XML Web Services: Standard by Standard

1
XML Web Services Standard by Standard

• Brand Niemann
• XML Web Services Evangelist
• Data Standards Branch
• December 15, 2001

Disclaimer Any reference to or depiction of the
commercial product of any vendor is for
illustrative purposes only and does not
constitute an endorsement by EPA or the trainer.
2
Overview

• 1. Preface
• 2. Introduction
• 3. Chapter 1. Evolution of Web Services
• 4. Chapter 3. SOAP Basics
• 5. Chapter 4 The Web Services Definition
  Language (WSDL)
• 6. Chapter 6. Universal Description, Discovery,
  and Integration (UDDI)
• 7. Chapter 11. NET Web Services
• 8. Web Services Web Agent Demonstration

3
1. Preface

• Today, the principal use of the World Wide Web
  is for interactive access to documents and
  applications. In almost all cases, such access is
  by human users, typically working through Web
  browsers, audio players, or other interactive
  front-end systems. The Web can grow significantly
  in power and scope if it is extended to support
  communications between applications, from one
  program to another.
• The beginning of the charter for the XML Protocol
  Workgroup at the W3C.

4
2. Introduction

• Source
• Professional XML Web Services, Wrox Press Ltd.,
  September 2001, 803 pp.
• 12 authors, 16 chapters plus introduction and 3
  appendices .
• Structure
• Introduction (cover Chapter 1).
• Web Service Languages (cover Chapters 3, 4, 6).
• Web Services Implementations (cover Chapter 11).
• Appendices (SOAP, WSDL, and UDDI specifications).
• Customer support
• Sample code and Errata http//www.wrox.com/
• Email support support_at_wrox.com
• Programmer-to-Programmer support
  http//p2p.wrox.com

5
2. Introduction

• The hype
• Solve world debt problems.
• Eliminate hunger.
• Bring back Elvis!
• The reality
• Huge investments by all the major software
  companies.
• Microsoft turns its whole focus to
  service-oriented software and Sun, HP, IBM,
  etc. are enthusiastic backers.
• Evolution to a high level of interoperability
  independent of platform and language.

6
The Web Services Standards stack

• Commonly used by the major vendors
• Work Flow (WFDL-Work Flow Description Language).
• Publication and Discovery (UDDI-Universal
  Description, Discovery, and Integration).
• Service Description (WSDL-Web Services
  Description/Definition Language).
• Messaging (XMLP-XML Protocol from SOAP-Simple
  Object Access Protocol).
• Content (XML-Extensible Markup Language).
• Transport (HTTP-Hypertext Transport Protocol).

7
3. Chapter 1. Evolution of Web Services

• Definition
• XML Web Services are modular applications that
  are self-describing, and can be published,
  located and invoked from anywhere on the Web or
  within any local network based on open Internet
  standards (speak XML and do so with SOAP).
• Outline
• Brief history of distributed computing and
  pre-XML Web Services.
• How the different Web Services technologies fit
  together (architecture).
• New and upcoming efforts.

8
3. Chapter 1. Evolution of Web Services

• Brief history of distributed computing and
  pre-XML Web Services
• Mainframes (MF).
• Terminals to connect to mainframes (T).
• Personal computers (1980s) (PC).
• Run your own applications.
• Making applications talk to each other on the
  same computer was enough of a challenge
  (communication protocols).

9
3. Chapter 1. Evolution of Web Services

• Brief history of distributed computing and
  pre-XML Web Services
• Object frameworks became popular (1990s) but were
  not interoperable (COM and CORBA).
• OMG was a cross-vendor initiative.
• Stand alone computing machines ruled the Earth.
• Need application-to-application communication
  that works on top of the operating system.
• Once local area networks became more widespread,
  peer-to-peer computing became a higher priority
  than it was before.

10
3. Chapter 1. Evolution of Web Services

• Brief history of distributed computing and
  pre-XML Web Services
• Object frameworks evolved, but were still not
  interoperable (COM to DCOM, CORBA to IIOP, and
  Sun to RMI).
• LANs evolved to WANs that evolved to The Web.
• The network became very large, very distributed,
  and extremely decentralized.
• None of the existing protocols were good
  candidates for a universal communication
  protocol, but still used in early attempts.

11
3. Chapter 1. Evolution of Web Services

• Brief history of distributed computing and
  pre-XML Web Services
• Early attempts at connecting Web applications
• Web links really re-directing users from one
  application to another.
• Frames still dont connect the applications,
  just the front-end interface.
• Post information from HTML form early
  generation of Web Services before XML.
• First generation portals (digital dashboards)
  links, frames, screen scraping, and posting,
  but lacked control of target application. Need
  Web sites to provide functions and real data.
• Others to mention
• XML-RPC (Remote Procedure Call) was a notable
  pioneer, but most vendors did not embrace it, but
  its successor, SOAP (Simple Object Access
  Protocol) instead.
• EAI (Enterprise Application Integration) was
  found to be less flexible and more expensive to
  implement.

12
3. Chapter 1. Evolution of Web Services

• How the different Web Services technologies fit
  together (architecture)
• Move from building tightly coupled or bound
  applications into building applications that are
  built with loosely bound components.
• Advantages Be bound or even discovered and bound
  at run-time. More scalable, manageable,
  extensible, and less susceptible to errors from
  modifications.
• Disadvantages More error conditions to handle.
  Tools and infrastructure needed for
  implementation are more difficult to design and
  create.
• XML and SOAP (Simple Object Access Protocol) are
  the base technologies of Web Services
  architectures.

13
3. Chapter 1. Evolution of Web Services

• How the different Web Services technologies fit
  together (architecture)
• SOAP is a simple wire protocol based on XML for
  messages between computers that specifies the
  message format that accesses and invokes the
  objects, rather than the particular objects
  themselves.
• SOAP was submitted jointly to the W3C in May 2000
  by a large diverse group of companies indicating
  industry acceptance and implementation.
• SOAP is being further developed by the XML
  Protocol Working Group at the W3C into the next
  version (SOAP 1.2).

14
3. Chapter 1. Evolution of Web Services

• How the different Web Services technologies fit
  together (architecture)
• The main building blocks are threefold and each
  consist of a number of layers
• Discovery (have to find it to use it).
• Description (representation of the meaning-meta
  data).
• Invocation (provide input to call it and receive
  the output).
• The Message (Invocation) building block sits on
  top of the Transport layer and contains the
  Description (Meaning) and the Discovery
  components.
• There is the core SOAP protocol and then its
  extensions (more detail in 4. Chapter 3).

15
3. Chapter 1. Evolution of Web Services

• How the different Web Services technologies fit
  together (architecture)
• Invocation
• SOAP is a simple and extensible
  computer-to-computer (peers) communication
  protocol that leverages existing Internet
  standards XML for message formatting, HTTP and
  other Internet protocols for message transport.
• It is based on XML Schemas, is analogous to
  regular postal mail (an envelope for the data),
  is easy to deploy, is extensible via the use of
  XML, and binds applications implemented in
  various object models languages, but has no
  object model.
• Advanced SOAP SOAP 1.2, SOAP Bindings, and SOAP
  Extensions.

16
3. Chapter 1. Evolution of Web Services

• How the different Web Services technologies fit
  together (architecture)
• Invocation
• A SOAP message contains three sections
• SOAP envelope
• SOAP header
• SOAP body
• A simple SOAP message used to call a procedure
  that requires a single parameter
• ltSOAP-ENVEnvelope
• xmlnsSOAP-ENV"http//schemas.xmlsoap.org/soap/e
  nvelope/"
• SOAP-ENVencodingStyle"http//schemas.xmlsoap.or
  g/soap/encoding/"gt
• ltSOAP-ENVBodygt
• ltmGetLastTradePrice xmlnsm"Some-URI"gt
• ltsymbolgtDISlt/symbolgt
• lt/mGetLastTradePricegt
• lt/SOAP-ENVBodygt
• lt/SOAP-ENVEnvelopegt

17
3. Chapter 1. Evolution of Web Services

• How the different Web Services technologies fit
  together (architecture)
• Description
• Description of the messages it can accept and
  generate (in essence, part of the XML Web
  Services contract).
• WSDL Web Services Description Language, which is
  based on other XML technologies like XML Schemas
  and XML namespaces.
• The layer stack includes Structure (using XML
  Schemas), RDF and Semantic Web (defined latter),
  and Process Flow and Pattern Description (very
  early stages of development).
• More detail in 5. Chapter 4. WSDL The Web
  Services Description/Definition Language.

18
3. Chapter 1. Evolution of Web Services

• How the different Web Services technologies fit
  together (architecture)
• Discovery
• Analogous to search engines, a provider needs to
  advertise the existence of their Web Service in a
  directory.
• Search UDDI 1.0 by category, inspect the details
  of it, such as its service description and
  process flow orchestration contract.
• UDDI 2.0 will use new taxonomies (vocabularies)
  to describe businesses.
• More detail in 6. Chapter 6 Universal
  Description, Discovery, and Integration.

19
3. Chapter 1. Evolution of Web Services

• How the different Web Services technologies fit
  together (architecture)
• The three building blocks are related and are
  meant to work together within one Web Services
  Framework.
• The Framework allows decentralized services to be
  defined, deployed, manipulated and evolved in an
  automated fashion without centralized control
  (services-oriented applications and a
  services-oriented Internet).
• Developers are not limited to a particular
  vendors products.
• The components are developed in an incremental
  fashion, from the bottom up.
• This interoperability is based on standards data
  formats and protocols and not APIs (Application
  Programming Interfaces).

20
3. Chapter 1. Evolution of Web Services

• New and upcoming efforts
• Vendor tools and frameworks (or platforms are
  wider and more encompassing offerings)
• HP and e-Speak (now HP Web Services Platform).
• IBMs Dynamic e-Business
• Alphaworks Program WebSphere Application
  Server.
• Service Provider publishes to a Service Registry
  where a Service Requestor finds binds to the
  Service Provider.
• WSFL (Web Services Flow Language).
• Microsofts .NET (more in 7. Chapter 11)
• Visual Studio .NET.
• .NET Enterprise Servers. .NET Framework, .NET
  Building Blocks.
• Operating System on Servers, Desktops, and
  Devices.
• Common Language Runtime (CLR) runs on top of the
  operating system and is the heart of the .NET
  Framework.

21
3. Chapter 1. Evolution of Web Services

• New and upcoming efforts
• Vendor tools and frameworks
• Sun Microsystems and Sun One
• Open Network Environment platform built around
  the Sun-Netscape Alliance iPlanet server suite
• JAX Pack Java API for XML Web Services.
• Other initiatives
• ebXML
• Electronic Business B2B XML framework.
• RosettaNet
• Consortium from three vertical industries
  (electronics).
• BizTalk Framework
• XML framework created by Microsoft for
  application integration and electronic commerce
  (BizTalk Server).
• Etc.

22
3. Chapter 1. Evolution of Web Services

• New and upcoming efforts
• The Service-Oriented Internet
• Web Services can allow universal access, from any
  computer or any device to any other, regardless
  of proprietary technology that is the base of the
  particular device.
• The services-oriented Internet would have just
  about any XML Web Service available, from
  consumer related ones to commercial services in
  a similar fashion to how the current Internet has
  just about all types of content on it.
• For example, HailStorm is a collection of Web
  Services. In particular, it is a set of
  user-centric Web Services that would be made
  available on the Internet, and it could be used
  as building blocks by incorporating them into any
  solution or application with access to the
  Internet.

23
3. Chapter 1. Evolution of Web Services

• New and upcoming efforts
• Web Agents
• Web Services implemented as autonomous agents
  that can run for a long time and can take actions
  on its own (e.g. crawl a Web site index it on a
  schedule) (NXT 3 P2P already does this see
  section 8!).
• DARPA is working on the Agent Markup Language
  (DAML).
• The Semantic Web
• Description of content and services that is
  meaningful to computers.
• Resources Description Framework (RDF) for
  specifying meta data and its XML syntax.
• The Semantic Web is an extension of the current
  web in which information is given well-defined
  meaning, better enabling computers and people to
  work in cooperation. Tim Berners-Lee, James
  Hendler, and Ora Lassila.

24
4. Chapter 3. SOAP Basics

• Basic SOAP
• Recall slides 12-16.
• See Appendix A for SOAP 1.1 Specification.
• Advanced SOAP
• SOAP 1.2 (new standard in process).
• SOAP Bindings (see Chapters 5).
• Microsoft SOAP Toolkit 2.0 (see Chapter 8).
• Other SOAP Implementations (see Chapter 9).

25
4. Chapter 3. SOAP Basics

• Whats Simple About It?
• It has become not simple anymore.
• But to be a generic messaging protocol it must be
  extensible and this extensibility does not come
  without a price.
• SOAP is simple when the needs of the application
  are simple, but able to handle the complexities
  of more sophisticated systems.
• As yet, not all SOAP implementations handle the
  more advanced aspects of the specification.

26
4. Chapter 3. SOAP Basics

• Summary
• A messaging protocol for Web Services based on
  XML that defines a modular architecture that
  allows any combinations of message routing,
  transports, and conventions to be used to build
  systems.
• It is the messaging protocol of choice for most
  vendors because of its growing acceptance as a
  standard.
• SOAP messages contain data based on rules for
  data types called encoding which relies on XML
  Schemas.
• SOAP defines a transport binding for HTTP like
  for XML transfer over HTTP, buts adds a header
  (SOAPAction) to help servers route messages
  without needing to examine their contents.

27
4. Chapter 3. SOAP Basics

• XML Spy Suite 4.2 supports SOAP Version 1.1.
• The SOAP interface is available is only in the
  XML Spy Suite version.
• XML Spy now includes full SOAP capabilities
• Interpretation of WSDL (see next section)
  document, creation of SOAP requests, submitting
  them to a Web Service and viewing the SOAP
  Response.
• Use the SOAP functionality
• To test your Web Services without having to
  implement client applications.
• For quick testing of third party Web Services.
• Example
• http//www.capescience.com/webservices/airportweat
  her/AirportWeather.wsdl

28
4. Chapter 3. SOAP Basics
29
4. Chapter 3. SOAP Basics
30
4. Chapter 3. SOAP Basics

• ltSOAP-ENVEnvelope xmlnsSOAP-ENV"http//schemas.
  xmlsoap.org/soap/envelope/" xmlnsxsi"http//www.
  w3.org/1999/XMLSchema-instance"
  xmlnsxsd"http//www.w3.org/1999/XMLSchema"gt
• ltSOAP-ENVBodygt
• ltmgetSummary xmlnsm"capeconnectAirportWeathe
  rcom.capeclear.weatherstation.Station"gt
• ltarg0gtKJFKlt/arg0gt
• lt/mgetSummarygt
• lt/SOAP-ENVBodygt
• lt/SOAP-ENVEnvelopegt

31
4. Chapter 3. SOAP Basics

• lt?xml version"1.0"?gt
• ltSOAP-ENVEnvelope xmlnsSOAP-ENV"http//schemas.
  xmlsoap.org/soap/envelope/" xmlnsxsd"http//www.
  w3.org/1999/XMLSchema" xmlnscc1"http//www.capec
  lear.com/AirportWeather.xsd" xmlnsxsi"http//www
  .w3.org/1999/XMLSchema-instance"
  xmlnsSOAP-ENC"http//schemas.xmlsoap.org/soap/en
  coding/"gt
• ltSOAP-ENVBody SOAP-ENVencodingStyle"http//sch
  emas.xmlsoap.org/soap/encoding/"gt
• ltcc2getSummaryResponse xmlnscc2"capeconnectA
  irportWeathercom.capeclear.weatherstation.Station
  "gt
• ltreturn xsitype"cc1WeatherSummary"gt
• ltlocation xsitype"xsdstring"gtNew York,
  Kennedy International Airport, NY, United
  Stateslt/locationgt
• ltwind xsitype"xsdstring"gtfrom the NW (310
  degrees) at 28 MPH (25 KT) gusting to 34 MPH (30
  KT)lt/windgt
• ltsky xsitype"xsdstring"gtclearlt/skygt
• lttemp xsitype"xsdstring"gt43.0 F (6.1
  C)lt/tempgt
• lthumidity xsitype"xsdstring"gt59lt/humiditygt
  
• ltpressure xsitype"xsdstring"gt30 in. Hg
  (1015 hPa)lt/pressuregt
• ltvisibility xsitype"xsdstring"gt10
  mile(s)lt/visibilitygt
• lt/returngt
• lt/cc2getSummaryResponsegt
• lt/SOAP-ENVBodygt
• lt/SOAP-ENVEnvelopegt

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4. Chapter 3. SOAP Basics

• Edit SOAP Request Parameters
• Connection EndPoint
• http//www.capescience.com/ccgw/GWXmlServlet
• Soapaction
• capeconnectAirportWeathercom.capeclear.weatherst
  ation.StationgetSummary
• Note Only change the SOAP action settings if a
  full list of the SOAP methods and their
  corresponding SOAP actions are available to, and
  accessible by you.

33
5. Chapter 4 The Web Services
Definition/Description Language (WSDL)

• The Web Services Definition Language seeks to
  define and describe Web Services
• Easy on the receiving end (server side) to write
  code to parse a specific SOAP message and turn it
  into a call to a binary function.
• Difficult on the calling (client) side to
  programmatically know how to create a SOAP
  message representing the call, without a header
  file to describe the creation of the SOAP
  message.
• Microsoft and IBM lead the effort to address this
  need.

34
5. Chapter 4 The Web Services
Definition/Description Language (WSDL)

• WSDL Toolkits (around Spring 2000)
• How to programmatically discover how to format a
  SOAP message to call a specific SOAP service
• IBM SOAP for Java.
• Microsoft SOAP Toolkit for Visual Studio.
• WSDL Specification 1.1 (Appendix B) (2001)
• The two major SOAP implementations were platform
  incompatible
• IBM Web Services Toolkit 2.3.
• Microsoft SOAP Toolkit 2.0 (and latest Visual
  Studio.Net).
• Vision If Web Services describe their interfaces
  and bindings, then it should be possible to call
  them from all over the Internet.

35
5. Chapter 4 The Web Services
Definition/Description Language (WSDL)

• Summary
• A common definition language is needed for the
  wide use of Web Services on the Internet.
• WSDL builds heavily upon existing standards like
  XSD, SOAP, and MIME to describe how Web
  Services are bound to transport protocols the
  types that they use can be stored directly in a
  UDDI registry.
• WSDL fills the gap between SOAP for message
  encoding and UDDI for service discovery by
  providing the ability to programmatically bind to
  a Web Service.
• At this time, at least two major players, IBM and
  Microsoft, have adopted WSDL and hopefully others
  will follow their lead.
• XSD (XML Schema Definition) and MIME
  (Multipurpose Internet Mail Extensions).

36
5. Chapter 4 The Web Services
Definition/Description Language (WSDL)

• Syntax
• Types definition of the data (default is XSD)
• Messages the data being communicated
• Operations things the service can do
• Port types composed of one or more operations
• Bindings maps a specific protocol to a port type
• Ports network endpoints to the services
• Services composed of the above descriptions
• Bindings
• SOAP 1.1 Defined previously.
• HTTP GET/POST Hypertext Transfer Protocol
  Requests the specific document Requests that the
  server treats the specified document as a
  server-executable file and passes it the
  information included in the request.
• MIME Multipurpose Internet Mail Extensions.

37
5. Chapter 4 The Web Services
Definition/Description Language (WSDL)

• Recall Slide 28 example (similar in book and XML
  Spy 4.2!)
• lt?xml version"1.0" encoding"UTF-8"?gt
• ltdefinitions name"AirportWeather"
  targetNamespace"http//www.capeclear.com/AirportW
  eather.wsdl" xmlns"http//schemas.xmlsoap.org/wsd
  l/" xmlnssoap"http//schemas.xmlsoap.org/wsdl/so
  ap/" xmlnstns"http//www.capeclear.com/AirportWe
  ather.wsdl" xmlnsxsd"http//www.w3.org/2001/XMLS
  chema" xmlnsxsd1"http//www.capeclear.com/Airpor
  tWeather.xsd"gt
• lttypesgt
• ltxsdschema targetNamespace"http//www.capeclea
  r.com/AirportWeather.xsd" xmlnsSOAP-ENC"http//s
  chemas.xmlsoap.org/soap/encoding/"
  xmlnswsdl"http//schemas.xmlsoap.org/wsdl/"
  xmlnsxsd"http//www.w3.org/2001/XMLSchema"gt
• ltxsdcomplexType name"WeatherSummary"gt
• ltxsdsequencegt
• ltxsdelement maxOccurs"1" minOccurs"1"
  name"location" type"xsdstring"/gt
• ..........
• lt/xsdsequencegt
• lt/xsdcomplexTypegt
• lt/xsdschemagt
• lt/typesgt
• ltmessage name"getLocation"gt
• ltpart name"arg0" type"xsdstring"/gt
• lt/messagegt
• ............

38
6. Chapter 6. Universal Description, Discovery,
and Integration (UDDI)

• Basic UDDI 2.0 (June 2001)
• Recall slide 18.
• Business-to-Business (B2B) Interaction.
• See Appendix C for UDDI 2.0 Data Types.
• Advanced UDDI
• Chapter 7 UDDI Implementations (an end-to-end
  Web Service IBMs UDDI4J)
• http//www.uddi.org
• http//www.ebXML.org

39
6. Chapter 6. Universal Description, Discovery,
and Integration (UDDI)

• Review
• A Web Service is a self-contained application or
  component that has
• A service description language (WSDL) that can be
  published.
• Client programs can find these descriptions, bind
  to the service, and invoke the services.
• UDDI
• The registry piece of the Web Services standards
  stack
• Publish How the provider registers itself and
  its services.
• Find How a client application finds the
  description and the provider.
• Bind How a client application connects to and
  interacts with it after finding it.

40
6. Chapter 6. Universal Description, Discovery,
and Integration (UDDI)
41
6. Chapter 6. Universal Description, Discovery,
and Integration (UDDI)

• Data Stored
• White pages Name of the business, etc.
• Yellow pages Classification of the company
  (NAICS).
• Green pages Technical information about
  services.
• Common use scenario
• Standards bodies populate with descriptions of
  services.
• Businesses (service providers) populate.
• UDDI Business Registry assigns unique
  identifiers.
• Online users query.
• Businesses use to invoke and integrate with each
  other.
• tModel element Acts as a fingerprint for a
  service.

42
6. Chapter 6. Universal Description, Discovery,
and Integration (UDDI)
43
6. Chapter 6. Universal Description, Discovery,
and Integration (UDDI)

• Discover businesses worldwide that offer the
  exact products and services that you need.
  Register the products and services of your own
  business for others to discover. Or both.
  Technology and business champions are leading the
  development and deployment of an open,
  Internet-based Universal Description, Discovery,
  and Integration (UDDI) specification. UDDI is the
  building block that will enable businesses to
  quickly, easily and dynamically find and transact
  business with one another using their preferred
  applications.

44
6. Chapter 6. Universal Description, Discovery,
and Integration (UDDI)

• Summary
• UDDI 2.0 is a simple specification for business
  registries with a data structure and a standard
  XML API (Application Programming Interface) for
  publishing and finding this information.
• UDDI does not concern itself with Web Services
  which are only advertised, but deployed outside
  the registry.
• Both global (public) and private (Intranet) UDDI
  registries have a major role in promoting the use
  of Web Services.
• UDDI and ebXML specifications have areas of
  overlap and UDDI seems to have more momentum and
  is adding features present in the ebXML stack.

45
7. Chapter 11. NET Web Services

• The Simplest Way to Define .NET (1-3-5)
• What is .NET about?
• Its about accelerating this one move to
  distributed computing.
• Its about pulling three levers
• Everything is a Web Service.
• Aggregating and integrating Web Services and
• Delivering simple, compelling user experiences.
• What is Microsoft doing about .NET?
• Tools, servers, .NET building block services,
  device software, and user experience.
• All of Microsofts flagship products will be
  folded into the .NET vision
• Operating systems (Windows XP)
• Office Suite (Office 2002)
• Enterprise Servers (Windows 2002 .NET Server).

46
7. Chapter 11. NET Web Services

• Basic
• .NET Framework
• XML Web Services are extremely important and
  building and deploying them and their clients is
  shockingly easy!
• .NET Building Block Services
• Passport for user authentication (165 million
  users claimed).
• Hailstorm (Beta 2) that makes user preferences
  available on the Web.
• Advanced
• Create an ASP.NET (Microsofts rewrite of its
  Active Server Pages) and a Visual Studio.NET Web
  Service.
• Deployment time in hours instead of weeks!
• See Unit 10 Overview of Microsoft .Net

47
7. Chapter 11. NET Web Services

• Summary
• Microsoft is very serious about Web Services!
• Developing Web Services and web services clients
  is a simple task with Visual Studio.Net.
• While ASP.NET will probably be more popular for
  creating Web Services, .NET Remoting offers the
  option of creating more complex applications.

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Tutorial Building Web Services with .NET

• Architecture
• SOAP messages can be sent between processes using
  HTTP.
• SOAP/HTTP Clients
• The types in the System.Net namespace are
  designed to support HTTP/SOAP client programming.
• SOAP/HTTP Servers
• The types in the System.Web namespace are
  designed to support HTTP/SOAP server programming.
• XML Serialization
• XML has its own type system that is based on XML
  Schemas.
• WebMethods
• The types defined in the System.Web.Services
  namespace use the HTTP pipeline (System.Web) and
  the XML stack (System.Xml) to map SOAP messages
  to methods invocations. They can be used to
  implement Web Services without handling raw SOAP
  and HTTP messages.

52
Other Resources

• Gartner Group
• Application Integration and Web Services The
  Foundation for Total Business Integration,
  Conference, October 22-24, 2001, CD-ROM and
  binder with presentations and handouts.
• Microsoft
• .NET My Services Specification, Microsoft Press,
  2001.
• Visual Studio.net, Version 2002 Release
  Candidate, DVD.
• OReilly
• P2P and Web Services Conference, November 5-8,
  2001, folder with presentations and handouts.
  Tutorial Building Web Services with .NET (Peter
  Drayton). Common Language Run Time a chip in
  software
• Open Source Bibliography, OReilly, 2nd Edition,
  2001.
• Wrox
• Introducing .NET, January 2001.
• Early Adopter HailStorm (.NET My Services),
  October 2001.
• Professional ebXML Foundations, November 2001.
• Professional XML for .NET Developers, December
  2001.

53
8. Web Services Web Agent Demonstration

• The NXT 3 P2P Platform from NextPage
• Provides an early implementation of the XML Web
  Services Standards stack including work flow in
  the new release called Matrix.
• Three building blocks, each with multiple layers
• Discovery (have to find it to use it).
• NXT 3 Interface with XIL (xml indexing) for
  searching (see advanced search interface slide).
• Description (representation of the meaning-meta
  data).
• Manage Content using RDF (see documentation
  display slide).
• Invocation (provide input to call it and receive
  the output).
• Content Network Manager (see interface slide).

54
8. Web Services Web Agent Demonstration

• Background
• Content Network Manager Interface
• Start at http//www.sdi.gov/server.htm
• Select Environmental XML Registry and Repository
  (A node on the FedGov Content Network)
• Select Java Tab, Expand Chesapeake Bay Program
  Node and Bay Journal Archive, and display
  archive.htm file
• Select Advanced Search, Check the Bay Journal
  Archive, enter freshet as the search word and
  Search
• Select Search and the first hit to display the
  highlighted hits

55
Background

• Our EPA Chesapeake Bay Program would like to
  include the nearly 8 years of the monthly issues
  of the Bay Journal The Chesapeake Bay Newsletter
  in their Web page system and make it searchable
  across all the issues as well as across their own
  key EPA documents.
• The NXT 3 P2P platform makes this possible as
  shown in the following screen captures using the
  Web Site Service and the File System Service. It
  took about 30 minutes to index about 100 MB of
  Web site files.
• Abnormally high flows of fresh water into the Bay
  or freshets during the springs of 1993 and
  1994 made it look like EPA pollution control
  efforts were failing when it was really caused by
  nature. A query across all Newsletter issues is
  of real interest because much has been written on
  this subject. 38 hits were found for the word
  freshet.

56
Content Network Manager Interface
57
Start at http//www.sdi.gov/server.htm
58
Select Environmental XML Registry and Repository
(A node on the FedGov Content Network)
59
Select Java Tab, Expand Chesapeake Bay Program
Node and Bay Journal Archive, and display
archive.htm file
60
Select Advanced Search, Check the Bay Journal
Archive, enter freshet as the search word and
Search
61
Select Search and the first hit to display the
hightlighted hits