Documentation
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Overview ¶
Package routing provides pipeline stages for routing messages to endpoints and within endpoints.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type Dispatcher ¶
type Dispatcher struct {
Routes HandlerTable
Logger twelf.Logger
// contains filtered or unexported fields
}
Dispatcher is an inbound pipeline stage that routes messages to the appropriate MessageHandler instances according to a "handler table".
func (*Dispatcher) Accept ¶
func (d *Dispatcher) Accept(ctx context.Context, s endpoint.MessageSink, env endpoint.InboundEnvelope) error
Accept dispatches env to zero or more message handlers as per the dispatch table.
The context passed to each handler contains the message envelope, such that any messages sent using s within that context are configured as children of env.
Each message handler is invoked on its own goroutine.
func (*Dispatcher) Initialize ¶
Initialize is called during initialization of the endpoint, after the transport is initialized. It can be used to inspect or further configure the endpoint as per the needs of the pipeline.
type EndpointTable ¶
type EndpointTable []route
EndpointTable is set of rules that determine the destination endpoint for unicast messages.
func NewEndpointTable ¶
func NewEndpointTable(r ...string) (EndpointTable, error)
NewEndpointTable returns an endpoint table that choses a destination endpoint based on a mapping of protocol buffers message name to endpoint name.
r is a sequence of key/value pairs that form the routing rules. The keys may be a fully-qualified protocol buffers message name, or a protocol buffers package name. The corresponding value is the endpoint name that such messages are routed to.
func (EndpointTable) Lookup ¶
func (t EndpointTable) Lookup(mt ax.MessageType) (ep string, ok bool)
Lookup returns the endpoint that messages of type mt are routed to.
Routes are chosen based on the longest match, hence an exact match to the message type is favored, then the longest matching package name, and finally the empty string, which becomes the default route.
If there is no default route and mt is a top-level message, that is, a message with no package name, then ok is false, indicating no route could be found.
type HandlerTable ¶
type HandlerTable map[ax.MessageType][]MessageHandler
HandlerTable is a set of rules that determines which handlers receive a message of a specific type.
func NewHandlerTable ¶
func NewHandlerTable(handlers ...MessageHandler) (HandlerTable, error)
NewHandlerTable returns a handler table that locates message handlers based on the message types that they handle.
func (HandlerTable) Lookup ¶
func (ht HandlerTable) Lookup(mt ax.MessageType) []MessageHandler
Lookup returns the message handlers that handle mt.
type MessageHandler ¶
type MessageHandler interface {
// MessageTypes returns the set of messages that the handler intends
// to handle.
//
// The return value should be constant as it may be cached by various
// independent stages in the message pipeline.
MessageTypes() ax.MessageTypeSet
// HandleMessage invokes application-defined logic that handles a
// message.
//
// It may panic if env.Message is not one of the types described by
// MessageTypes().
HandleMessage(ctx context.Context, s ax.Sender, mctx ax.MessageContext) error
}
MessageHandler is an interface for application-defined message handlers.
Message handlers are typically the last stage in the inbound message pipeline. Each message handler declares its interest in a specific set of message types and is notified when any matching message arrives.
func NewMessageHandler ¶
func NewMessageHandler(v interface{}) MessageHandler
NewMessageHandler returns a new message handler that dispatches messages to methods on an arbitrary value.
For each message type to be handled, the value must implement a "handler" method that adheres to one of the following signatures:
func (msg *<T>) func (msg *<T>, mctx ax.MessageContext) func (ctx context.Context, s ax.Sender, msg *<T>) error func (ctx context.Context, s ax.Sender, msg *<T>, mctx ax.MessageContext) error
Where T is a struct type that implements ax.Message.
The names of handler methods are not meaningful. By convention the methods are named the same as the message they accept, such as:
func (*BankAccount) CreditAccount(*messages.CreditAccount)
type Router ¶
type Router struct {
// Routes is the table used to determine the destination endpoint.
Routes EndpointTable
// Next is the next stage in the pipeline.
Next endpoint.OutboundPipeline
// contains filtered or unexported fields
}
Router is an outbound pipeline stage that choses a destination endpoint for unicast messages based on the message type.
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