README
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Eventsource 
Package eventsource provides an implementation to Server-sent events using goroutines to handle client (un)subscription and forwarding events to clients.
For more information about Eventsource / SSE check the MDN documentation
Documentation
For an example of a server sending and receiving messages check: Replay Poker Eventsource
Documentation
¶
Overview ¶
Package eventsource provides an implementation to Server-sent events using goroutines to handle client (un)subscription and forward events to clients. For more information about Eventsource / SSE check the MDN documentation: https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events
Index ¶
Constants ¶
const (
// HTTP HEADER sent to browser to upgrade the protocol to event-stream
HEADER = `HTTP/1.1 200 OK
Content-Type: text/event-stream
Cache-Control: no-cache
Connection: keep-alive`
)
Variables ¶
var HijackingError = "webserver doesn't support hijacking"
A HijackingError is displayed when the browser doesn't support connection hijacking. See http://golang.org/pkg/net/http/#Hijacker
Functions ¶
This section is empty.
Types ¶
type ChannelSubscriber ¶
ChannelSubscriber interface is used to determine which channels a client has subscribed to. This package has two built-in implementations: NoChannels and QueryStringChannels, but you can implement your own.
type DefaultEvent ¶
DefaultEvent implements the Event interface
func (DefaultEvent) Bytes ¶
func (e DefaultEvent) Bytes() []byte
Bytes returns the text/stream message to be sent to the client. If the event has name, it is added first, then the data. Optionally, the data can be compressed using zlib.
func (DefaultEvent) Clients ¶
func (e DefaultEvent) Clients(clients []client) []client
Clients selects clients that have at least one channel in common with the event or all clients if the event has no channel.
type DefaultHttpOptions ¶
type DefaultHttpOptions struct {
// Cors sets if the server has Cross-Origin Resource Sharing enabled
Cors bool
// Internet Explorer < 10 and Chrome < 13 needs a message padding to successfully establish a
// text stream connection See
//http://blogs.msdn.com/b/ieinternals/archive/2010/04/06/comet-streaming-in-internet-explorer-with-xmlhttprequest-and-xdomainrequest.aspx
OldBrowserSupport bool
// Retry is the amout of time in milliseconds that the client must retry a
// reconnection
Retry int
}
type DefaultMetrics ¶
type DefaultMetrics struct{}
DefaultMetrics implements the Metrics interface and logs events to the stdout.
func (DefaultMetrics) ClientCount ¶
func (DefaultMetrics) ClientCount(int)
ClientCount does nothing.
type Event ¶
type Event interface {
// Bytes returns the data to be written on the clients connection
Bytes() []byte
// Clients receives a list of clients and return a filtered list.
Clients([]client) []client
}
Event is an interface that defines what the event payload is and to which connections it must be sent
type Eventsource ¶
type Eventsource struct {
// Interface that implements how channels are assigned to clients. It
// defaults to NoChannels, meaning all events must be global.
ChannelSubscriber
// Interface that implements what options are sent during the initial http
// handshaking. See DefaultHttpOptions for built-in options.
HttpOptions
// Interface that implements basic metrics for events
Metrics
// contains filtered or unexported fields
}
An Eventsource is a high-level server abstraction. It can be used as a Handler for a http route and to send events to clients. Multiple servers can coexist and be used on more than one end-point.
func (*Eventsource) Errors ¶
func (es *Eventsource) Errors() chan error
func (*Eventsource) Send ¶
func (es *Eventsource) Send(event Event)
Send forwards an event to clients
func (*Eventsource) ServeHTTP ¶
func (es *Eventsource) ServeHTTP(res http.ResponseWriter, req *http.Request)
ServeHTTP implements the http handle interface. If the connection supports hijacking, it sends an initial header and body to switch to the text/stream protocol and start streaming.
func (*Eventsource) Start ¶
func (es *Eventsource) Start()
Start sets all undefined options to their defaults and configure the underlining server to start listening to events
type HttpOptions ¶
type NoChannels ¶
type NoChannels struct{}
NoChannels implements the ChannelSubscriber interface by always returning an empty list of channels. This is useful for implementing an eventsource with global messages only.
func (NoChannels) ParseRequest ¶
func (n NoChannels) ParseRequest(req *http.Request) []string
ParseRequest returns an empty list of channels.
type NoopMetrics ¶
type NoopMetrics struct{}
NoopMetrics implements the Metrics interface and does nothing. Useful for disable metrics.
type QueryStringChannels ¶
type QueryStringChannels struct {
Name string
}
QueryStringChannels implements the ChannelSubscriber interface by parsing the request querystring and extracting channels separated by commas. Eg.: /?channels=a,b,c
func (QueryStringChannels) ParseRequest ¶
func (n QueryStringChannels) ParseRequest(req *http.Request) []string
ParseRequest parses the querystring and extracts the Name params, spliting it by commas.
Source Files