Chapter 2 Flashcards
Mainframe architecture
All computing intelligence resides within a powerful central host computer. The host computer processes the data and displays the output on “workstations” that have little to no processing power
Client- server architecture
- A network architecture in which each computer on the network is either a client or a server
- client: apiece of hardware/ software that makes requests of a more powerful server in order to utilize a shareable resource such as applications or data
-Server-takes requests from clients and shares its resources - cient-server is distributed computing
Two-tier architecture
Comprised of the server, (back-end application), and the client ( front end application)
Fat and thin clients and servers
- fat client: a client that handles the presentation logic and business logic
- thin server: handles the data access logic
- thin client: a client that handles only the presentation logic
- fat server: handles Th business and data access logic
Client-server logic
- presentation logic: software that displays data to the user and accepts input from the user. Manages the user navigation experience with a GUI
- Business Logic: programming logic that specifies how business transactions are processed and what data needs to be accessed from The data storage device
- data access Logic: refers to the communication with the database, which is responsible for data storage and retrieval on The physical storage device
Three- tier client server
- places one or more application tiers between the client tiers and the database tiers. Each tier contains code belonging to just that layer
-Advantages: better security, easier maintenance, scales more easily
Web based architecture
- The presentation layer is split into a web server and a web browser
- web serven-delivers content or services to and user over the internet
-Web browser: “talks” to a server and asks it for the pages the user wants to see
Relational database
-Most ERP systems access a RDBMS. Advantages: data is only entered once and shared across departments and business units, minimizing maintenance costs errors, and data duplication
- ERP systems can work with other databases such as in-memory database. More expensive than RDBMS because all data is stored in Ram
Database terminology
- Data on an entity (something that can be uniquely identified) is stored in a two-dimensional table, also known as a relation.
- A field (columns in The table) is designed to maintain certain information about every row in the table
- records (rows in the table) are groupings of related fields
Entity integrity
- A primary key (Pk) is the unique attribute that defines each record in a table
- The entity integrity rule is the mechanism the database uses to enforce unique pk’s in each table
- rules: pls is unique, pls may not be null
Table relationships
- A FK points to a the in a different table and establishes and enforces a link between the 2 tables
- an entity relationship diagram is a graphical representation reflecting the database entities and the relationships among those entities
- relationship is established between 2 when tales one table has an fle that references the PK of another table
- types of relationships: 1 to M, 1 to 1, M TO M
One to many relationship
An occurrence of one entity can be linked to more than one (many) occurrences of another entity. Very common
One to one relationship
Each record in a table is associated with only one occurrence in another table- least Common
Many to many relationship
An occurrence in one table is associated with more than one occurrence in a second table (and vice versa).
- RDBMS don’t allow many to many and thus a join on junction is needed table
Junction table
- each record in the junction table contains fk’s from the 2 tables it joins together
- these 2 fks become the Pk in the junction table in order to make each record in the table Unique
- the two pus in the join table are called the concatenated keys.
Referential integrity
-Referential integrity rule: a database constraint that ensures that relationships between tables remain valid and consistent.
- referential integrity prevents the following from happening: adding records to a related table if there is no associated record in the primary table, changing values in a primary table that result in an orphaned records in a related table, deleting records from a primary table if there are related records in another table
Normalization
- Process that structures fields and tables in avdatabase. Eliminates redundant data divides Large tables in to smaller tables, links tables using relationships
First normal form
- 1nf: each Field must be single valued, and every record (row) is unique
Second normal form
- 2NF: table is in 1nf and a single column PK is identified
Third normal form
In 3NF the database table is in 2nf and does not contain any transitive dependencies
- A transitive dependency occurs when changing a non pk field might caus any other non Pk fields to change
Structured query language (SQL)
- A special purpose programming language used to directly communicate with a relational database SQL commands are used to insert, delete, update, and query data in the database
Types of data in ERP databases
Master data
Configuration data
Transaction data
Master data
-Static data, relatively permanent data collectedon entities. Four categories: people, things, places, concepts. Master data may get changed or edited over time.
Configuration data
- enables a company to tailor an aspect of the ERP system to the way it chooses to conduct its business operations. Examples: fiscal year end, default currency, language
Transaction data
-Dynamic data-supports the ongoing operations of the business by describing business events
Reflects the consequences of executing process steps. Represents the largest volume of data in the database
Configuration
-Process of selecting parameters that enable a company to tailor a particular aspect of the system to the way it chooses to do business. Examples: allowing different to currencies be used in transactions, setting $ limits
Customization
-Adding custom code that enhances the features and functionality of the ERP system typically done when all attempts to find a solution through configuration have been exhausted.
- larger companies customize more than smaller companies
System landscape
-A system, or instance, is an installation of ERP software and related components on a server or servers.
- The system landscape is the layout or architecture of the servers
- to complete a landscape, companies will purchase multiple servers and install the ERP system and database several times
ERP systems /instances
- Development (dev); this instance is installed so the ERP system can be configured and possibly customized. Sandbox is an area in the dev environment where members of the project team will explore configuration and customization options
- quality assurance (QAs): the configured system plus any customization will be tested by end users or members of the project team during implementation
Production (prd); the live system that end users will be working on
ERP scalability
- scalability refers to a system’s ability to keep pace a with a company’s trajectory
Dimensions of ERP scalability
Utilization, platform, user count, functionality
On-premise ERP
-Company runs its ERP system on its own servers and computers located at its own site and often supported by its own IT staff. Method is usually chosen by larger companies that have an existing it infrastructure in place and it personnel to support
Cloud ERP
- ERP system is hosted by a vendor or a 3rd party on shaved computing resources accessed over the internet
- resources are maintained in remote data centers dedicated hosting various applications on multiple platforms
-Customers pay for the software on a monthly or yearly basis
Public vs. Private Cloud
-Public cloud; tenants share hardware, storage, and network devices with other companies. Customers benefit from economies of scale, customers have more access to resources for scalability
-Private Cloud I dedicated ERP system to specific organization and accessible only to its employees
Mobile ERP
- The ability to access an ERP system on any device wherever and wherever needed
- growth fueled by cloud computing and faster and smarter mobile devices
- suitable for minimal data entry and display
- companies reed to consider security