Effective Application Scaling – Proven Techniques and Methods

This article will provide an overview of how to handle application scalability, its advantages, some techniques, and tips.

But first, let’s define what application scalability is.

What is Application Scaling?

When hundreds to thousands of users start using your application concurrently, it should handle such a heavy load without negatively affecting the user experience and disruptions. This is called application scaling.

App scalability is more concerned with the back-end than the front-end. Imagine a scenario where a single server gets millions of HTTP requests, including processing database queries and fetching images and front-end libraries within seconds. Too many requests of large-scale magnitude would cause a server crash provided a single server executes all the tasks.

As a result, you need to delegate the work among several servers. Let’s discover two techniques that cloud services frequently use:

• Horizontal scaling: This technique concerns scaling the number of servers to meet the demands of the dramatic increase in user requests. As a result, the number of requests each server receives is minimized as several servers share the workload.
• Vertical scaling: As opposed to horizontal scaling, vertical scaling deals with adding more vigorous CPUs, memory, or resources for I/O operations. It can also include replacing an existing server with a super-powerful server.

Later we will provide an overview of which approach is ideal. But for now, let’s focus on the perfect time to plan application scaling.

Vertical Scaling vs. Horizontal Scaling

When is Scaling an Application Necessary?

First, you must execute performance testing if a limited number of users use your app. You can then examine how the server performs and determine the approximate number of users the server can handle. Then when the server fails with the optimum capacity, you must execute comprehensive scalability testing. From then onwards, you have two options: scale horizontally or vertically.

The significant advantage of vertically scaling the app are:

• You do not touch the application code of web apps.
• Lower server costs.
• Lack of data inconsistencies as everything is in one machine.

However, if you scale horizontally, you can take advantage of multiple servers delegating work, and they would serve each concurrent request faster. The downside of this approach is that it requires modification of the application code and redoing the web app’s architectures. Nevertheless, it certainly helps the scalability.

The Most Popular Application Scaling Techniques

If you intend to build a static website without dynamic content, you” ll be fine with just adding a load balancer between the client and server machine. It would just forward the requests from the client to the server and vice versa.

However, the story differs from a dynamic web app, which dynamically generates content through databases. In such applications, millions to billions of read requests to the same database can crash before it crashes the front-end servers.

Therefore you need to be good at database techniques, as described below.

Cache database queries

You can perform a query logging analysis and determine which queries produce a faster response time than which ones take longer to respond. You can then store the results of the queries that took slower to respond temporarily into the memory of your web server. So when there are concurrent requests to these queries, your application code will use the data that the cache stores.

Database Sharding

Another technique to make the app scalable is sharding your database. With this technique, you partition a single dataset across multiple databases. So instead of a single database handling all the requests, the number of reading requests that a single database handles would be delegated across several databases.

As discussed above, horizontal and vertical scaling is involved even with database sharding. With the former method, you must place additional nodes to share the number of read operations. With vertical scaling, you increase the processing power of a single database server by maximizing the number of CPUs, Increasing the size of RAM or storage capacity.

In addition to horizontal and vertical scaling, you can replicate the data into several databases. This technique is instrumental in achieving scalable architecture in circumstances where you require geo-location routing- this implies adding database server replicas to distributed locations worldwide based on users’ locations. Though this technique provides a handful of benefits, it, too, has some drawbacks. That is, whenever you execute a write operation, you have to copy to each replica.

Manual scaling

So far, we have talked about how to scale your database. Now let’s focus on the HTTP calls that arrive concurrently. As discussed above, you can place a load balancer that redirects the request to different servers based on the geo-location of a client request. So for manual scaling, you can register the IP addresses of different servers to receive the incoming traffic and serve them.

Nevertheless, significant performance issues of this approach are that if the load balancer crashes, the whole application fails. So, to overcome these bottlenecks, the cloud environment provides autoscaling.

Auto Scaling

Services such as cloud computing offer an automatic scaling feature, and it automatically scales the number of computing resources based on your web app’s requirements during that particular time. Autoscaling does not just involve scaling up resources when the traffic spike is high; it also scales down the computing resources when the traffic declines over time at an affordable cost.

When a client calls the server, it goes to load balancers which communicate with the server on whether to upscale or downscale depending on the traffic.

Content Delivery Network (CDN)

The primary objective of the CDN is to serve users across multiple geographical locations. A Content Delivery Network stores front-end libraries like jQuery, Bootstrap, and other JS or CSS frameworks. Let’s say a web developer working on a PHP application in India needs to access the Bootstrap CSS framework located on a USA server.

Accessing this server in the USA would cause a network bottleneck. However, if a CDN exists in Singapore, the network latency would be negligible. So closer the CDN to the client enhances the scalability. Similarly, if your web app has heaps of images, video, and audio files, you can use a CDN in several diverse locations for better network performance.

What are the Advantages of Scaling Apps?

• Enhanced user experience – It’s evident that more users will not use an app with scalability issues. They will most likely uninstall it from their devices and move on to another app. They wouldn’t certainly wait until you fix all the problems in the application. By that time, you can’t hope for any rapid growth of your app.
• Provides outstanding performance – When an app’s performance is outstanding, regardless of the number of users (1000 or 10 million), it will perform as expected in the initial stages. So it’s vital to plan app scaling right from the development phase.
• Saves money – For any commercial application, the loss of money implies the loss of users. If you can not initially predict how an app will scale, then it’s better to go for an MVP( Minimal Viable Product); You build the product with fundamental features for minimal users. Then you can monitor how the application performs with increasing users and plan the app’s scalability accordingly. At least from that point onwards, if you’re still using the same infrastructure that you used to build the MVP, your web app would likely confront scalability issues. For applications with a large user base, you must consider using scalability from the planning stage; you will save time and money without restructuring your code and architecture.

Technical Tips When Scaling an Application

So far, you have gained an overview of the characteristics of scalable applications and how you can utilize hardware and software sides to achieve greater scalability. Now let’s dive into some technical steps to achieve app scalability.

A culmination of both vertical and horizontal scrolling

Vertical and horizontal are not mutually exclusive. However, you can certainly use them in tandem to achieve more processing power. You may have run into situations where part of your application vertically scales up, whereas the rest horizontally scales out.

When switching between the two scaling modes, it’s essential to keep in mind:

• It would require you to design the system architecture with decoupled services from the beginning.
• You need to partition the data to ensure that the parallel server units do not exchange data.

This concept also applies to databases, but you must ensure data consistency.

Assess whether scalability is a must for your application

It’s, in fact, easier to get caught up in the scalability hype. However, any scaling of an application should be preceded by a thorough analysis. You may find that scaling is not the best solution for your application or that the problem lies elsewhere.

Therefore under load testing, you must assess all of the following:

• Is the application capable of coping with an increase in users? Here it would help if you considered concurrency and latency—higher latency with more load translates to a poor user experience.
• Then if there is an increase in latency with more concurrent users, what storage are you planning to scale? Is it the hardware only, or will you include the file storage?
• Finally, what are the options in case you experience a heavy workload?

Summary

We hope we now have a comprehensive overview of web or mobile application scaling. Usually, a web app grows with more users, and scalability is a well-worth scenario to get into. Nevertheless, it can be a hectic process to consider all the options that you have with scalability. So choose the right technologies wisely and plan your scalability journey wisely.

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