client

Documentation

Overview

Package client provides a method to make synchronous, asynchronous and streaming requests to services. By default json and protobuf codecs are supported.

import "github.com/micro/go-micro/client"

c := client.NewClient()

req := c.NewRequest("go.micro.srv.greeter", "Greeter.Hello", &greeter.Request{
	Name: "John",
})

rsp := &greeter.Response{}

if err := c.Call(context.Background(), req, rsp); err != nil {
	return err
}

fmt.Println(rsp.Msg)

Index

• Variables
• func Call(ctx context.Context, request Request, response interface{}, opts ...CallOption) error
• func CallRemote(ctx context.Context, address string, request Request, response interface{}, ...) error
• func NewContext(ctx context.Context, c Client) context.Context
• func Publish(ctx context.Context, p Publication) error
• func String() string
• type BackoffFunc
• type CallOption
  • func WithBackoff(fn BackoffFunc) CallOption
  • func WithDialTimeout(d time.Duration) CallOption
  • func WithRequestTimeout(d time.Duration) CallOption
  • func WithRetries(i int) CallOption
  • func WithSelectOption(so ...selector.SelectOption) CallOption
• type CallOptions
• type Client
  • func FromContext(ctx context.Context) (Client, bool)
  • func NewClient(opt ...Option) Client
• type Option
  • func Backoff(fn BackoffFunc) Option
  • func Broker(b broker.Broker) Option
  • func Codec(contentType string, c codec.NewCodec) Option
  • func ContentType(ct string) Option
  • func DialTimeout(d time.Duration) Option
  • func Registry(r registry.Registry) Option
  • func RequestTimeout(d time.Duration) Option
  • func Retries(i int) Option
  • func Selector(s selector.Selector) Option
  • func Transport(t transport.Transport) Option
  • func Wrap(w Wrapper) Option
• type Options
• type Publication
  • func NewPublication(topic string, message interface{}) Publication
• type PublishOption
• type PublishOptions
• type Request
  • func NewJsonRequest(service, method string, request interface{}, reqOpts ...RequestOption) Request
  • func NewProtoRequest(service, method string, request interface{}, reqOpts ...RequestOption) Request
  • func NewRequest(service, method string, request interface{}, reqOpts ...RequestOption) Request
• type RequestOption
  • func StreamingRequest() RequestOption
• type RequestOptions
• type StreamWrapper
• type Streamer
  • func Stream(ctx context.Context, request Request, opts ...CallOption) (Streamer, error)
  • func StreamRemote(ctx context.Context, address string, request Request, opts ...CallOption) (Streamer, error)
• type Wrapper

Variables

var (
	// DefaultClient is a default client to use out of the box
	DefaultClient Client = newRpcClient()

	// DefaultBackoff is the default backoff function for retries
	DefaultBackoff = exponentialBackoff

	// DefaultRetries is the default number of times a request is tried
	DefaultRetries = 1
	// DefaultRequestTimeout is the default request timeout
	DefaultRequestTimeout = time.Second * 5
)

Functions

func Call

func Call(ctx context.Context, request Request, response interface{}, opts ...CallOption) error

Makes a synchronous call to a service using the default client

func CallRemote

func CallRemote(ctx context.Context, address string, request Request, response interface{}, opts ...CallOption) error

Makes a synchronous call to the specified address using the default client

func NewContext

func NewContext(ctx context.Context, c Client) context.Context

func Publish

func Publish(ctx context.Context, p Publication) error

Publishes a publication using the default client. Using the underlying broker set within the options.

func String

func String() string

Types

type BackoffFunc

type BackoffFunc func(ctx context.Context, req Request, attempts int) (time.Duration, error)

type CallOption

type CallOption func(*CallOptions)

CallOption used by Call or Stream

func WithBackoff

func WithBackoff(fn BackoffFunc) CallOption

WithBackoff is a CallOption which overrides that which set in Options.CallOptions

func WithDialTimeout

func WithDialTimeout(d time.Duration) CallOption

WithDialTimeout is a CallOption which overrides that which set in Options.CallOptions

func WithRequestTimeout

func WithRequestTimeout(d time.Duration) CallOption

WithRequestTimeout is a CallOption which overrides that which set in Options.CallOptions

func WithRetries

func WithRetries(i int) CallOption

WithRetries is a CallOption which overrides that which set in Options.CallOptions

func WithSelectOption

func WithSelectOption(so ...selector.SelectOption) CallOption

type CallOptions

type CallOptions struct {
	SelectOptions []selector.SelectOption

	// Backoff func
	Backoff BackoffFunc
	// Transport Dial Timeout
	DialTimeout time.Duration
	// Number of Call attempts
	Retries int
	// Request/Response timeout
	RequestTimeout time.Duration

	// Other options for implementations of the interface
	// can be stored in a context
	Context context.Context
}

type Client

type Client interface {
	Init(...Option) error
	Options() Options
	NewPublication(topic string, msg interface{}) Publication
	NewRequest(service, method string, req interface{}, reqOpts ...RequestOption) Request
	NewProtoRequest(service, method string, req interface{}, reqOpts ...RequestOption) Request
	NewJsonRequest(service, method string, req interface{}, reqOpts ...RequestOption) Request
	Call(ctx context.Context, req Request, rsp interface{}, opts ...CallOption) error
	CallRemote(ctx context.Context, addr string, req Request, rsp interface{}, opts ...CallOption) error
	Stream(ctx context.Context, req Request, opts ...CallOption) (Streamer, error)
	StreamRemote(ctx context.Context, addr string, req Request, opts ...CallOption) (Streamer, error)
	Publish(ctx context.Context, p Publication, opts ...PublishOption) error
	String() string
}

Client is the interface used to make requests to services. It supports Request/Response via Transport and Publishing via the Broker. It also supports bidiectional streaming of requests.

func FromContext

func FromContext(ctx context.Context) (Client, bool)

func NewClient

func NewClient(opt ...Option) Client

Creates a new client with the options passed in

type Option

type Option func(*Options)

Option used by the Client

func Backoff

func Backoff(fn BackoffFunc) Option

Backoff is used to set the backoff function used when retrying Calls

func Broker

func Broker(b broker.Broker) Option

Broker to be used for pub/sub

func Codec

func Codec(contentType string, c codec.NewCodec) Option

Codec to be used to encode/decode requests for a given content type

func ContentType

func ContentType(ct string) Option

Default content type of the client

func DialTimeout

func DialTimeout(d time.Duration) Option

Transport dial timeout

func Registry

func Registry(r registry.Registry) Option

Registry to find nodes for a given service

func RequestTimeout

func RequestTimeout(d time.Duration) Option

The request timeout. Should this be a Call Option?

func Retries

func Retries(i int) Option

Number of retries when making the request. Should this be a Call Option?

func Selector

func Selector(s selector.Selector) Option

Select is used to select a node to route a request to

func Transport

func Transport(t transport.Transport) Option

Transport to use for communication e.g http, rabbitmq, etc

func Wrap

func Wrap(w Wrapper) Option

Adds a Wrapper to a list of options passed into the client

type Options

type Options struct {
	// Used to select codec
	ContentType string

	// Plugged interfaces
	Broker    broker.Broker
	Codecs    map[string]codec.NewCodec
	Registry  registry.Registry
	Selector  selector.Selector
	Transport transport.Transport

	// Middleware for client
	Wrappers []Wrapper

	// Default Call Options
	CallOptions CallOptions

	// Other options for implementations of the interface
	// can be stored in a context
	Context context.Context
}

type Publication

type Publication interface {
	Topic() string
	Message() interface{}
	ContentType() string
}

Publication is the interface for a message published asynchronously

func NewPublication

func NewPublication(topic string, message interface{}) Publication

Creates a new publication using the default client

type PublishOption

type PublishOption func(*PublishOptions)

PublishOption used by Publish

type PublishOptions

type PublishOptions struct {
	// Other options for implementations of the interface
	// can be stored in a context
	Context context.Context
}

type Request

type Request interface {
	Service() string
	Method() string
	ContentType() string
	Request() interface{}
	// indicates whether the request will be a streaming one rather than unary
	Stream() bool
}

Request is the interface for a synchronous request used by Call or Stream

func NewJsonRequest

func NewJsonRequest(service, method string, request interface{}, reqOpts ...RequestOption) Request

Creates a new json request using the default client

func NewProtoRequest

func NewProtoRequest(service, method string, request interface{}, reqOpts ...RequestOption) Request

Creates a new protobuf request using the default client

func NewRequest

func NewRequest(service, method string, request interface{}, reqOpts ...RequestOption) Request

Creates a new request using the default client. Content Type will be set to the default within options and use the appropriate codec

type RequestOption

type RequestOption func(*RequestOptions)

RequestOption used by NewRequest

func StreamingRequest

func StreamingRequest() RequestOption

type RequestOptions

type RequestOptions struct {
	Stream bool

	// Other options for implementations of the interface
	// can be stored in a context
	Context context.Context
}

type StreamWrapper

type StreamWrapper func(Streamer) Streamer

StreamWrapper wraps a Stream and returns the equivalent

type Streamer

type Streamer interface {
	Context() context.Context
	Request() Request
	Send(interface{}) error
	Recv(interface{}) error
	Error() error
	Close() error
}

Streamer is the inteface for a bidirectional synchronous stream

func Stream

func Stream(ctx context.Context, request Request, opts ...CallOption) (Streamer, error)

Creates a streaming connection with a service and returns responses on the channel passed in. It's up to the user to close the streamer.

func StreamRemote

func StreamRemote(ctx context.Context, address string, request Request, opts ...CallOption) (Streamer, error)

Creates a streaming connection to the address specified.

type Wrapper

type Wrapper func(Client) Client

Wrapper wraps a client and returns a client