broker: refactor (#396)

* remove subscribe from server
* remove publish from client
* broker package refactoring

Co-authored-by: vtolstov <vtolstov@users.noreply.github.com>
Reviewed-on: #396
Co-authored-by: Vasiliy Tolstov <v.tolstov@unistack.org>
Co-committed-by: Vasiliy Tolstov <v.tolstov@unistack.org>

metadata/headers.go

@@ -0,0 +1,19 @@
+// Package metadata is a way of defining message headers
+package metadata
+
+var (
+	// HeaderTopic is the header name that contains topic name
+	HeaderTopic = "Micro-Topic"
+	// HeaderContentType specifies content type of message
+	HeaderContentType = "Content-Type"
+	// HeaderEndpoint specifies endpoint in service
+	HeaderEndpoint = "Micro-Endpoint"
+	// HeaderService specifies service
+	HeaderService = "Micro-Service"
+	// HeaderTimeout specifies timeout of operation
+	HeaderTimeout = "Micro-Timeout"
+	// HeaderAuthorization specifies Authorization header
+	HeaderAuthorization = "Authorization"
+	// HeaderXRequestID specifies request id
+	HeaderXRequestID = "X-Request-Id"
+)