SAP user interface for HTML 5 (SAP UI5) is a collection of libraries that developers can use to build desktop and mobile applications that run in a browser.
WebDynpro is SAP state-of-the-art technology for creating application user interfaces.
SAP WebDynpro Java check out the WebDynpro homepage here on SDN, it’s a good starting point.
SAP Workflow enables the design and execution of business processes within SAP application systems Workflow processes are delivered as content in the SAP Business Suite.
SAP XI is SAP's enterprise application integration (EAI) software, a component of the NetWeaver product group used.