Applications: Web Services and workflow modeling

• Remote procedure calls (CORBA, Java RMI, SOAP) - see notes R (pointers C).
  • One approach to distributed system design is to make abstraction of the distribution as much as possible and use structuring concepts well understood from the sequential programming context. Procedure calls (or object-oriented method call interfaces) are a basic structuring concept for object-oriented design. It introduces the idea of client (who calls) and server (who provides the interface). If the server is remote, we can use Remote Procedure Calls (RPCs). If communication is reliable and the server does not fail, one could make abstraction from the distribution. The only issue that remains is whether large objects which are referenced in procedure calls as parameters should be transferred to the server or not, and similarly for large objects that are included in the results of method calls.
• Web protocols (HTTP, HTML, XML, Stylesheets, schemas), Web Services - see notes R (recipe example in HDML, XML, DTD and XML-Schema).
• Notations for workflow modeling, BPEL - see notes R (pointers C).