Flashcards
Presentation B
Cards in this deck (12)
- 1Application Architecture Evolution
- 2Application Programs and User InterfacesAn application program acts as the intermediary between users and the database
Applications split into
front-end
middle layer
backend - 3Front-end: user interfaceForms
Graphical user interfaces
Many interfaces are Web-based - 4Two-Layer Web Architecture
- 5Two-Layer Web ArchitectureDatabase runs on its own server:
Separated from the application (website)
Easily swap databases
But, the presentation (visible) and business logic layers are still joined
Server becomes overloaded
Network congestion is likely
No separation of concern between form and content - 6Three-Layer Web Architecture
- 7Three-Layer Web ArchitectureEverything can run on its own server
Disconnection between Presentation, Logic and Data layers - 8Application layersPresentation or user interface
model-view-controller (MVC) architecture
model: business logic
view: presentation of data, depends on display device
controller: receives events, executes actions, and returns a view to the user - 9Application Architecture
- 10Application Architecturesbusiness-logic layer
provides high level view of data and actions on data
often using an object data model
hides details of data storage schema - 11Application Architecturesdata access layer
interfaces between business logic layer and the underlying database
provides mapping from object model of business layer to relational model of database - 12Business Logic Layer – Why?Enforces business rules for carrying out actions
E.g. student can enroll in a class only if she has completed pre-requsites, and has paid her tuition fees
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- Database Technology Flashcards on Presentation B, created by Gary Burrows on 15/01/2015.
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- Gary Burrows
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