural mismatch stems from mismatched assumptions a reusable component makes about the system structure of which it is to be part
Components– functionality– interfaces– behavior– control model
Connectors– protocols– data model
System topology Construction
– dependencies– initialization
How much adaptation is too much adaptation?
(c) 2009 University of California, Irvine – André van der Hoek 11February 21, 2009 – 18:05:18
Component Reuse Process
identifypreliminaryarchitecture
identifypotentialplaces for
reuse
establishselection
criteria (perplace)
search forapplicable
components
evaluatecomponents
selectcomponent
updatearchitecture
(c) 2009 University of California, Irvine – André van der Hoek 12February 21, 2009 – 18:05:18
Identify Preliminary Architecture
Largely as usual Familiarity with certain reusable components may
influence the architectural choices being made
(c) 2009 University of California, Irvine – André van der Hoek 13February 21, 2009 – 18:05:18
Identify Potential Places for Reuse
There are components for just about anything– graph layout– database access– regular expression handling– numerical computing– protein visualization– speech recognition– e-mail handling– index and search– maps– geocoding– …
Judiciously mark the architecture in terms of where reusable components may fit in
(c) 2009 University of California, Irvine – André van der Hoek 14February 21, 2009 – 18:05:18
Establish Selection Criteria (Per Place)
What kind of component does the architecture really need?– functionality – absolutely necessary versus desired functionality– software qualities
How is the component to fit with the rest of the architecture?– some adaptation can be accommodated
Investment– cost– future cost
Reputation– component provider– component itself
…
(c) 2009 University of California, Irvine – André van der Hoek 15February 21, 2009 – 18:05:18
Search for Applicable Components
Google is a wonderful thing– www.google.com– code.google.com
Component repositories– rich in available components
many junk some decent occasional gems
Research and professional development literature
Too many is no good Too few is no good either
– although one perfect component would solve the problem
(c) 2009 University of California, Irvine – André van der Hoek 16February 21, 2009 – 18:05:18
sourceforge.net
(c) 2009 University of California, Irvine – André van der Hoek 17February 21, 2009 – 18:05:19
apache.org
(c) 2009 University of California, Irvine – André van der Hoek 18February 21, 2009 – 18:05:19
Evaluate Components
Apply selection criteria to each of the components found– beware of the platform, deployment needs, licensing terms– matrix of criteria versus components
Additional approaches– trial / evaluation licenses– reading component code– examine sample programs using the component– writing code using the component
Examine the component’s documentation Analyze architectural impact of the component
Perhaps even “mini integrate” the component
(c) 2009 University of California, Irvine – André van der Hoek 19February 21, 2009 – 18:05:19
Select Component
Choose the optimum component– understand tradeoffs– be prepared to not choose a component
(c) 2009 University of California, Irvine – André van der Hoek 20February 21, 2009 – 18:05:19
Update Architecture
Design any adapters necessary to fit the component
Redesign other components as needed Restructure architecture as needed
Consider implementers– special role for documentation
(c) 2009 University of California, Irvine – André van der Hoek 21February 21, 2009 – 18:05:19
A Quick Sample Among the Graduate Students
Xalan Xerces Lucene Jung Kaffe Bcel Equip JLoox Schematron GraphViz Jython Scriptalicious …
Xacml SWT JOAL Jetty Batik JmDNS Darwin Streaming Server Spook Mplayer MySQL live.com RTP/RTSP gaim im client …
(c) 2009 University of California, Irvine – André van der Hoek 22February 21, 2009 – 18:05:19
Assignment 5
Research available components that provide a particular kind of functionality for Palantír, set up selection criteria, make a choice of the component that you believe is best, and detail how you would go about integrating the component
Specifically, research components for the following situations– code clones – we want to augment the functionality of
Palantír with awareness of clones (code that is very similar or even identical across multiple files), we need a component that helps us detect such clones
– graphics – we want to augment the Eclipse visualization with an external visualization that annotates UML diagrams of the code with awareness information of changes, clones, etc., we need a component that displays UML diagrams and allow us to easily make various kinds of annotations
– events – we want to replace Siena with another event delivery system (publish-subscribe system), because Siena has some bugs, we want a reliable component that is as backwards compatible as possible
(c) 2009 University of California, Irvine – André van der Hoek 23February 21, 2009 – 18:05:19
Assignment 5
Additional constraint– we have $1250 in funds to spend on this project, but we
want to save money for user studies and other assorted expenses, so cost should be minimized
– if truly warranted, management can be requested to fund one “big ticket” component, up to possibly $10,000
(c) 2009 University of California, Irvine – André van der Hoek 24February 21, 2009 – 18:05:19
Assignment 5
Create a 10 minute presentation that describes for one of the three categories (specific assignments of which category by which team on slide 26)– your search process– candidate components you considered
strengths weaknesses
– your selection criteria– the component you deem best (and why)
Create a document that describes, at the design and code level, the impact of incorporating the chosen components– from this document, someone should be able to make these
changes “effortlessly”
(c) 2009 University of California, Irvine – André van der Hoek 25February 21, 2009 – 18:05:19
Assignment 5
Presentation in class Monday, March 2nd
Document due at the beginning of class Monday, March 2nd
Graded on breadth and depth of component evaluation, as well as the thoroughness and insightfulness of the document
Each person also needs to submit a team evaluation (new forms available on class webpage)
(c) 2009 University of California, Irvine – André van der Hoek 26February 21, 2009 – 18:05:19
Team Assignments
Team 1 (clones) Lance Cacho Jeffrey Gaskill Derek Lee Ben Kahn Jordan Sinclair
Team 2 (clones) Scott Roeder Robert Jolly Daniel Morgan James Rose David Schramm
Team 3 (graphics) Leslie Liu Alexander Doan Aylwin Villanueva Scott Ditch James Milewski
Team 4 (graphics) Tomas Ruiz-Lopez Alton Chislom Chad Curtis Jay Bacuetes Matt Shigekawa
Team 5 (events) Matt Fritz Alex Kaiser Robert Duncan Rakesh Rajput Joshua Villamarzo Lance Zepeda
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