DEVELOP.md

LHTTP header filter develop

We know lhttp has some standard headers like subscribe/publish/unsubscribe/upstream ... But if you want to define your own header for example auth, then you need to add your own filter, this document shows you upstream header develop

• Add the header name in lhttpDefine.go

HEADER_KEY_UPSTREAM = "upstream"

• create a file named upstreamFilter.go, add filter module

type upstreamHeadFilter struct {
    *HeadFilterBase
}

Here we need combine HeadFilterBase, so we need't implements all the interface witch we don't need.

• implements filter method

type HeadFilterHandler interface{
  	OnOpenFilterHandler(*WsHandler)      //when open the link, this method been called.
	BeforeRequestFilterHandle(*WsHandler) //before the service module handle, this method been called
	AfterRequestFilterHandle(*WsHandler)  //after the service module handle,this method been called
	OnCloseFilterHandle(*WsHandler)       //close the link, this method been called.
}

for example, after the service handle, upstream module send the message to upstream server, so we implement AfterRequestFilterHandle interface.

func (*upstreamHeadFilter) AfterRequestFilterHandle(ws *WsHandler) {
	var value string
	if value = ws.GetHeader(HEADER_KEY_UPSTREAM); value == "" {
		log.Print("no upstream header found:", ws.message.message, ws.message.headers)
		return
	}
    //....
    //send message to upstream server
}

• Regist upstream filter in headerFilter.go

	RegistHeadFilter(&upstreamHeadFilter{})