GA 2 Flashcards
Foundation for Web Servies
Compose and Combine Services: BPEL Publish, Find, Use Services: UDDI Formal Service Descriptions: WSDL Service Interactions: SOAP Universal Data Format: XML Ubiquitous Communications: Internet
XML Document Structure
XML document (aka XML document instance or instance)
A specific data set for a given markup language
Base for fundamental Web services technologies (SOAP, WSDL, UDDI and BPEL)
XML Structure
Well-formedness (syntactically correct)
- XML documents must have a root element
- XML elements must have a closing tag
- XML tags are case sensitive
- XML elements must be properly nested
- XML attribute values must be quoted
Validity (grammatically correct)
- Well-formed and:
- referring to correct document type declaration
- Document obeys declaration constrains
XML Schema Definition Language
XSD: description of content and structure of XML documents in XML
- Declaration of elements and attributes and how they are arranged inside a document
- Reuse of elements rom other schemas
- Definition of complex elements
- Definition of restrictions (data types, values etc.)
XSD document structure
- Root element: schema
- Element & Attribute declarations (instantiations)
- (New) type definitions
- Simple/complex
XML element vs. attribute
Both are used to store data
but:
- attribute can be seen as a characteristic or property while nested element as embedded hierarchical child element of the parent element
- attribute has no cardinalities
- attribute has no internal structure
What is SOAP?
SOAP is a lightweight protocol intended for exchanging structured information in a decentralised, distributed environment
SOAP is a way for a program running in one operating system to communicate with a program running in either the s are or a different operating system, using HTTP (or any other transport protocol) and XML
SOAP Messaging Framework
= XML-based messaging framework that is:
- Extensible
- Interoperable
- Independent
SOAP Extensible
- Simplicity remains one of SOAP’s primary design goals
- SOAP defines a communication framework that allows for features such as security, routing, and reliability to be added later as layered extensions
SOAP Independent
- SOAP allows for any programming model
- SOAP defines a model for processing individual, one-way messages
- SOAP also allows for any number of message exchange patterns (MEPs)
SOAP Message Format
SOAP message consists of three parts:
- SOAP Envelope
- SOAP Header (optional)
- SOAP Body
SOAP Envelope
The SOAP Envelope construct defines an overall framework for expressing what is in a message and who should deal with it
SOAP Header
- The Header element is a generic container for
control information - It may contain any number of elements from
any namespace - Header blocks should contain information that
influences payload processing - Header is optional
SOAP Body
The body element represents the message payload
Web Services Description Language
Why?
- Description in consistent manner for providers, clients, developers etc.
- Precise XML interface along with misc. messages defined a priori
- XML Schema not enough
What?
- Machine understandable XML specification describing:
- Structure
- Operational characteristics
- Wire format & transport protocol
- Payload data via type system (based on XML Schema complex types)
