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Encyclopedia > Web service
Web services architecture
Web services architecture

A 'Web service' (also Web Service) is defined by the W3C as "a software system designed to support interoperable Machine to Machine interaction over a network." Web services are frequently just Web APIs that can be accessed over a network, such as the Internet, and executed on a remote system hosting the requested services. , creator: H. Voormann (send an e-mail to me, if you like to have the original; made with Adobe Illustrator) File links The following pages link to this file: Web service Categories: GFDL images ... The World Wide Web Consortium (W3C) is a consortium that produces standards—recommendations, as they call them—for the World Wide Web. ... Interoperability is connecting people, data and diverse systems. ... M2M refers to data communications between machines. ... A computer network is an interconnection of a group of computers. ... Look up web in Wiktionary, the free dictionary. ... API and Api redirect here. ...


The W3C Web service definition encompasses many different systems, but in common usage the term refers to clients and servers that communicate using XML messages that follow the SOAP standard. Common in both the field and the terminology is the assumption that there is also a machine readable description of the operations supported by the server written in the Web Services Description Language (WSDL). The latter is not a requirement of a SOAP endpoint, but it is a prerequisite for automated client-side code generation in many Java and .NET SOAP frameworks (frameworks such as Spring and Apache CXF being notable exceptions). Some industry organizations, such as the WS-I, mandate both SOAP and WSDL in their definition of a Web service. The World Wide Web Consortium (W3C) is a consortium that produces standards—recommendations, as they call them—for the World Wide Web. ... In computing, a client is a system that accesses a (remote) service on another computer by some kind of network. ... In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ... The Extensible Markup Language (XML) is a general-purpose markup language. ... For other uses, see Soap (disambiguation). ... In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ... WSDL redirects here. ... Client/Server is a network application architecture which separates the client (usually the graphical user interface) from the server. ... Java language redirects here. ... Microsoft . ... The Spring Framework (or Spring for short) is an open source application framework for the Java platform. ... CXF is an open-source Web Services frameworks developed by the Apache Software Foundation. ... The Web Services Interoperability (WS-I) organisation is committed to supporting the use of Web Services and promoting interoperability between vendor solutions. ...

Contents

Specifications

Profiles

To improve interoperability of Web Services, the WS-I publishes profiles. A profile is a set of core specifications (SOAP, WSDL, ...) in a specific version (SOAP 1.1, UDDI 2, ...) with some additional requirements to restrict the use of the core specifications. The WS-I also publishes use cases and test tools to help deploying profile compliant Web Service. The Web Services Interoperability (WS-I) organisation is committed to supporting the use of Web Services and promoting interoperability between vendor solutions. ... For other uses, see Soap (disambiguation). ... WSDL redirects here. ...


Additional specifications, WS

Some specifications have been developed or are currently being developed to extend Web Services capabilities. These specifications are generally referred to as WS-*. Here is a non-exhaustive list of these WS-* specifications. WS-* is the shorthand moniker for the collection of protocols that fall under the umbrella heading: Web Services. ...

WS-Security
Defines how to use XML Encryption and XML Signature in SOAP to secure message exchanges, as an alternative or extension to using HTTPS to secure the channel.
WS-Reliability
An OASIS standard protocol for reliable messaging between two Web services.
WS-ReliableMessaging 
A protocol for reliable messaging between two Web services, issued by Microsoft, BEA and IBM it is currently being standardized by the OASIS organization [1].
WS-Addressing
A way of describing the address of the recipient (and sender) of a message, inside the SOAP message itself.
WS-Transaction
A way of handling transactions.

Some of these additional specifications have come from the W3C. There is much discussion around the organization's participation, as the general Web and the Semantic Web story appear to be at odds with much of the Web Services vision. This has surfaced most recently in February 2007, at the Web of Services for the Enterprise workshop. Some of the participants advocated a withdrawal of the W3C from further WS-* related work, and a focus on the core Web. WS-Security (Web Services Security) is a communications protocol providing a means for applying security to Web Services. ... XML Encryption is a specification that defines how to encrypt the content of an XML element. ... XML Signature (also called XMLDsig) is a W3C recommendation that defines an XML syntax for digital signatures. ... For other uses, see Soap (disambiguation). ... https is a URI scheme used to indicate a secure HTTP connection. ... WS-Reliability is a SOAP-based ([SOAP 1. ... The Organization for the Advancement of Structured Information Standards (OASIS) is a global consortium that drives the development, convergence and adoption of e-business and web service standards. ... WS-ReliableMessaging is a specification that describes a protocol for reliable delivery of messages between distributed applications that are connected by software, system, hardware and network components that may not be fail-safe. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... BEA Systems, Inc. ... For other uses, see IBM (disambiguation) and Big Blue. ... WS-Addressing is a specification of transport-neutral mechanisms that allow web services to communicate addressing information. ... A Web Services specification developed by BEA Systems, International Business Machines Corporation, and Microsoft Corporation. ... WWWC redirects here. ... W3Cs Semantic Web logo The Semantic Web is an evolving extension of the World Wide Web in which web content can be expressed not only in natural language, but also in a format that can be read and used by software agents, thus permitting them to find, share and...


In contrast, OASIS has standardized many Web service extensions, including Web Services Resource Framework and WSDM. The Organization for the Advancement of Structured Information Standards (OASIS) is a global consortium that drives the development, convergence and adoption of e-business and web service standards. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Web Services Distributed Management (WSDM, pronounced wisdom) is a web service standard for managing and monitoring the status of other services. ...


Styles of use

Web services are a set of tools that can be used in a number of ways. The three most common styles of use are RPC, SOA and REST.


Remote procedure calls

Architectural elements involved in the XML-RPC.
Architectural elements involved in the XML-RPC.

RPC Web services present a distributed function (or method) call interface that is familiar to many developers. Typically, the basic unit of RPC Web services is the WSDL operation. Image File history File links Webservice_xrpc. ... Image File history File links Webservice_xrpc. ... Remote procedure call (RPC) is a protocol that allows a computer program running on one computer to cause a subroutine on another computer to be executed without the programmer explicitly coding the details for this interaction. ...


The first Web services tools were focused on RPC, and as a result this style is widely deployed and supported. However, it is sometimes criticised for not being loosely coupled, because it was often implemented by mapping services directly to language-specific functions or method calls. Many vendors felt this approach to be a dead end, and pushed for RPC to be disallowed in the WS-I Basic Profile. Loosely coupled describes a resilient relationship between two or more computer systems that are exchanging data. ... The WS-I Basic Profile (official abbreviation is BP), a specification from the Web Services Interoperability industry consortium (WS-I), provides interoperability guidance for core Web Services specifications such as SOAP, WSDL, and UDDI. The profile uses Web Services Description Language (WSDL) to enable the description of services as sets...


Service-oriented architecture

Web services can also be used to implement an architecture according to Service-oriented architecture (SOA) concepts, where the basic unit of communication is a message, rather than an operation. This is often referred to as "message-oriented" services. Service Oriented Architecture (SOA) is a computer systems architectural style for creating and using business processes, packaged as services, throughout their lifecycle. ...


SOA Web services are supported by most major software vendors and industry analysts. Unlike RPC Web services, loose coupling is more likely, because the focus is on the "contract" that WSDL provides, rather than the underlying implementation details. Loosely coupled describes a resilient relationship between two or more computer systems that are exchanging data. ...


Representational state transfer

Finally, RESTful Web services attempt to emulate HTTP and similar protocols by constraining the interface to a set of well-known, standard operations (e.g., GET, PUT, DELETE). Here, the focus is on interacting with stateful resources, rather than messages or operations. RESTful Web services can use WSDL to describe SOAP messaging over HTTP, which defines the operations, or can be implemented as an abstraction purely on top of SOAP (e.g., WS-Transfer). “REST” redirects here. ...


WSDL version 2.0 offers support for binding to all the HTTP request methods (not only GET and POST as in version 1.1) so it enables a better implementation of RESTful Web services[1]. However support for this specification is still poor in software development kits, which often offer tools only for WSDL 1.1. WSDL redirects here. ... Hypertext Transfer Protocol (HTTP) is a communications protocol used to transfer or convey information on intranets and the World Wide Web. ... “REST” redirects here. ... A software development kit (SDK or devkit) is typically a set of development tools that allows a software engineer to create applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar. ...


Criticisms

Critics of non-RESTful Web services often complain that they are too complex[2] and biased towards large software vendors or integrators, rather than open source implementations. Open source refers to projects that are open to the public and which draw on other projects that are freely available to the general public. ...


One big concern of the REST Web Service developers is that the SOAP WS toolkits make it easy to define new interfaces for remote interaction, often relying on introspection to extract the WSDL and service API from Java, C# or VB code. This is viewed as a feature by the SOAP stack authors (and many users) but it is feared that it can increase the brittleness of the systems, since a minor change on the server (even an upgrade of the SOAP stack) can result in different WSDL and a different service interface. The client-side classes that can be generated from WSDL and XSD descriptions of the service are often similarly tied to a particular version of the SOAP endpoint and can break if the endpoint changes or the client-side SOAP stack is upgraded. Well designed SOAP endpoints (with handwritten XSD and WSDL) do not suffer from this but there is still the problem that a custom interface for every service requires a custom client for every service. In computing, type introspection is a capability of some object-oriented programming languages to determine the type of an object at runtime. ... An XML Schema Definition (XSD) is an instance of a W3C XML Schema. ...


There are also concerns about performance due to Web services' use of XML as a message format and SOAP and HTTP in enveloping and transport.


Similar efforts

There are several other approaches to solving the set of problems that Web services address, both preceding and contemporary to it. RMI was one of many middleware systems that have seen wide deployment. More ambitious efforts like CORBA and DCOM attempted to effect distributed objects, which Web services implementations sometimes try to mimic. A typical implementation model of Java-RMI using Stub and Skeleton objects. ... This article is about integration software. ... In computing, Common Object Request Broker Architecture (CORBA) is a standard for software componentry, created and controlled by the Object Management Group (OMG). ... Distributed Component Object Model (DCOM) is a Microsoft proprietary technology for software components distributed across several networked computers to communicate with each other. ... Object-oriented programming (OOP) is a computer programming paradigm in which a software system is modeled as a set of objects that interact with each other. ...


More basic efforts include XML-RPC, a precursor to SOAP that was only capable of RPC, and various forms of HTTP usage without SOAP. XML-RPC is a remote procedure call protocol encoded in XML. It is a very simple protocol, defining only a handful of data types and commands, and the entire description can be printed on two pages of paper. ... HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ...


See also

A List of Web Service Frameworks : List of Web service specifications List of web service protocols Category: ... The following is a list of Web service protocols. ... There are a variety of specifications associated with web services. ... ≠A service system (or value co-creation system) is a configuration of technology and organizational networks designed to deliver services that satisfy the needs, wants, or aspirations of customers. ... In computing, the term Service-Oriented Architecture (SOA) expresses a software architectural concept that defines the use of services to support the requirements of software users. ... EII is the industry acronym for Enterprise Information Integration. ... The term Business Intelligence (BI) refers to technologies, applications, and practices for the collection, integration, analysis, and presentation of business information. ... There are very few or no other articles that link to this one. ... An OGC Web Processing Service (WPS) is a Web Service that takes a defined set of inputs, applies a calculation, and produces a defined set of outputs. ... The inside/front of a Dell PowerEdge web server The term Web server can mean one of two things: A computer program that is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them HTTP responses along with optional data contents, which usually are... Microsoft Connected Services Framework (CSF) is a service aggregation SOA platform from Microsoft. ... After Web services are created and published in Web services registries such as UDDI or Web Services Inspection Language (WSIL) documents, the service users or consumers need to search Web services manually or automatically. ... OAuth is Web-based protocol for delegated authentication. ...

Notes

External links


  Results from FactBites:
 
Web service - Wikipedia, the free encyclopedia (675 words)
Web services is a set of tools that can be used in a number of ways.
RPC Web services present a distributed function (or method) call interface that is familiar to many developers.
Web services can also be used to implement a Service-oriented architecture, where the basic unit of communication is a message, rather than an operation.
Web service: Definition and Much More from Answers.com (1189 words)
Web services have been initially successful in private environments where large enterprises need to exchange data with their divisions and subsidiaries or with partners and clients.
However, Web services use XML-based protocols that are lightweight and simpler and thus have a better chance of being widely implemented.
Web services standards only define the format and transport architectures, but the meaning of each element of data exchanged also has to be defined ahead of time by industry consensus (see ebXML).
  More results at FactBites »

 
 

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