Imagine that you come to the store, pick up a cart of groceries, go to the checkout – and the cashier is busy. And you drop the cart and go.
This is how some IT systems work: the server is broken, overloaded, does not respond – and requests from clients and other servers do not reach it. Or they come, but not where they need to, and at the wrong time. As a result, you can lose customers, data and money. Message queuing services will help solve this problem – with them, requests will queue up, like buyers in a store.
We will tell you how message queues work and what problems such tools are used to solve.
What Are Message Queues?
Requests from buyers or clients of any online services are processed on the servers where the service is hosted. These requests should reach the server and back as quickly as possible so that the client receives the response that it expects: “Payment passed”, “Order completed”, or something else.
Message queues store requests, so they are not lost and transfer them to servers gradually. For example, a client places an order in an online store, and the order goes not immediately to the server but the queue. If the server fails, the line will save the order and send it later; nothing is lost.
Now let’s look at examples of who and in what cases message queues are helpful and how they will help optimize IT infrastructure costs.
Handling User Requests When There Are Too Many
Situation: The load on servers fluctuates: it is higher in some hours or days; in others, it is lower.
The store launched a significant promotion for just a day. On this day, the site received ten times more visitors than usual. They all tried to place an order or at least put the product in the basket. The online course launched an ad, and everyone rushed to register.
There is a loan application form on the bank’s website. People often fill it out in the first hour or two after work, when they have finished their business and collected the necessary papers.
What happens without queues. At times of increased load, the servers can not cope. And instead of putting an excess of requests on hold, they issue refusals to customers: they write something like “Unable to process the order” or altogether disable the necessary functions.
How Queues Can Help
All requests from clients do not go directly to the server but are queued. And the queue sends a response to the client, for example: “Order accepted”. On the other hand, the server takes requests from the queue as it becomes free. As a result, processing will take a little longer, but the client immediately sees that his action has been completed, not a single request is lost, and the site and all forms work without crashes and errors.
Note that queues won’t help if you need an instant response to a request. For example, if the user is waiting for the calculator to calculate the cost of the order for him. Or that the order will immediately go to payment.