Steps to be followed for creating UML diagrams?

What are the steps to be followed when we start UML diagrams for new features or req开发者_如何学Pythonuirements?

I need the entire steps like

1. Identify the actor,
2. Identify the use cases,

   like this etc....

What you need is some sort of methodology.UML doesn't come with any, because it is ment to be methodology independent. However, the authors of UML have created some methodologies, which heavily use UML. One of the methodologies, which is free, is Unified Process or UP for short. Try to look at that, there are plenty of books, which discuss UML and UP at the same time.

Create a simple model of the existing system, and a detailed model of the area you plan on working in. There are a number of different types of diagrams (activity, sequence, class, etc), you should use the ones most appropriate for the complexity of your system and its interactions with other components, systems, and people.

This is a very board expression. In general, I would start with Use Case diagrams and go from there. As Gabriel pointed out, there are entire books written on this and there is no one right answer. My personal favorites for Use Cases are:

Advanced Use Case Modelling

and

Writing Effective Use Cases

Take a look at Craig Larman's book "Applying UML and Patterns". That describes very accessibly how to use UML to tackle a problem (Use Cases, Class Diagrams, ...).