Web Services

• The purpose of Systems Integration is to support each of the following:

  • Human to Human Interaction
  • Human to Machine (Apps) Interaction
  • Machine (Apps) to Machine Interaction
• There are different things necessary to support interactions:

  • Language
  • Vocabulary
  • Context
  • Medium
  • Situation awareness
• Websites like Amazon, Shopee, Lazada and others are not a web service, but rather called services over the web
• Referral Program


  where website owners create product links in return for referral fees
• Web services support application-to-application communication
• supports "loosely coupled" integration
• Web services are designed to enable application modules to communicate with other application modules
• Service-Oriented Architecture (SOA)
• Three basic participants:

  • Service Provider
  • Service Registry
  • Service Requestor

  Three basic operations:

  • Publishing Services
  • Discovering Services
  • Binding Services
• Service Provider

  • Develops an app and converts into a service
  • Creates a WSDL document describing the capabilities of the service
  • Publishes the WSDL document in the service registry (UDDI)
• Service Requestor

  • Needs a service for specific task/purpose
  • Searches for serviced in the service registry meeting needs
  • Selects a service that is satisfactory
• Simple Object Access Protocol (SOAP)

  • Initially named XML-RPC in June 1998
  • Submitted to W3C in 2000
  • SOAP 1.1 became standard in July 2003
  • SOAP 1.2 replaced 1.1 in April 2007 (current standard version)
  • This is an XML-Based messaging format that established a transmission framework of interapplication (or inter-service) communication via HTTP
  • SOAP specification is vendor-neutral technology, therefore, it was an attractive alternative to proprietary protocols such as CORBA and DCOM
• Web Service Description Language (WSDL)

  • XML-based language for describing the interface of web services.
  • WSDL 1.1 became standard in March 2001
  • WSDL 2.0 became standard in June 2007 (current standard version)
  • Uses the file extension .wsdl
• Universal Description, Discovery, and Implementation (UDDI)

  • Mechanism for the dynamic discovery of service descriptions.
  • UDDI V2 became standard in April 2003
  • UDDI V3 (short version for V3.0.2) became standard in February 2005 (current standard version)
• • The description of a web service interface is known as an abstract if the definition is independent of implementation details.
  • An abstract interface definition is made up of interface and message elements
• • The description is known as concrete, on the other hand, if it specifies the location and implementation information about a web service.
  • A concrete interface definition is made up of binding, endpoint, and service elements.
• Interface


  contains a group of logically-related operations
• Operations


  represents a single action or function performed by an application
• Message Elements


  can contain one or more input or output parameter that belong to an operation
• Part Elements


  provides a name and value set, along with an associated data type.
• Service


  represents one or more endpoints at which the web service can be accessed
• Endpoint


  consists of location (URI) and protocol information
• Binding


  defines invocation requirements of each of its operation
• Public Registry


  a global directory of services
• Private Registry


  repositories of services hosted in an organization
• Business Entities


  Provides profile information about the registered business, including its name, description, and unique identifier (UID)
• Business Services


  Records of the actual services offered by the registered business are nested within the business entity element
• Specification Pointers (Binding Template Element)


  Provides address linking for business service and implementation information
• Service Types


  Points to location of service interface definitions (WSDL), message formats, as well as message and security protocols
• Business Relationships (Publisher Assertion)


  Provides a means of establishing the relationship of the current business entity with another business entity
• Subscription


  Allows subscribers to be notified when business entity profile information is updated