Principles of System Design Exam 3
Block sequence codes
- Use blocks of numbers for different classifications. - Sequence of numbers in a particular block can have additional meaning.
Standard Notation Format
- Used to show a table's structure, fields, and primary key - Recognition of repeating group fields is important.
Two-tier design
- User interface resides on the client - Data resides on the server - Application runs either on the server or on the client, or is divided between the client and the server.
Users
- Work with predefined queries and switchboard commands - Use query languages to access stored data
Multiple Platforms
Web-based design is not dependent on a specific combination of hardware or software. All that is required is a browser and an Internet connection.
Web Integration
Web-centric architecture enables a company to integrate new application into its ecommerce strategy
Entity, Table/File, Field/Attribute, Record
What are the data definitions?
- Manage applications that perform the processing logic. - Handle data storage and access - Provide an interface that allows users to interact with the system
What are the functions of a business information system?
Primary key, candidate key, foreign key, secondary key
What are the key fields?
- Corporate organization and culture - Enterprise resource planning (ERP) - Initial and total cost of ownership (TCO) - Scalability - Web integration - Legacy system interface requirements - Processing options - Security issues - Corporate protocols
What are the requirements that influence the architecure?
- Unnormalized - First normal form - Second normal form - Third normal form
What are the standard normalization formats?
- Fat client - Thin client
What are the two types of client roles?
- Two-tier design - Three-tier (n-tier) design
What are the two types of server tiers?
- category codes - abbreviation codes - mnemonic codes
What are the types of alphabetic codes?
- Sequence codes - Block sequence codes - Significant digit codes - Alphabetic codes - Derivation codes - Cipher codes - Action codes
What are the types of codes?
- One-to-one - One-to-Many - Many-to-Many
What are the types of relationships in an ERD?
- Determine where the functions will be carried out - Identify the advantages and disadvantages of each design approach
While planning system design what needs to be taken into consideration?
Adaptability Issues
The Internet offers many advantages in terms of access, connectivity, and flexibility. Migrating a traditional database design to the Web, however, can require design modification, additional software, and some added expense.
Data Control
- DBMS must provide built-in control and security features. - Forms of data protection. - Backup copies of databases must be retained for a specified period of time.
Connecting to the Web
- Databases are created and managed by using languages and commands that have nothing to do with HTML. - Objective, a front-end or interface to connect the database to the web and enable data to be viewed and updated. - Middleware, used to integrate different applications and allow them to exchange data.
Cardinality
- Describes the numeric relationship between two entities. - Shows how instances of one entity relate to instances of another entity.
Third Normal Form (3NF)
- Design is in 3NF it is in 2NF and if no nonkey field is dependent on another nonkey field. - Avoids redundancy and data integrity problems that still can exist in 2NF designs.
Fat client
- Design, locates all or most of the application processing logic at the client. - Off-loads computing from the server to the client.
First Normal Form (1NF)
- Does not contain a repeating group - Converting an unnormalized design to 1NF requires expansion of the table's primary key to include the primary key of the repeating group.
Corporate Portals
- Entry point to website access for customers, employees, suppliers, general public. - Integrate with various other systems - Provide a consistent look and feel across organizational divisions, customer experiences.
Data Structures
- Framework for organizing, storing, and managing data - Consists of files or tables that interact in various ways - Each file or table contains data about people, places, things, or events. - Over time, between file-oriented systems and relational databases the standard became the relational model for database systems.
Second Normal Form (2NF)
- Functional dependence, when the value of one field is dependent on the value of another field. - Field A is functionally dependent on Field B if the value of Field A depends on Field B.
Initial Cost and Total Cost of Ownership (TCO)
- Includes hard costs such as tangible purchases, fees, and contracts - Includes soft costs which are management, support, training, and more which are costs that are more difficult to measure. - TCO analysis answers questions about alternatives: In-house development versus types of outsourcing, vendor soundness and application effectiveness, and today versus new trends in systems planning
Client/Server Archietecture
- Includes systems that divide processing between one or more networked clients and a central server - Client handles the entire user interface - Server stores data and provides data access and database management functions
Personal Computer
- Individuals could work in stand-alone mode, where the PC performed the functions of a server. - PC help distribute many IT department tasks and resulted in increased productivity. - Lack of central data storage created issues with security, integrity, and consistency - and shared hardware.
Data Mining (clickstream storage)
- Looks for meaningful data patterns and relationships - Increase the number of pages viewed per session - Increase checkouts per visit and average profit per checkout
File-oriented systems
- May still be used by some companies to handle large volumes of structured data in a single system.
Sequence codes
- Numbers or letters assigned in a specific order. - Contain no additional information other than on indication of order of entry into the system.
Enterprise resource planning (ERP)
- Objective - establish a company-wide strategy for using IT that includes a specific architecture, standards for data, processing, network, and user interface design. - Companies are extending internal ERP systems to their suppliers and customers, using supply chain management (SCM) and customer relationship management (CRM)
What are advantages of DBMS?
- Scalability, systems can be expanded, modified, or downsized. - Economy of scale, database design allows better utilization of hardware across enterprise-wide application - Stronger standards for data names, formats, and documentation are followed uniformly throughout the organization. - Better security, only legitimate users can access the database and different users have different levels of access. - Data independence, systems that interact with a DBMS are relatively independent of how physical data is maintained.
Security Issues
- Security is a universal issue, but internet connectivity raises special concerns. - These can be addressed with a combination of good design, software that can protect the system and detect intrusion, stringent rules for passwords and user identification, and vigilant users and managers.
Codes
- Set of letters and numbers that represent a date item. - Shorter than the data they represent - Save storage space and costs - Decrease data entry time and transmission time. - Can reveal or conceal information - Can reduce data input errors - Easier to remember
Referential Integrity
- Set of rules that avoid data inconsistency and quality problems - Means that a foreign key value cannot be entered in one table unless it matches an existing primary key in another table.
Entity-Relationship Diagram (ERD)
- Shows the logical relationship and interactions among system entities. - List the entities that were identified during the systems analysis phase. - Consider the nature of the relationship that link them.
Physical Data Repository
- The transformation of the data dictionary into the schema and subschemas - Can be centralized or distributed across several locations - Uses open database connectivity (ODBC) that enables communication among the systems and DBMS
Nonkey field
A field that is not a candidate key for the primary key.
Network Evolution
Addresses the need to share data and hardware with stand-alone computing.
Abbreviation codes
Alphabetic abbreviations
Candidate Key
Any field that could serve as a primary key
Ease of use
Web browsers provide a familiar interface that is user-friendly and easily learned.
Client Role
Client/server relationship must specify how the processing will be divided between the client and the server.
Derivation codes
Combine data from different item attributes, or characteristics
Server
Computer that supplies data
Security Issues
Consideration for security issues and how the company will address them
Table or File
Contains a set of related records that store data about a specific entity.
Data Manipulation Language (DML)
Controls database operations including storing, retrieving, updating, and deleting.
Related information system
DBMS can provide support to several related information systems
Logical storage
Data that a user can view, understand, and access, regardless of how or where that information actually is organized or stored.
Schema
Descriptions of all fields, tables, and relationships
Thin client
Design, locates all or most of the processing logic at the server. - Provides better performance as the program code resides on the server.
Data mart
Designed to serve the needs of a specific department.
Significant digit codes
Distinguish items by using a series of subgroups of digits
Mainframe computers
Earliest servers, perform all data input and output processing from a central location
Associate entity
Event or transaction that links the two entities is actually a third entity.
One-to-one relationship (1:1)
Exists when exactly one of the second entity occurs for each instance of the first entity.
Many-to-many (M:M)
Exists when one instance of the first entity can relate to many instances of the second entity, and one instance of the second entity can relate to many instances of the first entity.
One-to-many relationship (1:M)
Exists when one occurrence of the first entity can relate to many instances of the second entity, yet each instance of the second can associate with only one instance of the first entity.
Foreign key
Field in one table that must match a primary key value in another table for a relationship between the two tables to exist.
Secondary Key
Field or combination of fields that can be used to access or retrieve records
Primary Key
Field or combination of fields that uniquely and minimally identifies a particular member of an entity
Database administrators
Responsible for DBMS management and support
Category codes
Identify a group of related items
Action codes
Indicate what action is to be taken with an associated item
Crow's foot notation
Indicates various possibilisties using circles, bars, and symbols.
Corporate Organization and Culture
Information systems must perform well in a company's organization and culture (centralized, decentralized, etc.)
Cost effectiveness
Initial investment is relatively low because the Internet serves as the communication network. Users require only a browser, and Web-based systems do not require powerful workstations. Flexibility is high because numerous outsourcing options exist for development, hosting, maintenance, and system support.
Data warehouse
Integrated collection of data that can include seemingly unrelated information, no matter where it is stored in the company.
Cipher codes
Keyword to encode a number
Alphabetic codes
Letters to distinguish one item from another
System Architecture
Logical design of an information system that translates into the physical structure that includes hardware, software, network, processing methods, and security.
Orphan
Missing primary to foreign key value match
Relational model
Need to find
Legacy systems
New system have to interface with existing systems and involves analysis of data formats and compatibility
Database Management System (DBMS)
Offers timely, interactive, and flexible data access that can support multiple business systems.
Entity
Person, place, thing, or event for which data is collected and maintained.
Subschema
Portions of the database that a system or user is allowed to access
Normalization
Process of creating table designs by assigning specific fields or attributes to each table in the database.
Binary storage format
Represents numbers as actual binary values
Data Security
Web-based data must be secure, yet easily accessible to authorized users
Repeating group
Set of one or more fields that can occur any number of times in a single record.
Record
Set of related fields (in a row) that describes one instance, or occurrence of an entity.
Local area network (LAN)
Sharing of data and hardware resources
Field or attribute
Single characteristic or fact about an entity
Wide area network (WAN)
Spans long distances and can connect LANS that may be continents apart.
Mnemonic codes
Specific combination of letters that are easy to remember
Table design
Specifies fields and identifies the primary key in a particular table or file.
Physical storage
Strictly hardware-related, involves the process of reading and writing binary data to physical media.
Scalability
System's ability to expand, change, or downsize easily to meet the changing needs of a business - for example, volume of transactions, number of employees, scale f business.
Processing Options
Systems can process data online or in batches
Global Access
The Internet enables worldwide access, using existing infrastructure and standard telecommunication protocols.
Mainframe architecture
Today's servers, can still be in a mainframe or computer connections with multiple servers providing the processing from multiple remote locaitons
Extended Binary Coded Decimal Interchange Code (EBCDIC)
Used on mainframe computers, high capacity servers
American Standard Code for Information Interchange (ASCII)
Used on most personal computers
Unicode
Uses two bytes per character
Clients
server, processing services, or other support to one or more computers
