WEB-SERVICES

DEFINITIONS

Technological approach definition:

Constitute a distributed computer architecture made up of many different computers trying to communicate over the network to form one system.

Business or conceptual view definition:

a model in which small pieces of application functionality are available as services to be consumed and combined with other applications over a network.

Other definition:

If an application can be accessed over a network using a combination of protocols like HTTP, XML, SMTP, or Jabber, then it is a web services.

*web services also known as application services

CHARACTERISTICS

- XML-based

- Loosely coupled

- Ability to be synchronous or asynchronous

- Supports document exchange

- Machine-to-machine interaction

- Mechanisms for service registry and discovery (UDDI)

TECHNOLOGY

WSDL (Web Services Description Language)

An XML format for the description of network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information.

SOAP (Simple Object Access Protocol)

A lightweight XML-based protocol for exchange of information in a decentralized, distributed environment.

UDDI (Universal Description, Discovery and Integration)

An XML-based framework to enable businesses to discover each other, define how they interact and share information in global registry.

PRINCIPLE OF WEB SERVICES

1. Every data record and collection is a resource.

2. Every resource should have a URI.

3. Data queries on existing resources should be done with a GET.

4. Use POST to create new resources.

5. Preserve the structure of data until the last possible moment (i.e. return XML).

6. Make XML Schemas available online for your XML.

7. Make data available in multiple flavors.

8. Use Metadata (RDF) for XML.

9. Document your service API using WSDL, WRDL, or some other standard.

10. Advertise the presence of the data using WSIL

13. Use HTTP authentication as much as possible.

WEB SERVICES TECHNOLOGY(EXTENSION)

WS-Inspection (Web Services Inspection Language)

An XML format for assisting in the inspection of a site for available services and a set of rules for how inspection related information should be made available for consumption.

WSFL (Web Services Flow Language)

An XML format for the description of Web Services compositions that specify usage and interaction patterns.

WEB SERVICES PACKAGING PROTOCOLS

SOAP/XML Protocol

Originally an acronym for the "Simple Object Access Protocol," now the basis for the W3C XML Protocol effort.

XML-RPC

The original manifestation of SOAP invented by Dave Winer of Userland software. This simple, popular protocol—while not officially a standard—has a significant, vocal user base in the open source community.

Jabber

Jabber is both a transport protocol and a simple packaging protocol that can be used in asynchronous peer-to-peer style web services. It too is not an official standard but is building a significant user and developer base.

DIME

The Direct Internet Message Encapsulation (DIME) protocol is "a lightweight, binary encapsulation format that can be used to encapsulate multiple application defined entities or payloads of arbitrary type as well as to provide efficient message delimiting."

WEB SERVICES DESCRIPTION PROTOCOLS

WSDL

The Web Service Description Language is the de facto standard language for describing web services. It has been submitted to the W3C for standardization and a working group is being organized. WSDL replaces the previous description proposals put forth by IBM and Microsoft (NASSL and SDL respectively).

DAML-S

The DARPA Agent Markup Language Ontology for web services is an academic research project for semantically describing web services.

RDF

There has been some discussion around the fact that RDF could have "very easily" been used as a method of describing web services. Several examples have cropped up, including a demonstration of how WSDL could be modified to conform to RDF syntax. DAML-S is another example that is built completely on top of RDF.

WEB SERVICES DISCOVERY PROTOCOLS

UDDI

The Universal Description, Discovery, and Integration initiative promises to define a standard service registry.

WS-Inspection

The Web Service Inspection Language provides an XML index for discovering the services available at a given network location.

ebXML Registry

Part of the ebXML effort was to define a standard registry model for discovering business services. The approach is somewhat different, but not incompatible with UDDI, and includes many more types of information than UDDI does.

JXTA Search

The Sun-sponsored JXTA peer-to-peer services infrastructure defines a distributed search protocol for discovering content and services in a peer-to-peer architecture.

WEB SERVICES SECURITY PROTOCOLS

XML Digital Signatures

A joint W3C and IETF effort to define a standard method of representing digital signatures as XML content.

XML Encryption

A W3C effort to define a standard way of both encrypting XML content and representing encrypted data as XML content.

SAML

The Security Assertions Markup Language, being developed under the auspices of Oasis.

XKMS

The XML Key Management Service is a web service specification submitted to the W3C for implementing a service-based public key infrastructure.

XACML

An effort to define a standard access control mechanism for XML documents.

WS-Security and WS-License

These are two proposals from Microsoft defining how to carry authentication, encryption, and digital signatures within a SOAP Envelope. These specifications are used primarily by in Microsoft .NET and the .NET My Services (Hailstorm).

SOAP Security Extensions

Initially worked on as a joint effort between IBM and Microsoft, these specifications define how to carry authentication, encryption, and digital signatures within a SOAP Envelope. The Digital Signatures portion of the specification has already been submitted to the W3C with the encryption and authentication parts soon to be released and submitted. Currently, IBM's Web Services ToolKit is the only known available implementation of the SOAP Security Extensions.

WEB SERVICES TRANSPORT PROTOCOLS

HTTP

The most common transport used for web services.

Jabber

A new, XML-based asynchronous transport protocol used most frequently in peer-to-peer style applications.

BEEP

A new XML-based transport protocol being worked on by the IETF that claims a duplexed connection and asynchronous transport.

Reliable HTTP (HTTPr)

A new version of HTTP proposed by IBM for adding reliable messaging support to the venerable HTTP protocol.

WEB SERVICES ROUTING AND WORKFLOW

WSFL

The Web Services Flow Language provides a WSDL-based grammar for scripting business processes out of web services.

XLANG

Microsoft's own workflow scripting language for web services.

WS-Routing

A Microsoft proposed mechanism for defining the route that a SOAP message must take through various intermediaries.

WEB SERVICES LANGUAGES/PLATFORMS

JAXP

Java API for XML Parsing is the Java Community Process (JCP) effort to standardized XML API's in Java

JAX-RPC

Java API for XML RPC is the JCP effort to standardized Java API's for using web services

JAXR

Java API for XML Registries is the JCP effort to define Java API's for discovery registries such as UDDI

JAXM

Java API for XML Messaging is the JCP effort to define Java API's for XML messaging

JSR-109

JCP effort to define how web services are to be integrated into the Java 2 Enterprise Edition architecture.

JSR-105

JCP effort to create standard Java API's for XML digital signature

JSR-106

JCP effort to create standard Java API's for XML encryption

JSR-110

JCP effort to define a standard Java API for WSDL

*A Web Service IS NOT : a Web site or portal

Contributed by: NIk NOor Diana Mohd NOor (2007239692)