Question

ER Modeling: Assignment In order to receive credit for this assignment, you must draw your ER model using a compute program and then turn in on the blackboard. Your ER model should include all of the necessary entity sets, relationships and keys, as well a weak entities and superclass/subclass relationships, if needed. A company decides to implement a software to monitor its employees' web surfing, and stores history of each employee's surfing in a database, as well as all of the files that are viewed b each employee. In this assignment, you are asked to design an ER model that can be used as th starting point for developing the software to manage such a history. The company whose Web usage you are trying to model has many employees. Each employe a name (a first name and a last name), a department, and an EID (the employee's ID, thi uniquely identifies each employee). Each employee can have multiple computer logins. computer login is uniquely identified by the login ID. The login has an associated security leve an activation date, and an issuing department. Each one of the company's computers is identified by a unique machine identifier, and it has fixed IP address as well as the physical location of the computer. When an employee uses one his/her logins to log into a computer, the login day/time is recorded, as well as the number times that the employee had to enter his/her login password, and a socalled "session" is begur During a session, an employee visits one or more websites. When an employee visits a website, the URL (web set address) is recorded, the time is recorded as well as the HTML code that is displayed to the employee. Note that web pages are update frequently and web pages are often customized for a particular person. Thus, when someon visits the same URL twice they may see different versions of the web page, or two peopl visiting the same web page may see different version of the page. This is important, because will affect how you design your web page” entity; in particular, it will have a significant effe on what the key of this entity is. Each URL also has a "domain" (for example, my website http://www.cise.ufl.edul-cjermain has the domain "ufl.edu"; this string uniquely identifies the domain). The domain also has an ! address, a name, a country, and a label indicating whether accessing the domain is acceptable prohibited, or unknown. When an employee visits a website, one or more media files (either a picture or a video) are als displayed on the website. Each media file has its own URL, a size in bytes, and it has its actua binary content. Each media file has a type or extension (.jpg, .wav, .bmp, etc). The file i uniquely identified by the file's name and the web page that it is displayed on. A video has length in seconds, a bit rate, and whether or not it was streamed in real time. A picture has pixel size in the vertical dimension, a pixel size in the horizontal dimension. In addition, th picture has a label that is automatically generated by a filter that attempts to figure out the type the picture - that way, it is easy to identify employees who view a lot of pictures wit questionable" content

Answer 1

Let’s create ERD for the given system description with below steps:

Step 1: List entities:

· Employee

· Login

· Computer

· Session

· Website

· WebsiteFiles : A weak entity with Website as owner entity

· Video and Picture: Sub entity to WebsiteFiles.

Step 2: Assign attributes to the entities:

· Employee(EID, name(firstname, lastname), department)

· Login(Login_ID, security_level, activation_date, issuing_department)

· Computer(Machine_id, IP, physical_location)

· Session(session_id,login_date_time, login_input_count)

· Website(Domain, URL, HTML_code, IP, country, accepting_label)

· WebsiteFiles(Domain, file_name, URL, extension, binary_content)

· Video(length, bit_rate, is_real_time_streamed )

· Picture(pic_type_label,horizontal_pixel_dim, vertical_pixel_dim)

Step 3: List relationship

· An Employee can have multiple logins, whereas a login will be associated with one Employee only. This is a One to Many relationship.

· A Machine has many logins and a login can be made on one or many machines.

· A Session has many websites.

· A Website has many websitefiles.

· A website file can be either video or picture.

Step 4: Final ERD with entities, attributes and relationships:

lastname firstname security_level department name Login ID activation_date EID Employee issuing department 1 are issued with (1,M) Login (1,1) session_id Machine id IP has (1.M) Session (1.M) (1,M) physical_location login_input_count has Computer login_date_time (1.M) domain Website (1,1) file name shows (1,M) WebsiteFiles URL URL HTML code extensiom accepting_label binary content ПІР country ISA Video Picture pic_type_label length horizontal _pixel_dim is_Real_time streaming vertical_pixel_dim bit_rate