endpoint

package
v0.7.0 Latest Latest
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Published: Mar 19, 2018 License: MIT Imports: 1 Imported by: 0

Documentation

Overview

Package endpoint defines an abstraction for RPCs.

Endpoints are a fundamental building block for many Go kit components. Endpoints are implemented by servers, and called by clients.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func Nop

func Nop(context.Context, interface{}) (interface{}, error)

Nop is an endpoint that does nothing and returns a nil error. Useful for tests.

Types

type Endpoint

type Endpoint func(ctx context.Context, request interface{}) (response interface{}, err error)

Endpoint is the fundamental building block of servers and clients. It represents a single RPC method.

type Middleware

type Middleware func(Endpoint) Endpoint

Middleware is a chainable behavior modifier for endpoints.

func Chain

func Chain(outer Middleware, others ...Middleware) Middleware

Chain is a helper function for composing middlewares. Requests will traverse them in the order they're declared. That is, the first middleware is treated as the outermost middleware.

Example
package main

import (
	"context"
	"fmt"

	"github.com/go-kit/kit/endpoint"
)

func main() {
	e := endpoint.Chain(
		annotate("first"),
		annotate("second"),
		annotate("third"),
	)(myEndpoint)

	if _, err := e(ctx, req); err != nil {
		panic(err)
	}

}

var (
	ctx = context.Background()
	req = struct{}{}
)

func annotate(s string) endpoint.Middleware {
	return func(next endpoint.Endpoint) endpoint.Endpoint {
		return func(ctx context.Context, request interface{}) (interface{}, error) {
			fmt.Println(s, "pre")
			defer fmt.Println(s, "post")
			return next(ctx, request)
		}
	}
}

func myEndpoint(context.Context, interface{}) (interface{}, error) {
	fmt.Println("my endpoint!")
	return struct{}{}, nil
}
Output:

first pre
second pre
third pre
my endpoint!
third post
second post
first post

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