micro-employees.slide

Micro Employees

Brian Ketelsen
me@brianketelsen.com
@bketelsen

* Micro Employees

* Your first service

Employee Service

For our first micro service, let's put together the everything from the previous lectures on Go and sqlx and build an Employee service.

We'll keep it simple and only access the employees table in this service.

* Requirements

Our employee service should look like a real-world microservice. Its primary concern will be providing access to the employee information in the database.

* Get an employee

Plan of Action

We'll start by creating our proto definition. The proto file defines the RPC methods and the messages for each RPC request and response.

* employees.proto

Proto Definition

If we look at the proto definition from the example service in Go micro we have a pretty good starting point for our own service definition. Let's review it again:

syntax = "proto3";
service Greeter {
rpc Hello(HelloRequest) returns (HelloResponse) {}
}
message HelloRequest {
string name = 1;
}
message HelloResponse {
string greeting = 2;
}

* Service

The proto file defines one Service called "Greeter".

The Greeter service defines one RPC method called Hello.

The Hello RPC method accepts a HelloRequest and returns a HelloResponse.

The HelloRequest and HelloResponse messages are defined at the bottom of the file. Each of them has one field which is a string.

* Employee Proto

Let's use this example to build our proto definition for the employee microservice.

Here's what we can deduce from our requirements:

syntax = "proto3";
service Employees {
    rpc Get(GetRequest) returns (GetResponse) {}
}

* Creating Common Messages

Let's start by creating a message called Employee that matches the table in the database.


message Employee {
	int64 emp_no = 1;        
        string first_name = 2;
        string last_name = 3;
        enum Gender {
	        MALE = 0;
                FEMALE = 1;
        }
        int64 birth_date= 4;    
        int64 hire_date= 5;    
}

* Request/Response Messages

Now it will be easy to create Request/Response messages for each of RPC calls we've defined.

message GetRequest {
	int64 emp_no = 1;
}
message GetResponse {
	Employee employee = 1;
}

That was pretty easy. Now it's time to use the protoc generator to generate the Go implementation of this service definition.

* Generate Go Code From Proto

Running protoc

We need to run the protoc compiler and tell it that we'll be using the "micro" plugin.

Make sure you've got the micro plugin installed:

$ go get github.com/micro/protobuf/{proto,protoc-gen-go}

protoc -I$GOPATH/src --go_out=plugins=micro:$GOPATH/src $GOPATH/src/github.com/bketelsen/micro-employees/proto/employees.proto

* Exercise

	go get github.com/bketelsen/micro-employees

	Finish the micro service.

- Use the sqlx package to retrieve the employee in the `db` package
- Modify the handler to call the db package