Service-driven content delivery :

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Service-driven content delivery

• Do more for your patrons through Web services

Marshall Breeding Director for Innovative
Technology and Research Vanderbilt
University http//staffweb.library.vanderbilt.edu/
breeding
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Service Oriented Architecture

• Increasingly becoming the preferred architecture
  and framework for Web programming
• A key supporting technology for Web 2.0
• Infrastructure for behind-the-scenes
  communication among applications.
• Data exchange, conversions, lookups, etc.
• Appropriate for portal integration, e-commerce,
  distributed applications.

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SOA Architecture diagram

• http//www.w3.org/TR/2002/WD-ws-arch-20021114/

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Web services communication Path
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An XML oriented Architecture

• All the components of SOA are expressed in XML
• Definition of a service
• Directories of services
• Messages involved in the operation of the service

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Roles

• Service provider
• Technically more challenging
• Service Requestor
• Simple to implement

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Adoption of Web services

• Widespread use in many industries
• Mainstream programming approach
• Basis for Microsoft .NET technologies
• SOAP support available for all common Web
  programming environments
• Perl SOAPLite

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SAO Architecture Components
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WDSL Web Service Description Language

• The definition, expressed in XML, of how the Web
  service operates and the data structures involved

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SOAP Simple Object Access Protocol

• A transport and encapsulation protocol
• The envelope that carries the messages involved
  in an XML Web service
• Similar to RPC (Remote procedure calls)

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UDDI Universal Description, Discovery and
Integration

• A directory architecture that describes the
  services available
• Provides an automated mechanism for an
  application to know where to go to find a web
  service.
• Web service implementations

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Benefits of Web services

• Easy way to add e-commerce capabilities to Web
  site
• Leverage services offered by other providers for
  the benefit of your users.

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Web Service implementation methods

• REST
• Representational State Transfer
• Easier, more common approach
• SOAP
• Used in more complex environments
• Requires more set-up and infrastructure

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Rest-like Example Google search

• http//www.google.com/search?
• qmarshallbreeding
• hlen
• safeoff

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RSS as an example of REST

• http//www.librarytechnology.org/rss

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REST Example SRU

• http//law-library2.rutgers.edu/SRU/srucql.pl?
• query"NewJersey"
• startRecord1
• maximumRecords10
• collectionlawlib
• version1.1
• operationsearchRetrieve
• recordSchemadc

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Example Google API

• http//api.google.com/GoogleSearch.wsdl
• http//www.google.com/apis/reference.html
• Perl example for implementing the Google Web
  services

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Example

• print "Top library automation sites according to
  Google" if key is not provided,
  GoogleSearchService looks in ENVHOME, or in
  the location of GoogleSearchService.pm for
  googlekey.txtmy key your google API goes
  here'my google new GoogleSearch()my
  returnuse GoogleSearchmy search 'Library
  Technology'return google-gt
• doGoogleSearch(query gt search,start gt
  0,maxResults gt 10,restrict gt
  'xml',)-gtresult()foreach my entry
  (_at_return-gt'resultElements') print
  "" print "lta href\" entry-gtURL\"gtentry-gtti
  tle\n" print "entry-gtsnippet\n" print
  "\n"

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Mashups

• A new resource based on content or services from
  multiple sources
• Usually created through Web services
• Many examples

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Lets Build a mashup using Web Services
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Recipe

• Ingredients
• Information about the library from the local
  database
• Name, photo, street address
• Latitude and Longitude from an external Web
  service
• USGS Web service
• Map, positioning and display services from Google

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Step 1. Launch map

• Create button to launch a new window for the map
• Pass Library name, address and photo location
• sub ViewMap
• local (Library,StreetAddress,libphoto)
  _at__
• print "ltinput type\"button\"
• value\"view street map\"
• onclick\"newWindow(
• \'lwc-viewmap.pl
• sessionstringamp
• addressStreetAddress
• libraryLibrary
• libphotolibphoto
• \',\'window2\')\" buttonstyle /gt\n"

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Step 2. Turn address into Geocode data

• my d get(
• http//rpc.geocoder.us/service/rest?addressfield
  s'address'
• ) d /geolonggt(lt ).?geolatgt(lt
  )/is lat 2

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Step 3. Invoke Google MAP API

• Use pre-established API key
• Fetch the correct map specifying size and
  location
• Place the marker on the map
• Label the marker
• Create and populate info window

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Call the subroutine

• MapScript("lat","long","fields'libphoto'")

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Invoke the subroutine

• sub MapScript
• local(lat,long,photo) _at__
• local libphototext ""
• libphototext " \"ltbr /gtltimg
  src\\\"imageserver//\" libphoto \".jpg\\\"
  height \\\"100\\\"gt\"" if (length(photo) gt 0)
• print "ltscript type\"text/javascript\"gt\n"
• print " //lt!CDATA\n"
• print "\n"
• print " function createMarker(point,
  name, address, libphoto) \n"
• print " var marker new
  GMarker(point)\n"
• print " GEvent.addListener(marker,
  \"click\", function() \n"
• print " marker.openInfoWindowHtml(\"lts
  tronggt\" name \"lt/stronggtltbr /gt\" address
  libphototext)\n"
• print " )\n"
• print " return marker\n"
• print " \n"
• print " function load() \n"
• print " if (GBrowserIsCompatible())
  \n"
• print " var map new
  GMap2(document.getElementById(\"map\"))\n"

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Step 4. Stir, bake and serve
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