I am wondering if anyone is aware of framework that would aid in building a graphical workflow type UI that would basically look similar to many Visio style designers that exist in the industry. Something that woudl allow for a pallette where you would drag objects out onto the design surface, connect those objects, and have properties assigned to those objects. Ultimately, each completed 'project' in the designer would result in the creation of one or more XML files that would be used by another system. I am just curious if anyone is aware of any open source or paid tools that allow this type of UI to be built, or is this something that would likely follow more of a custom route?

Any info would be greatly appreciated.

Thank you!