README.md

@@ -107,12 +107,17 @@ func main() {
         log.Fatalf("invalid config: %s", err)
     }
 
+    // add http middlewares (logger)
+    builder.With(func(next http.Handler) http.Handler{ /* ... */ })
+
+    // add contextual middlewares (authentication)
+    builder.WithContext(func(next http.Handler) http.Handler{ /* ... */ })
+
     // bind handlers
     err = builder.Bind(http.MethodGet, "/user/{id}", getUserById)
     if err != nil {
         log.Fatalf("cannog bind GET /user/{id}: %s", err)
     }
-    // ...
 
     // build your services
     handler, err := builder.Build()
@@ -261,7 +266,7 @@ type res struct{
     Output2 bool
 }
 
-func myHandler(r req) (*res, api.Err) {
+func myHandler(ctx context.Context, r req) (*res, api.Err) {
     err := doSomething()
     if err != nil {
         return nil, api.ErrFailure

api/adapter.go

@@ -1,13 +0,0 @@
-package api
-
-import "net/http"
-
-// Adapter to encapsulate incoming requests
-type Adapter func(http.HandlerFunc) http.HandlerFunc
-
-// AuthHandlerFunc is http.HandlerFunc with additional Authorization information
-type AuthHandlerFunc func(Auth, http.ResponseWriter, *http.Request)
-
-// AuthAdapter to encapsulate incoming request with access to api.Auth
-// to manage permissions
-type AuthAdapter func(AuthHandlerFunc) AuthHandlerFunc

api/auth.go

@@ -21,7 +21,7 @@ type Auth struct {
 
 // Granted returns whether the authorization is granted
 // i.e. Auth.Active fulfills Auth.Required
-func (a Auth) Granted() bool {
+func (a *Auth) Granted() bool {
 	var nothingRequired = true
 
 	// first dimension: OR ; at least one is valid
@@ -43,7 +43,7 @@ func (a Auth) Granted() bool {
 }
 
 // returns whether Auth.Active fulfills (contains) all @required roles
-func (a Auth) fulfills(required []string) bool {
+func (a *Auth) fulfills(required []string) bool {
 	for _, requiredRole := range required {
 		var found = false
 		for _, activeRole := range a.Active {

api/context.go

@@ -1,17 +1,44 @@
 package api
 
 import (
+	"context"
 	"net/http"
+
+	"git.xdrm.io/go/aicra/internal/ctx"
 )
 
-// Ctx contains additional information for handlers
+// GetRequest extracts the current request from a context.Context
-//
+func GetRequest(c context.Context) *http.Request {
-// usually input/output arguments built by aicra are sufficient
+	var (
-// but the Ctx lets you manage your request from scratch if required
+		raw      = c.Value(ctx.Request)
-//
+		cast, ok = raw.(*http.Request)
-// If required, set api.Ctx as the first argument of your handler; if you
+	)
-// don't need it, only use standard input arguments and it will be ignored
+	if !ok {
-type Ctx struct {
+		return nil
-	Res http.ResponseWriter
+	}
-	Req *http.Request
+	return cast
+}
+
+// GetResponseWriter extracts the response writer from a context.Context
+func GetResponseWriter(c context.Context) http.ResponseWriter {
+	var (
+		raw      = c.Value(ctx.Response)
+		cast, ok = raw.(http.ResponseWriter)
+	)
+	if !ok {
+		return nil
+	}
+	return cast
+}
+
+// GetAuth returns the api.Auth associated with this request from a context.Context
+func GetAuth(c context.Context) *Auth {
+	var (
+		raw      = c.Value(ctx.Auth)
+		cast, ok = raw.(*Auth)
+	)
+	if !ok {
+		return nil
+	}
+	return cast
 }

builder.go

@@ -5,7 +5,6 @@ import (
 	"io"
 	"net/http"
 
-	"git.xdrm.io/go/aicra/api"
 	"git.xdrm.io/go/aicra/datatype"
 	"git.xdrm.io/go/aicra/internal/config"
 	"git.xdrm.io/go/aicra/internal/dynfunc"
@@ -13,10 +12,16 @@ import (
 
 // Builder for an aicra server
 type Builder struct {
+	// the server configuration defining available services
 	conf *config.Server
+	// user-defined handlers bound to services from the configuration
 	handlers []*apiHandler
-	adapters     []api.Adapter
+	// http middlewares wrapping the entire http connection (e.g. logger)
-	authAdapters []api.AuthAdapter
+	middlewares []func(http.Handler) http.Handler
+	// custom middlewares only wrapping the service handler of a request
+	// they will benefit from the request's context that contains service-specific
+	// information (e.g. required permisisons from the configuration)
+	ctxMiddlewares []func(http.Handler) http.Handler
 }
 
 // represents an api handler (method-pattern combination)
@@ -41,26 +46,36 @@ func (b *Builder) AddType(t datatype.T) error {
 	return nil
 }
 
-// With adds an http adapter (middleware)
+// With adds an http middleware on top of the http connection
-func (b *Builder) With(adapter api.Adapter) {
+//
+// Authentication management can only be done with the WithContext() methods as
+// the service associated with the request has not been found at this stage.
+// This stage is perfect for logging or generic request management.
+func (b *Builder) With(mw func(http.Handler) http.Handler) {
 	if b.conf == nil {
 		b.conf = &config.Server{}
 	}
-	if b.adapters == nil {
+	if b.middlewares == nil {
-		b.adapters = make([]api.Adapter, 0)
+		b.middlewares = make([]func(http.Handler) http.Handler, 0)
 	}
-	b.adapters = append(b.adapters, adapter)
+	b.middlewares = append(b.middlewares, mw)
 }
 
-// WithAuth adds an http adapter with auth capabilities (middleware)
+// WithContext adds an http middleware with the fully loaded context
-func (b *Builder) WithAuth(adapter api.AuthAdapter) {
+//
+// Logging or generic request management should be done with the With() method as
+// it wraps the full http connection. Middlewares added through this method only
+// wrap the user-defined service handler. The context.Context is filled with useful
+// data that can be access with api.GetRequest(), api.GetResponseWriter(),
+// api.GetAuth(), etc methods.
+func (b *Builder) WithContext(mw func(http.Handler) http.Handler) {
 	if b.conf == nil {
 		b.conf = &config.Server{}
 	}
-	if b.authAdapters == nil {
+	if b.ctxMiddlewares == nil {
-		b.authAdapters = make([]api.AuthAdapter, 0)
+		b.ctxMiddlewares = make([]func(http.Handler) http.Handler, 0)
 	}
-	b.authAdapters = append(b.authAdapters, adapter)
+	b.ctxMiddlewares = append(b.ctxMiddlewares, mw)
 }
 
 // Setup the builder with its api definition file

builder_test.go

@@ -1,6 +1,7 @@
 package aicra
 
 import (
+	"context"
 	"errors"
 	"net/http"
 	"strings"
@@ -72,7 +73,7 @@ func TestBind(t *testing.T) {
 			Config:        "[]",
 			HandlerMethod: "",
 			HandlerPath:   "",
-			HandlerFn:     func() (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			HandlerFn:     func(context.Context) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			BindErr:       errUnknownService,
 			BuildErr:      nil,
 		},
@@ -108,7 +109,7 @@ func TestBind(t *testing.T) {
 			]`,
 			HandlerMethod: http.MethodPost,
 			HandlerPath:   "/path",
-			HandlerFn:     func() (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			HandlerFn:     func(context.Context) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			BindErr:       errUnknownService,
 			BuildErr:      errMissingHandler,
 		},
@@ -126,7 +127,7 @@ func TestBind(t *testing.T) {
 			]`,
 			HandlerMethod: http.MethodGet,
 			HandlerPath:   "/paths",
-			HandlerFn:     func() (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			HandlerFn:     func(context.Context) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			BindErr:       errUnknownService,
 			BuildErr:      errMissingHandler,
 		},
@@ -144,7 +145,7 @@ func TestBind(t *testing.T) {
 			]`,
 			HandlerMethod: http.MethodGet,
 			HandlerPath:   "/path",
-			HandlerFn:     func() (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			HandlerFn:     func(context.Context) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			BindErr:       nil,
 			BuildErr:      nil,
 		},
@@ -164,7 +165,7 @@ func TestBind(t *testing.T) {
 			]`,
 			HandlerMethod: http.MethodGet,
 			HandlerPath:   "/path",
-			HandlerFn:     func(struct{ Name int }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			HandlerFn:     func(context.Context, struct{ Name int }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			BindErr:       nil,
 			BuildErr:      nil,
 		},
@@ -184,7 +185,7 @@ func TestBind(t *testing.T) {
 			]`,
 			HandlerMethod: http.MethodGet,
 			HandlerPath:   "/path",
-			HandlerFn:     func(struct{ Name uint }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			HandlerFn:     func(context.Context, struct{ Name uint }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			BindErr:       nil,
 			BuildErr:      nil,
 		},
@@ -204,7 +205,7 @@ func TestBind(t *testing.T) {
 			]`,
 			HandlerMethod: http.MethodGet,
 			HandlerPath:   "/path",
-			HandlerFn:     func(struct{ Name string }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			HandlerFn:     func(context.Context, struct{ Name string }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			BindErr:       nil,
 			BuildErr:      nil,
 		},
@@ -224,7 +225,7 @@ func TestBind(t *testing.T) {
 			]`,
 			HandlerMethod: http.MethodGet,
 			HandlerPath:   "/path",
-			HandlerFn:     func(struct{ Name bool }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			HandlerFn:     func(context.Context, struct{ Name bool }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			BindErr:       nil,
 			BuildErr:      nil,
 		},

handler.go

@@ -1,12 +1,14 @@
 package aicra
 
 import (
+	"context"
 	"fmt"
 	"net/http"
 	"strings"
 
 	"git.xdrm.io/go/aicra/api"
 	"git.xdrm.io/go/aicra/internal/config"
+	"git.xdrm.io/go/aicra/internal/ctx"
 	"git.xdrm.io/go/aicra/internal/reqdata"
 )
 
@@ -15,30 +17,31 @@ type Handler Builder
 
 // ServeHTTP implements http.Handler and wraps it in middlewares (adapters)
 func (s Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	var h = http.HandlerFunc(s.resolve)
+	var h http.Handler = http.HandlerFunc(s.resolve)
 
-	for _, adapter := range s.adapters {
+	for _, mw := range s.middlewares {
-		h = adapter(h)
+		h = mw(h)
 	}
-	h(w, r)
+	h.ServeHTTP(w, r)
 }
 
+// ServeHTTP implements http.Handler and wraps it in middlewares (adapters)
 func (s Handler) resolve(w http.ResponseWriter, r *http.Request) {
-	// 1. find a matching service from config
+	// 1ind a matching service from config
 	var service = s.conf.Find(r)
 	if service == nil {
 		handleError(api.ErrUnknownService, w, r)
 		return
 	}
 
-	// 2. extract request data
+	// extract request data
 	var input, err = extractInput(service, *r)
 	if err != nil {
 		handleError(api.ErrMissingParam, w, r)
 		return
 	}
 
-	// 3. find a matching handler
+	// find a matching handler
 	var handler *apiHandler
 	for _, h := range s.handlers {
 		if h.Method == service.Method && h.Path == service.Pattern {
@@ -46,59 +49,38 @@ func (s Handler) resolve(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	// 4. fail on no matching handler
+	// fail on no matching handler
 	if handler == nil {
 		handleError(api.ErrUncallableService, w, r)
 		return
 	}
 
-	// replace format '[a]' in scope where 'a' is an existing input's name
+	// build context with builtin data
-	scope := make([][]string, len(service.Scope))
+	c := r.Context()
-	for a, list := range service.Scope {
+	c = context.WithValue(c, ctx.Request, r)
-		scope[a] = make([]string, len(list))
+	c = context.WithValue(c, ctx.Response, w)
-		for b, perm := range list {
+	c = context.WithValue(c, ctx.Auth, buildAuth(service.Scope, input.Data))
-			scope[a][b] = perm
-			for name, value := range input.Data {
-				var (
-					token       = fmt.Sprintf("[%s]", name)
-					replacement = ""
-				)
-				if value != nil {
-					replacement = fmt.Sprintf("[%v]", value)
-				}
-				scope[a][b] = strings.ReplaceAll(scope[a][b], token, replacement)
-			}
-		}
-	}
 
-	var auth = api.Auth{
+	// create http handler
-		Required: scope,
+	var h http.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		Active:   []string{},
+		// use context defined in the request
-	}
+		s.handle(r.Context(), input, handler, service, w, r)
-
-	// 5. run auth-aware middlewares
-	var h = api.AuthHandlerFunc(func(a api.Auth, w http.ResponseWriter, r *http.Request) {
-		if !a.Granted() {
-			handleError(api.ErrPermission, w, r)
-			return
-		}
-
-		s.handle(input, handler, service, w, r)
 	})
 
-	for _, adapter := range s.authAdapters {
+	// run middlewares the handler
-		h = adapter(h)
+	for _, mw := range s.ctxMiddlewares {
+		h = mw(h)
 	}
-	h(auth, w, r)
 
+	// serve using the context with values
+	h.ServeHTTP(w, r.WithContext(c))
 }
 
-func (s *Handler) handle(input *reqdata.T, handler *apiHandler, service *config.Service, w http.ResponseWriter, r *http.Request) {
+func (s *Handler) handle(c context.Context, input *reqdata.T, handler *apiHandler, service *config.Service, w http.ResponseWriter, r *http.Request) {
-	// 5. pass execution to the handler
+	// pass execution to the handler
-	ctx := api.Ctx{Res: w, Req: r}
+	var outData, outErr = handler.dyn.Handle(c, input.Data)
-	var outData, outErr = handler.dyn.Handle(ctx, input.Data)
 
-	// 6. build res from returned data
+	// build response from returned arguments
 	var res = api.EmptyResponse().WithError(outErr)
 	for key, value := range outData {
 
@@ -149,3 +131,35 @@ func extractInput(service *config.Service, req http.Request) (*reqdata.T, error)
 
 	return dataset, nil
 }
+
+// buildAuth builds the api.Auth struct from the service scope configuration
+//
+// it replaces format '[a]' in scope where 'a' is an existing input argument's
+// name with its value
+func buildAuth(scope [][]string, in map[string]interface{}) *api.Auth {
+	updated := make([][]string, len(scope))
+
+	// replace '[arg_name]' with the 'arg_name' value if it is a known variable
+	// name
+	for a, list := range scope {
+		updated[a] = make([]string, len(list))
+		for b, perm := range list {
+			updated[a][b] = perm
+			for name, value := range in {
+				var (
+					token       = fmt.Sprintf("[%s]", name)
+					replacement = ""
+				)
+				if value != nil {
+					replacement = fmt.Sprintf("[%v]", value)
+				}
+				updated[a][b] = strings.ReplaceAll(updated[a][b], token, replacement)
+			}
+		}
+	}
+
+	return &api.Auth{
+		Required: updated,
+		Active:   []string{},
+	}
+}

handler_test.go

@@ -48,15 +48,15 @@ func TestWith(t *testing.T) {
 	type ckey int
 	const key ckey = 0
 
-	middleware := func(next http.HandlerFunc) http.HandlerFunc {
+	middleware := func(next http.Handler) http.Handler {
-		return func(w http.ResponseWriter, r *http.Request) {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			newr := r
 
 			// first time -> store 1
 			value := r.Context().Value(key)
 			if value == nil {
 				newr = r.WithContext(context.WithValue(r.Context(), key, int(1)))
-				next(w, newr)
+				next.ServeHTTP(w, newr)
 				return
 			}
 
@@ -67,8 +67,8 @@ func TestWith(t *testing.T) {
 			}
 			cast++
 			newr = r.WithContext(context.WithValue(r.Context(), key, cast))
-			next(w, newr)
+			next.ServeHTTP(w, newr)
-		}
+		})
 	}
 
 	// add middleware @n times
@@ -82,9 +82,9 @@ func TestWith(t *testing.T) {
 		t.Fatalf("setup: unexpected error <%v>", err)
 	}
 
-	pathHandler := func(ctx api.Ctx) (*struct{}, api.Err) {
+	pathHandler := func(ctx context.Context) (*struct{}, api.Err) {
 		// write value from middlewares into response
-		value := ctx.Req.Context().Value(key)
+		value := ctx.Value(key)
 		if value == nil {
 			t.Fatalf("nothing found in context")
 		}
@@ -93,7 +93,7 @@ func TestWith(t *testing.T) {
 			t.Fatalf("cannot cast context data to int")
 		}
 		// write to response
-		ctx.Res.Write([]byte(fmt.Sprintf("#%d#", cast)))
+		api.GetResponseWriter(ctx).Write([]byte(fmt.Sprintf("#%d#", cast)))
 
 		return nil, api.ErrSuccess
 	}
@@ -212,8 +212,13 @@ func TestWithAuth(t *testing.T) {
 			}
 
 			// tester middleware (last executed)
-			builder.WithAuth(func(next api.AuthHandlerFunc) api.AuthHandlerFunc {
+			builder.WithContext(func(next http.Handler) http.Handler {
-				return func(a api.Auth, w http.ResponseWriter, r *http.Request) {
+				return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+					a := api.GetAuth(r.Context())
+					if a == nil {
+						t.Fatalf("cannot access api.Auth form request context")
+					}
+
 					if a.Granted() == tc.granted {
 						return
 					}
@@ -222,14 +227,20 @@ func TestWithAuth(t *testing.T) {
 					} else {
 						t.Fatalf("expected granted auth")
 					}
-				}
+					next.ServeHTTP(w, r)
+				})
 			})
 
-			builder.WithAuth(func(next api.AuthHandlerFunc) api.AuthHandlerFunc {
+			builder.WithContext(func(next http.Handler) http.Handler {
-				return func(a api.Auth, w http.ResponseWriter, r *http.Request) {
+				return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-					a.Active = tc.permissions
+					a := api.GetAuth(r.Context())
-					next(a, w, r)
+					if a == nil {
+						t.Fatalf("cannot access api.Auth form request context")
 					}
+
+					a.Active = tc.permissions
+					next.ServeHTTP(w, r)
+				})
 			})
 
 			err := builder.Setup(strings.NewReader(tc.manifest))
@@ -237,7 +248,7 @@ func TestWithAuth(t *testing.T) {
 				t.Fatalf("setup: unexpected error <%v>", err)
 			}
 
-			pathHandler := func(ctx api.Ctx) (*struct{}, api.Err) {
+			pathHandler := func(ctx context.Context) (*struct{}, api.Err) {
 				return nil, api.ErrNotImplemented
 			}
 
@@ -290,7 +301,7 @@ func TestDynamicScope(t *testing.T) {
 				}
 			]`,
 			path:        "/path/{id}",
-			handler:     func(struct{ Input1 uint }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			handler:     func(context.Context, struct{ Input1 uint }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			url:         "/path/123",
 			body:        ``,
 			permissions: []string{"user[123]"},
@@ -311,7 +322,7 @@ func TestDynamicScope(t *testing.T) {
 				}
 			]`,
 			path:        "/path/{id}",
-			handler:     func(struct{ Input1 uint }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			handler:     func(context.Context, struct{ Input1 uint }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			url:         "/path/666",
 			body:        ``,
 			permissions: []string{"user[123]"},
@@ -332,7 +343,7 @@ func TestDynamicScope(t *testing.T) {
 				}
 			]`,
 			path:        "/path/{id}",
-			handler:     func(struct{ User uint }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			handler:     func(context.Context, struct{ User uint }) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			url:         "/path/123",
 			body:        ``,
 			permissions: []string{"prefix.user[123].suffix"},
@@ -354,7 +365,7 @@ func TestDynamicScope(t *testing.T) {
 				}
 			]`,
 			path: "/prefix/{pid}/user/{uid}",
-			handler: func(struct {
+			handler: func(context.Context, struct {
 				Prefix uint
 				User   uint
 			}) (*struct{}, api.Err) {
@@ -381,7 +392,7 @@ func TestDynamicScope(t *testing.T) {
 				}
 			]`,
 			path: "/prefix/{pid}/user/{uid}",
-			handler: func(struct {
+			handler: func(context.Context, struct {
 				Prefix uint
 				User   uint
 			}) (*struct{}, api.Err) {
@@ -409,7 +420,7 @@ func TestDynamicScope(t *testing.T) {
 				}
 			]`,
 			path: "/prefix/{pid}/user/{uid}/suffix/{sid}",
-			handler: func(struct {
+			handler: func(context.Context, struct {
 				Prefix uint
 				User   uint
 				Suffix uint
@@ -438,7 +449,7 @@ func TestDynamicScope(t *testing.T) {
 				}
 			]`,
 			path: "/prefix/{pid}/user/{uid}/suffix/{sid}",
-			handler: func(struct {
+			handler: func(context.Context, struct {
 				Prefix uint
 				User   uint
 				Suffix uint
@@ -460,8 +471,12 @@ func TestDynamicScope(t *testing.T) {
 			}
 
 			// tester middleware (last executed)
-			builder.WithAuth(func(next api.AuthHandlerFunc) api.AuthHandlerFunc {
+			builder.WithContext(func(next http.Handler) http.Handler {
-				return func(a api.Auth, w http.ResponseWriter, r *http.Request) {
+				return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+					a := api.GetAuth(r.Context())
+					if a == nil {
+						t.Fatalf("cannot access api.Auth form request context")
+					}
 					if a.Granted() == tc.granted {
 						return
 					}
@@ -470,15 +485,20 @@ func TestDynamicScope(t *testing.T) {
 					} else {
 						t.Fatalf("expected granted auth")
 					}
-				}
+					next.ServeHTTP(w, r)
+				})
 			})
 
 			// update permissions
-			builder.WithAuth(func(next api.AuthHandlerFunc) api.AuthHandlerFunc {
+			builder.WithContext(func(next http.Handler) http.Handler {
-				return func(a api.Auth, w http.ResponseWriter, r *http.Request) {
+				return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-					a.Active = tc.permissions
+					a := api.GetAuth(r.Context())
-					next(a, w, r)
+					if a == nil {
+						t.Fatalf("cannot access api.Auth form request context")
 					}
+					a.Active = tc.permissions
+					next.ServeHTTP(w, r)
+				})
 			})
 
 			err := builder.Setup(strings.NewReader(tc.manifest))

internal/ctx/ctx.go

@@ -0,0 +1,13 @@
+package ctx
+
+// Key defines a custom context key type
+type Key int
+
+const (
+	// Request is the key for the current *http.Request
+	Request Key = iota
+	// Response is the key for the associated http.ResponseWriter
+	Response
+	// Auth is the key for the request's authentication information
+	Auth
+)

internal/dynfunc/errors.go

@@ -14,16 +14,19 @@ const errHandlerNotFunc = cerr("handler must be a func")
 const errNoServiceForHandler = cerr("no service found for this handler")
 
 // errMissingHandlerArgumentParam - missing params arguments for handler
-const errMissingHandlerArgumentParam = cerr("missing handler argument : parameter struct")
+const errMissingHandlerContextArgument = cerr("missing handler first argument of type context.Context")
+
+// errMissingHandlerInputArgument - missing params arguments for handler
+const errMissingHandlerInputArgument = cerr("missing handler argument: input struct")
 
 // errUnexpectedInput - input argument is not expected
 const errUnexpectedInput = cerr("unexpected input struct")
 
-// errMissingHandlerOutput - missing output for handler
+// errMissingHandlerOutputArgument - missing output for handler
-const errMissingHandlerOutput = cerr("handler must have at least 1 output")
+const errMissingHandlerOutputArgument = cerr("missing handler first output argument: output struct")
 
 // errMissingHandlerOutputError - missing error output for handler
-const errMissingHandlerOutputError = cerr("handler must have its last output of type api.Err")
+const errMissingHandlerOutputError = cerr("missing handler last output argument of type api.Err")
 
 // errMissingRequestArgument - missing request argument for handler
 const errMissingRequestArgument = cerr("handler first argument must be of type api.Request")
@@ -34,17 +37,14 @@ const errMissingParamArgument = cerr("handler second argument must be a struct")
 // errUnexportedName - argument is unexported in struct
 const errUnexportedName = cerr("unexported name")
 
-// errMissingParamOutput - missing output argument for handler
+// errWrongOutputArgumentType - wrong type for output first argument
-const errMissingParamOutput = cerr("handler first output must be a *struct")
+const errWrongOutputArgumentType = cerr("handler first output argument must be a *struct")
 
-// errMissingParamFromConfig - missing a parameter in handler struct
+// errMissingConfigArgument - missing an input/output argument in handler struct
-const errMissingParamFromConfig = cerr("missing a parameter from configuration")
+const errMissingConfigArgument = cerr("missing an argument from the configuration")
-
-// errMissingOutputFromConfig - missing a parameter in handler struct
-const errMissingOutputFromConfig = cerr("missing a parameter from configuration")
 
 // errWrongParamTypeFromConfig - a configuration parameter type is invalid in the handler param struct
 const errWrongParamTypeFromConfig = cerr("invalid struct field type")
 
-// errMissingHandlerErrorOutput - missing handler output error
+// errMissingHandlerErrorArgument - missing handler output error
-const errMissingHandlerErrorOutput = cerr("last output must be of type api.Err")
+const errMissingHandlerErrorArgument = cerr("last output must be of type api.Err")

internal/dynfunc/handler.go

@@ -1,6 +1,7 @@
 package dynfunc
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"reflect"
@@ -9,73 +10,69 @@ import (
 	"git.xdrm.io/go/aicra/internal/config"
 )
 
-// Handler represents a dynamic api handler
+// Handler represents a dynamic aicra service handler
 type Handler struct {
-	spec *signature
+	// signature defined from the service configuration
+	signature *Signature
+	// fn provided function that will be the service's handler
 	fn interface{}
-	// whether fn uses api.Ctx as 1st argument
-	hasContext bool
-	// index in input arguments where the data struct must be
-	dataIndex int
 }
 
-// Build a handler from a service configuration and a dynamic function
+// Build a handler from a dynamic function and checks its signature against a
-//
+// service configuration
-// @fn must have as a signature : `func(inputStruct) (*outputStruct, api.Err)`
+//e
-//  - `inputStruct` is a struct{} containing a field for each service input (with valid reflect.Type)
+// `fn` must have as a signature : `func(*api.Context, in) (*out, api.Err)`
-//  - `outputStruct` is a struct{} containing a field for each service output (with valid reflect.Type)
+//  - `in` is a struct{} containing a field for each service input (with valid reflect.Type)
+//  - `out` is a struct{} containing a field for each service output (with valid reflect.Type)
 //
 // Special cases:
-//  - a first optional input parameter of type `api.Ctx` can be added
+//  - it there is no input, `in` MUST be omitted
-//  - it there is no input, `inputStruct` must be omitted
+//  - it there is no output, `out` MUST be omitted
-//  - it there is no output, `outputStruct` must be omitted
 func Build(fn interface{}, service config.Service) (*Handler, error) {
-	h := &Handler{
+	var (
-		spec: signatureFromService(service),
+		h = &Handler{
+			signature: BuildSignature(service),
 			fn:        fn,
 		}
+		fnType = reflect.TypeOf(fn)
+	)
 
-	impl := reflect.TypeOf(fn)
+	if fnType.Kind() != reflect.Func {
-
-	if impl.Kind() != reflect.Func {
 		return nil, errHandlerNotFunc
 	}
-
+	if err := h.signature.ValidateInput(fnType); err != nil {
-	h.hasContext = impl.NumIn() >= 1 && reflect.TypeOf(api.Ctx{}).AssignableTo(impl.In(0))
-	if h.hasContext {
-		h.dataIndex = 1
-	}
-
-	if err := h.spec.checkInput(impl, h.dataIndex); err != nil {
 		return nil, fmt.Errorf("input: %w", err)
 	}
-	if err := h.spec.checkOutput(impl); err != nil {
+	if err := h.signature.ValidateOutput(fnType); err != nil {
 		return nil, fmt.Errorf("output: %w", err)
 	}
 
 	return h, nil
 }
 
-// Handle binds input @data into the dynamic function and returns map output
+// Handle binds input `data` into the dynamic function and returns an output map
-func (h *Handler) Handle(ctx api.Ctx, data map[string]interface{}) (map[string]interface{}, api.Err) {
+func (h *Handler) Handle(ctx context.Context, data map[string]interface{}) (map[string]interface{}, api.Err) {
-	var ert = reflect.TypeOf(api.Err{})
+	var (
-	var fnv = reflect.ValueOf(h.fn)
+		ert      = reflect.TypeOf(api.Err{})
+		fnv      = reflect.ValueOf(h.fn)
+		callArgs = make([]reflect.Value, 0)
+	)
 
-	callArgs := []reflect.Value{}
+	// bind context
-
-	// bind context if used in handler
-	if h.hasContext {
 	callArgs = append(callArgs, reflect.ValueOf(ctx))
-	}
 
-	// bind input data
+	inputStructRequired := fnv.Type().NumIn() > 1
-	if fnv.Type().NumIn() > h.dataIndex {
+
+	// bind input arguments
+	if inputStructRequired {
 		// create zero value struct
-		callStructPtr := reflect.New(fnv.Type().In(0))
+		var (
-		callStruct := callStructPtr.Elem()
+			callStructPtr = reflect.New(fnv.Type().In(1))
+			callStruct    = callStructPtr.Elem()
+		)
 
 		// set each field
-		for name := range h.spec.Input {
+		for name := range h.signature.Input {
 			field := callStruct.FieldByName(name)
 			if !field.CanSet() {
 				continue
@@ -115,12 +112,12 @@ func (h *Handler) Handle(ctx api.Ctx, data map[string]interface{}) (map[string]i
 		callArgs = append(callArgs, callStruct)
 	}
 
-	// call the HandlerFn
+	// call the handler
 	output := fnv.Call(callArgs)
 
 	// no output OR pointer to output struct is nil
 	outdata := make(map[string]interface{})
-	if len(h.spec.Output) < 1 || output[0].IsNil() {
+	if len(h.signature.Output) < 1 || output[0].IsNil() {
 		var structerr = output[len(output)-1].Convert(ert)
 		return outdata, api.Err{
 			Code:   int(structerr.FieldByName("Code").Int()),
@@ -132,7 +129,7 @@ func (h *Handler) Handle(ctx api.Ctx, data map[string]interface{}) (map[string]i
 	// extract struct from pointer
 	returnStruct := output[0].Elem()
 
-	for name := range h.spec.Output {
+	for name := range h.signature.Output {
 		field := returnStruct.FieldByName(name)
 		outdata[name] = field.Interface()
 	}

internal/dynfunc/handler_test.go

@@ -1,6 +1,7 @@
 package dynfunc
 
 import (
+	"context"
 	"fmt"
 	"reflect"
 	"testing"
@@ -8,7 +9,7 @@ import (
 	"git.xdrm.io/go/aicra/api"
 )
 
-type testsignature signature
+type testsignature Signature
 
 // builds a mock service with provided arguments as Input and matched as Output
 func (s *testsignature) withArgs(dtypes ...reflect.Type) *testsignature {
@@ -52,7 +53,7 @@ func TestInput(t *testing.T) {
 		{
 			Name:           "none required none provided",
 			Spec:           (&testsignature{}).withArgs(),
-			Fn:             func() (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			Fn:             func(context.Context) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			HasContext:     false,
 			Input:          []interface{}{},
 			ExpectedOutput: []interface{}{},
@@ -61,7 +62,7 @@ func TestInput(t *testing.T) {
 		{
 			Name: "int proxy (0)",
 			Spec: (&testsignature{}).withArgs(reflect.TypeOf(int(0))),
-			Fn: func(in intstruct) (*intstruct, api.Err) {
+			Fn: func(ctx context.Context, in intstruct) (*intstruct, api.Err) {
 				return &intstruct{P1: in.P1}, api.ErrSuccess
 			},
 			HasContext:     false,
@@ -72,7 +73,7 @@ func TestInput(t *testing.T) {
 		{
 			Name: "int proxy (11)",
 			Spec: (&testsignature{}).withArgs(reflect.TypeOf(int(0))),
-			Fn: func(in intstruct) (*intstruct, api.Err) {
+			Fn: func(ctx context.Context, in intstruct) (*intstruct, api.Err) {
 				return &intstruct{P1: in.P1}, api.ErrSuccess
 			},
 			HasContext:     false,
@@ -83,7 +84,7 @@ func TestInput(t *testing.T) {
 		{
 			Name: "*int proxy (nil)",
 			Spec: (&testsignature{}).withArgs(reflect.TypeOf(new(int))),
-			Fn: func(in intptrstruct) (*intptrstruct, api.Err) {
+			Fn: func(ctx context.Context, in intptrstruct) (*intptrstruct, api.Err) {
 				return &intptrstruct{P1: in.P1}, api.ErrSuccess
 			},
 			HasContext:     false,
@@ -94,7 +95,7 @@ func TestInput(t *testing.T) {
 		{
 			Name: "*int proxy (28)",
 			Spec: (&testsignature{}).withArgs(reflect.TypeOf(new(int))),
-			Fn: func(in intptrstruct) (*intstruct, api.Err) {
+			Fn: func(ctx context.Context, in intptrstruct) (*intstruct, api.Err) {
 				return &intstruct{P1: *in.P1}, api.ErrSuccess
 			},
 			HasContext:     false,
@@ -105,7 +106,7 @@ func TestInput(t *testing.T) {
 		{
 			Name: "*int proxy (13)",
 			Spec: (&testsignature{}).withArgs(reflect.TypeOf(new(int))),
-			Fn: func(in intptrstruct) (*intstruct, api.Err) {
+			Fn: func(ctx context.Context, in intptrstruct) (*intstruct, api.Err) {
 				return &intstruct{P1: *in.P1}, api.ErrSuccess
 			},
 			HasContext:     false,
@@ -119,16 +120,9 @@ func TestInput(t *testing.T) {
 		t.Run(tcase.Name, func(t *testing.T) {
 			t.Parallel()
 
-			var dataIndex = 0
-			if tcase.HasContext {
-				dataIndex = 1
-			}
-
 			var handler = &Handler{
-				spec:       &signature{Input: tcase.Spec.Input, Output: tcase.Spec.Output},
+				signature: &Signature{Input: tcase.Spec.Input, Output: tcase.Spec.Output},
 				fn:        tcase.Fn,
-				dataIndex:  dataIndex,
-				hasContext: tcase.HasContext,
 			}
 
 			// build input
@@ -138,7 +132,7 @@ func TestInput(t *testing.T) {
 				input[key] = val
 			}
 
-			var output, err = handler.Handle(api.Ctx{}, input)
+			var output, err = handler.Handle(context.Background(), input)
 			if err != tcase.ExpectedErr {
 				t.Fatalf("expected api error <%v> got <%v>", tcase.ExpectedErr, err)
 			}

internal/dynfunc/signature.go

@@ -1,6 +1,7 @@
 package dynfunc
 
 import (
+	"context"
 	"fmt"
 	"reflect"
 	"strings"
@@ -9,15 +10,17 @@ import (
 	"git.xdrm.io/go/aicra/internal/config"
 )
 
-// signature represents input/output arguments for a dynamic function
+// Signature represents input/output arguments for service from the aicra configuration
-type signature struct {
+type Signature struct {
+	// Input arguments of the service
 	Input map[string]reflect.Type
+	// Output arguments of the service
 	Output map[string]reflect.Type
 }
 
-// builds a spec from the configuration service
+// BuildSignature builds a signature for a service configuration
-func signatureFromService(service config.Service) *signature {
+func BuildSignature(service config.Service) *Signature {
-	s := &signature{
+	s := &Signature{
 		Input:  make(map[string]reflect.Type),
 		Output: make(map[string]reflect.Type),
 	}
@@ -44,31 +47,37 @@ func signatureFromService(service config.Service) *signature {
 	return s
 }
 
-// checks for HandlerFn input arguments
+// ValidateInput validates a handler's input arguments against the service signature
-func (s *signature) checkInput(impl reflect.Type, index int) error {
+func (s *Signature) ValidateInput(handlerType reflect.Type) error {
-	var requiredInput, structIndex = index, index
+	ctxType := reflect.TypeOf((*context.Context)(nil)).Elem()
-	if len(s.Input) > 0 { // arguments struct
+
-		requiredInput++
+	// missing or invalid first arg: context.Context
+	if handlerType.NumIn() < 1 {
+		return errMissingHandlerContextArgument
+	}
+	firstArgType := handlerType.In(0)
+
+	if !firstArgType.Implements(ctxType) {
+		return fmt.Errorf("fock")
 	}
 
-	// missing arguments
+	// no input required
-	if impl.NumIn() > requiredInput {
+	if len(s.Input) == 0 {
+		// input struct provided
+		if handlerType.NumIn() > 1 {
 			return errUnexpectedInput
 		}
-
-	// none required
-	if len(s.Input) == 0 {
 		return nil
 	}
 
 	// too much arguments
-	if impl.NumIn() != requiredInput {
+	if handlerType.NumIn() > 2 {
-		return errMissingHandlerArgumentParam
+		return errMissingHandlerInputArgument
 	}
 
 	// arg must be a struct
-	structArg := impl.In(structIndex)
+	inStruct := handlerType.In(1)
-	if structArg.Kind() != reflect.Struct {
+	if inStruct.Kind() != reflect.Struct {
 		return errMissingParamArgument
 	}
 
@@ -78,9 +87,9 @@ func (s *signature) checkInput(impl reflect.Type, index int) error {
 			return fmt.Errorf("%s: %w", name, errUnexportedName)
 		}
 
-		field, exists := structArg.FieldByName(name)
+		field, exists := inStruct.FieldByName(name)
 		if !exists {
-			return fmt.Errorf("%s: %w", name, errMissingParamFromConfig)
+			return fmt.Errorf("%s: %w", name, errMissingConfigArgument)
 		}
 
 		if !ptype.AssignableTo(field.Type) {
@@ -91,16 +100,18 @@ func (s *signature) checkInput(impl reflect.Type, index int) error {
 	return nil
 }
 
-// checks for HandlerFn output arguments
+// ValidateOutput validates a handler's output arguments against the service signature
-func (s signature) checkOutput(impl reflect.Type) error {
+func (s Signature) ValidateOutput(handlerType reflect.Type) error {
-	if impl.NumOut() < 1 {
+	errType := reflect.TypeOf(api.ErrUnknown)
-		return errMissingHandlerOutput
+
+	if handlerType.NumOut() < 1 {
+		return errMissingHandlerErrorArgument
 	}
 
 	// last output must be api.Err
-	errOutput := impl.Out(impl.NumOut() - 1)
+	lastArgType := handlerType.Out(handlerType.NumOut() - 1)
-	if !errOutput.AssignableTo(reflect.TypeOf(api.ErrUnknown)) {
+	if !lastArgType.AssignableTo(errType) {
-		return errMissingHandlerErrorOutput
+		return errMissingHandlerErrorArgument
 	}
 
 	// no output -> ok
@@ -108,19 +119,19 @@ func (s signature) checkOutput(impl reflect.Type) error {
 		return nil
 	}
 
-	if impl.NumOut() != 2 {
+	if handlerType.NumOut() < 2 {
-		return errMissingParamOutput
+		return errMissingHandlerOutputArgument
 	}
 
 	// fail if first output is not a pointer to struct
-	structOutputPtr := impl.Out(0)
+	outStructPtr := handlerType.Out(0)
-	if structOutputPtr.Kind() != reflect.Ptr {
+	if outStructPtr.Kind() != reflect.Ptr {
-		return errMissingParamOutput
+		return errWrongOutputArgumentType
 	}
 
-	structOutput := structOutputPtr.Elem()
+	outStruct := outStructPtr.Elem()
-	if structOutput.Kind() != reflect.Struct {
+	if outStruct.Kind() != reflect.Struct {
-		return errMissingParamOutput
+		return errWrongOutputArgumentType
 	}
 
 	// fail on invalid output
@@ -129,9 +140,9 @@ func (s signature) checkOutput(impl reflect.Type) error {
 			return fmt.Errorf("%s: %w", name, errUnexportedName)
 		}
 
-		field, exists := structOutput.FieldByName(name)
+		field, exists := outStruct.FieldByName(name)
 		if !exists {
-			return fmt.Errorf("%s: %w", name, errMissingOutputFromConfig)
+			return fmt.Errorf("%s: %w", name, errMissingConfigArgument)
 		}
 
 		// ignore types evalutating to nil

internal/dynfunc/signature_test.go

@@ -1,6 +1,7 @@
 package dynfunc
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"reflect"
@@ -20,22 +21,22 @@ func TestInputCheck(t *testing.T) {
 		{
 			Name:  "no input 0 given",
 			Input: map[string]reflect.Type{},
-			Fn:    func() {},
+			Fn:    func(context.Context) {},
-			FnCtx: func(api.Ctx) {},
+			FnCtx: func(context.Context) {},
 			Err:   nil,
 		},
 		{
 			Name:  "no input 1 given",
 			Input: map[string]reflect.Type{},
-			Fn:    func(int) {},
+			Fn:    func(context.Context, int) {},
-			FnCtx: func(api.Ctx, int) {},
+			FnCtx: func(context.Context, int) {},
 			Err:   errUnexpectedInput,
 		},
 		{
 			Name:  "no input 2 given",
 			Input: map[string]reflect.Type{},
-			Fn:    func(int, string) {},
+			Fn:    func(context.Context, int, string) {},
-			FnCtx: func(api.Ctx, int, string) {},
+			FnCtx: func(context.Context, int, string) {},
 			Err:   errUnexpectedInput,
 		},
 		{
@@ -43,17 +44,17 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(int(0)),
 			},
-			Fn:    func() {},
+			Fn:    func(context.Context) {},
-			FnCtx: func(api.Ctx) {},
+			FnCtx: func(context.Context) {},
-			Err:   errMissingHandlerArgumentParam,
+			Err:   errMissingHandlerInputArgument,
 		},
 		{
 			Name: "1 input non-struct given",
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(int(0)),
 			},
-			Fn:    func(int) {},
+			Fn:    func(context.Context, int) {},
-			FnCtx: func(api.Ctx, int) {},
+			FnCtx: func(context.Context, int) {},
 			Err:   errMissingParamArgument,
 		},
 		{
@@ -61,8 +62,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"test1": reflect.TypeOf(int(0)),
 			},
-			Fn:    func(struct{}) {},
+			Fn:    func(context.Context, struct{}) {},
-			FnCtx: func(api.Ctx, struct{}) {},
+			FnCtx: func(context.Context, struct{}) {},
 			Err:   errUnexportedName,
 		},
 		{
@@ -70,17 +71,17 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(int(0)),
 			},
-			Fn:    func(struct{}) {},
+			Fn:    func(context.Context, struct{}) {},
-			FnCtx: func(api.Ctx, struct{}) {},
+			FnCtx: func(context.Context, struct{}) {},
-			Err:   errMissingParamFromConfig,
+			Err:   errMissingConfigArgument,
 		},
 		{
 			Name: "1 input invalid given",
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(int(0)),
 			},
-			Fn:    func(struct{ Test1 string }) {},
+			Fn:    func(context.Context, struct{ Test1 string }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 string }) {},
+			FnCtx: func(context.Context, struct{ Test1 string }) {},
 			Err:   errWrongParamTypeFromConfig,
 		},
 		{
@@ -88,8 +89,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(int(0)),
 			},
-			Fn:    func(struct{ Test1 int }) {},
+			Fn:    func(context.Context, struct{ Test1 int }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 int }) {},
+			FnCtx: func(context.Context, struct{ Test1 int }) {},
 			Err:   nil,
 		},
 		{
@@ -97,17 +98,17 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new(int)),
 			},
-			Fn:    func(struct{}) {},
+			Fn:    func(context.Context, struct{}) {},
-			FnCtx: func(api.Ctx, struct{}) {},
+			FnCtx: func(context.Context, struct{}) {},
-			Err:   errMissingParamFromConfig,
+			Err:   errMissingConfigArgument,
 		},
 		{
 			Name: "1 input ptr invalid given",
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new(int)),
 			},
-			Fn:    func(struct{ Test1 string }) {},
+			Fn:    func(context.Context, struct{ Test1 string }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 string }) {},
+			FnCtx: func(context.Context, struct{ Test1 string }) {},
 			Err:   errWrongParamTypeFromConfig,
 		},
 		{
@@ -115,8 +116,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new(int)),
 			},
-			Fn:    func(struct{ Test1 *string }) {},
+			Fn:    func(context.Context, struct{ Test1 *string }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 *string }) {},
+			FnCtx: func(context.Context, struct{ Test1 *string }) {},
 			Err:   errWrongParamTypeFromConfig,
 		},
 		{
@@ -124,8 +125,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new(int)),
 			},
-			Fn:    func(struct{ Test1 *int }) {},
+			Fn:    func(context.Context, struct{ Test1 *int }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 *int }) {},
+			FnCtx: func(context.Context, struct{ Test1 *int }) {},
 			Err:   nil,
 		},
 		{
@@ -133,8 +134,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(string("")),
 			},
-			Fn:    func(struct{ Test1 string }) {},
+			Fn:    func(context.Context, struct{ Test1 string }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 string }) {},
+			FnCtx: func(context.Context, struct{ Test1 string }) {},
 			Err:   nil,
 		},
 		{
@@ -142,8 +143,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(uint(0)),
 			},
-			Fn:    func(struct{ Test1 uint }) {},
+			Fn:    func(context.Context, struct{ Test1 uint }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 uint }) {},
+			FnCtx: func(context.Context, struct{ Test1 uint }) {},
 			Err:   nil,
 		},
 		{
@@ -151,8 +152,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(float64(0)),
 			},
-			Fn:    func(struct{ Test1 float64 }) {},
+			Fn:    func(context.Context, struct{ Test1 float64 }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 float64 }) {},
+			FnCtx: func(context.Context, struct{ Test1 float64 }) {},
 			Err:   nil,
 		},
 		{
@@ -160,8 +161,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf([]byte("")),
 			},
-			Fn:    func(struct{ Test1 []byte }) {},
+			Fn:    func(context.Context, struct{ Test1 []byte }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 []byte }) {},
+			FnCtx: func(context.Context, struct{ Test1 []byte }) {},
 			Err:   nil,
 		},
 		{
@@ -169,8 +170,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf([]rune("")),
 			},
-			Fn:    func(struct{ Test1 []rune }) {},
+			Fn:    func(context.Context, struct{ Test1 []rune }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 []rune }) {},
+			FnCtx: func(context.Context, struct{ Test1 []rune }) {},
 			Err:   nil,
 		},
 		{
@@ -178,8 +179,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new(string)),
 			},
-			Fn:    func(struct{ Test1 *string }) {},
+			Fn:    func(context.Context, struct{ Test1 *string }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 *string }) {},
+			FnCtx: func(context.Context, struct{ Test1 *string }) {},
 			Err:   nil,
 		},
 		{
@@ -187,8 +188,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new(uint)),
 			},
-			Fn:    func(struct{ Test1 *uint }) {},
+			Fn:    func(context.Context, struct{ Test1 *uint }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 *uint }) {},
+			FnCtx: func(context.Context, struct{ Test1 *uint }) {},
 			Err:   nil,
 		},
 		{
@@ -196,8 +197,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new(float64)),
 			},
-			Fn:    func(struct{ Test1 *float64 }) {},
+			Fn:    func(context.Context, struct{ Test1 *float64 }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 *float64 }) {},
+			FnCtx: func(context.Context, struct{ Test1 *float64 }) {},
 			Err:   nil,
 		},
 		{
@@ -205,8 +206,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new([]byte)),
 			},
-			Fn:    func(struct{ Test1 *[]byte }) {},
+			Fn:    func(context.Context, struct{ Test1 *[]byte }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 *[]byte }) {},
+			FnCtx: func(context.Context, struct{ Test1 *[]byte }) {},
 			Err:   nil,
 		},
 		{
@@ -214,8 +215,8 @@ func TestInputCheck(t *testing.T) {
 			Input: map[string]reflect.Type{
 				"Test1": reflect.TypeOf(new([]rune)),
 			},
-			Fn:    func(struct{ Test1 *[]rune }) {},
+			Fn:    func(context.Context, struct{ Test1 *[]rune }) {},
-			FnCtx: func(api.Ctx, struct{ Test1 *[]rune }) {},
+			FnCtx: func(context.Context, struct{ Test1 *[]rune }) {},
 			Err:   nil,
 		},
 	}
@@ -225,13 +226,12 @@ func TestInputCheck(t *testing.T) {
 			t.Parallel()
 
 			// mock spec
-			s := signature{
+			s := Signature{
 				Input:  tcase.Input,
 				Output: nil,
 			}
 
-			t.Run("with-context", func(t *testing.T) {
+			err := s.ValidateInput(reflect.TypeOf(tcase.FnCtx))
-				err := s.checkInput(reflect.TypeOf(tcase.FnCtx), 1)
 			if err == nil && tcase.Err != nil {
 				t.Errorf("expected an error: '%s'", tcase.Err.Error())
 				t.FailNow()
@@ -248,25 +248,6 @@ func TestInputCheck(t *testing.T) {
 				}
 			}
 		})
-			t.Run("without-context", func(t *testing.T) {
-				err := s.checkInput(reflect.TypeOf(tcase.Fn), 0)
-				if err == nil && tcase.Err != nil {
-					t.Errorf("expected an error: '%s'", tcase.Err.Error())
-					t.FailNow()
-				}
-				if err != nil && tcase.Err == nil {
-					t.Errorf("unexpected error: '%s'", err.Error())
-					t.FailNow()
-				}
-
-				if err != nil && tcase.Err != nil {
-					if !errors.Is(err, tcase.Err) {
-						t.Errorf("expected the error <%s> got <%s>", tcase.Err, err)
-						t.FailNow()
-					}
-				}
-			})
-		})
 	}
 }
 
@@ -279,25 +260,37 @@ func TestOutputCheck(t *testing.T) {
 		// no input -> missing api.Err
 		{
 			Output: map[string]reflect.Type{},
-			Fn:     func() {},
+			Fn:     func(context.Context) {},
-			Err:    errMissingHandlerOutput,
+			Err:    errMissingHandlerOutputArgument,
 		},
 		// no input -> with last type not api.Err
 		{
 			Output: map[string]reflect.Type{},
-			Fn:     func() bool { return true },
+			Fn:     func(context.Context) bool { return true },
-			Err:    errMissingHandlerErrorOutput,
+			Err:    errMissingHandlerErrorArgument,
 		},
 		// no input -> with api.Err
 		{
 			Output: map[string]reflect.Type{},
-			Fn:     func() api.Err { return api.ErrSuccess },
+			Fn:     func(context.Context) api.Err { return api.ErrSuccess },
 			Err:    nil,
 		},
+		// no input -> missing context.Context
+		{
+			Output: map[string]reflect.Type{},
+			Fn:     func(context.Context) api.Err { return api.ErrSuccess },
+			Err:    errMissingHandlerContextArgument,
+		},
+		// no input -> invlaid context.Context type
+		{
+			Output: map[string]reflect.Type{},
+			Fn:     func(context.Context, int) api.Err { return api.ErrSuccess },
+			Err:    errMissingHandlerContextArgument,
+		},
 		// func can have output if not specified
 		{
 			Output: map[string]reflect.Type{},
-			Fn:     func() (*struct{}, api.Err) { return nil, api.ErrSuccess },
+			Fn:     func(context.Context) (*struct{}, api.Err) { return nil, api.ErrSuccess },
 			Err:    nil,
 		},
 		// missing output struct in func
@@ -306,7 +299,7 @@ func TestOutputCheck(t *testing.T) {
 				"Test1": reflect.TypeOf(int(0)),
 			},
 			Fn:  func() api.Err { return api.ErrSuccess },
-			Err: errMissingParamOutput,
+			Err: errWrongOutputArgumentType,
 		},
 		// output not a pointer
 		{
@@ -314,7 +307,7 @@ func TestOutputCheck(t *testing.T) {
 				"Test1": reflect.TypeOf(int(0)),
 			},
 			Fn:  func() (int, api.Err) { return 0, api.ErrSuccess },
-			Err: errMissingParamOutput,
+			Err: errWrongOutputArgumentType,
 		},
 		// output not a pointer to struct
 		{
@@ -322,7 +315,7 @@ func TestOutputCheck(t *testing.T) {
 				"Test1": reflect.TypeOf(int(0)),
 			},
 			Fn:  func() (*int, api.Err) { return nil, api.ErrSuccess },
-			Err: errMissingParamOutput,
+			Err: errWrongOutputArgumentType,
 		},
 		// unexported param name
 		{
@@ -338,7 +331,7 @@ func TestOutputCheck(t *testing.T) {
 				"Test1": reflect.TypeOf(int(0)),
 			},
 			Fn:  func() (*struct{}, api.Err) { return nil, api.ErrSuccess },
-			Err: errMissingParamFromConfig,
+			Err: errMissingConfigArgument,
 		},
 		// output field invalid type
 		{
@@ -371,12 +364,12 @@ func TestOutputCheck(t *testing.T) {
 			t.Parallel()
 
 			// mock spec
-			s := signature{
+			s := Signature{
 				Input:  nil,
 				Output: tcase.Output,
 			}
 
-			err := s.checkOutput(reflect.TypeOf(tcase.Fn))
+			err := s.ValidateOutput(reflect.TypeOf(tcase.Fn))
 			if err == nil && tcase.Err != nil {
 				t.Errorf("expected an error: '%s'", tcase.Err.Error())
 				t.FailNow()