opollo

An online computer assembling mobile phone Application provides interfaces for end users to factories themselves. For example, users can to open the App first, register an Account inputting usernames and passwords. Then a main$-$case, a main$-$board, one to multiple CPUs, of the APP. A computer usually consists of a m$.$ one to multiple mechanical hard disks or sultiple memory card, zero to multiple display power, zero to multiple screens, one mound common attributes of name, model type, manufacturer, unique attributes of frequency, core numbers, etc. Memory has the unique aurib. There are mainly two types of screens: Similarly, other components have some other unique attributes. There are two types of CPU, on is two types of screens: one is curved screen and another type is flat screen. There are two types of CFU, one is for business $($such as Xeon$)$ and another is for home and usual use $($Core i$5,$ Core i$7).$

$(1)$ Prepare a domain class diagram for this software including classes "Computer, Component, Maincase, Mainboard, CPU, Business$-$CPU, Home$-$CPU, Memory$-$card, Power, Screen, User, Account, etc" $(15\text{'})$

$(2)$ Add appropriate properties to classes in the domain class diagram $(10\text{'})$

$(3)$ Build an activity diagram to describe the process of registering and logging into the system. Tips for the process: The user needs to input a user name first. Then the system will check with remote server whether the user name is available. If it is$,$ the password need to be input two times. If the password is not input correctly or too simple, a message is displayed to notice user to change it$.$ If all of these information is correctly provided, the account is created for the user. Next, the user need to go to the login page to login by inputting usemame and password. $(10\text{'})$