Web service concepts and terminology

Web service concepts and terminology

1. Basic concepts of Web Service XML (Extensible Markup Language)

XML is used to organize documents and business data. xml
Files can be stored or transmitted between two applications on
Network. Basically, they are just plain text documents that contain
Special tags that label different parts of a document or fields of data.

XML is a metadata language defined by a specification. The XML Markup Language defines a set of tags used to organize and describe texts ). Tags are usually paired. One of the tags is the start tag, and the other is the end tag. All content between the two tags is an element.

Soap (Simple Object Access Protocol)

Soap defines a standard packaging format for transmitting XML
Data between applications on a network. a soap message is just an XML
Document. Soap is specially designed, however, to contain and transmit
Other XML documents as well as information related to routing,
Processing, security, transactions, and other qualities of service.

A soap message is an XML document that has its own XML schema, namespace, and processing rules. The current version is soap 1.2.

WSDL (Web Services Description Language)

WSDL is a standard for describing the structure of the XML data exchanged between two systems using soap.

WSDL is a document format used to accurately describe Web services. It is used to specify the exact message format, Internet protocol, and address that a customer must use when communicating with a specific web service. The current version is WSDL 2.0.

UDDI (Universal Description, discovery, and integration)

UDDI defines a standard set of web service operations
(Methods) that are used to store and look up information about other
Web service applications. In other words, UDDI defines a standard
Soap-based interface for a web services registry. You can use a UDDI
Registry to find a participant type of web service, or to find out about
The Web Services hosted by a specific organization. a uddi registry is
Often referred to as a "Yellow Pages" for Web Services. The UDDI
Specification is now maintained byOrganization for the Advancement of Structured Information Standards
(OASIS)

UDDI defines a set of standard web service operation methods for storing and searching information about other Web service applications.

WS-I BP (Web Services Interoperability basic profile)

Web Services Interoperability organization is an organization of Web
Services vendors that are committed to defining a standard for Web
Services Interoperability. The first deliverable of the WS-I was
Basic profile 1.0, the second is WS-I basic profile 2.0

 

Ii. Web Service Advanced Concepts WS-Addressing

WS-Addressing specification is to provide the meansIdentify a web service endpoint
And a way to use such identifiers in soap messages forDelivery and exchange of messages
Between Web service providers and Web Service requesters.

WS-Addressing extends the SOAP message
Services addressing issues provide more powerful support. The WS-Addressing Specification mainly describes two concepts: endpointreference
And message addressing properties. In the Web
Services may have different endpoints for Service implementations that represent a type of logical functions. Each endpoint may represent a different binding method, or even an external
The same interface, for example, endpoint A may use TCP protocol communication, while endpoint
B may use the HTTP protocol. With endpointreferrence, We can reference the corresponding endpoint to access the server.
Service. Message addressing properties will be included in every SOAP header Extension
The addressing of the message.

WS-Policy

WS-policy defines a general-purpose framework for representing
And combining statements about the quality of service properties.
WS-policy is an extensible framework that can accommodate
Domain-specific dialects to represent these assertions and allow
Attachment of policies to arbitrary types of subjects though
Generic attachment mechanisms that WS-policy attachments define.

Web Service Policy Framework specification (Web Services Policy Framework, WS-Policy
)
Provides a flexible and scalable syntax for expressing XML-based Web
The capabilities, requirements, and general features of the services system. WS-policy defines a framework and a model that expresses these features as policies. Rule representation supports simple declaration
Type assertion, also supports more complex conditional assertion. Policy assertions indicate behaviors.Individual
Requirements, capabilities, or other features. For example, you can create a policy assertion to define such a requirement:
You must use a trusted X.509 Certificate to sign the SOAP message body. WS-policy provides a common model and syntax used to describe the Web
Service Policy and Communication. WS-policy assertions describe the functions and constraints of a specific web service. WS-policyattachments defines
WS-policy expressions are associated with Web Services (WSDL.

WS-reliable messaging

WS-reliable messaging promises to bring the benefits
Reliable messaging to SOA and web services, enabling implements ISES
Extend web services to support reliable business-to-business (B2B)
Exchanges.

WS-Coordination (WS-AT and WS-BA)

WS atomic transactions Application
Operations on web services occur completely or not at all, and results
Are not available until the transaction is complete.

WS business activity Application
Operations on Web Services exhibit a loose unit of work, in which
Results are shared prior to completion of the overall activity. Each
Particle ant undoes the operations it has completed MED within
Conversation.

WS-Coordination specification provides the generic Foundation
For coordinating outcome agreements between interoperating Web
Services. WS-atomic transaction and WS-Business Activity specifications
Contain definitions of atomic and business transaction protocols,
Respectively, that you can use with WS-coordination. WS-coordination is
Defined as an extensible framework that can support additional
Protocols for other coordination patterns as required.

WS-AT and WS-BA are used to define transactions that regulate ws.

WS-Security

WS-Security
SOAP message security is optimized
Exchanging a small number of messages. A requester might engage in
Prolonged "conversation" with a web service. WS-secureconversation
Builds
On WS-trust and message security to provide support for multimessage,
Long-lived conversations. WS-secureconversation provides a better level
Of security and improved efficiency. This chapter also provides
Overview of WS-secure conversation.

WS-Trust

WS-Security
Supports security tokens. Collaboration
Between incluises often requires sharing additional information, such
As customer identity information and preferences. WS-Federation
Extends WS-Trust to provide these functions, and is discussed later in this chapter.

WS-authorization/WS-Privacy

WS-Authorization
And WS-Privacy
Are in progress.

WS-BPEL

Web Services Business Process Execution Language is
Extensible workflow-based language that aggregates services
Choreographing service interactions. The aggregation is recursive, such
That the process exposes WSDL interfaces to those that interact
It, and the corresponding services may be used in other choreographies.

It is used to describe and standardize ws business processes.

 

III. Basic concepts of J2EE Web Service APIs

It is used to implement web services on the J2EE platform. Includes JAX-RPC, SAAJ, jaxr, and JAXP

The JAX-RPC (Java API for XML-based RPC)

You can think of JAX-RPC as Java RMI over soap. JAX-RPC is
Divided into two parts: a set of client-side APIs, and a set
Server-side components, calledEndpoints
.

The client-side APIs allow you to communicate with Web Service
Endpoints hosted on some other platform. There are three client-side
APIS:Generated stub, dynamic proxy,
AndDii
(Dynamic invocation interface)
.
The generated stub is the one you will use the most, and its Semantics
Closely resemble those of Java RMI. The dynamic proxy API also follows
Memory of the Java RMI semantics, but is used less often. The DiI is
Very low-level API used primarily by vendor tools, but can also be
Employed by Web Services developers if necessary.

The server-side components includeJAX-RPC
Service endpoint (JSE)
AndThe EJB endpoint
.
The JSE component is actually a type of servlet that has been adapted
For use as a web services component. The EJB endpoint is simply a type
Of stateless session EJB that has been adapted for use as a Web Service
Endpoint. The EJB endpoint provides all the transactional and security
Features of a normal stateless Session Bean, But it's specifically
Designed to process SOAP requests.

SAAJ (soap with attachments API for Java)

SAAJ is a low-level soap API that complies with soap 1.1 and
The soap messages with attachments specification. SAAJ allows you
Build soap messages from scratch as well as read and manipulate soap
Messages. You can use it alone to create, transmit, and process soap
Messages, but you're more likely to use it in conjunction with JAX-RPC.
In JAX-RPC, SAAJ is used primarily to process SOAP header blocks (
SOAP message meta-data ).

Jaxr (Java API for XML registries)

Jaxr provides an API for Accessing UDDI registries. it
Simplifies the process of publishing and searching for Web Service
Endpoints.

JAXP (Java API for XML Processing)

JAXP provides a framework for usingDom 2 and sax2,
Standard Java APIs that read, write, and modify XML documents.

Dom 2 (Document Object Model, level 2)
Is a Java API
That models XML documents ents as trees of objects. It contains objects that
Represent elements, attributes, values, and so on. Dom 2 is used a lot
In situations where speed and memory are not factors, but complex
Manipulation of XML documents is required. Dom 2 is also the basis
SAAJ 1.1.

Dom 2 creates corresponding objects in the memory of all infosets when processing XML documents, which consumes more memory.

Sax2 (Simple API for XML, version 2)
Is very different
In functionality from Dom 2. When a SAX Parser reads an XML document,
It fires events as it encounters start and end tags, attributes,
Values, etc. You can register listeners for these events, and they will
Be notified as the sax2 parser detects changes in the XML document it
Is reading.

Sax2 is based on the push method, and Stax is the pull method.

Streaming API for XML (Stax)

Stax is a streaming Java-based, event-driven,
Pull-parsing API for reading and writing XML documents. Stax provides
Is the latest API in the JAXP family, and provides an alternative
Sax, Dom, Trax, and Dom for developers looking to do high-performance
Stream filtering, processing, and modification, particle ly with low
Memory and limited extensibility requirements.

Stax is a bidirectional API, meaning that it can both read and
Write XML documents. Sax is read only, so another API is needed if you
Want to write XML documents ENTs.

JAX-WS2.0

JAX-WS2.0 is Java API for XML Web Services (JAX-WS) 2.0, JAX-RPC
1.1 is Java API for XML-based RPC (JAX-RPC) 1.1. They are sun's use of Java technology to develop Web
Service specifications. The former is an upgraded version of the latter.

The binding layer of the JAX-WS2.0 uses jaxb (JSR 222), and the XML parsing layer uses Stax (JSR 173), which is fully based on standards and greatly improves the performance; Support for annotation of Java 5 ), easy to develop.

Javaarchitecture for XML binding (jaxb)

Jaxb provides a fast and convenient wayBind Between XML Schemas and Java representations,
Making it easy for Java developers to in‑ate XML data and
Processing functions in Java applications. jaxb provides methods
Unmarshalling XML instance documents into Java content trees, and then
Using alling Java content trees back into XML instance documents.