grav

Documentation

Index

• Constants
• Variables
• type ConnectFunc
• type CreateTransportFunc
• type Grav
  • func New() *Grav
  • func NewWithTransport(tsptFunc CreateTransportFunc, opts *TransportOpts) *Grav
  • func (g *Grav) Connect() *Pod
  • func (g *Grav) ConnectEndpoint(endpoint string) error
  • func (g *Grav) Serve() error
• type Message
  • func MsgFromBytes(bytes []byte) (Message, error)
  • func MsgFromRequest(r *http.Request) (Message, error)
  • func NewMsg(msgType string, data []byte) Message
  • func NewMsgResponseTo(msgType, responseTo string, data []byte) Message
  • func NewMsgWithParentID(msgType, parentID string, data []byte) Message
• type MsgChan
• type MsgFunc
• type Pod
  • func (mf Pod) FilterType(msgType string, allow bool)
  • func (mf Pod) FilterUUID(uuid string, allow bool)
  • func (p *Pod) On(onFunc MsgFunc)
  • func (p *Pod) OnType(onFunc MsgFunc, msgTypes ...string)
  • func (p *Pod) Send(msg Message)
  • func (p *Pod) WaitOn(onFunc MsgFunc) error
• type Transport
• type TransportOpts
  • func DefaultTransportOpts() *TransportOpts

Constants

const (
	MsgTypeDefault string = "grav.default"
)

MsgTypeDefault and other represent message consts

Variables

var ErrMsgNotWanted = errors.New("message not wanted")

ErrMsgNotWanted is used by WaitOn to determine if the current message is what's being waited on

var (
	ErrTransportNotConfigured = errors.New("transport plugin not configured")
)

ErrTransportNotConfigured represent package-level vars

Types

type ConnectFunc

type ConnectFunc func() *Pod

ConnectFunc represents a function that returns a pod conntected to Grav

type CreateTransportFunc

type CreateTransportFunc func(*TransportOpts, ConnectFunc) Transport

CreateTransportFunc is a function that returns a transport

type Grav

type Grav struct {
	// contains filtered or unexported fields
}

Grav represents a Grav message bus instance

func New

func New() *Grav

New creates a new Grav instance

func NewWithTransport

func NewWithTransport(tsptFunc CreateTransportFunc, opts *TransportOpts) *Grav

NewWithTransport creates a new Grav with a transport plugin configured

func (*Grav) Connect

func (g *Grav) Connect() *Pod

Connect creates a new connection (pod) to the bus

func (*Grav) ConnectEndpoint

func (g *Grav) ConnectEndpoint(endpoint string) error

ConnectEndpoint uses the configured transport to connect the bus to an external endpoint

func (*Grav) Serve

func (g *Grav) Serve() error

Serve directs the configured transport plugin to serve an endpoint that other nodes can connect to Calling Serve will block, so if the Grav endpoint is meant to run in the background, it should be called on a goroutine. Calling Serve is optional if incoming connections are not needed (or if no transport is being used)

type Message

type Message interface {
	// Unique ID for this message
	UUID() string
	// ID of the parent event or request, such as HTTP request
	ParentID() string
	// The UUID of the message being responded to, if any
	ResponseTo() string
	// Type of message (application-specific)
	Type() string
	// Time the message was sent
	Timestamp() time.Time
	// Raw data of message
	Data() []byte
	// Unmarshal the message's data into a struct
	UnmarshalData(interface{}) error
	// Marshal the message itself to encoded bytes (JSON or otherwise)
	Marshal() ([]byte, error)
	// Unmarshal encoded Message into object
	Unmarshal([]byte) error
}

Message represents a message

func MsgFromBytes

func MsgFromBytes(bytes []byte) (Message, error)

MsgFromBytes returns a default _message that has been unmarshalled from bytes. Should only be used if the default _message type is being used.

func MsgFromRequest

func MsgFromRequest(r *http.Request) (Message, error)

MsgFromRequest extracts an encoded Message from an HTTP request

func NewMsg

func NewMsg(msgType string, data []byte) Message

NewMsg creates a new Message with the built-in `_message` type

func NewMsgResponseTo

func NewMsgResponseTo(msgType, responseTo string, data []byte) Message

NewMsgResponseTo creates a new message in response to a previous message

func NewMsgWithParentID

func NewMsgWithParentID(msgType, parentID string, data []byte) Message

NewMsgWithParentID returns a new message with the provided parent ID

type MsgChan

type MsgChan chan Message

MsgChan is a channel that accepts a message

type MsgFunc

type MsgFunc func(Message) error

MsgFunc is a callback function that accepts a message and returns an error

type Pod

type Pod struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

Pod is a connection to Grav Pods are bi-directional. Messages can be sent to them from the bus, and they can be used to send messages to the bus. Pods are meant to be extremely lightweight with no persistence they are meant to quickly and immediately route a message between its owner and the Bus. The Bus is responsible for any "smarts". Messages coming from the bus are filtered using the pod's messageFilter, which is configurable by the caller.

func (Pod) FilterType

func (mf Pod) FilterType(msgType string, allow bool)

func (Pod) FilterUUID

func (mf Pod) FilterUUID(uuid string, allow bool)

FilterUUID likely should not be used in normal cases, it adds a message UUID to the pod's filter.

func (*Pod) On

func (p *Pod) On(onFunc MsgFunc)

On sets the function to be called whenever this pod recieves a message from the bus. If nil is passed, the pod will ignore all messages. Calling On multiple times causes the function to be overwritten. To recieve using two different functions, create two pods.

func (*Pod) OnType

func (p *Pod) OnType(onFunc MsgFunc, msgTypes ...string)

OnType sets the function to be called whenever this pod recieves a message and sets the pod's filter to only include certain message types

func (*Pod) Send

func (p *Pod) Send(msg Message)

Send emits a message to be routed to the bus

func (*Pod) WaitOn

func (p *Pod) WaitOn(onFunc MsgFunc) error

WaitOn takes a function to be called whenever this pod recieves a message and blocks until that function returns something other than ErrMsgNotWanted. WaitOn should be used if there is a need to wait for a particular message. When the onFunc returns something other than ErrMsgNotWanted (such as nil or a different error), WaitOn will return and set the onFunc to nil. If an error other than ErrMsgNotWanted is returned from the onFunc, it will be propogated to the caller.

type Transport

type Transport interface {
	// Serve is a transport-specific function that exposes a connection point
	Serve() error
	// ConnectEndpoint indicates to the Transport that a connection to a remote endpoint is needed
	ConnectEndpoint(string) error
}

Transport represents a Grav transport plugin

type TransportOpts

type TransportOpts struct {
	// contains filtered or unexported fields
}

TransportOpts is a set of options for transports

func DefaultTransportOpts

func DefaultTransportOpts() *TransportOpts

DefaultTransportOpts returns the default Grav Transport options