SOA (Service Oriented Architecture) is an architectural paradigm that aims to
achieve loose coupling and reuse among software components. It's emerging as
the main integration and architectural style in today's complex software
infrastructure.
Web Services aim to provide interoperability in machine-to-machine
interaction over the network. XML-based open standards like Web Services
Description Language (WSDL), Simple Object Access Protocol (SOAP), and
Universal Description, Discovery, and Integration (UDDI) are used to achieve
interoperability for defining, publishing, and invoking Web Services. Two
applications, regardless of operating system or programming language,
communicate using XML messages over open Internet transport protocols such as
HTTP, HTTPS, SMTP, and FTP
Web Services existed before the principles of SOA were defined but they came
into the limelight... (more)