Web Service Flashcards
- Simple requests to complete business applications that access and combine information from multiple sources
- A distributed technology that enables disparate applications running on different machines to exchange messages and integrate with one another without requiring additional, proprietary third party software or hardware.
- Self-describing and self-contained network available software modules that perform concrete tasks and are deployed easily because they are based on common industry standards and existing technology, such as XML and HTTP.
- Reduce application interface costs, and provide a universal mechanism for integrating business processes within an enterprise and, ultimately, among multiple organizations.
Web Services
What problems do Web Services are addressing?
It addresses the rigid implementations of predefined relationships and isolated services scattered across the internet.
- A computing paradigm that utilizes services as the constructs to support the development of rapid, low cost composition of distributed applications.
- Services are self-contained modules deployed over standard middleware platforms that can be described published located orchestrated and programmed using xml-based technologies over a network any piece of code and any application component developed on a system can be transformed into a network available service
- Software services (or simply services) a service-oriented approach to programming, based on the idea of describing available computational resources , for example application programs and information system components , as services that can be delivered through a standard and well-defined interface.
- Represents the fusion of several technologies, including
distributed systems, software engineering, information systems, computer languages, web-based computing, and xml technologies, rather than being a new technology
Service Oriented Computing
“An application can no longer be thought of as a single process running within a single organization. The value of an application is actually no longer measured by its functional capabilities but rather by its ability to integrate with its surrounding environment”
Services can help integrate applications that were not written with the intent to be integrated with other applications and define architectures and to build new functionality leveraging existing application functionality.
A collection of interactive services offering well defined interfaces to their potential users. These applications process the ability to integrate with other service based applications.
Composite applications
This relationship is used by services, it is the link between applications of transacting partners. At the middleware level, this concept requires that the service oriented approach be independent of specific technologies or OS. The service oriented model does not even mandate any kind of predetermined agreements before the use of an offered service is allowed.
Loosely coupled applications
THREE TYPES OF SOFTWARE ORGANIZATIONS
Service Providers
Service Clients
Service Aggregators
Provide the service implementations, supply their service descriptions and provide related technical and business support
Service Providers
End user or consumer organizations that use some service
Service Clients
Organizations that consolidate multiple services into a new, single
orchestrated service offering that is commonly known as a business process
Service Aggregators
- Application service providers (ASP) are companies that package software and infrastructure elements together with business & professional services to create a complete solution that they present to the end customer as service on a subscription basis. This model is also called on-demand software or software as a service (SaaS)
- Basic idea behind this model is to bill customers on a per-use basis or rent applications to subscribers on a monthly/annual fee.
SOFTWARE AS A SERVICE (SaaS)
Important characteristics of Web services (simple, complex web services, stateful, stateless services, service granularity, loose coupling, synchronous, asynchronous, etc)
CHARACTERISTICS OF WEB SERVICES
Types of Web service
Simple or Informational
Complex Services or business process
Provide Programmatic access to content , interacting with an end-user by means of simple request or response sequences or alternatively may expose back and business applications to other applications
Simple or Informational (atomic or discrete or singular)
Involved the assembly and indication of many pre existing services , possibly found in diverse enterprises , to complete a multi-step business interaction that requires coordination
Complex Services or business process
Sub-categories of Informational Services
Pure content services
Simple trading services
Simple syndication services
a. Weather report information
b. Simple financial information
c. Stock quote information
d. Design information
e. News item
Pure content services
Can provide a seamless aggregation of information across
disparate existing systems and information sources, including back end systems, giving programmatic access to a business information system so that the requester can make informed decisions
a. Logistic services, where automated services are the actual front ends to fairly complex physical organizational IS
Simple trading services
value-added information web services that purport to plug into
commerce sites of various types, such as e-marketplaces, or sell-sites.
a. Reservation services on a travel site
b. Rate quote services on an insurance site
Simple syndication services
Two Types of Complex Web Services
Complex services that compose programmatic Web services
Complex services that compose interactive Web services
the clients of these web services can assemble them to build complex services
a. Ex. inventory checking service that comprises part of an inventory management process
Complex services that compose programmatic Web services
these services expose the functionality of a web application’s presentation (browser) layer.
Complex services that compose interactive Web services
The operational characteristics that define the overall behavior of
the service.
Functional
concentrates on the service quality attributes
Non-functional Description
If services can be invoked repeatedly without having to maintain context or state
Stateless
If services that may require their context to be preserved from one invocation to the next
Stateful
Means that the protocol has no concepts of a job or a session and does not make any assumptions about eventual
delivery.
Connectionless protocol
