Abstract: A business application development environment and a corresponding business application execution environment is disclosed. A graphical user interface based Workflow Designer allows a user to easily create business applications graphically. The business applications are converted into the Business Process Modeling Language (BPML). Existing BPML applications may also be edited with the graphical user interface BMPL designer of the present invention. Created business applications (that are represented in BPML) can then be hosted on any XML based web services server system. Business applications generally operate on business objects. The objects allow for fields to include functions that combine other fields. Once an application has been designed, the BPML code may be executed using a BPML execution engine. The BPML execution engine executes the BPML based applications. One embodiment interprets BPML applications with an interpreter in the execution engine.