Workflow (WF) management is a very rich research area trying to automate business processes. The basic concept of the WF management is to separate the flow control logic of business processes from the functionalities offered by the applications. However, the architecture of most of the current workflow management systems (WFMSs) makes it hard for them to be integrated with applications due to their heavyweight architectures that cover a comprehensive set of features targeting non-technical users. This work aims at: one, achieving a better understanding of the WF field through studying the WF basic concepts and some of the related works; two, investigating Petri Nets (PNs) as a solid business process modeling technique; and three, utilizing the Unified Modeling Language (UML) for designing an object-oriented lightweight WF engine that can be integrated easily in Java applications. So, it is a platform independent and can work on the Internet.