Lecture 5 - e-Business Technological Infrastructure Flashcards
What are the 4 layers of the technical infrastructure of e-Businesses top to bottom?
(know by heart)
- Collaborative Technologies
Workflow or EDI - Web-based Technologies and Applications
Web applications used in multi-tier system
Static vs. dynamic sources - Basic Infrastructure
Two-tier, three-tier or multi-tier client/server (the infrastructure of it) - Networking facilities
- The higher, the closer to the business
- The lower, the closer to IT.
What is distributing computing?
Using multiple systems that perform tasks in collaboration to reach an end-goal.
-> classical paradigm in support of e-Business processes and applications.
What is client/server computing?
A form of distributed processing that handles the need for both centralized data control and widespread data accessibility.
It is an architecture that involves client (application) processes (consumers of a service, can be internal) that request service from service processes (providers).
It does not focus on hardware distinctions, but on the applications itself.
Of which layer of the technical infrastructure of e-Business is the client/servers part?
Basic infrastructure
In which 2 ways can the processing tasks be divided between the client and the server?
- Thin clients with heavy servers.
- Thick clients that do all the processing of the data, while the servers only contain common data.
*solutions are chosen based on application requirements, local vs central control, number of users etc.
What are the 5 basic features of the client/server model?
- Clients and servers are functional modules with well-defined interfaces. The functions can be implemented by a set of software modules, hardware components or a combination thereof.
- The relationship between client/server is established between two functional modules. One module, the client, initiates service requests and the other module, the server, responds to these requests.
- Information exchange between clients and servers are strictly through messages.
- Message exchange is typically interactive
- Clients and servers may run on separate dedicated machines, connected through a network.
What types of architectures are possible in the client/server architectures?
- Two-tier client/server
- Three-tier client/server
- Four-tier / multi-tier client/server
The latter is when web-apps are incorporated.
What do the tiers refer to?
The number of elements into which the application is partitioned, NOT the number of platforms used.
This is based on LOGICAL partitioning (opposed to PHYSICAL partitioning).
How does the two-tier system look like?
You have two tiers. The one tier is the ‘Client-tier’, which is comprised of the client application. The other tier is the ‘Server-tier’, which is the database server.
The client is a fat client. The sever is called the database server.
Conversations happen at the level of the server’s database language.
What are the drawbacks of the two-tier architecture?
- Scalability problems
- Poor business logic sharing (as communication happens in database language)
- Client reliance on the database structure
- Limited interoperability
- High-maintenance costs
How does the three-tier system look like?
Base is the same as the two-tier system, but a middle tier is introduced between the user system interface client environment and the database management server environment.
- Presentation tier
Shows a GUI for the layer, usually as a web browser - Processing/middle tier
Contains the business logic and is responsible for the processing of the data - Data tier
Holds the permanent data
What are the 2 advantages of the three-tier system?
- It enables developers to isolate the processing tier - they can further develop it, without having to change the database or the client
- It can decouple the business logic from the presentation function AND from the database function
What two types of web applications exist?
- Static documents
Delivered from the file system of the web server.
Can be read from an existing file - Dynamic documents
Have an interactive and usually time-sensitive nature.
Needs to be generated from database, because it might not exist on a disk at all.
What is a multi-tiered (or 4-tiered) architecture and how does it look like?
Often for the development of web-based applications (for an e-Business).
- Client Tier
Web browser running on a user’s machine. Displays data and lets users enter/update data. - Presentation Tier (web server)
Generates web pages with dynamic content. Supports different types of clients (e.g. HTML or Java). Also retrieves the changed data from the client and forwards it to the business logic/processing tier. - Processing Tier (Business Logic Tier)
Includes performing calculations, maanging workflow and data access for the presentation tier. Supports the function of business logic. - Data Tier
Responsible for managing the data. Provides and stores data.
What is a workflow?
A workflow system automates a business process (complete or part), during which documents, information or tasks are passed from one participant to another for action, according to a set of rules.
Comprises a number of logical steps.
