For learning web services we should know the following things.
4) web services
SOAP is an XML based protocol for exchanging information between computers. Soap is an XML. That is soap application of the XML specification.
For exchanging information between computers SOAP is an XML based protocol.
Features of SOAP
1) SOAP is a communication protocol
2) SOAP is for communication between applications
3) SOAP is a format for sending messages
4) SOAP is designed to communicate via Internet
5) SOAP is platform independent
6) SOAP is language independent
7) SOAP is simple and extensible
8) SOAP allows you to get around firewalls
9) SOAP will be developed as a W3C standard
10) SOAP is acronym for Simple Object Access Protocol
11) SOAP can extend HTTP for XML messaging
12) SOAP provides data transport for Web services
SOAP is the XML way of defining what information gets sent and how SOAP is used for a variety of messaging systems. It is delivered in a variety of transport protocols. SOAP is easily connected to remote services. It invokes remote methods. SOAP messages are written entirely in XML. Therefore it is uniquely platform and language in depended.
Soap recommended knowledge
Before you proceed further you should be familiar with XML and XML namespace. As background for their principles, a quick overview of some common web services terms will be helpful. It is useful to have a cursory view of existing management platforms. A SOAP interface is a set of operations. This article uses the terms SOAP interface and WSDL interchangeably. WSDL bears many similarities to the interface definition language in CORBA, COMT and distributed computing environment styles of computing. That is the WSDL document itself written in XML. The other important flavor of SOAP is the document exchange form.
2. WSDL definitions and their relationship to code
It is used in combination with SOAP Web service can read the WSDL to determine what functions are available on the server. Data types used are embedded in the WSDL file in the form of XML scheme. The client use SOA to call one of the functions listed in the WSDL.
1) WSDL is an XML based language.
2) WSDL stands for Web Services Description Language.
3) WSDL is an XML based protocol for information exchange in decentralized and distributed environments.
4) WSDL is the standard format for describing a web service.
5) WSDL definition describes how to access a web service and what operations it will perform.
6) WSDL is a language for describing how to interface with XML-based services.
7) WSDL is an integral part of UDDI, an XML-based worldwide business registry.
8) WSDL is the language that UDDI uses.
9) WSDL was developed jointly by Microsoft and IBM.
10) WSDL is pronounced as ‘wiz-dull’ and spelled out as ‘W-S-D-L’
11) WSDL Abstract:
3. Publishing services to a UDDI directory
UDDI stands for universal description, discovery and integration. It aims to enable business to quickly ,easily and dynamically find and carry out transactions with one another. UDDI creates a global, platform – independent, open architecture space that will benefit businesses.The UDDI registry can be divided into two categories. They are
- UDDI and web services
- UDDI and business registry
1. UDDI and web services
The owners of web services publish them to the UDDI registry. The UDDI registry maintains pointers to the web service description and to the service. The UDDI allows clients to search this registry find the intended service and retrieve its details. These details include the service innovation. Through a programming interface web services capabilities are exposed. A typical client inquiry consists of two objects. They are
1) To find an implementation of a known interface.
2) To find the updated value of the inn vocation point [ that is , access point] of a known binding template ID.
2. UDDI and business registry
UDDI enables companies to advertise the business products and services they provide, as well as how they conduct business transactions on the web. The minimum required information to publish a business is a single business name .
A business registry includes the following things.
a) Business identification
b) Service Description
c) Standards compliance
Exposing legacy applications as web services
Some of the definitions are given below and all the definitions are correct
1. A web service is available over the internet. It uses a standardized XML messaging system.XML is used to encode all communications to a web service. Web services are self contained Categories
2. Modular, distributed dynamic applications that can be described, published, located. These applications can be local, distributed or web based. Web services are built on top of open standards.
E.g.:- TCP/IP, HTTP, Java, HTML and XML.
3. Web services are XML based information. It uses the internet for direct application to application interaction. These systems include program, objects, messages or documents.
4. A web service is a collection of open protocols. It is used for exchanging data between applications or systems.
Some services that are used for summarizing a web service is given below.
• Is available over the Internet or private (intranet) networks
• Uses a standardized XML messaging system
• Is not tied to any one operating system or programming language
• Is self-describing via a common XML grammar
• Is discoverable via a simple find mechanism
Components of Web Services
Some of the components of web services are given below.
• SOAP (Simple Object Access Protocol)
• UDDI (Universal Description, Discovery and Integration)
• WSDL (Web Services Description Language)
5. Advanced topics such as security
Security is critical to web services. There are 3 specific security issues with web services.
3. Network security
A client sends an XML request to a server. The question is that the communication remains confidential. Answer lies here.
• XML-RPC and SOAP run primary on top of HTTP.
• HTTP has support for Secure Sockets Layer (SSL).
• Communication can be encrypted via the SSL.
• SSL is a proven technology and widely deployed.
A single web service may consist of a chain of applications.
The following options can be considered for some of the questions but there is no clear consensus on a strong authentication Scheme.
1. HTTP includes built in support for basic and digest authentication.
2. SOAP security extentions; Digital signature leverages is the public key cryptography to digitally sign SOAP messages. This enables the client or server to validate the identity of the other party.
3. The OASIS is working on the SAML.
3. Network Security
It has been the subject of much debate. One possibility to filter out all HTTP post requests that set their content type to text/XML. Another alternative is to filter for the SOAP action HTTP header attribute. Firewall vendors are also currently developing tools designed to filter web service traffic.