BIS 494: Topics in Information Systems 1 M/M/c Queuing Simulation with VBA (1) Business Process Modeling, Simulation and Design

2 Overview Problem (VBA Assignment 1) Logics – Flowchart –Main Sub –Arrival Sub –ServerOpen Sub –Report, and others Coding Flowchart

3 Problem Spreadsheet simulation usually means creating a spreadsheet model with random numbers (e.g. exponential) in certain cell and then replicating the model with a data table and add-in such as VBA. Multi-server queuing system is very difficult to model with spreadsheet formulas because of the timing and bookkeeping involved (like which server has finished the service). A more natural approach is to take care of all the model’s logic in VBA and then simply report the results on a worksheet.

4 Outline of the Simulation Arrival Rate (λ) Multiple Servers (c) with identical service rate (μ) Single line queue Limited time length (no more customers at some point of time) Limited queue length (?) User Inputs

5 Output See example Sample output.xlsSample output.xls To get these values in the end, what variables should be kept for each event?

6 Logic Flowchart Main Sub –Structure the entire logic –Subroutines are used to hide unnecessary details –Think logics first before translating into coding Sub Flowchart.vsd