Web Services and Data Integration Zachary G. Ives University of Pennsylvania CIS 455 / 555 – Internet and Web Systems September 20, 2015 Some slides by Berthier Ribeiro-Neto

2 Reminders & Announcements  Assignment 3 now officially released  Midterm next Wednesday, 3/31

3 How Do We Declare Functions?  WSDL is the interface definition language for web services  Defines notions of protocol bindings, ports, and services  Generally describes data types using XML Schema  In CORBA, this was called an IDL  In Java, the interface uses the same language as the Java code

4 A WSDL Service Service Port PortType Operation PortType Operation PortType Operation Binding

5 Web Service Terminology  Service: the entire Web Service  Port: maps a set of port types to a transport binding (a protocol, frequently SOAP, COM, CORBA, …)  Port Type: abstract grouping of operations, i.e. a class  Operation: the type of operation – request/response, one-way  Input message and output message; maybe also fault message  Types: the XML Schema type definitions

6 Example WSDL

7 JAX-RPC: Java and Web Services  To write JAX-RPC web service “endpoint”, you need two parts:  An endpoint interface – this is basically like the IDL statement  An implementation class – your actual code public interface BookQuote extends java.rmi.Remote { public float getBookPrice(String isbn) throws java.rmi.RemoteException; } public class BookQuote_Impl_1 implements BookQuote { public float getBookPrice(String isbn) { return 3.22; } }

8 Different Options for Calling  The conventional approach is to generate a stub, as in the RPC model described earlier  You can also dynamically generate the call to the remote interface, e.g., by looking up an interesting function to call  Finally, the “DII” (Dynamic Instance Invocation) method allows you to assemble the SOAP call on your own

9 Creating a Java Web Service  A compiler called wscompile is used to generate your WSDL file and stubs  You need to start with a configuration file that says something about the service you’re building and the interfaces that you’re converting into Web Services

10 Example Configuration File

11 Starting a WAR  The Web Service version of a Java JAR file is a Web Archive, WAR  There’s a tool called wsdeploy that generates WAR files  Generally this will automatically be called from a build tool such as Ant  Finally, you may need to add the WAR file to the appropriate location in Apache Tomcat (or WebSphere, etc.) and enable it  See WSPack2/jaxrpc.html for a detailed example WSPack2/jaxrpc.html

12 Finding a Web Service  UDDI: Universal Description, Discovery, and Integration registry  Think of it as DNS for web services  It’s a replicated database, hosted by IBM, HP, SAP, MS  UDDI takes SOAP requests to add and query web service interface data

13 What’s in UDDI White pages:  Information about business names, contact info, Web site name, etc. Yellow pages:  Types of businesses, locations, products  Includes predefined taxonomies for location, industry, etc. Green pages – what we probably care the most about:  How to interact with business services; business process definitions; etc  Pointer to WSDL file(s)  Unique ID for each service

14 Data Types in UDDI  businessEntity: top-level structure describing info about the business  businessService: name and description of a service  bindingTemplate: how to access the service  tModel (t = type/technical): unique identifier for each service-template specification  publisherAssertion: describes relationship between businessEntities (e.g., department, division)

15 Relationships between UDDI Structures publisherAssertion businessEntity businessServicebindingTemplate tModel n 2 1 n 1n m n

16 Example UDDI businessEntity My Books Technical Book Wholesaler … … <!– keyedReferences to tModels  …

17 UDDI in Perspective  Original idea was that it would just organize itself in a way that people could find anything they wanted  Today UDDI is basically a very simple catalog of services, which can be queried with standard APIs  It’s not clear that it really does what people really want: they want to find services “like Y” or “that do Z”

18 The Problem  There’s no universal, unambiguous way of describing “what I mean”  Relational database idea of “normalization” doesn’t convert concepts into some normal form – it just helps us cluster our concepts in meaningful ways  “Knowledge representation” tries to encode definitions clearly – but even then, much is up to interpretation  The best we can do: describe how things relate

19 This Brings Us to XQuery, Whose Main Role Is to Relate XML Suppose we define an XML schema for our target data and our source data XQuery allows us to define mappings from input XPath matches to output trees Can directly translate between XML schemas or structures  Describes a relationship between two items  Transform 2 into 6 by “add 4” operation  Convert from S1 to S2 by applying the query described by view V Often, we don’t need to transfer all data – instead, we want to use the data at one source to help answer a query over another source…

20 Let’s Look at Some Simple Mappings  Beginning with examples of using XQuery to convert from one schema to another, e.g., to import data  First: let’s review what our XQuery mappings need to accomplish…

21 Challenges of Mapping Schemas In a perfect world, it would be easy to match up items from one schema with another  Each element would have a simple correspondence to an element in the other schema  Every value would clearly map to a value in the other schema Real world: as with human languages, things don’t map clearly!  Different decompositions into elements  Different structures  Tag name vs. value  Values may not exactly correspond  It may be unclear whether a value is the same It’s a tough job, but often things can be mapped

22 Example Schemas Bob’s Movie Database … … … … … * * Mary’s Art List … … … … … * Want to map data from one schema to the other

23 Mapping Bob’s Movies  Mary’s Art Start with the schema of the output as a template: $i $y $a $s $t Then figure out where to find the values in the source, and create XPaths

24 The Final Schema Mapping Mary’s Art  Bob’s Movies for $m in doc(“movie.xml”)//movie, $a in $m/director/text(), $i in $m/title/text(), $t in $m/title/text() return $i movie $a $t Note the absence of subject… We had no reasonable source, so we are leaving it out.

25 Mapping Values  Sometimes two schemas use different representations for the same thing  ID  SSN  English  Hungarian  We typically use an intermediate table defining correspondences – a “concordance table”  It can be generated automatically, and then corrected by hand (since there will often be exceptions)

26 An Example Value Mapping Problem Penn student enrollment DB: … Mary McDonald F03 cse Jon Doh Penn dental plan: Dental sealant Want to output student names + treatments…

27 Translating Values with a Concordance Table return { { $n } { $tr }

28 Translating Values with a Concordance Table for $p in doc (“student.xml”) /db/student, $pid in $p/pennid/text(), $n in $p/name/text(), $m in doc (“concord.xml”) /db/mapping, $f in $m/from/text(), $t in $m/to/text(), $d in doc(“dental.xml”)/db/patient, $s in $d/ssn/text(), $tr in $d/treatment/text() where ____________________ return { { $n } { $tr } student.xml: Mary McDonald F03 cse330 $pid: PennID $n: name

29 Translating Values with a Concordance Table for $p in doc (“student.xml”) /db/student, $pid in $p/pennid/text(), $n in $p/name/text(), $d in doc(“dental.xml”)/db/patient, $s in $d/ssn/text(), $tr in $d/treatment/text(), $m in doc (“concord.xml”) /db/mapping, $f in $m/from/text(), $t in $m/to/text() where ____________________ return { { $n } { $tr } student.xml: Mary McDonald F03 cse330 dental.xml: Dental sealant $pid: PennID $n: name $s: ssn $tr: treatment

30 Translating Values with a Concordance Table for $p in doc (“student.xml”) /db/student, $pid in $p/pennid/text(), $n in $p/name/text(), $d in doc(“dental.xml”)/db/patient, $s in $d/ssn/text(), $tr in $d/treatment/text(), $m in doc (“concord.xml”) /db/mapping, $f in $m/from/text(), $t in $m/to/text() where ____________________ return { { $n } { $tr } student.xml: Mary McDonald F03 cse330 dental.xml: Dental sealant concord.xml: $pid: PennID $n: name $s: ssn $tr: treatment $f: PennID $t: ssn

31 Translating Values with a Concordance Table for $p in doc (“student.xml”) /db/student, $pid in $p/pennid/text(), $n in $p/name/text(), $d in doc(“dental.xml”)/db/patient, $s in $d/ssn/text(), $tr in $d/treatment/text(), $m in doc (“concord.xml”) /db/mapping, $f in $m/from/text(), $t in $m/to/text() where ____________________ return { { $n } { $tr } student.xml: Mary McDonald F03 cse330 dental.xml: Dental sealant concord.xml: $pid: PennID $n: name $s: ssn $tr: treatment $f: PennID $t: ssn

32 Summary: Mapping, Integrating, and Sharing Data  Mappings based on XQuery rather than XSLT  Can do point-to-point mappings to exchange data  UDDI versus this approach?  What about search and its relationship to integration? In particular, search over Amazon, Google Maps, Google, Yahoo, …