From 56a13bc71168c14d41bfe0825e3c54c7306b10d2 Mon Sep 17 00:00:00 2001
From: Oleg Jukovec <oleg.jukovec@tarantool.org>
Date: Fri, 24 Mar 2023 16:27:30 +0300
Subject: [PATCH] api: add separate types for constants

Part of #158
---
 CHANGELOG.md                 |  3 ++
 connection.go                | 28 ++++++++-----
 connector.go                 |  6 +--
 const.go                     | 45 +-------------------
 crud/common.go               |  2 +-
 crud/request_test.go         | 50 +++++++++++-----------
 crud/tarantool_test.go       |  2 +-
 errors.go                    |  2 +-
 example_test.go              |  4 +-
 export_test.go               |  4 +-
 future.go                    |  2 +-
 future_test.go               | 20 ++++-----
 iterator.go                  | 19 +++++++++
 pool/connection_pool.go      |  9 ++--
 pool/connection_pool_test.go | 22 +++++-----
 pool/connector.go            |  7 ++--
 pool/connector_test.go       | 23 ++++++-----
 pool/pooler.go               |  9 ++--
 prepared.go                  |  6 +--
 protocol.go                  |  2 +-
 request.go                   | 80 +++++++++++++++++++++++++-----------
 request_test.go              | 44 ++++++++++----------
 response.go                  | 20 ++++++---
 settings/request.go          |  4 +-
 settings/request_test.go     | 44 ++++++++++----------
 stream.go                    |  6 +--
 tarantool_test.go            | 34 +++++++--------
 test_helpers/request_mock.go |  2 +-
 watch.go                     |  6 +--
 29 files changed, 271 insertions(+), 234 deletions(-)
 create mode 100644 iterator.go

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a96fd42b8..d161655b3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,12 +15,15 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 - Support CRUD API (#108)
 - An ability to replace a base network connection to a Tarantool
   instance (#265)
+- Enumeration types for response codes and iterators (#158)
+- A separate type for a request code (#158)
 
 ### Changed
 
 - connection_pool renamed to pool (#239)
 - msgpack/v5 is default at now (#236)
 - Call/NewCallRequest = Call17/NewCall17Request (#235)
+- Constants <Call>RequestCode renamed to RequestCode<Call> (#158)
 
 ### Removed
 
diff --git a/connection.go b/connection.go
index ad5aa76bd..768cda4bd 100644
--- a/connection.go
+++ b/connection.go
@@ -230,6 +230,19 @@ type connShard struct {
 	enc             *msgpack.Encoder
 }
 
+// RLimitActions is an enumeration type for an action to do when a rate limit
+// is riched.
+type RLimitAction int
+
+const (
+	// RLimitDrop immediately aborts request,
+	RLimitDrop RLimitAction = iota
+	// RLimitWait waits during timeout period for some request to be answered.
+	// If no request answered during timeout period, this request is aborted.
+	// If no timeout period is set, it will wait forever.
+	RLimitWait
+)
+
 // Opts is a way to configure Connection
 type Opts struct {
 	// Auth is an authentication method.
@@ -268,14 +281,9 @@ type Opts struct {
 	// It is disabled by default.
 	// See RLimitAction for possible actions when RateLimit.reached.
 	RateLimit uint
-	// RLimitAction tells what to do when RateLimit reached:
-	//   RLimitDrop - immediately abort request,
-	//   RLimitWait - wait during timeout period for some request to be answered.
-	//                If no request answered during timeout period, this request
-	//                is aborted.
-	//                If no timeout period is set, it will wait forever.
+	// RLimitAction tells what to do when RateLimit is reached.
 	// It is required if RateLimit is specified.
-	RLimitAction uint
+	RLimitAction RLimitAction
 	// Concurrency is amount of separate mutexes for request
 	// queues and buffers inside of connection.
 	// It is rounded up to nearest power of 2.
@@ -845,14 +853,14 @@ func (conn *Connection) reader(r io.Reader, c Conn) {
 		}
 
 		var fut *Future = nil
-		if resp.Code == EventCode {
+		if resp.Code == keyWatchEvent {
 			if event, err := readWatchEvent(&resp.buf); err == nil {
 				events <- event
 			} else {
 				conn.opts.Logger.Report(LogWatchEventReadFailed, conn, err)
 			}
 			continue
-		} else if resp.Code == PushCode {
+		} else if resp.Code == CodePush {
 			if fut = conn.peekFuture(resp.RequestId); fut != nil {
 				fut.AppendPush(resp)
 			}
@@ -1072,7 +1080,7 @@ func (conn *Connection) putFuture(fut *Future, req Request, streamId uint64) {
 		if fut = conn.fetchFuture(reqid); fut != nil {
 			resp := &Response{
 				RequestId: reqid,
-				Code:      OkCode,
+				Code:      CodeOk,
 			}
 			fut.SetResponse(resp)
 			conn.markDone(fut)
diff --git a/connector.go b/connector.go
index d93c69ec8..3aa2f9542 100644
--- a/connector.go
+++ b/connector.go
@@ -8,7 +8,7 @@ type Connector interface {
 	Ping() (resp *Response, err error)
 	ConfiguredTimeout() time.Duration
 
-	Select(space, index interface{}, offset, limit, iterator uint32, key interface{}) (resp *Response, err error)
+	Select(space, index interface{}, offset, limit uint32, iterator Iter, key interface{}) (resp *Response, err error)
 	Insert(space interface{}, tuple interface{}) (resp *Response, err error)
 	Replace(space interface{}, tuple interface{}) (resp *Response, err error)
 	Delete(space, index interface{}, key interface{}) (resp *Response, err error)
@@ -21,7 +21,7 @@ type Connector interface {
 	Execute(expr string, args interface{}) (resp *Response, err error)
 
 	GetTyped(space, index interface{}, key interface{}, result interface{}) (err error)
-	SelectTyped(space, index interface{}, offset, limit, iterator uint32, key interface{}, result interface{}) (err error)
+	SelectTyped(space, index interface{}, offset, limit uint32, iterator Iter, key interface{}, result interface{}) (err error)
 	InsertTyped(space interface{}, tuple interface{}, result interface{}) (err error)
 	ReplaceTyped(space interface{}, tuple interface{}, result interface{}) (err error)
 	DeleteTyped(space, index interface{}, key interface{}, result interface{}) (err error)
@@ -32,7 +32,7 @@ type Connector interface {
 	EvalTyped(expr string, args interface{}, result interface{}) (err error)
 	ExecuteTyped(expr string, args interface{}, result interface{}) (SQLInfo, []ColumnMetaData, error)
 
-	SelectAsync(space, index interface{}, offset, limit, iterator uint32, key interface{}) *Future
+	SelectAsync(space, index interface{}, offset, limit uint32, iterator Iter, key interface{}) *Future
 	InsertAsync(space interface{}, tuple interface{}) *Future
 	ReplaceAsync(space interface{}, tuple interface{}) *Future
 	DeleteAsync(space, index interface{}, key interface{}) *Future
diff --git a/const.go b/const.go
index 65d0d3b59..f24cc4b8b 100644
--- a/const.go
+++ b/const.go
@@ -31,6 +31,7 @@ const (
 	keySQLBind      = 0x41
 	keySQLInfo      = 0x42
 	keyStmtID       = 0x43
+	keyWatchEvent   = 0x4c
 	keyError        = 0x52 /* Extended error in >= 2.4 format. */
 	keyVersion      = 0x54
 	keyFeatures     = 0x55
@@ -40,47 +41,3 @@ const (
 	keyTxnIsolation = 0x59
 	keyAuthType     = 0x5b
 )
-
-const (
-	SelectRequestCode    = 1
-	InsertRequestCode    = 2
-	ReplaceRequestCode   = 3
-	UpdateRequestCode    = 4
-	DeleteRequestCode    = 5
-	Call16RequestCode    = 6 /* call in 1.6 format */
-	AuthRequestCode      = 7
-	EvalRequestCode      = 8
-	UpsertRequestCode    = 9
-	Call17RequestCode    = 10 /* call in >= 1.7 format */
-	ExecuteRequestCode   = 11
-	PrepareRequestCode   = 13
-	BeginRequestCode     = 14
-	CommitRequestCode    = 15
-	RollbackRequestCode  = 16
-	PingRequestCode      = 64
-	SubscribeRequestCode = 66
-	IdRequestCode        = 73
-	WatchRequestCode     = 74
-	UnwatchRequestCode   = 75
-	CallRequestCode      = Call17RequestCode
-
-	// https://github.com/fl00r/go-tarantool-1.6/issues/2
-
-	IterEq            = uint32(0) // key == x ASC order
-	IterReq           = uint32(1) // key == x DESC order
-	IterAll           = uint32(2) // all tuples
-	IterLt            = uint32(3) // key < x
-	IterLe            = uint32(4) // key <= x
-	IterGe            = uint32(5) // key >= x
-	IterGt            = uint32(6) // key > x
-	IterBitsAllSet    = uint32(7) // all bits from x are set in key
-	IterBitsAnySet    = uint32(8) // at least one x's bit is set
-	IterBitsAllNotSet = uint32(9) // all bits are not set
-
-	RLimitDrop = 1
-	RLimitWait = 2
-
-	OkCode    = uint32(0)
-	EventCode = uint32(0x4c)
-	PushCode  = uint32(0x80)
-)
diff --git a/crud/common.go b/crud/common.go
index bb882fb8b..42b78f7f6 100644
--- a/crud/common.go
+++ b/crud/common.go
@@ -68,7 +68,7 @@ func newCall(method string) *tarantool.CallRequest {
 }
 
 // Code returns IPROTO code for CRUD request.
-func (req baseRequest) Code() int32 {
+func (req baseRequest) Code() tarantool.RequestCode {
 	return req.impl.Code()
 }
 
diff --git a/crud/request_test.go b/crud/request_test.go
index 5a81e0d1e..d5a5c3148 100644
--- a/crud/request_test.go
+++ b/crud/request_test.go
@@ -22,7 +22,7 @@ const validSpace = "test" // Any valid value != default.
 const defaultSpace = 0    // And valid too.
 const defaultIndex = 0    // And valid too.
 
-const CrudRequestCode = tarantool.Call17RequestCode
+const RequestCodeCrud = tarantool.RequestCodeCall17
 
 var reqObject = crud.MapObject{
 	"id": uint(24),
@@ -167,31 +167,31 @@ func BenchmarkSelectRequest(b *testing.B) {
 func TestRequestsCodes(t *testing.T) {
 	tests := []struct {
 		req  tarantool.Request
-		code int32
+		code tarantool.RequestCode
 	}{
-		{req: crud.MakeInsertRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeInsertObjectRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeInsertManyRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeInsertObjectManyRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeGetRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeUpdateRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeDeleteRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeReplaceRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeReplaceObjectRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeReplaceManyRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeReplaceObjectManyRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeUpsertRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeUpsertObjectRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeUpsertManyRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeUpsertObjectManyRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeMinRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeMaxRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeSelectRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeTruncateRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeLenRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeCountRequest(validSpace), code: CrudRequestCode},
-		{req: crud.MakeStorageInfoRequest(), code: CrudRequestCode},
-		{req: crud.MakeStatsRequest(), code: CrudRequestCode},
+		{req: crud.MakeInsertRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeInsertObjectRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeInsertManyRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeInsertObjectManyRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeGetRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeUpdateRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeDeleteRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeReplaceRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeReplaceObjectRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeReplaceManyRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeReplaceObjectManyRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeUpsertRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeUpsertObjectRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeUpsertManyRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeUpsertObjectManyRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeMinRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeMaxRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeSelectRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeTruncateRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeLenRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeCountRequest(validSpace), code: RequestCodeCrud},
+		{req: crud.MakeStorageInfoRequest(), code: RequestCodeCrud},
+		{req: crud.MakeStatsRequest(), code: RequestCodeCrud},
 	}
 
 	for _, test := range tests {
diff --git a/crud/tarantool_test.go b/crud/tarantool_test.go
index 65cf72d10..90dd97887 100644
--- a/crud/tarantool_test.go
+++ b/crud/tarantool_test.go
@@ -374,7 +374,7 @@ func getCrudError(req tarantool.Request, crudError interface{}) (interface{}, er
 
 	code := req.Code()
 	if crudError != nil {
-		if code == tarantool.Call17RequestCode {
+		if code == tarantool.RequestCodeCall17 {
 			return crudError, nil
 		}
 
diff --git a/errors.go b/errors.go
index 980e4e5bd..e96ef5c01 100644
--- a/errors.go
+++ b/errors.go
@@ -4,7 +4,7 @@ import "fmt"
 
 // Error is wrapper around error returned by Tarantool.
 type Error struct {
-	Code         uint32
+	Code         Code
 	Msg          string
 	ExtendedInfo *BoxError
 }
diff --git a/example_test.go b/example_test.go
index a7582647a..174455025 100644
--- a/example_test.go
+++ b/example_test.go
@@ -591,10 +591,10 @@ func ExampleFuture_GetIterator() {
 	var it tarantool.ResponseIterator
 	for it = fut.GetIterator().WithTimeout(timeout); it.Next(); {
 		resp := it.Value()
-		if resp.Code == tarantool.PushCode {
+		if resp.Code == tarantool.CodePush {
 			// It is a push message.
 			fmt.Printf("push message: %v\n", resp.Data[0])
-		} else if resp.Code == tarantool.OkCode {
+		} else if resp.Code == tarantool.CodeOk {
 			// It is a regular response.
 			fmt.Printf("response: %v", resp.Data[0])
 		} else {
diff --git a/export_test.go b/export_test.go
index 879d345ac..23e17bae6 100644
--- a/export_test.go
+++ b/export_test.go
@@ -24,8 +24,8 @@ func RefImplPingBody(enc *msgpack.Encoder) error {
 
 // RefImplSelectBody is reference implementation for filling of a select
 // request's body.
-func RefImplSelectBody(enc *msgpack.Encoder, space, index, offset, limit, iterator uint32,
-	key, after interface{}, fetchPos bool) error {
+func RefImplSelectBody(enc *msgpack.Encoder, space, index, offset, limit uint32,
+	iterator Iter, key, after interface{}, fetchPos bool) error {
 	return fillSelect(enc, space, index, offset, limit, iterator, key, after, fetchPos)
 }
 
diff --git a/future.go b/future.go
index a92a4c091..db87a0dbc 100644
--- a/future.go
+++ b/future.go
@@ -135,7 +135,7 @@ func (fut *Future) AppendPush(resp *Response) {
 	if fut.isDone() {
 		return
 	}
-	resp.Code = PushCode
+	resp.Code = CodePush
 	fut.pushes = append(fut.pushes, resp)
 
 	fut.ready <- struct{}{}
diff --git a/future_test.go b/future_test.go
index 274bee7d5..cd6050399 100644
--- a/future_test.go
+++ b/future_test.go
@@ -10,7 +10,7 @@ import (
 )
 
 func assertResponseIteratorValue(t testing.TB, it ResponseIterator,
-	code uint32, resp *Response) {
+	code Code, resp *Response) {
 	t.Helper()
 
 	if it.Err() != nil {
@@ -56,7 +56,7 @@ func TestFutureGetIteratorNoResponse(t *testing.T) {
 	fut.AppendPush(push)
 
 	if it := fut.GetIterator(); it.Next() {
-		assertResponseIteratorValue(t, it, PushCode, push)
+		assertResponseIteratorValue(t, it, CodePush, push)
 		if it.Next() == true {
 			t.Errorf("An unexpected next value.")
 		}
@@ -72,7 +72,7 @@ func TestFutureGetIteratorNoResponseTimeout(t *testing.T) {
 	fut.AppendPush(push)
 
 	if it := fut.GetIterator().WithTimeout(1 * time.Nanosecond); it.Next() {
-		assertResponseIteratorValue(t, it, PushCode, push)
+		assertResponseIteratorValue(t, it, CodePush, push)
 		if it.Next() == true {
 			t.Errorf("An unexpected next value.")
 		}
@@ -99,10 +99,10 @@ func TestFutureGetIteratorResponseOnTimeout(t *testing.T) {
 		var it ResponseIterator
 		var cnt = 0
 		for it = fut.GetIterator().WithTimeout(5 * time.Second); it.Next(); {
-			code := PushCode
+			code := CodePush
 			r := push
 			if cnt == 1 {
-				code = OkCode
+				code = CodeOk
 				r = resp
 			}
 			assertResponseIteratorValue(t, it, code, r)
@@ -131,7 +131,7 @@ func TestFutureGetIteratorFirstResponse(t *testing.T) {
 	fut.SetResponse(resp2)
 
 	if it := fut.GetIterator(); it.Next() {
-		assertResponseIteratorValue(t, it, OkCode, resp1)
+		assertResponseIteratorValue(t, it, CodeOk, resp1)
 		if it.Next() == true {
 			t.Errorf("An unexpected next value.")
 		}
@@ -163,7 +163,7 @@ func TestFutureGetIteratorResponse(t *testing.T) {
 	responses := []*Response{
 		{},
 		{},
-		{Code: OkCode},
+		{Code: CodeOk},
 	}
 	fut := NewFuture()
 	for i, resp := range responses {
@@ -181,9 +181,9 @@ func TestFutureGetIteratorResponse(t *testing.T) {
 	for _, it := range its {
 		var cnt = 0
 		for it.Next() {
-			code := PushCode
+			code := CodePush
 			if cnt == len(responses)-1 {
-				code = OkCode
+				code = CodeOk
 			}
 			assertResponseIteratorValue(t, it, code, responses[cnt])
 			cnt += 1
@@ -216,7 +216,7 @@ func TestFutureGetIteratorError(t *testing.T) {
 	for _, it := range its {
 		var cnt = 0
 		for it.Next() {
-			code := PushCode
+			code := CodePush
 			assertResponseIteratorValue(t, it, code, responses[cnt])
 			cnt += 1
 		}
diff --git a/iterator.go b/iterator.go
new file mode 100644
index 000000000..353b74cd2
--- /dev/null
+++ b/iterator.go
@@ -0,0 +1,19 @@
+package tarantool
+
+// Iter is an enumeration type of a select iterator.
+type Iter uint32
+
+// https://github.com/fl00r/go-tarantool-1.6/issues/2
+
+const (
+	IterEq            Iter = 0 // key == x ASC order
+	IterReq           Iter = 1 // key == x DESC order
+	IterAll           Iter = 2 // all tuples
+	IterLt            Iter = 3 // key < x
+	IterLe            Iter = 4 // key <= x
+	IterGe            Iter = 5 // key >= x
+	IterGt            Iter = 6 // key > x
+	IterBitsAllSet    Iter = 7 // all bits from x are set in key
+	IterBitsAnySet    Iter = 8 // at least one x's bit is set
+	IterBitsAllNotSet Iter = 9 // all bits are not set
+)
diff --git a/pool/connection_pool.go b/pool/connection_pool.go
index 53dc3b6bf..4f4e21998 100644
--- a/pool/connection_pool.go
+++ b/pool/connection_pool.go
@@ -277,7 +277,8 @@ func (connPool *ConnectionPool) Ping(userMode Mode) (*tarantool.Response, error)
 }
 
 // Select performs select to box space.
-func (connPool *ConnectionPool) Select(space, index interface{}, offset, limit, iterator uint32, key interface{}, userMode ...Mode) (resp *tarantool.Response, err error) {
+func (connPool *ConnectionPool) Select(space, index interface{}, offset, limit uint32,
+	iterator tarantool.Iter, key interface{}, userMode ...Mode) (resp *tarantool.Response, err error) {
 	conn, err := connPool.getConnByMode(ANY, userMode)
 	if err != nil {
 		return nil, err
@@ -409,7 +410,8 @@ func (connPool *ConnectionPool) GetTyped(space, index interface{}, key interface
 }
 
 // SelectTyped performs select to box space and fills typed result.
-func (connPool *ConnectionPool) SelectTyped(space, index interface{}, offset, limit, iterator uint32, key interface{}, result interface{}, userMode ...Mode) (err error) {
+func (connPool *ConnectionPool) SelectTyped(space, index interface{}, offset, limit uint32,
+	iterator tarantool.Iter, key interface{}, result interface{}, userMode ...Mode) (err error) {
 	conn, err := connPool.getConnByMode(ANY, userMode)
 	if err != nil {
 		return err
@@ -517,7 +519,8 @@ func (connPool *ConnectionPool) ExecuteTyped(expr string, args interface{}, resu
 }
 
 // SelectAsync sends select request to Tarantool and returns Future.
-func (connPool *ConnectionPool) SelectAsync(space, index interface{}, offset, limit, iterator uint32, key interface{}, userMode ...Mode) *tarantool.Future {
+func (connPool *ConnectionPool) SelectAsync(space, index interface{}, offset, limit uint32,
+	iterator tarantool.Iter, key interface{}, userMode ...Mode) *tarantool.Future {
 	conn, err := connPool.getConnByMode(ANY, userMode)
 	if err != nil {
 		return newErrorFuture(err)
diff --git a/pool/connection_pool_test.go b/pool/connection_pool_test.go
index 1d68e3f48..40dfbd2b2 100644
--- a/pool/connection_pool_test.go
+++ b/pool/connection_pool_test.go
@@ -1809,7 +1809,7 @@ func TestNewPrepared(t *testing.T) {
 	if resp == nil {
 		t.Fatalf("nil response")
 	}
-	if resp.Code != tarantool.OkCode {
+	if resp.Code != tarantool.CodeOk {
 		t.Fatalf("failed to execute prepared: code %d", resp.Code)
 	}
 	if reflect.DeepEqual(resp.Data[0], []interface{}{1, "test"}) {
@@ -1827,7 +1827,7 @@ func TestNewPrepared(t *testing.T) {
 	if err != nil {
 		t.Errorf("failed to unprepare prepared statement: %v", err)
 	}
-	if resp.Code != tarantool.OkCode {
+	if resp.Code != tarantool.CodeOk {
 		t.Errorf("failed to unprepare prepared statement: code %d", resp.Code)
 	}
 
@@ -1895,7 +1895,7 @@ func TestStream_Commit(t *testing.T) {
 	resp, err = stream.Do(req).Get()
 	require.Nilf(t, err, "failed to Begin")
 	require.NotNilf(t, resp, "response is nil after Begin")
-	require.Equalf(t, tarantool.OkCode, resp.Code, "failed to Begin: wrong code returned")
+	require.Equalf(t, tarantool.CodeOk, resp.Code, "failed to Begin: wrong code returned")
 
 	// Insert in stream
 	req = tarantool.NewInsertRequest(spaceName).
@@ -1903,7 +1903,7 @@ func TestStream_Commit(t *testing.T) {
 	resp, err = stream.Do(req).Get()
 	require.Nilf(t, err, "failed to Insert")
 	require.NotNilf(t, resp, "response is nil after Insert")
-	require.Equalf(t, tarantool.OkCode, resp.Code, "failed to Insert: wrong code returned")
+	require.Equalf(t, tarantool.CodeOk, resp.Code, "failed to Insert: wrong code returned")
 
 	// Connect to servers[2] to check if tuple
 	// was inserted outside of stream on RW instance
@@ -1947,7 +1947,7 @@ func TestStream_Commit(t *testing.T) {
 	resp, err = stream.Do(req).Get()
 	require.Nilf(t, err, "failed to Commit")
 	require.NotNilf(t, resp, "response is nil after Commit")
-	require.Equalf(t, tarantool.OkCode, resp.Code, "failed to Commit: wrong code returned")
+	require.Equalf(t, tarantool.CodeOk, resp.Code, "failed to Commit: wrong code returned")
 
 	// Select outside of transaction
 	resp, err = conn.Do(selectReq).Get()
@@ -1994,7 +1994,7 @@ func TestStream_Rollback(t *testing.T) {
 	resp, err = stream.Do(req).Get()
 	require.Nilf(t, err, "failed to Begin")
 	require.NotNilf(t, resp, "response is nil after Begin")
-	require.Equalf(t, tarantool.OkCode, resp.Code, "failed to Begin: wrong code returned")
+	require.Equalf(t, tarantool.CodeOk, resp.Code, "failed to Begin: wrong code returned")
 
 	// Insert in stream
 	req = tarantool.NewInsertRequest(spaceName).
@@ -2002,7 +2002,7 @@ func TestStream_Rollback(t *testing.T) {
 	resp, err = stream.Do(req).Get()
 	require.Nilf(t, err, "failed to Insert")
 	require.NotNilf(t, resp, "response is nil after Insert")
-	require.Equalf(t, tarantool.OkCode, resp.Code, "failed to Insert: wrong code returned")
+	require.Equalf(t, tarantool.CodeOk, resp.Code, "failed to Insert: wrong code returned")
 
 	// Connect to servers[2] to check if tuple
 	// was not inserted outside of stream on RW instance
@@ -2045,7 +2045,7 @@ func TestStream_Rollback(t *testing.T) {
 	resp, err = stream.Do(req).Get()
 	require.Nilf(t, err, "failed to Rollback")
 	require.NotNilf(t, resp, "response is nil after Rollback")
-	require.Equalf(t, tarantool.OkCode, resp.Code, "failed to Rollback: wrong code returned")
+	require.Equalf(t, tarantool.CodeOk, resp.Code, "failed to Rollback: wrong code returned")
 
 	// Select outside of transaction
 	resp, err = conn.Do(selectReq).Get()
@@ -2099,7 +2099,7 @@ func TestStream_TxnIsolationLevel(t *testing.T) {
 		resp, err = stream.Do(req).Get()
 		require.Nilf(t, err, "failed to Begin")
 		require.NotNilf(t, resp, "response is nil after Begin")
-		require.Equalf(t, tarantool.OkCode, resp.Code, "wrong code returned")
+		require.Equalf(t, tarantool.CodeOk, resp.Code, "wrong code returned")
 
 		// Insert in stream
 		req = tarantool.NewInsertRequest(spaceName).
@@ -2107,7 +2107,7 @@ func TestStream_TxnIsolationLevel(t *testing.T) {
 		resp, err = stream.Do(req).Get()
 		require.Nilf(t, err, "failed to Insert")
 		require.NotNilf(t, resp, "response is nil after Insert")
-		require.Equalf(t, tarantool.OkCode, resp.Code, "wrong code returned")
+		require.Equalf(t, tarantool.CodeOk, resp.Code, "wrong code returned")
 
 		// Select not related to the transaction
 		// while transaction is not committed
@@ -2145,7 +2145,7 @@ func TestStream_TxnIsolationLevel(t *testing.T) {
 		resp, err = stream.Do(req).Get()
 		require.Nilf(t, err, "failed to Rollback")
 		require.NotNilf(t, resp, "response is nil after Rollback")
-		require.Equalf(t, tarantool.OkCode, resp.Code, "wrong code returned")
+		require.Equalf(t, tarantool.CodeOk, resp.Code, "wrong code returned")
 
 		// Select outside of transaction
 		resp, err = conn.Do(selectReq).Get()
diff --git a/pool/connector.go b/pool/connector.go
index 2cf094858..ffa3edd26 100644
--- a/pool/connector.go
+++ b/pool/connector.go
@@ -63,7 +63,7 @@ func (c *ConnectorAdapter) ConfiguredTimeout() time.Duration {
 
 // Select performs select to box space.
 func (c *ConnectorAdapter) Select(space, index interface{},
-	offset, limit, iterator uint32,
+	offset, limit uint32, iterator tarantool.Iter,
 	key interface{}) (*tarantool.Response, error) {
 	return c.pool.Select(space, index, offset, limit, iterator, key, c.mode)
 }
@@ -143,7 +143,7 @@ func (c *ConnectorAdapter) GetTyped(space, index interface{},
 
 // SelectTyped performs select to box space and fills typed result.
 func (c *ConnectorAdapter) SelectTyped(space, index interface{},
-	offset, limit, iterator uint32,
+	offset, limit uint32, iterator tarantool.Iter,
 	key interface{}, result interface{}) error {
 	return c.pool.SelectTyped(space, index, offset, limit, iterator, key, result, c.mode)
 }
@@ -210,7 +210,8 @@ func (c *ConnectorAdapter) ExecuteTyped(expr string, args interface{},
 
 // SelectAsync sends select request to Tarantool and returns Future.
 func (c *ConnectorAdapter) SelectAsync(space, index interface{},
-	offset, limit, iterator uint32, key interface{}) *tarantool.Future {
+	offset, limit uint32, iterator tarantool.Iter,
+	key interface{}) *tarantool.Future {
 	return c.pool.SelectAsync(space, index, offset, limit, iterator, key, c.mode)
 }
 
diff --git a/pool/connector_test.go b/pool/connector_test.go
index d4d197607..34b18f584 100644
--- a/pool/connector_test.go
+++ b/pool/connector_test.go
@@ -125,13 +125,14 @@ func TestConnectorConfiguredTimeoutWithError(t *testing.T) {
 
 type baseRequestMock struct {
 	Pooler
-	called                  int
-	functionName            string
-	offset, limit, iterator uint32
-	space, index            interface{}
-	args, tuple, key, ops   interface{}
-	result                  interface{}
-	mode                    Mode
+	called                int
+	functionName          string
+	offset, limit         uint32
+	iterator              tarantool.Iter
+	space, index          interface{}
+	args, tuple, key, ops interface{}
+	result                interface{}
+	mode                  Mode
 }
 
 var reqResp *tarantool.Response = &tarantool.Response{}
@@ -141,7 +142,7 @@ var reqFuture *tarantool.Future = &tarantool.Future{}
 var reqFunctionName string = "any_name"
 var reqOffset uint32 = 1
 var reqLimit uint32 = 2
-var reqIterator uint32 = 3
+var reqIterator tarantool.Iter = tarantool.IterEq
 var reqSpace interface{} = []interface{}{1}
 var reqIndex interface{} = []interface{}{2}
 var reqArgs interface{} = []interface{}{3}
@@ -188,7 +189,7 @@ type selectMock struct {
 }
 
 func (m *selectMock) Select(space, index interface{},
-	offset, limit, iterator uint32, key interface{},
+	offset, limit uint32, iterator tarantool.Iter, key interface{},
 	mode ...Mode) (*tarantool.Response, error) {
 	m.called++
 	m.space = space
@@ -224,7 +225,7 @@ type selectTypedMock struct {
 }
 
 func (m *selectTypedMock) SelectTyped(space, index interface{},
-	offset, limit, iterator uint32, key interface{},
+	offset, limit uint32, iterator tarantool.Iter, key interface{},
 	result interface{}, mode ...Mode) error {
 	m.called++
 	m.space = space
@@ -262,7 +263,7 @@ type selectAsyncMock struct {
 }
 
 func (m *selectAsyncMock) SelectAsync(space, index interface{},
-	offset, limit, iterator uint32, key interface{},
+	offset, limit uint32, iterator tarantool.Iter, key interface{},
 	mode ...Mode) *tarantool.Future {
 	m.called++
 	m.space = space
diff --git a/pool/pooler.go b/pool/pooler.go
index 626c5af93..4ac9088b6 100644
--- a/pool/pooler.go
+++ b/pool/pooler.go
@@ -13,7 +13,8 @@ type Pooler interface {
 	Ping(mode Mode) (*tarantool.Response, error)
 	ConfiguredTimeout(mode Mode) (time.Duration, error)
 
-	Select(space, index interface{}, offset, limit, iterator uint32,
+	Select(space, index interface{}, offset, limit uint32,
+		iterator tarantool.Iter,
 		key interface{}, mode ...Mode) (*tarantool.Response, error)
 	Insert(space interface{}, tuple interface{},
 		mode ...Mode) (*tarantool.Response, error)
@@ -38,7 +39,8 @@ type Pooler interface {
 
 	GetTyped(space, index interface{}, key interface{}, result interface{},
 		mode ...Mode) error
-	SelectTyped(space, index interface{}, offset, limit, iterator uint32,
+	SelectTyped(space, index interface{}, offset, limit uint32,
+		iterator tarantool.Iter,
 		key interface{}, result interface{}, mode ...Mode) error
 	InsertTyped(space interface{}, tuple interface{}, result interface{},
 		mode ...Mode) error
@@ -59,7 +61,8 @@ type Pooler interface {
 	ExecuteTyped(expr string, args interface{}, result interface{},
 		mode Mode) (tarantool.SQLInfo, []tarantool.ColumnMetaData, error)
 
-	SelectAsync(space, index interface{}, offset, limit, iterator uint32,
+	SelectAsync(space, index interface{}, offset, limit uint32,
+		iterator tarantool.Iter,
 		key interface{}, mode ...Mode) *tarantool.Future
 	InsertAsync(space interface{}, tuple interface{},
 		mode ...Mode) *tarantool.Future
diff --git a/prepared.go b/prepared.go
index ce90fbeb6..320d35638 100644
--- a/prepared.go
+++ b/prepared.go
@@ -69,7 +69,7 @@ type PrepareRequest struct {
 // NewPrepareRequest returns a new empty PrepareRequest.
 func NewPrepareRequest(expr string) *PrepareRequest {
 	req := new(PrepareRequest)
-	req.requestCode = PrepareRequestCode
+	req.requestCode = RequestCodePrepare
 	req.expr = expr
 	return req
 }
@@ -100,7 +100,7 @@ type UnprepareRequest struct {
 // NewUnprepareRequest returns a new empty UnprepareRequest.
 func NewUnprepareRequest(stmt *Prepared) *UnprepareRequest {
 	req := new(UnprepareRequest)
-	req.requestCode = PrepareRequestCode
+	req.requestCode = RequestCodePrepare
 	req.stmt = stmt
 	return req
 }
@@ -137,7 +137,7 @@ type ExecutePreparedRequest struct {
 // NewExecutePreparedRequest returns a new empty preparedExecuteRequest.
 func NewExecutePreparedRequest(stmt *Prepared) *ExecutePreparedRequest {
 	req := new(ExecutePreparedRequest)
-	req.requestCode = ExecuteRequestCode
+	req.requestCode = RequestCodeExecute
 	req.stmt = stmt
 	req.args = []interface{}{}
 	return req
diff --git a/protocol.go b/protocol.go
index ead0edec4..5e0b001d2 100644
--- a/protocol.go
+++ b/protocol.go
@@ -130,7 +130,7 @@ func fillId(enc *msgpack.Encoder, protocolInfo ProtocolInfo) error {
 // NewIdRequest returns a new IdRequest.
 func NewIdRequest(protocolInfo ProtocolInfo) *IdRequest {
 	req := new(IdRequest)
-	req.requestCode = IdRequestCode
+	req.requestCode = RequestCodeId
 	req.protocolInfo = protocolInfo.Clone()
 	return req
 }
diff --git a/request.go b/request.go
index 4df5e059e..4f6efb0b7 100644
--- a/request.go
+++ b/request.go
@@ -30,7 +30,7 @@ func fillSearch(enc *msgpack.Encoder, spaceNo, indexNo uint32, key interface{})
 	return enc.Encode(key)
 }
 
-func fillIterator(enc *msgpack.Encoder, offset, limit, iterator uint32) error {
+func fillIterator(enc *msgpack.Encoder, offset, limit uint32, iterator Iter) error {
 	if err := enc.EncodeUint(keyIterator); err != nil {
 		return err
 	}
@@ -65,7 +65,8 @@ func fillInsert(enc *msgpack.Encoder, spaceNo uint32, tuple interface{}) error {
 	return enc.Encode(tuple)
 }
 
-func fillSelect(enc *msgpack.Encoder, spaceNo, indexNo, offset, limit, iterator uint32,
+func fillSelect(enc *msgpack.Encoder, spaceNo, indexNo, offset, limit uint32,
+	iterator Iter,
 	key, after interface{}, fetchPos bool) error {
 	mapLen := 6
 	if fetchPos {
@@ -173,7 +174,8 @@ func (conn *Connection) Ping() (resp *Response, err error) {
 // Select performs select to box space.
 //
 // It is equal to conn.SelectAsync(...).Get().
-func (conn *Connection) Select(space, index interface{}, offset, limit, iterator uint32, key interface{}) (resp *Response, err error) {
+func (conn *Connection) Select(space, index interface{}, offset, limit uint32,
+	iterator Iter, key interface{}) (resp *Response, err error) {
 	return conn.SelectAsync(space, index, offset, limit, iterator, key).Get()
 }
 
@@ -293,7 +295,8 @@ func (conn *Connection) GetTyped(space, index interface{}, key interface{}, resu
 // SelectTyped performs select to box space and fills typed result.
 //
 // It is equal to conn.SelectAsync(space, index, offset, limit, iterator, key).GetTyped(&result)
-func (conn *Connection) SelectTyped(space, index interface{}, offset, limit, iterator uint32, key interface{}, result interface{}) (err error) {
+func (conn *Connection) SelectTyped(space, index interface{}, offset, limit uint32,
+	iterator Iter, key interface{}, result interface{}) (err error) {
 	return conn.SelectAsync(space, index, offset, limit, iterator, key).GetTyped(result)
 }
 
@@ -372,7 +375,8 @@ func (conn *Connection) ExecuteTyped(expr string, args interface{}, result inter
 }
 
 // SelectAsync sends select request to Tarantool and returns Future.
-func (conn *Connection) SelectAsync(space, index interface{}, offset, limit, iterator uint32, key interface{}) *Future {
+func (conn *Connection) SelectAsync(space, index interface{}, offset, limit uint32,
+	iterator Iter, key interface{}) *Future {
 	req := NewSelectRequest(space).
 		Index(index).
 		Offset(offset).
@@ -597,11 +601,38 @@ func encodeSQLBind(enc *msgpack.Encoder, from interface{}) error {
 	return nil
 }
 
+// RequestCode is a code of a request.
+type RequestCode int32
+
+const (
+	RequestCodeSelect    RequestCode = 1
+	RequestCodeInsert    RequestCode = 2
+	RequestCodeReplace   RequestCode = 3
+	RequestCodeUpdate    RequestCode = 4
+	RequestCodeDelete    RequestCode = 5
+	RequestCodeCall16    RequestCode = 6 /* call in 1.6 format */
+	RequestCodeAuth      RequestCode = 7
+	RequestCodeEval      RequestCode = 8
+	RequestCodeUpsert    RequestCode = 9
+	RequestCodeCall17    RequestCode = 10 /* call in >= 1.7 format */
+	RequestCodeExecute   RequestCode = 11
+	RequestCodePrepare   RequestCode = 13
+	RequestCodeBegin     RequestCode = 14
+	RequestCodeCommit    RequestCode = 15
+	RequestCodeRollback  RequestCode = 16
+	RequestCodePing      RequestCode = 64
+	RequestCodeSubscribe RequestCode = 66
+	RequestCodeId        RequestCode = 73
+	RequestCodeWatch     RequestCode = 74
+	RequestCodeUnwatch   RequestCode = 75
+	RequestCodeCall      RequestCode = RequestCodeCall17
+)
+
 // Request is an interface that provides the necessary data to create a request
 // that will be sent to a tarantool instance.
 type Request interface {
 	// Code returns a IPROTO code for the request.
-	Code() int32
+	Code() RequestCode
 	// Body fills an msgpack.Encoder with a request body.
 	Body(resolver SchemaResolver, enc *msgpack.Encoder) error
 	// Ctx returns a context of the request.
@@ -619,13 +650,13 @@ type ConnectedRequest interface {
 }
 
 type baseRequest struct {
-	requestCode int32
+	requestCode RequestCode
 	async       bool
 	ctx         context.Context
 }
 
 // Code returns a IPROTO code for the request.
-func (req *baseRequest) Code() int32 {
+func (req *baseRequest) Code() RequestCode {
 	return req.requestCode
 }
 
@@ -689,8 +720,8 @@ func newPapSha256AuthRequest(user, password string) authRequest {
 }
 
 // Code returns a IPROTO code for the request.
-func (req authRequest) Code() int32 {
-	return AuthRequestCode
+func (req authRequest) Code() RequestCode {
+	return RequestCodeAuth
 }
 
 // Async returns true if the request does not require a response.
@@ -720,7 +751,7 @@ type PingRequest struct {
 // NewPingRequest returns a new PingRequest.
 func NewPingRequest() *PingRequest {
 	req := new(PingRequest)
-	req.requestCode = PingRequestCode
+	req.requestCode = RequestCodePing
 	return req
 }
 
@@ -745,14 +776,15 @@ func (req *PingRequest) Context(ctx context.Context) *PingRequest {
 type SelectRequest struct {
 	spaceIndexRequest
 	isIteratorSet, fetchPos bool
-	offset, limit, iterator uint32
+	offset, limit           uint32
+	iterator                Iter
 	key, after              interface{}
 }
 
 // NewSelectRequest returns a new empty SelectRequest.
 func NewSelectRequest(space interface{}) *SelectRequest {
 	req := new(SelectRequest)
-	req.requestCode = SelectRequestCode
+	req.requestCode = RequestCodeSelect
 	req.setSpace(space)
 	req.isIteratorSet = false
 	req.fetchPos = false
@@ -786,7 +818,7 @@ func (req *SelectRequest) Limit(limit uint32) *SelectRequest {
 
 // Iterator set the iterator for the select request.
 // Note: default value is IterAll if key is not set or IterEq otherwise.
-func (req *SelectRequest) Iterator(iterator uint32) *SelectRequest {
+func (req *SelectRequest) Iterator(iterator Iter) *SelectRequest {
 	req.iterator = iterator
 	req.isIteratorSet = true
 	return req
@@ -858,7 +890,7 @@ type InsertRequest struct {
 // NewInsertRequest returns a new empty InsertRequest.
 func NewInsertRequest(space interface{}) *InsertRequest {
 	req := new(InsertRequest)
-	req.requestCode = InsertRequestCode
+	req.requestCode = RequestCodeInsert
 	req.setSpace(space)
 	req.tuple = []interface{}{}
 	return req
@@ -902,7 +934,7 @@ type ReplaceRequest struct {
 // NewReplaceRequest returns a new empty ReplaceRequest.
 func NewReplaceRequest(space interface{}) *ReplaceRequest {
 	req := new(ReplaceRequest)
-	req.requestCode = ReplaceRequestCode
+	req.requestCode = RequestCodeReplace
 	req.setSpace(space)
 	req.tuple = []interface{}{}
 	return req
@@ -946,7 +978,7 @@ type DeleteRequest struct {
 // NewDeleteRequest returns a new empty DeleteRequest.
 func NewDeleteRequest(space interface{}) *DeleteRequest {
 	req := new(DeleteRequest)
-	req.requestCode = DeleteRequestCode
+	req.requestCode = RequestCodeDelete
 	req.setSpace(space)
 	req.key = []interface{}{}
 	return req
@@ -998,7 +1030,7 @@ type UpdateRequest struct {
 // NewUpdateRequest returns a new empty UpdateRequest.
 func NewUpdateRequest(space interface{}) *UpdateRequest {
 	req := new(UpdateRequest)
-	req.requestCode = UpdateRequestCode
+	req.requestCode = RequestCodeUpdate
 	req.setSpace(space)
 	req.key = []interface{}{}
 	req.ops = []interface{}{}
@@ -1060,7 +1092,7 @@ type UpsertRequest struct {
 // NewUpsertRequest returns a new empty UpsertRequest.
 func NewUpsertRequest(space interface{}) *UpsertRequest {
 	req := new(UpsertRequest)
-	req.requestCode = UpsertRequestCode
+	req.requestCode = RequestCodeUpsert
 	req.setSpace(space)
 	req.tuple = []interface{}{}
 	req.ops = []interface{}{}
@@ -1116,7 +1148,7 @@ type CallRequest struct {
 // Tarantool >= 1.7.
 func NewCallRequest(function string) *CallRequest {
 	req := new(CallRequest)
-	req.requestCode = CallRequestCode
+	req.requestCode = RequestCodeCall
 	req.function = function
 	return req
 }
@@ -1153,7 +1185,7 @@ func (req *CallRequest) Context(ctx context.Context) *CallRequest {
 // Deprecated since Tarantool 1.7.2.
 func NewCall16Request(function string) *CallRequest {
 	req := NewCallRequest(function)
-	req.requestCode = Call16RequestCode
+	req.requestCode = RequestCodeCall16
 	return req
 }
 
@@ -1161,7 +1193,7 @@ func NewCall16Request(function string) *CallRequest {
 // Tarantool >= 1.7.
 func NewCall17Request(function string) *CallRequest {
 	req := NewCallRequest(function)
-	req.requestCode = Call17RequestCode
+	req.requestCode = RequestCodeCall17
 	return req
 }
 
@@ -1176,7 +1208,7 @@ type EvalRequest struct {
 // NewEvalRequest returns a new empty EvalRequest.
 func NewEvalRequest(expr string) *EvalRequest {
 	req := new(EvalRequest)
-	req.requestCode = EvalRequestCode
+	req.requestCode = RequestCodeEval
 	req.expr = expr
 	req.args = []interface{}{}
 	return req
@@ -1216,7 +1248,7 @@ type ExecuteRequest struct {
 // NewExecuteRequest returns a new empty ExecuteRequest.
 func NewExecuteRequest(expr string) *ExecuteRequest {
 	req := new(ExecuteRequest)
-	req.requestCode = ExecuteRequestCode
+	req.requestCode = RequestCodeExecute
 	req.expr = expr
 	req.args = []interface{}{}
 	return req
diff --git a/request_test.go b/request_test.go
index b9a3a656d..197b87bc4 100644
--- a/request_test.go
+++ b/request_test.go
@@ -172,29 +172,29 @@ func TestRequestsInvalidIndex(t *testing.T) {
 func TestRequestsCodes(t *testing.T) {
 	tests := []struct {
 		req  Request
-		code int32
+		code RequestCode
 	}{
-		{req: NewSelectRequest(validSpace), code: SelectRequestCode},
-		{req: NewUpdateRequest(validSpace), code: UpdateRequestCode},
-		{req: NewUpsertRequest(validSpace), code: UpsertRequestCode},
-		{req: NewInsertRequest(validSpace), code: InsertRequestCode},
-		{req: NewReplaceRequest(validSpace), code: ReplaceRequestCode},
-		{req: NewDeleteRequest(validSpace), code: DeleteRequestCode},
-		{req: NewCallRequest(validExpr), code: CallRequestCode},
-		{req: NewCallRequest(validExpr), code: Call17RequestCode},
-		{req: NewCall16Request(validExpr), code: Call16RequestCode},
-		{req: NewCall17Request(validExpr), code: Call17RequestCode},
-		{req: NewEvalRequest(validExpr), code: EvalRequestCode},
-		{req: NewExecuteRequest(validExpr), code: ExecuteRequestCode},
-		{req: NewPingRequest(), code: PingRequestCode},
-		{req: NewPrepareRequest(validExpr), code: PrepareRequestCode},
-		{req: NewUnprepareRequest(validStmt), code: PrepareRequestCode},
-		{req: NewExecutePreparedRequest(validStmt), code: ExecuteRequestCode},
-		{req: NewBeginRequest(), code: BeginRequestCode},
-		{req: NewCommitRequest(), code: CommitRequestCode},
-		{req: NewRollbackRequest(), code: RollbackRequestCode},
-		{req: NewIdRequest(validProtocolInfo), code: IdRequestCode},
-		{req: NewBroadcastRequest(validKey), code: CallRequestCode},
+		{req: NewSelectRequest(validSpace), code: RequestCodeSelect},
+		{req: NewUpdateRequest(validSpace), code: RequestCodeUpdate},
+		{req: NewUpsertRequest(validSpace), code: RequestCodeUpsert},
+		{req: NewInsertRequest(validSpace), code: RequestCodeInsert},
+		{req: NewReplaceRequest(validSpace), code: RequestCodeReplace},
+		{req: NewDeleteRequest(validSpace), code: RequestCodeDelete},
+		{req: NewCallRequest(validExpr), code: RequestCodeCall},
+		{req: NewCallRequest(validExpr), code: RequestCodeCall17},
+		{req: NewCall16Request(validExpr), code: RequestCodeCall16},
+		{req: NewCall17Request(validExpr), code: RequestCodeCall17},
+		{req: NewEvalRequest(validExpr), code: RequestCodeEval},
+		{req: NewExecuteRequest(validExpr), code: RequestCodeExecute},
+		{req: NewPingRequest(), code: RequestCodePing},
+		{req: NewPrepareRequest(validExpr), code: RequestCodePrepare},
+		{req: NewUnprepareRequest(validStmt), code: RequestCodePrepare},
+		{req: NewExecutePreparedRequest(validStmt), code: RequestCodeExecute},
+		{req: NewBeginRequest(), code: RequestCodeBegin},
+		{req: NewCommitRequest(), code: RequestCodeCommit},
+		{req: NewRollbackRequest(), code: RequestCodeRollback},
+		{req: NewIdRequest(validProtocolInfo), code: RequestCodeId},
+		{req: NewBroadcastRequest(validKey), code: RequestCodeCall},
 	}
 
 	for _, test := range tests {
diff --git a/response.go b/response.go
index 962912675..1ec88d562 100644
--- a/response.go
+++ b/response.go
@@ -6,9 +6,19 @@ import (
 	"github.com/vmihailenco/msgpack/v5"
 )
 
+// Code is an enumeration type for a success response code.
+type Code uint32
+
+const (
+	// CodeOk is a regular response.
+	CodeOk Code = 0
+	// CodePush is a push message.
+	CodePush Code = 0x80
+)
+
 type Response struct {
 	RequestId uint32
-	Code      uint32
+	Code      Code
 	// Error contains an error message.
 	Error string
 	// Data contains deserialized data for untyped requests.
@@ -151,7 +161,7 @@ func (resp *Response) decodeHeader(d *msgpack.Decoder) (err error) {
 			if rcode, err = d.DecodeUint64(); err != nil {
 				return
 			}
-			resp.Code = uint32(rcode)
+			resp.Code = Code(rcode)
 		default:
 			if err = d.Skip(); err != nil {
 				return
@@ -280,7 +290,7 @@ func (resp *Response) decodeBody() (err error) {
 			resp.Data = []interface{}{serverProtocolInfo}
 		}
 
-		if resp.Code != OkCode && resp.Code != PushCode {
+		if resp.Code != CodeOk && resp.Code != CodePush {
 			resp.Code &^= errCodeBit
 			err = Error{resp.Code, resp.Error, errorExtendedInfo}
 		}
@@ -341,7 +351,7 @@ func (resp *Response) decodeBodyTyped(res interface{}) (err error) {
 				}
 			}
 		}
-		if resp.Code != OkCode && resp.Code != PushCode {
+		if resp.Code != CodeOk && resp.Code != CodePush {
 			resp.Code &^= errCodeBit
 			err = Error{resp.Code, resp.Error, errorExtendedInfo}
 		}
@@ -351,7 +361,7 @@ func (resp *Response) decodeBodyTyped(res interface{}) (err error) {
 
 // String implements Stringer interface.
 func (resp *Response) String() (str string) {
-	if resp.Code == OkCode {
+	if resp.Code == CodeOk {
 		return fmt.Sprintf("<%d OK %v>", resp.RequestId, resp.Data)
 	}
 	return fmt.Sprintf("<%d ERR 0x%x %s>", resp.RequestId, resp.Code, resp.Error)
diff --git a/settings/request.go b/settings/request.go
index df6dcd0ac..811b797ec 100644
--- a/settings/request.go
+++ b/settings/request.go
@@ -86,7 +86,7 @@ func (req *SetRequest) Context(ctx context.Context) *SetRequest {
 }
 
 // Code returns IPROTO code for set session settings request.
-func (req *SetRequest) Code() int32 {
+func (req *SetRequest) Code() tarantool.RequestCode {
 	return req.impl.Code()
 }
 
@@ -126,7 +126,7 @@ func (req *GetRequest) Context(ctx context.Context) *GetRequest {
 }
 
 // Code returns IPROTO code for get session settings request.
-func (req *GetRequest) Code() int32 {
+func (req *GetRequest) Code() tarantool.RequestCode {
 	return req.impl.Code()
 }
 
diff --git a/settings/request_test.go b/settings/request_test.go
index 7623a6cac..34d171d30 100644
--- a/settings/request_test.go
+++ b/settings/request_test.go
@@ -40,29 +40,29 @@ func TestRequestsAPI(t *testing.T) {
 	tests := []struct {
 		req   tarantool.Request
 		async bool
-		code  int32
+		code  tarantool.RequestCode
 	}{
-		{req: NewErrorMarshalingEnabledSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewErrorMarshalingEnabledGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLDefaultEngineSetRequest("memtx"), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLDefaultEngineGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLDeferForeignKeysSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLDeferForeignKeysGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLFullColumnNamesSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLFullColumnNamesGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLFullMetadataSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLFullMetadataGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLParserDebugSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLParserDebugGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLRecursiveTriggersSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLRecursiveTriggersGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLReverseUnorderedSelectsSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLReverseUnorderedSelectsGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLSelectDebugSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLSelectDebugGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSQLVDBEDebugSetRequest(false), async: false, code: tarantool.UpdateRequestCode},
-		{req: NewSQLVDBEDebugGetRequest(), async: false, code: tarantool.SelectRequestCode},
-		{req: NewSessionSettingsGetRequest(), async: false, code: tarantool.SelectRequestCode},
+		{req: NewErrorMarshalingEnabledSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewErrorMarshalingEnabledGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLDefaultEngineSetRequest("memtx"), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLDefaultEngineGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLDeferForeignKeysSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLDeferForeignKeysGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLFullColumnNamesSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLFullColumnNamesGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLFullMetadataSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLFullMetadataGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLParserDebugSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLParserDebugGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLRecursiveTriggersSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLRecursiveTriggersGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLReverseUnorderedSelectsSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLReverseUnorderedSelectsGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLSelectDebugSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLSelectDebugGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSQLVDBEDebugSetRequest(false), async: false, code: tarantool.RequestCodeUpdate},
+		{req: NewSQLVDBEDebugGetRequest(), async: false, code: tarantool.RequestCodeSelect},
+		{req: NewSessionSettingsGetRequest(), async: false, code: tarantool.RequestCodeSelect},
 	}
 
 	for _, test := range tests {
diff --git a/stream.go b/stream.go
index acb5c0104..3d9d0c40c 100644
--- a/stream.go
+++ b/stream.go
@@ -92,7 +92,7 @@ type BeginRequest struct {
 // NewBeginRequest returns a new BeginRequest.
 func NewBeginRequest() *BeginRequest {
 	req := new(BeginRequest)
-	req.requestCode = BeginRequestCode
+	req.requestCode = RequestCodeBegin
 	req.txnIsolation = DefaultIsolationLevel
 	return req
 }
@@ -136,7 +136,7 @@ type CommitRequest struct {
 // NewCommitRequest returns a new CommitRequest.
 func NewCommitRequest() *CommitRequest {
 	req := new(CommitRequest)
-	req.requestCode = CommitRequestCode
+	req.requestCode = RequestCodeCommit
 	return req
 }
 
@@ -166,7 +166,7 @@ type RollbackRequest struct {
 // NewRollbackRequest returns a new RollbackRequest.
 func NewRollbackRequest() *RollbackRequest {
 	req := new(RollbackRequest)
-	req.requestCode = RollbackRequestCode
+	req.requestCode = RequestCodeRollback
 	return req
 }
 
diff --git a/tarantool_test.go b/tarantool_test.go
index 09d6c3cc3..cdf5979e6 100644
--- a/tarantool_test.go
+++ b/tarantool_test.go
@@ -1277,7 +1277,7 @@ func TestClientSessionPush(t *testing.T) {
 				t.Errorf("Response.Data is empty after CallAsync")
 				break
 			}
-			if resp.Code == PushCode {
+			if resp.Code == CodePush {
 				pushCnt += 1
 				if val, err := test_helpers.ConvertUint64(resp.Data[0]); err != nil || val != pushCnt {
 					t.Errorf("Unexpected push data = %v", resp.Data)
@@ -1765,7 +1765,7 @@ func TestNewPrepared(t *testing.T) {
 	if err != nil {
 		t.Errorf("failed to execute prepared: %v", err)
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Errorf("failed to execute prepared: code %d", resp.Code)
 	}
 	if reflect.DeepEqual(resp.Data[0], []interface{}{1, "test"}) {
@@ -1782,7 +1782,7 @@ func TestNewPrepared(t *testing.T) {
 	if err != nil {
 		t.Errorf("failed to unprepare prepared statement: %v", err)
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Errorf("failed to unprepare prepared statement: code %d", resp.Code)
 	}
 
@@ -1806,7 +1806,7 @@ func TestNewPrepared(t *testing.T) {
 	if resp.Data == nil {
 		t.Errorf("failed to prepare: Data is nil")
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Errorf("failed to unprepare prepared statement: code %d", resp.Code)
 	}
 
@@ -2443,7 +2443,7 @@ func TestClientRequestObjects(t *testing.T) {
 	if len(resp.Data) != 0 {
 		t.Fatalf("Response Body len != 0")
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Fatalf("Failed to Execute: %d", resp.Code)
 	}
 	if resp.SQLInfo.AffectedCount != 1 {
@@ -2464,7 +2464,7 @@ func TestClientRequestObjects(t *testing.T) {
 	if len(resp.Data) != 0 {
 		t.Fatalf("Response Body len != 0")
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Fatalf("Failed to Execute: %d", resp.Code)
 	}
 	if resp.SQLInfo.AffectedCount != 1 {
@@ -2676,7 +2676,7 @@ type waitCtxRequest struct {
 	wg  sync.WaitGroup
 }
 
-func (req *waitCtxRequest) Code() int32 {
+func (req *waitCtxRequest) Code() RequestCode {
 	return NewPingRequest().Code()
 }
 
@@ -2811,7 +2811,7 @@ func TestStream_Commit(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to Begin: %s", err.Error())
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Fatalf("Failed to Begin: wrong code returned %d", resp.Code)
 	}
 
@@ -2822,7 +2822,7 @@ func TestStream_Commit(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to Insert: %s", err.Error())
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Errorf("Failed to Insert: wrong code returned %d", resp.Code)
 	}
 	defer test_helpers.DeleteRecordByKey(t, conn, spaceNo, indexNo, []interface{}{uint(1001)})
@@ -2877,7 +2877,7 @@ func TestStream_Commit(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to Commit: %s", err.Error())
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Fatalf("Failed to Commit: wrong code returned %d", resp.Code)
 	}
 
@@ -2926,7 +2926,7 @@ func TestStream_Rollback(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to Begin: %s", err.Error())
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Fatalf("Failed to Begin: wrong code returned %d", resp.Code)
 	}
 
@@ -2937,7 +2937,7 @@ func TestStream_Rollback(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to Insert: %s", err.Error())
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Errorf("Failed to Insert: wrong code returned %d", resp.Code)
 	}
 	defer test_helpers.DeleteRecordByKey(t, conn, spaceNo, indexNo, []interface{}{uint(1001)})
@@ -2992,7 +2992,7 @@ func TestStream_Rollback(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Failed to Rollback: %s", err.Error())
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Fatalf("Failed to Rollback: wrong code returned %d", resp.Code)
 	}
 
@@ -3047,7 +3047,7 @@ func TestStream_TxnIsolationLevel(t *testing.T) {
 		resp, err = stream.Do(req).Get()
 		require.Nilf(t, err, "failed to Begin")
 		require.NotNilf(t, resp, "response is nil after Begin")
-		require.Equalf(t, OkCode, resp.Code, "wrong code returned")
+		require.Equalf(t, CodeOk, resp.Code, "wrong code returned")
 
 		// Insert in stream
 		req = NewInsertRequest(spaceName).
@@ -3055,7 +3055,7 @@ func TestStream_TxnIsolationLevel(t *testing.T) {
 		resp, err = stream.Do(req).Get()
 		require.Nilf(t, err, "failed to Insert")
 		require.NotNilf(t, resp, "response is nil after Insert")
-		require.Equalf(t, OkCode, resp.Code, "wrong code returned")
+		require.Equalf(t, CodeOk, resp.Code, "wrong code returned")
 
 		// Select not related to the transaction
 		// while transaction is not committed
@@ -3097,7 +3097,7 @@ func TestStream_TxnIsolationLevel(t *testing.T) {
 		resp, err = stream.Do(req).Get()
 		require.Nilf(t, err, "failed to Rollback")
 		require.NotNilf(t, resp, "response is nil after Rollback")
-		require.Equalf(t, OkCode, resp.Code, "wrong code returned")
+		require.Equalf(t, CodeOk, resp.Code, "wrong code returned")
 
 		// Select outside of transaction
 		resp, err = conn.Do(selectReq).Get()
@@ -3675,7 +3675,7 @@ func TestBroadcastRequest(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Got broadcast error: %s", err)
 	}
-	if resp.Code != OkCode {
+	if resp.Code != CodeOk {
 		t.Errorf("Got unexpected broadcast response code: %d", resp.Code)
 	}
 	if !reflect.DeepEqual(resp.Data, []interface{}{}) {
diff --git a/test_helpers/request_mock.go b/test_helpers/request_mock.go
index 0eaa11739..1d007203f 100644
--- a/test_helpers/request_mock.go
+++ b/test_helpers/request_mock.go
@@ -15,7 +15,7 @@ func NewStrangerRequest() *StrangerRequest {
 	return &StrangerRequest{}
 }
 
-func (sr *StrangerRequest) Code() int32 {
+func (sr *StrangerRequest) Code() tarantool.RequestCode {
 	return 0
 }
 
diff --git a/watch.go b/watch.go
index c937533e8..1ad41be64 100644
--- a/watch.go
+++ b/watch.go
@@ -35,7 +35,7 @@ func (req *BroadcastRequest) Context(ctx context.Context) *BroadcastRequest {
 }
 
 // Code returns IPROTO code for the broadcast request.
-func (req *BroadcastRequest) Code() int32 {
+func (req *BroadcastRequest) Code() RequestCode {
 	return req.call.Code()
 }
 
@@ -66,7 +66,7 @@ type watchRequest struct {
 // newWatchRequest returns a new watchRequest.
 func newWatchRequest(key string) *watchRequest {
 	req := new(watchRequest)
-	req.requestCode = WatchRequestCode
+	req.requestCode = RequestCodeWatch
 	req.async = true
 	req.key = key
 	return req
@@ -100,7 +100,7 @@ type unwatchRequest struct {
 // newUnwatchRequest returns a new unwatchRequest.
 func newUnwatchRequest(key string) *unwatchRequest {
 	req := new(unwatchRequest)
-	req.requestCode = UnwatchRequestCode
+	req.requestCode = RequestCodeUnwatch
 	req.async = true
 	req.key = key
 	return req