I've only created web application with one programming language (like python or js).
I'm aware that multiple programming languages are used to create advanced services. But I don't how exactly does it works together, what are the different patterns to implement this.
Here's a scenario. If we have a Nodejs application that accepts like 100s of key-value pair data ( say JSON ) from a user and if we need to work on the data using Haskell... which are compiled to binary.
I have a hierarchy of data of say, a set of people and their managers along with some performance metrics and their points. And I want to pass them to a program written in Haskell to compute some values based on their role etc...
What methods could be used to pass the data into the program?
should I be running a server that accepts the values as JSON (via HTTP) and parses them inside Haskell?
or can I link them with my nodejs application in some other way ? in that case, how can I pass the data from nodejs application to Haskell?
My concern is also about the latency, It's a real-time computation that would happen every time requested.
For instance, facebook uses Haskell for spam filtering and an engineer states they use c++ and Haskell in that service.. c++ accepts input passes to Haskell, which returns back with info. how might be the interfacing working here?
What are the methods used to pass the data into the program ? Should the binary services be Daemon ?
The exact approach depends on the exact requirement in hand, software components planned for usage.
If you are looking for interworking between different languages, there are various ways.
The method based on Addons(dynamically-linked shared objects written in C++) provides an interface between JavaScript and C/C++ libraries. The Foreign Function Interface (FFI) and Dynamic Libraries (.dylib) allow a function written in another language(rust) to be called from language in host(node.js) language. This shall rely on the require() function that shall load Addon as ordinary Node.js modules.
For example, the node-ffi addon can be used to create bindings to native libraries without writing any C++ code for loading and calling dynamic libraries using pure JavaScript. The FFI based approach is used for dynamically loading and calling exported Go functions as well.
In case if you would like to call the Go functions from python, then you can use the ctypes foreign function library for calling the the exported Go functions
In general, if you would like to develop a loosely coupled solution taking advantage of emerging technologies (various language, frameworks), then microservices based architecture can be more beneficial. This shall bring in more independency as a change in a module/service shall not impact other services drastically. If your application is large/complex, then you may need to go with microservices pattern like , "Decompose by business capability" or "Decompose by subdomain". There are many patterns related to the microservices pattern like "Database per Service" pattern where each service shall have own database based on your requirement, "API gateway" pattern that is based on how services are accessed by the clients ("Client-side Discovery pattern" or "Server-side Discovery pattern") and other related variants of microservices are available which you can deploy based on your requirement.
The approach in-turn also shall be based on the the messaging mechanism (synchronous / asynchronous), message formats between microservices as per the solution requirement.