What happens when a website uses two or more backend programming languages? Why?

For example, if PHP is used, Python is used, and node. js is used? 1.1.29 for example, PHP, Python, and node. js reply content: as a website, Typescript/C #/SQL/C ++ is widely used, the php and php c extensions that the website does not just see are not two languages = question:
Look at the scale of your website, "One website uses two backend programming languages"It is common in production. First, the UI layer uses a rapidly developed server language, such as php. then, some performance-sensitive backend services use low-level languages such as C/C ++; some http services may also choose java/c #, while some services choose fast development languages such as python or even fashionable node. js. Don't ignore the database. SQL is also a language.
Websites of the upper scale cannot have only one backend.
"What will happen ? "-- No situation ...... True
"Why ?"-- Because this is a requirement and is also adapted to local conditions


By the way, let's see how many languages a website needs ......
Page:
Required: html, css, and js
Optional: some front-end templates, such as jade and ejs; some pre-processing languages, such as less/sass/stylus/coffee script
Server UI layer:
Required: select at least one server language, such as php, java, python, ruby, and javascript.
Optional: some template engines, such as smarty and velocity.
Data layer:
Required: select at least one SQL statement.
Other services (not available on small websites ):
C/C ++/java/C #...... Too many programming languages, as you can imagine, can appear in any module.
Tool chain:
Various scripts (including shell scripts) and makefile ......
Documentation:
WORD (language) and markdown answers the premise: a website, I understand as a general user's mind for a website and domain name definition, rather than a non-technical level of a solution/project.

This is normal for large Internet enterprises.
For a single scenario, the consistent attitude is that only the most appropriate and not the best.
For complex scenarios, it is normal to perform their respective duties, isn't it?

The disadvantage of multiple languages seems to be that there is a problem with the cost, mainly the management cost.
If the technical director wants to HOLD his salary, his salary will naturally not be higher than that of senior coders. (Of course, the management cost structure is much more complex, that is, a point-to-point discussion .)
But are internet companies really concerned about these costs?
Care companies are all marginalized and life-and-death Companies. if they do not get up, they will be suspended. I have no money to play with P's internet...

I will not elaborate on other advantages. Limited by capabilities.
However, I don't mean the harm, not the excuse, but because it is a choice. if the harm cannot be tolerated, you will naturally not choose it. Only use two languages? That is the simplest website. Generally, websites use four or more languages.

Do I think websites in only two languages are not high-end websites?

Well, you don't have to worry about this illusory reputation. when your website grows, there must be more than two languages. At this stage, only two languages can save you a lot of trouble. What will happen here... This is too generic. How do you ask others to answer?

1. teamwork
2. project control
3. two language integration solutions

It can be said that all aspects of the project are affected. I am a layman and I will not elaborate on it. Are PHP and SQL counted?
What? Not a simple SELECT? Isn't the stored procedure counted?
None of SQL statements? Isn't the C extension of PHP/Python counted?

So what can I say about this? Each language has problems that you are good at and that you are not good at. as long as the entire system module is clearly divided and the interface is clearly defined (including clear call specifications, such as JSON/Thrift. And using a variety of tools to make a chair. The key is to solve the problem. The language that can solve the problem is a good language. As long as the connection is good, there will be no problem. I made a website and it was originally written in asp + sqlserver2000. some of the php rewriting times were too late to be written, cookie is added to ensure that data can be transmitted to each other and the database also adds a mysql storage article.