Setup
Install grpc-tools and google-protobuf as node module
Folder structure will be as below:
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Let’s create a dummy proto file
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Its time to generate the code from the proto file. Let’s use the command that we have used in our previous blog of Protocol Buffers.
GRPC_TOOLS_PLUGIN="$HOME/AppData/Roaming/npm/grpc_tools_node_protoc_plugin.cmd" && C:/Users/deepak.sood/Downloads/protoc-3.13.0-win64/bin/protoc.exe -I=. ./proto/*.proto --js_out=import_style=commonjs,binary:./server --grpc_out=./server --plugin=protoc-gen-grpc=$GRPC_TOOLS_PLUGIN
#I ran this command on gitbash
This command will generate the below files:
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Server Setup
It’s time to setup a gRPC server with no service on it and we will start out server on a specific node.
Let’s create an index.js inside the server. But before that install grpc module
npm install grpc
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Our server is up and running on the defined port now.
Client Setup
In this we will connect our client to the server and will start our client on a specific port.
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Unary API
- Unary RPC calls are the basic Request/Response that everyone is familiar with
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- The client will send one message to the server and will receive one response from the server
- Unary RPC calls are the most commonly used API calls
– They are suited when the data is small - In gRPC Unary calls are defined using Protocol Buffers
- For each RPC call we have to define a “Request” message and a “Response” message
Let’s create a “Unary” Greet API in which:
- Our message is Greeting and contains firstname and lastname string field
- It will take a GreetRequest that contains a Greeting
- It will return a GreetResponse that contains a result string
Step 1 – Creating our proto
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Step 2 – Generating code from the proto file
GRPC_TOOLS_PLUGIN="$HOME/AppData/Roaming/npm/grpc_tools_node_protoc_plugin.cmd" && C:/Users/deepak.sood/Downloads/protoc-3.13.0-win64/bin/protoc.exe -I=. ./protos/greet.proto --js_out=import_style=commonjs,binary:./server --grpc_out=./server --plugin=protoc-gen-grpc=$GRPC_TOOLS_PLUGIN
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Step 3 – Server Implementation
In this:
- We will implement a Unary Greet RPC
- We will hook our new GreetService to our Server
- We will start our server
We would require the files generated in the implementation of our server. Therefore, we will import those files in the server file.
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We are not done yet, we need to add the service now.
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Along with this we need to pass few other things for it to work i.e the RPC methods that we will be calling.
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var greets = require('../server/protos/greet_pb');
var service = require('../server/protos/greet_grpc_pb');
var grpc = require('grpc');
/*
Implementing the greet RPC method
*/
// this should be the same name as our API as present in greet_grpc_pb file
function greet(call, callback){
// creating the actual greeting response
var greeting = new greets.GreetResponse();
//now we have our greet response, so let's now construct the response
// call is used as it will have all the information from line 11 when called
//getGreeting is from the GreetRequest object
greeting.setResult(
"Hello" + call.getGreeting().getFirstName()
)
callback(null, greeting); // passed in the greeting to be passed on to the client
}
function main(){
var server = new grpc.Server();
server.addService(service.GreetServiceService, {greet: greet})
server.bind("127.0.0.1:50051", grpc.ServerCredentials.createInsecure());
server.start();
console.log("Server running on port 127.0.0.1:50051")
}
main();var greets = require('../server/protos/greet_pb');
var service = require('../server/protos/greet_grpc_pb');
var grpc = require('grpc');
/*
Implementing the greet RPC method
*/
// this should be the same name as our API as present in greet_grpc_pb file
function greet(call, callback){
// creating the actual greeting response
var greeting = new greets.GreetResponse();
//now we have our greet response, so let's now construct the response
// call is used as it will have all the information from line 11 when called
//getGreeting is from the GreetRequest object
greeting.setResult(
"Hello" + call.request.getGreeting().getFirstName()
)
callback(null, greeting); // passed in the greeting to be passed on to the client
}
function main(){
var server = new grpc.Server();
server.addService(service.GreetServiceService, {greet: greet})
server.bind("127.0.0.1:50051", grpc.ServerCredentials.createInsecure());
server.start();
console.log("Server running on port 127.0.0.1:50051")
}
main();var greets = require('../server/protos/greet_pb');
var service = require('../server/protos/greet_grpc_pb');
var grpc = require('grpc');
/*
Implementing the greet RPC method
*/
// this should be the same name as our API as present in greet_grpc_pb file
function greet(call, callback){
// creating the actual greeting response
var greeting = new greets.GreetResponse();
//now we have our greet response, so let's now construct the response
// call is used as it will have all the information from line 11 when called
//getGreeting is from the GreetRequest object
greeting.setResult(
"Hello" + call.getGreeting().getFirstName()
)
callback(null, greeting); // passed in the greeting to be passed on to the client
}
function main(){
var server = new grpc.Server();
server.addService(service.GreetServiceService, {greet: greet})
server.bind("127.0.0.1:50051", grpc.ServerCredentials.createInsecure());
server.start();
console.log("Server running on port 127.0.0.1:50051")
}
main();
Let’s test this now:
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Step 4 – Client Implementation
We will test our client against the server running.
Let’s import the files as we did in server implementation.
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The second step would be to create a greet request.
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var grpc = require('grpc');
var greets = require('../server/protos/greet_pb');
var service = require('../server/protos/greet_grpc_pb');
function main(){
console.log('Hello from Client');
var client = new service.GreetServiceClient(
'localhost:50051',
grpc.credentials.createInsecure()
)
console.log('client', client)
// we code here later
var request = new greets.GreetRequest();
//creating the actual greeting as we did for protobuf in previous blog
//refer line 15 of proto file
//created a protocol buffer greeting message
var greeting = new greets.Greeting();
greeting.setFirstName("Deepak")
greeting.setLastName("Sood")
//set the greeting
request.setGreeting(greeting);
//setting up the client now and calling the greet from the server which knows what should be the request and response
client.greet(request, (error, response)=>{
if(!error){
console.log("Greeting response: "+ response.getResult());
}else{
console.error(error)
}
})
}
main()
It’s time to run our server and client.
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Let’s see what happens when we stop our server
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