Single-Tier Architecture Example
This type of architecture is called single-tier because all layers including the user interface, business, and data access are grouped together into one software package. This application is very easy to maintain and can be reinstalled quickly in the case of any changes.
The application layer is unaware of the database, but it provides users with abstract views of data and acts as a go-between for the different operations.
The presentation layer standardizes the representation of information that is sent to the application layer. This is also where things like encoding (converting from one computer’s representation to another) and compression take place. This helps to reduce the number of bits needed for transmission and to speed up data transfer.
It is also responsible for data encryption and decryption. This ensures that only those who have the correct key can read the data being transmitted.
The Presentation layer is also responsible for converting complex structures into flat byte strings to minimize the amount of data required for transmission. This includes things such as converting hierarchies into trees and converting graphical formats into standard text-based file formats (e.g., GIFs, JPEGs and TIFFs) and musical formats such as MIDI. The Presentation layer also supports a wide range of other functions, such as serialization, formatting and character translation. The data residing in the presentation layer is typically stored locally or on a shared drive.
The Business Layer handles the logical operations of an application. It is responsible for the validation, calculations and data processing that the application performs. It also communicates with the data layer to retrieve information and send it back.
For example, if a user requests customer information from the screen, the business layer would sanitize the request and send it to the data layer to retrieve the customer information. The information would then be displayed on the screen.
The business layer is also responsible for determining what data is needed to answer the request. It then uses predefined logic to manipulate the database and pass the information back to the presentation layer. This architecture allows for faster response times and increases security by separating the application from the physical database. It also provides program data independence and improved scalability by eliminating the need to connect directly to the database server. This is the most popular software architecture used today.
Data Access Layer
The data access layer enables the business layer to work with and manipulate data. It consists of methods that manage data connections and maps application entities to data source structures. It also contains code that performs CRUD operations on data.
The function of the DAL is to shuffle information between the program and database, making it easier for the main body of the program to achieve its goals. It prevents the business layer from using too much database-specific code, improving its performance and reducing maintenance time.
The DAL must also determine how it will handle exceptions that occur in the database helper component and that may propagate to other layers or tiers. It is recommended to encapsulate these exceptions in the DAL whenever possible, so that they are handled at a single place and do not affect the stability of the entire application. The DAL should also take into account scalability and performance objectives for the application, as well as implementing a retry process when necessary.
The application layer defines protocols that identify how users and hosts communicate with software applications. Examples of these applications include telnet, FTP and DNS. These applications allow you to download files and send information over the World Wide Web.
For example, if you’re having trouble with your web browser or can’t find an online doctor to make an appointment, you may be experiencing problems at the application layer. Understanding the functions of this level of the network can help you fix these issues and optimize performance.
The 1-Tier architecture places the business and data access layers on the same machine. This helps with scalability and allows you to change one layer without affecting another. It also makes it easier to debug if a problem occurs. It’s important to try to decouple each layer as much as possible. For example, if your phpMyAdmin code contains both SQL queries and generating HTML (presentation), try to separate them.