For users of online banking at OzBank, before access to their account details is provided, their login credentials must first be authenticated. The procedure for login authentication begins with the entry of a username and password. First, the username is authenticated. If the username is not valid, the invalid username attempt is logged, control returns to the login page, an appropriate message is displayed and the procedure ends. If the username is valid, a counter for the number of password attempts is set to zero, and the password is authenticated. If it is not valid, the attempt counter is incremented and if it remains less than three, control returns to the login screen, the user is shown a message to re-enter their password, and a CAPTCHA test is also invoked to increase the security level for subsequent attempts (i.e. a CAPTCHA test is used for all login attempts after the first attempt). If the password is valid, and if invoked the CAPTCHA test is also successful, then the user is given access to their bank account and the authentication procedure ends. After three failed attempts, the account is locked, the error is logged, control returns to the login page, an appropriate message is displayed and the procedure ends. It is also possible that after the username and password are entered the validation server is not available, in which case the error is logged, control returns to the login page, an appropriate message is displayed and the procedure ends. Similarly, the CAPTCHA server may not be available when required, in which case the error is logged, control returns to the login page, an appropriate message is displayed and the procedure ends. At any time during the authentication procedure, the user may close the page, resulting in the immediate completion of the authentication procedure TASK 1 (20 Marks) Develop a Petri net system that captures all the processes in the scenario description. As this model will be used as a basis for implementing an information system to support OzBank's business, it must reflect the proposed scenario as closely as possible. Ensure that your model is free of syntactic errors. Also, the model must be semantically valid and complete as per the scenario description, i.e. every execution sequence of your Petri net system must reflect a valid sequence of steps from the scenario description and every sequence of steps from the scenario description must be reflected in some execution sequence of your Petri net system

Task:

a) Analyse the Petri net you developed in Task 1 and discuss possible improvements. For example, are there any bottlenecks in the process? If so, what can be done to remove them? Also, describe any subsystems identified. b) Discuss any difficulties or limitations you may have experienced when capturing the scenario in a Petri net. Were there any aspects of the scenario that were difficult to effectively capture? If so, explain why do you think Petri nets are not appropriate for modelling that aspect? Also, discuss the advantages and disadvantages of using a Petri net diagram, such as the one modelled, as a means of defining, analysing and communicating processes within an information system.