The main aim of service-oriented architecture is to allow users to mix large chunks of functionalities into one in order to build an application and services by combining services. This architectural design of node backend application is considered a best practice in industrial labels.

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Service Oriented Architecture in NodeJS
What is Service oriented Architecture in NodeJS?
Serviceoriented architecture is a way to Building a backend applications by consisting
multiple independent services. A service can be any business logic that completes an action
and provides a specified result to the end point user.
Each service in SOA is a complete business function in itself.
For an Example
Let’s discuss about a grocery store.
The owner add the product details in the inventory. Then owner search to find data about a
unique product. And the backend application database query should be inside the service
section by leveraging data access layer. Then it securely fetch data and give the response to
the owner.
Layers in Service oriented Architecture
How SOA Works
● Here first when API call, in node app first it face router section where all the
authentication and validation occur through the middleware function. Then control
moves towards controller section which work is collect the incoming data related to
APIrequest. Here all the business logic to access data are combined inside a service.
So the controller invokes that service and service leverage data access layer to
connect with database and calculation. Then services return the data to the
controller. After that controller give the response to the end point user.
● The most important benefit in SOA is as all the services are independent and small
chunks so whenever we want to change our programing language it should be very
fast and easy in development process.
Router layer
Service layer
Data access layer

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Flow chart diagram:
SOA Advantages
● Reliable– Even though service-oriented architecture has small and independent
services, it becomes easier to debug code as it checks small chunks instead of
checking a large codebase
● Independent of location– Services can be accessed through URL therefore change in
location doesn’t affect customer experience
● Scalable– Service-oriented architecture can run on multiple platforms and can
operate various servers within the given environment
● Reusability– The SOA uses its services in multiple applications independently without
disturbing other services
● Easy maintenance– SOA is an independent unit therefore updating becomes easy as
it is a single entity
● Agile– Due to reusable components and services, it helps developers to integrate
and build applications quickly according to requirements and consequently increases
the agility of service-oriented architecture.
Now question is why we shouldn’t did this directly inside the controller?

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As router built with express so it combined with req and res object.So when we put our
business logic inside controller then at the testing we have to write mock for test with
response mock.
The problem is when we try to only test our business logic we can’t do that but when we
combined that inside service we can test that service without req, res object.
Code Example:
In this example we create a service that to resister a user in data base for sign up API.
In user.js controller receive all the request data and call the user service
// controllers/user.js
constUserService=require( "../services/UserService" );
constUserServicesec=newUserService();
asyncfunctionmakeUser ( req, res ) {
try {
letbodyData=req.body;
constmakeUser=awaitUserServicesec.create( bodyData );
returnres.send( makeUser );
} catch( err ) {
res.
status(500 ).
send( err );
}
}
module.exports={ makeUser };
Then in the user service folder import the data access layer and database model then
service used that data access layer and execute query in database
// services/UserService.js
// Data Access Layer
constMongooseService=require( "./MongooseService" );

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constuserModel=require( "../models/user" );
classUserService {
constructor () {
this.MongooseService=newMongooseService(userModel );
}
asynccreate ( createUser ) {
try {
constresult=awaitthis.MongooseService.create( createUser );
return { success:true, body:result };
} catch( err ) {
return { success:false, error: err };
}
}
}
module.exports=UserService;
Conclusion:
The main aim of service-oriented architecture is to allow users to mix large chunks of
functionalities into one in order to build an application and services by combining services.
This architectural design of node backend application is considered as a best practice in
industrial label.