The phrase designing the code can have different meanings; for example, we’ll need to have a short talk about naming conventions. Yet, the most important aspect that we need to take a look at is the application architecture. The architecture refers to the way you split the code into smaller components (for example, the product search feature) for a simple piece of functionality. Although it might be easier to implement that functionality as quickly and as simply as possible in a single component, you gain great long-term advantages by creating smaller, more simple components that work together to achieve the desired result.

Apart from the fact that you want a fast web site, each of the phases of development we talked about brings new requirements that must be met. Every time you proceed to a new stage, you want to be able to reuse most of the already existing solution. It would be very inefficient to redesign the whole site (not just the visual part but the code as well!) just because you need to add a new feature. You can make it easier to reuse a solution by planning ahead, so any new functionality that needs to be added can be plugged in with ease, rather than each change causing a new headache. When building the web site, implementing a flexible architecture composed of pluggable components allows you to add new features, such as the shopping cart, the departments list, or the product search feature, by coding them as separate components and plugging them into the existing application. Achieving a good level of flexibility is one of the main goals regarding the application’s architecture shows how you can put this into practice.
You will see that the flexibility level is proportional to the amount of time required to design and implement it, so we will try to find a compromise that will provide the best gains without complicating the code too much. Another major requirement that is common to all online applications is having a scalable architecture. Scalability is defined as the capability to increase resources to yield a linear increase in service capacity. In other words, ideally, in a scalable system, the ratio (proportion) between the number of client requests and the hardware resources required to handle those requests is constant, even when the number of clients increases. An unscalable system can’t deal with an increasing number of clients, no matter how many hardware resources are provided. Because we are optimistic about the number of customers, we must be sure that the site will be capable of delivering its functionality to a large number of clients without throwing out errors or performing sluggishly.
Reliability is also a critical aspect for an e-commerce application. With the help of a coherent error-handling strategy and a powerful relational database, you can ensure data integrity and ensure that noncritical errors are properly handled without bringing the site to its knees.