Web Service

• Software system designed to support interoperable machine-to-machine interaction over a network

Terminology

• Request and Response: input & output
• Message Exchange Format: xml, json, format
• Service Provider (Server): hosts the web service
• Service Consumer (Client): consumes the web service
• Service Definition: contract between provider and consumer

• Transport: HTTP (all the web), MQ (websphere MQ - SOAP layer)

• Service Definition

• Request/Response Format
• Request Structure
• Response Structure
• Endpoint
• Operations

Web Service Groups

• SOAP (Simple Object Access Protocol)
• XML Request exchange format
• Specific XML Request Envelope format
  • The envelope contains a header and a body
• Transport over HTTP or MQ
• Service Definition WSDL

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/">
  <SOAP-ENV:Header />
  <SOAP-ENV:Body>
    <ns2:getCourseDetailsRequest>
      <ns2:course>
        <ns2:id>Course1</ns2:id>
        <ns2:name>Spring</ns2:name>
        <ns2:description>Awesome Spring Course</ns2:description>
      </ns2:course>
    </ns2:getCourseDetailsRequest>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

• REST (REpresentational State Transfer)
• Uses HTTP Methods (GET, POST, PUT, DELETE, ...)
• Uses HTTP Status Codes
• Resource has an URI /users/Ranga/todos/1
• No restriction on exchange format (although json is the most popular)
• Transport is only via HTTP!
• Service Definition WADL, Swagger, ...