Multi-Tier Architecture or N Tier Architecture

An N-Tier Application program is one that is distributed among three or more separate computers in a distributed network.

1. N-Tier or Multi-Tier Architecture or 3-Tier Architecture S.REVATHI AP/CSE 1

2. N-Tier or Multi-Tier Architecture or 3-Tier Architecture An  N-Tier Application  program is one that is distributed among three or more separate computers in a distributed network. Distributed network: A network configuration where every participant can communicate with one another without going through a centralized point. Example: Cellular networks (Cellular networks are distributed networks with base stations physically distributed in areas called cells). The most common form of n-tier is the 3-tier Application: User interface Business logic Database S.REVATHI AP/CSE 2

3. Example S.REVATHI AP/CSE 3

4. Ctd … This architecture model provides Software Developers to create Reusable application/systems with maximum flexibility. In  N-tier, “N”  refers to a number of tiers or layers are being used like –  2-tier, 3-tier or 4-tier, etc . The n-tier architecture  is an industry-proven software architecture model. It is suitable to support enterprise level client-server applications by providing solutions to scalability, security, fault tolerance, reusability, and maintainability . It helps developers to create flexible and reusable applications. S.REVATHI AP/CSE 4

5. Common terms in Multi-tier Architecture a. Distributed Network b. Client-Server Architecture c. Platform d. Database S.REVATHI AP/CSE 5

6. a. Distributed Network It is a network architecture, where the computers coordinate and communicate their actions only by passing messages. It is a collection of multiple systems situated at different nodes but appears to the user as a single system. . S.REVATHI AP/CSE 6

7. b. Client-Server Architecture   It is an architecture model where the client (one program) requests a service from a server (another program)   i.e.  It is a request-response service provided over the internet or through an intranet. In this, client computer provides an interface to an end user to request a service from a server and on the other hand server then processes the request and displays the result to the end user. An example of Client-Server Model– an ATM machine. A bank is the server for processing the application within the large customer databases and ATM machine is the client having a user interface with some simple application processing. S.REVATHI AP/CSE 7

8. c. Platform In computer science or software industry, a platform is a system on which applications program can run . It consists of a combination of hardware and software that have a built-in instruction for a processors/microprocessors to perform specific operations. An example of Platform – A personal machine loaded with Windows or Mac OS X. S.REVATHI AP/CSE 8

9. d. Database Database:  It is a collection of information in an organized way so that it can be easily accessed, managed and updated. Examples of Database – MySQL,  SQL  Server, and Oracle Database are some common Db’s. S.REVATHI AP/CSE 9

10. 3-Tier Architecture Presentation layer Business Logic layer Database layer S.REVATHI AP/CSE 10

11. N Tier Architecture  Diagram Some of the popular sites who have applied this architecture are: MakeMyTrip.com Sales Force enterprise application Indian Railways – IRCTC Amazon.com, etc. S.REVATHI AP/CSE 11

12. Presentation tier The presentation tier is the user interface and communication layer of the application, where the end user interacts with the application. Its main purpose is to display information to and collect information from the user. This top-level tier can run on a web browser, as desktop application, or a graphical user interface (GUI), Example. Web presentation tiers are usually developed using HTML, CSS and JavaScript. S.REVATHI AP/CSE 12

13. application tier The application tier, also known as the logic tier or middle tier, is the heart of the application. In this tier, information collected in the presentation tier is processed- using business logic, a specific set of business rules. The application tier can also add, delete or modify data in the data tier. The application tier is typically developed using Python, Java, Perl, PHP or Ruby, and communicates with the data tier using  API  calls. S.REVATHI AP/CSE 13

14. Database tier The data tier, sometimes called database tier , data access tier or back-end , is where the information processed by the application is stored and managed. This can be a  relational database management system  such as  PostgreSQL , MySQL, MariaDB, Oracle, DB2, Informix or Microsoft SQL Server, or in a  NoSQL  Database server such as Cassandra,  CouchDB  or  MongoDB .  In a three-tier application, all communication goes through the application tier. The presentation tier and the data tier cannot communicate directly with one another. S.REVATHI AP/CSE 14

15. Advantages Scalability Data Integrity Reusability Improved Security Improved Availability S.REVATHI AP/CSE 15

16. Disadvantages Increase in Complexity Increase in Effort S.REVATHI AP/CSE 16