New: gRPC MVC features, new WithLowercaseRouting option and add some new context methods

read HISTORY.md


Former-commit-id: 30a16cceb11f754aa32923058abeda1e736350e7

mvc/grpc.go

@@ -0,0 +1,66 @@
+package mvc
+
+import (
+	"net/http"
+	"path"
+
+	"github.com/kataras/iris/v12/context"
+)
+
+// GRPC registers a controller which serves gRPC clients.
+// It accepts the controller ptr to a struct value,
+// the gRPCServer itself, and a strict option which is explained below.
+//
+// The differences by a common controller are:
+// HTTP verb: only POST (Party.AllowMethods can be used for more),
+// method parsing is disabled: path is the function name as it is,
+// if 'strictMode' option is true then this controller will only serve gRPC-based clients
+// and fires 404 on common HTTP clients,
+// otherwise HTTP clients can send and receive JSON (protos contain json struct fields by-default).
+type GRPC struct {
+	// Server is required and should be gRPC Server derives from google's grpc package.
+	Server http.Handler
+	// ServiceName is required and should be the name of the service (used to build the gRPC route path),
+	// e.g. "helloworld.Greeter".
+	// For a controller's method of "SayHello" and ServiceName "helloworld.Greeter",
+	// both gRPC and common HTTP request path is: "/helloworld.Greeter/SayHello".
+	//
+	// Tip: the ServiceName can be fetched through proto's file descriptor, e.g.
+	// serviceName := pb.File_helloworld_proto.Services().Get(0).FullName().
+	ServiceName string
+
+	// When Strict option is true then this controller will only serve gRPC-based clients
+	// and fires 404 on common HTTP clients.
+	Strict bool
+}
+
+// Apply parses the controller's methods and registers gRPC handlers to the application.
+func (g GRPC) Apply(c *ControllerActivator) {
+	defer c.Activated()
+
+	pre := func(ctx context.Context) {
+		if ctx.IsGRPC() { // gRPC, consumes and produces protobuf.
+			g.Server.ServeHTTP(ctx.ResponseWriter(), ctx.Request())
+			ctx.StopExecution()
+			return
+		}
+
+		if g.Strict {
+			ctx.NotFound()
+		} else {
+			// Allow common HTTP clients, consumes and produces JSON.
+			ctx.Next()
+		}
+	}
+
+	for i := 0; i < c.Type.NumMethod(); i++ {
+		m := c.Type.Method(i)
+		path := path.Join(g.ServiceName, m.Name)
+		if route := c.Handle(http.MethodPost, path, m.Name, pre); route != nil {
+			route.Description = "gRPC"
+			if g.Strict {
+				route.Description = "-only"
+			}
+		}
+	}
+}