3 Tier Architecture in DBMS

3-tier DBMS (Database Management System) architecture is a design approach that divides the database system into three interconnected tiers, each serving a specific purpose. These tiers are:

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Diagram of 3 Tier DBMS Architecture

Presentation Layer:

• The top layer is responsible for user interaction and interface.

• It handles the presentation of data to users and captures user inputs.

• It includes components such as web browsers, mobile apps, or desktop interfaces that users interact with.

• In web applications, this layer often involves creating the graphical user interface (GUI) that users interact with.

Application Layer (Business Logic):

• The middle layer, also known as the business logic layer

• It contains the application logic and business rules.

• Processes user inputs, communicates with the database, and manages the flow of data between the presentation layer and the data layer.

Data Layer:

• The bottom layer deals with data storage and retrieval.

• It manages the actual database, including storing and retrieving data, enforcing data integrity, and handling database transactions.

• Involves defining the database schema, tables, relationships, and ensuring data consistency

The Work flow typically begins with user interactions at the presentation layer, which then sends requests to the application layer for processing. The application layer communicates with the data layer to retrieve or store data in the database. The separation of these layers deliver the modularity that making it easier to manage and update certain aspects of the system without getting to affect the entire architecture.

3-Layer Architecture of DBMS

The three-level architecture in database management system (DBMS) consists of the following levels: external, conceptual, and internal. Each level serves a specific purpose in managing and accessing data.

External Level:

Also known as the view level, the external level is the top level of the three-tier DBMS architecture.

It allows multiple users to view their desired data without needing to know the database schema details such as data structure and table definitions.

Users interact with the data at this level, and the data is fetched from the database with the help of mapping between the conceptual and internal levels.

Conceptual Level:

Also referred to as the logical level, the conceptual level describes the entire design of the database, including the relationships among data and the schema of the data.

Database constraints and security are implemented at this level, and it is maintained by the database administrator (DBA).

Internal Level:

Also known as the physical level, the internal level describes how the data is actually stored in the storage devices and is responsible for allocating space to the data.

It deals with the physical storage details such as the location of database objects in the data store and how the data is stored in secondary storage devices like disks and tapes.

The DBMS is responsible for the correspondence between the three types of schema, which is called mapping. There are two types of mapping in the database architecture: conceptual/internal mapping and external/conceptual mapping.

Database Schema in 3-Tier Architecture

In 3-tier DBMS architecture, the database schema refers to the organization and structure of the database, specifically divided into three tiers or layers: presentation, application, and data.

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Presentation Layer: In this, database schema focuses on defining the structure of data as it appears to users, including how information is displayed and interacted with.

Application Layer: The database schema in this layer defines how data is processed and manipulated to meet business requirements. It includes stored procedures, triggers, and other database objects related to business rules.

Data Layer: In this layer, database schema defines the structure of the actual database tables, relationships between them, constraints, and other data-related aspects. It includes entities, attributes, primary and foreign keys, ensuring data integrity and consistency.

Data Independence in 3-Tier DBMS Architecture

Data independence is a concept in database management systems (DBMS) that represent to the separation in between the logical and physical aspects of data storage and manipulation. It allows changes to be made at one level without affecting the other levels.

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In the context of the 3-tier DBMS architecture, data independence is typically represented into terms of logical and physical independence.

Logical Data Independence:

Logical data independence refers to the ability to change the logical structure of the database schema without affecting the application programs or the user interface.

In 3-tier architecture, logical independence means that modifications to the database schema (changes to tables, relationships, views, etc.) do not necessitate changes to the application logic in the middle tier or the user interface in the presentation tier.

This separation allows for flexibility in adapting the database design to evolving business requirements without disrupting the overall system.

Physical Data Independence:

Physical data independence refers to the ability to change the physical storage and access mechanisms without impacting the application programs or the logical schema.

In 3-tier architecture, physical independence means that changes to the underlying storage structures, indexing methods, or data compression techniques at the physical level do not affect the logical schema or the application logic.

This separation enables optimizations at the physical level (e.g., changes to indexing strategies or storage formats) without requiring modifications to the higher-level components.

Three-Tier DBMS Architecture Examples

Examples of three-tier architecture are prevalent in various software applications and systems. Here are some examples:

Web Applications: Many web applications are designed using three-tier architecture. The presentation tier is the user interface that is typically a web browser. The application tier manages the business logic and processing, but data tier manages the storage and retrieval of data.

This architecture is commonly used in e-commerce platforms, content management systems, and online banking applications.

Enterprise Resource Planning (ERP) Systems: ERP systems often employ three-tier architecture. The presentation tier offers the user interface for interacting with the system, the application tier keeps managing the business logic and workflow processes; and the data tier manages the storage and retrieval of enterprise data.

This architecture allows for scalability, flexibility, and security in managing complex business processes and data.

Cloud-Native Applications: Modern cloud-native applications often utilize three-tier architecture. The presentation tier can be easily hosted on web servers or served via cloud-based content delivery networks. The application tier that may consist of micro services; handles the business logic and processing, while the data tier can leverage cloud-based databases or storage services.

This architecture enables scalability, resilience, and efficient resource utilization in cloud environments.

Mobile Applications: Three-tier architecture is also going to use in mobile applications. The presentation tier is the mobile app interface, the application tier handles the business logic and making communication with external services, and the data tier manages the storage and retrieval of data that can be hosted on cloud-based or on-device databases.

This architecture supports the development of scalable and responsive mobile applications.

Difference between 2-Tier and 3-Tier Architecture

Here are the five differences between two-tier and three-tier database architecture, including:

Advantages of 3-Tier Architecture

Here are some key advantages of the 3-tier architecture, including:

Modularity and Scalability

The separation of concerns into three distinct tiers (presentation, application, and data) allows for modular development. Each tier can be developed and maintained independently, promoting scalability as components can be added or upgraded without affecting the entire system.

Easy Maintenance and Updates

Changes to one tier do not necessarily impact the other tiers. This separation facilitates easier maintenance and updates. For example, updates to the user interface can be made without altering the underlying business logic or database structure.

Improved Security

Security measures can be utilised at each tier as independently. Access control, authentication, and encryption can be implemented at the presentation, application, and data tiers that help to enhance the overall security of the system.

Enhanced Performance

The modular structure allows for performance optimizations at each tier. For instance, caching mechanisms can be implemented in the application tier to reduce redundant database queries, improving overall system performance.

Support for Multiple Platforms

Different tiers can be implemented using technologies and platforms that are best suited for their specific functions. This flexibility helps to use of diverse technologies, including web-based interfaces, desktop applications, or mobile apps at the presentation tier.

Disadvantages of 3-Tier Architecture

There are some common drawbacks associated with the 3-tier architecture, as following them:

Increased Complexity

Managing three separate tiers can increase the complexity of the system. Coordinating communication and ensuring proper data flow between tiers may require additional effort.

Latency and Performance Issues

The separation of tiers refers to make communication overhead in between the presentation, application, and data tiers. This can make leading to latency, especially in situations whereas enlarge amounts of data require to be transferred in between tiers, and impacting overall performance.

Lack of Scalability

Some crucial argue that the 3-tier architecture lacks scalability; especially in the respect of modern requirements for elasticity and rapid scaling. This criticism suggests that the architecture was developed in an era where the idea of rapid scaling did not broadly exist, potentially limiting its suitability for highly scalable and dynamic applications.

Maintenance Challenges

While the modular structure makes individual components easy to maintain, coordinating updates across multiple tiers can be challenging. Changes in one tier may necessitate corresponding modifications in other tiers to maintain compatibility.

FAQs (Frequently Asked Questions)

What are the Components of 3 Tier Architecture?

In 3-tier architecture, the system is divided into five main components, and each component has specific responsibilities, including Presentation Tier, Application Tier, Data Tier, Communication Tier, and Security & Management Tier.

How does the 3-tier architecture differ from other architectures in DBMS?

The 3-tier architecture differs from other architectures by getting to separation the application logic from the data and the user interface that are providing the added security, scalability, and flexibility as compared to two-tier architectures.

Is 3-tier architecture suitable for all types of applications?

While 3-tier architecture is widely used, its suitability depends on the specific requirements of the application. It is particularly beneficial for complex and scalable applications with diverse user interfaces.

When is the 3-tier architecture in DBMS used?

The 3-tier architecture is mainly used for large applications on the web and provides features such as data backup, recovery, security, and concurrency control. It is suitable for applications that require scalability, flexibility, and enhanced security.

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