What is your opinion on the current usage, relevance and applicability of UML models in the current phase of Agile Development? In general, do you think that UML is still widely used in organisations for business analysis and Design/Development?
If so, what is the best lightweight tool to use these days?
First of all, thank you for your question. UML is widely used notation (language) for software engineering. Business Process Modeling Notation (BPMN) is another very popular modeling language for business process modeling. We see more and more users using BPMN to model current and target business workflow and then use the Business Process Diagram(s) as input for system modeling (e.g. develop Use Case Diagram).
Following is one of the possible usage of UML and BPMN (simple process)
1.Business Analyst develop business process diagram by BPMN
2.Business Analyst confirm the current (As-Is) and the target (To-be) workflow with customer (walk through the Business Process Diagram)
3.System Analyst develop Use Case Diagram base on the To-be BPD
4.System Analyst elaborate the Use Case Diagram by Sequence Diagram (System Level Sequence Diagram)
5.System Analyst confirm the system interaction with Customer
6.System Designer develop User Interface base on System Level Sequence Diagram)
7.System Analyst develop detail Sequence Diagram
8.System Designer develop State Diagram for some critical objects
9.System Designer develop static structure of the system (Class Diagram)
Above is just a reference usage. The Agilian (http://www.visual-paradigm.com/product/ag/) covered all of above usage.