Rewire the Net
Davide Eynard
eynard@elet.polimi.it
Dipartimento di Elettronica e Informazione
Politecnico di Milano
2007/05/30
Mobile, Context Aware Databases and Database Systems

Intro
 The problem
 Wrapping vs Mashup
 Mashup tools and technologies
 Open problems
 Conclusions
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The problem
S
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C E
T D
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R N
E S
D T
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What is a wrapper?
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What is a wrapper?
Content
Provider
Desired
Interface
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Is a wrapper enough?
 A wrapper takes a (usually unstructured) data
source and returns information in a desired
format
• All the uninteresting stuff is hidden within it
• From outside we see only the desired interface
 What we want to do is work with this information
• aggregate/filter it
• use it as input for other services
• mash it!
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An example
... and now?
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An example
Convert data structures
to LaTeX and generate
a Sudoku book in PDF
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An example
Create a Web app
which delivers data
in a standard format
Create a Java app
that runs Sudokus
on your mobile
Create another app
that solves Sudokus!
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What kind of mashup?
 Imagination is your only limit
• and... uhm, well... ability
 So, most of the mashups around belong to one of
the following families:
• mapping mashups
• video and photo mashups
• search and shopping mashups
• news mashups
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Examples
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Examples
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Examples
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Examples
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Examples
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Examples
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Features
Source:
“Five Ways to Mix, Rip, and Mash Your Data”
Nick Gonzalez, March 2 2007
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The architecture
API/Content
Provider
I
N
T API/Content
E Provider
Client R MASHUP
F SITE/SERVICE
A
C ...
E
API/Content
Provider
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The architecture
API/Content
Provider
API/Content
A Provider
Client J MASHUP
A SITE/SERVICE
X
...
API/Content
Provider
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AJAX
 Asynchronous Javascript and XML
 It's a Web application model, rather than a
specific technology, and comprises several
different technologies:
• XHTML and CSS for style presentation
• The DOM API exposed by the browser for
dynamic display and interaction
• Asynchronous data exchange (typically XML)
• Browser-side scripting (typically Javascript)
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Protocols and standards
 Web protocols
• SOAP (Services-Oriented Access Protocol)
− XML message format
− Message structure: head and body parts
• REST (Representational State Transfer)
− Web-based communication using HTTP+XML
− Few operations: GET, POST, PUT, DELETE
applicable to all pieces of information
 Syndication formats
• RSS (v1.0 is RDF based, while 2.0 is not)
• ATOM (more attention on metadata)
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Wrappers, spiders, scrapers
 Wrapper is quite a general term used to describe
a particular architecture
Remember
this one?
 A wrapper needs at least other two components
to accomplish its task
• A spider (or crawler), to follow links and
download web pages
• A scraper, to extract useful content from pages
full of uninteresting data
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Scrapers
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Scrapers
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Scrapers
 However powerful, screen scraping is usually
considered an inelegant solution
• Lack of sophisticated, re-usable screen
scraping toolkit software (most of the scrapers
are created ad hoc). Difficult to program
• Unlike API-interfaces, scraping has no explicit
contract between content provider and content
consumer. Difficult to update/maintain
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Semantic Web and RDF Hey, that's my job!
 Content created for human consumption does not
make good content for automated machine
consumption
• Data becomes information when it conveys
meaning
 XML in itself is not sufficient (too arbitrary).
 RDF is quickly finding an adoption in a variety of
domains.
• possibility to query over it (RDQL, SPARQL)
• possibility to reason over it (Jena, RACER)
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Challenges
 Technical:
• data integration (what if mapping is not a
complete one?)
• data that need to be fixed/cleaned/converted
• robust standards, protocols, models and
toolkits (... and try to avoid scrapers)
 Social:
• encouraging user contributions
• data pollution (lack of precision, gaming)
• tradeoff between the protection of intellectual
property and consumer privacy versus fair use
and free flow of information
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Conclusions
 Considering information as freely flowing on the
Internet, and creating “pipes” to redirect,
aggregate, reuse it is a great and powerful idea
 We're still at the very beginning
 User participation might offer new chances for
improvement
... and create new problems, of course!
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Webography
 Duane Merrill:
“Mashups: The new breed of Web app”
 Tim O'Reilly: “Pipes and filters for the Internet”
 Nick Gonzales:
“Five ways to Mix, Rip and Mash Your Data”
 Davide Eynard: “PowerBrowsing Projects”,
“SukaSudoku”
 www.webmashup.com
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That's All, Folks
Thank you!
Questions are welcome
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