What analysis and modeling techniques should ba use >

What analysis and modeling techniques should ba use to translate business objectives into system requirements? Say, business object is to develop trading system?
OR
What is Requirements elicitation?
OR 
Describes techniques for collecting requirements from stakeholders in a project. 
OR 
What are Techniques for requirements 

Answer
These are :
BFII DW  RS UP

• Brainstorming
• Focus group
• Interface analysis
• Interviews
• Document analysis
• Workshops
• Reverse engineering
• Surveys
• User task analysis
• Process mapping