micro/client/client.go
2018-04-17 11:00:22 +01:00

115 lines
3.6 KiB
Go

// Package client is an interface for an RPC client
package client
import (
"context"
"time"
)
// 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.
type Client interface {
Init(...Option) error
Options() Options
NewMessage(topic string, msg interface{}) Message
NewRequest(service, method string, req interface{}, reqOpts ...RequestOption) Request
Call(ctx context.Context, req Request, rsp interface{}, opts ...CallOption) error
Stream(ctx context.Context, req Request, opts ...CallOption) (Stream, error)
Publish(ctx context.Context, msg Message, opts ...PublishOption) error
String() string
}
// Message is the interface for publishing asynchronously
type Message interface {
Topic() string
Payload() interface{}
ContentType() string
}
// Request is the interface for a synchronous request used by Call or Stream
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
}
// Stream is the inteface for a bidirectional synchronous stream
type Stream interface {
Context() context.Context
Request() Request
Send(interface{}) error
Recv(interface{}) error
Error() error
Close() error
}
// Option used by the Client
type Option func(*Options)
// CallOption used by Call or Stream
type CallOption func(*CallOptions)
// PublishOption used by Publish
type PublishOption func(*PublishOptions)
// RequestOption used by NewRequest
type RequestOption func(*RequestOptions)
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
// DefaultRetry is the default check-for-retry function for retries
DefaultRetry = alwaysRetry
// DefaultRetries is the default number of times a request is tried
DefaultRetries = 1
// DefaultRequestTimeout is the default request timeout
DefaultRequestTimeout = time.Second * 5
// DefaultPoolSize sets the connection pool size
DefaultPoolSize = 0
// DefaultPoolTTL sets the connection pool ttl
DefaultPoolTTL = time.Minute
)
// Makes a synchronous call to a service using the default client
func Call(ctx context.Context, request Request, response interface{}, opts ...CallOption) error {
return DefaultClient.Call(ctx, request, response, opts...)
}
// Publishes a publication using the default client. Using the underlying broker
// set within the options.
func Publish(ctx context.Context, msg Message) error {
return DefaultClient.Publish(ctx, msg)
}
// Creates a new message using the default client
func NewMessage(topic string, payload interface{}) Message {
return DefaultClient.NewMessage(topic, payload)
}
// Creates a new client with the options passed in
func NewClient(opt ...Option) Client {
return newRpcClient(opt...)
}
// Creates a new request using the default client. Content Type will
// be set to the default within options and use the appropriate codec
func NewRequest(service, method string, request interface{}, reqOpts ...RequestOption) Request {
return DefaultClient.NewRequest(service, method, request, reqOpts...)
}
// 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 NewStream(ctx context.Context, request Request, opts ...CallOption) (Stream, error) {
return DefaultClient.Stream(ctx, request, opts...)
}
func String() string {
return DefaultClient.String()
}