What do we actually mean by large scale web application? [closed]

Question

What do we actually mean by large scale web application ? What is the criteria to call it large scale web application
Is it number of code lines of a application or Number of user per day of a web application. say 10K per day ?

Answer 1

What do we actually mean by large scale web applications? That depends who you ask.

If people have build smaller applications in the past and need to build a larger one now that handles more data and more traffic, they might call it a large scale web application. But if you then compare that site with ones like LinkedIn, Facebook, or Google then it will still be a small application.

People have different notions of what large is, what's large for some might be medium size for others and small for some others. But a large scale web application has characteristics such as these:

• performance, being able to handle a large number (millions) of users/request or a large number (thousands) of transactions per second. Both have challenges depending on the type of app (CPU bound, IO bound or both).
• scalability, the horizontal type, not only at the web server level but also at the database level. Depending on what you are doing a RDBMS might not cut it anymore so you have to walk the NoSQL path, sometimes using more than one producs as NoSQL solutions tend to be specialized systems tackling a specific use cases as opposed to being a general purpose database as RDBMSs are. A lot of integration challenges arise from connecting heterogeneous solutions together and make them behave as a single application.
• large scale applications are distributed, taking advantage of CDNs or running the app on servers geographically closer to the user. You can easily have hundreds or thousands of server nodes, with a large sys admin team having to manage the setup. If you don't have your own data centers you can run in the cloud.
• besides a large sys admin team, you often have a large development team needing to optimize for performance and scalability, designers and front end developers working on providing a fluid user interface, with mobile support, etc;
• having to deal with a large volume of data and with lots of data types. No longer handling just products, customers, orders, etc, but also clicks, page views/hits, events, logs, customer behavior tracking, etc. This is in relation to the previous NoSQL point, but also with this volume of data these apps tend to have a large back-office that offers all kinds of reports, graphs, administrative tools, etc to manage the app itself.
• availability 24/7;
• some other, miscellaneous keywords to throw into the mix like SOA architecture, microservices, data-warehouses, security, distributed caches, continuous deployment, etc.
• etc.

These are some of the characteristics (I think) large web scale web apps have in common and it's important to think about these aspects up front and deal with all challenges that come from them from the beginning, when building the app.