Lecture 5 - e-Business Technological Infrastructure

Question 1

The 4 layers of e-Business technological infrastructure

Answer 1

• Collaborative Technologies: Tools that can make the machine collaborate from the view of the business and value chain (workflow systems, EDI etc.)
• Web-based Technologies & Applications: Certain tool that is actually presented to the user
• Basic Infrastructure: Applications and the way they are designed (client/server and tiered architectures)
• Networking Factilities: Physical hardware, computers, databases, operating systems, protocols

Question 2

Client/server architecture

Answer 2

Involves client processes (service consumers) requesting service from server processes (service providers)
Solutions chosen depend on specific application requirements (local vs central control, # of users, processing needs etc.)
- Clients and servers are functional modules with well-defined interfaces. The functions of a client and a server can be implemented by a set of software modules, hardware components, or any combination thereof.
- Each client/server relationship is established between two functional modules, where one module, the client, initiates service requests and the other module, the server, responds to these requests.
- Information exchange between clients and servers, i.e., requests and responses, are strictly through messages.
- Message exchange is typically interactive (stock price refreshes automatically).
- Clients and servers may run on separate dedicated machines connected through a network.

Question 3

Two tier client/server architecture

Answer 3

• Client/server introduces a two-tier client/server architecture.
• The machine on the left communicates with the software that delivers the things, the server part is running the operations
• The server is in charge of delivering what the business needs, the client is in charge of displaying that information
• The tiers in a client/server application refer to the # of elements into which the application is partitioned, not the # of platforms where the executable are deployed.
• The tiers into which an application is partitioned is known as the logical partitioning (of what you need to do) of an application as opposed to physical partitioning (# of platforms where the application executables are deployed).

Question 4

Fat client

Answer 4

Client in a two tier client/server architecture. Most of the work is done on the client side. This is not an optimal situation

Question 5

Drawbacks of the two tier client/server architecture

Answer 5

• The two-tier architecture has several drawbacks, which are especially problematic for large and distributed applications:
  o Scalability problems (only holds the information for one client, but several clients would want to access, which could create inconsistencies)
  o Poor business logic sharing (each computer is in charge of one thing)
  o Client reliance on the database structure
  o Limited interoperability (all about accessing a bunch of data)
  o High-maintenance costs (major problem)

Question 6

Three tier client/server architecture

Answer 6

• The three-tier architecture overcomes the limitations of the two-tier architecture. A middle (logical) tier is introduced between the user system interface client environment and the database management server environment.
• The application is partitioned into 3 logical tiers:
   presentation tier: responsible for the graphical user interface (GUI) layer usually in the form of a web-browser
   processing tier (or middle-tier): contains the business logic & is responsible for the processing associated applications supported.
   data tier: holds the permanent data associated with the applications supported e.g., modern and legacy application databases, and transaction management applications. It interprets requests from a client and routes them to a suitable data resource.
• The processing tier enables developers to isolate the main part of an application that can change over time: data & relationships inherent in the data.

Question 7

Web server

Answer 7

Application (technically a server process) that receives calls from web clients and retrieves web pages and/or receives information from gateways

Question 8

Multi-tiered architecture

Answer 8

• The client-tier is implemented as a web browser running on the user’s client machine. It displays data & lets users & client applications enter/update data.
• The presentation-tier generates Web pages in which it includes dynamic content. It supports different types of clients, e.g., HTML & Java capable clients. A Web-server also finds the client application or user-entered data in Web pages coming back from the client & forwards it to the business logic-tier.
• Application logic is written in the processing or business logic-tier. This includes performing calculations and validations, managing workflow & all data access for the presentation-tier. An application-server supports the functions of business logic-tier.
• The data-tier is responsible for managing the data. It provides the business logic-tier with required data when needed & store data when requested.

The first two are about presentation and visualization (front-end)
The last two are about processing and storing (back-end)

Question 9

Electronic Data Interchange (EDI)

Answer 9

The transfer of structured data by agreed message standards between computer applications (paperless, routine documents, translated into standard business language). Mainly used in the order execution (order, deliver) and settlement (invoice, payment) and less in pre-sale or after sales

Question 10

Problems with EDI

Answer 10

• Fixed transaction sets (if there is some change, we need to change the whole standard)
• Resilience to change (hard to change because you work together with another party, you mainly make these standards on things you expect not to change)
• Reliance on proprietary communications networks (don’t want it to be changed)
• Encapsulation of business rules in transaction sets (you expect certain kind of behavior  less flexibility)