diff --git a/modules/gapi/CMakeLists.txt b/modules/gapi/CMakeLists.txt
index 9df2447b29..ae4d20c024 100644
--- a/modules/gapi/CMakeLists.txt
+++ b/modules/gapi/CMakeLists.txt
@@ -31,7 +31,7 @@ file(GLOB gapi_ext_hdrs
 
 set(gapi_srcs
     # Front-end part
-    src/api/gapi_priv.cpp
+    src/api/gorigin.cpp
     src/api/gmat.cpp
     src/api/garray.cpp
     src/api/gscalar.cpp
diff --git a/modules/gapi/src/api/garray.cpp b/modules/gapi/src/api/garray.cpp
index 0fd19a7e65..793f44a2b4 100644
--- a/modules/gapi/src/api/garray.cpp
+++ b/modules/gapi/src/api/garray.cpp
@@ -7,7 +7,7 @@
 
 #include "precomp.hpp"
 #include "opencv2/gapi/garray.hpp"
-#include "api/gapi_priv.hpp" // GOrigin
+#include "api/gorigin.hpp"
 
 // cv::detail::GArrayU public implementation ///////////////////////////////////
 cv::detail::GArrayU::GArrayU()
diff --git a/modules/gapi/src/api/gmat.cpp b/modules/gapi/src/api/gmat.cpp
index dc8fc734d8..ac58a9caf1 100644
--- a/modules/gapi/src/api/gmat.cpp
+++ b/modules/gapi/src/api/gmat.cpp
@@ -10,7 +10,7 @@
 #include <opencv2/gapi/own/mat.hpp> //gapi::own::Mat
 
 #include "opencv2/gapi/gmat.hpp"
-#include "api/gapi_priv.hpp" // GOrigin
+#include "api/gorigin.hpp"
 
 // cv::GMat public implementation //////////////////////////////////////////////
 cv::GMat::GMat()
diff --git a/modules/gapi/src/api/gapi_priv.cpp b/modules/gapi/src/api/gorigin.cpp
similarity index 97%
rename from modules/gapi/src/api/gapi_priv.cpp
rename to modules/gapi/src/api/gorigin.cpp
index 744db16715..312d614709 100644
--- a/modules/gapi/src/api/gapi_priv.cpp
+++ b/modules/gapi/src/api/gorigin.cpp
@@ -8,7 +8,7 @@
 #include "precomp.hpp"
 #include <ade/util/assert.hpp>
 
-#include "api/gapi_priv.hpp"
+#include "api/gorigin.hpp"
 #include "api/gnode_priv.hpp"
 
 cv::GOrigin::GOrigin(GShape s,
diff --git a/modules/gapi/src/api/gapi_priv.hpp b/modules/gapi/src/api/gorigin.hpp
similarity index 70%
rename from modules/gapi/src/api/gapi_priv.hpp
rename to modules/gapi/src/api/gorigin.hpp
index edab0a08b6..ad4ebf534d 100644
--- a/modules/gapi/src/api/gapi_priv.hpp
+++ b/modules/gapi/src/api/gorigin.hpp
@@ -5,42 +5,22 @@
 // Copyright (C) 2018 Intel Corporation
 
 
-#ifndef OPENCV_GAPI_PRIV_HPP
-#define OPENCV_GAPI_PRIV_HPP
+#ifndef OPENCV_GAPI_GORIGIN_HPP
+#define OPENCV_GAPI_GORIGIN_HPP
 
 #include <set>   // set
 #include <map>   // map
-#include <limits>
 
 #include "opencv2/gapi/util/variant.hpp"   // variant
-#include "opencv2/gapi/garray.hpp"         // ConstructVec
-#include "opencv2/gapi/gscalar.hpp"
 #include "opencv2/gapi/gcommon.hpp"
-
 #include "opencv2/gapi/opencv_includes.hpp"
+#include "compiler/gobjref.hpp"
 
 #include "api/gnode.hpp"
 
 namespace cv
 {
 
-namespace gimpl
-{
-    // Union type for various user-defined type constructors (GArray<T>, etc)
-    // FIXME: Replace construct-only API with a more generic one
-    //    (probably with bits of introspection)
-    // Not required for non-user-defined types (GMat, GScalar, etc)
-    using HostCtor = util::variant
-        < util::monostate
-        , detail::ConstructVec
-        >;
-
-    using ConstVal = util::variant
-        < util::monostate
-        , cv::gapi::own::Scalar
-        >;
-}
-
 // TODO namespace gimpl?
 
 struct GOrigin
@@ -74,4 +54,4 @@ template<typename T> using GOriginMap = std::map<GOrigin, T, detail::GOriginCmp>
 
 } // namespace cv
 
-#endif // OPENCV_GAPI_PRIV_HPP
+#endif // OPENCV_GAPI_GORIGIN_HPP
diff --git a/modules/gapi/src/api/gproto.cpp b/modules/gapi/src/api/gproto.cpp
index 2482d628b4..70604cbbca 100644
--- a/modules/gapi/src/api/gproto.cpp
+++ b/modules/gapi/src/api/gproto.cpp
@@ -12,7 +12,7 @@
 #include "opencv2/gapi/garg.hpp"
 #include "opencv2/gapi/gproto.hpp"
 
-#include "api/gapi_priv.hpp"
+#include "api/gorigin.hpp"
 #include "api/gproto_priv.hpp"
 
 // FIXME: it should be a visitor!
diff --git a/modules/gapi/src/api/gproto_priv.hpp b/modules/gapi/src/api/gproto_priv.hpp
index 2684924c75..ca23ad875f 100644
--- a/modules/gapi/src/api/gproto_priv.hpp
+++ b/modules/gapi/src/api/gproto_priv.hpp
@@ -11,7 +11,7 @@
 #include "opencv2/gapi/gproto.hpp"
 #include "opencv2/gapi/garg.hpp"
 
-#include "api/gapi_priv.hpp"
+#include "api/gorigin.hpp"
 
 namespace cv {
 namespace gimpl {
diff --git a/modules/gapi/src/api/gscalar.cpp b/modules/gapi/src/api/gscalar.cpp
index 30f3dc9447..2e42ae6241 100644
--- a/modules/gapi/src/api/gscalar.cpp
+++ b/modules/gapi/src/api/gscalar.cpp
@@ -9,7 +9,7 @@
 
 #include "opencv2/gapi/gscalar.hpp"
 #include "opencv2/gapi/own/convert.hpp"
-#include "api/gapi_priv.hpp" // GOrigin
+#include "api/gorigin.hpp"
 
 // cv::GScalar public implementation ///////////////////////////////////////////
 cv::GScalar::GScalar()
diff --git a/modules/gapi/src/backends/common/gbackend.hpp b/modules/gapi/src/backends/common/gbackend.hpp
index 613022cb9c..daa95026f6 100644
--- a/modules/gapi/src/backends/common/gbackend.hpp
+++ b/modules/gapi/src/backends/common/gbackend.hpp
@@ -53,8 +53,8 @@ using Mag = magazine::Class<cv::gapi::own::Mat, cv::gapi::own::Scalar, cv::detai
 
 namespace magazine
 {
-    void         bindInArg (Mag& mag, const RcDesc &rc, const GRunArg  &arg, bool is_umat = false);
-    void         bindOutArg(Mag& mag, const RcDesc &rc, const GRunArgP &arg, bool is_umat = false);
+    void         GAPI_EXPORTS bindInArg (Mag& mag, const RcDesc &rc, const GRunArg  &arg, bool is_umat = false);
+    void         GAPI_EXPORTS bindOutArg(Mag& mag, const RcDesc &rc, const GRunArgP &arg, bool is_umat = false);
 
     void         resetInternalData(Mag& mag, const Data &d);
     cv::GRunArg  getArg    (const Mag& mag, const RcDesc &ref);
diff --git a/modules/gapi/src/backends/cpu/gcpubackend.hpp b/modules/gapi/src/backends/cpu/gcpubackend.hpp
index 6ce8c4883a..218cac1be0 100644
--- a/modules/gapi/src/backends/cpu/gcpubackend.hpp
+++ b/modules/gapi/src/backends/cpu/gcpubackend.hpp
@@ -17,8 +17,7 @@
 #include "opencv2/gapi/gproto.hpp"
 #include "opencv2/gapi/cpu/gcpukernel.hpp"
 
-
-#include "api/gapi_priv.hpp"
+#include "api/gorigin.hpp"
 #include "backends/common/gbackend.hpp"
 #include "compiler/gislandmodel.hpp"
 
diff --git a/modules/gapi/src/backends/fluid/gfluidbackend.cpp b/modules/gapi/src/backends/fluid/gfluidbackend.cpp
index 6aec049fb6..52a9a497ff 100644
--- a/modules/gapi/src/backends/fluid/gfluidbackend.cpp
+++ b/modules/gapi/src/backends/fluid/gfluidbackend.cpp
@@ -10,6 +10,7 @@
 #include <functional>
 #include <iostream>
 #include <iomanip> // std::fixed, std::setprecision
+#include <set>
 #include <unordered_set>
 #include <stack>
 
diff --git a/modules/gapi/src/backends/ocl/goclbackend.hpp b/modules/gapi/src/backends/ocl/goclbackend.hpp
index 3548dff75e..b57c66209d 100644
--- a/modules/gapi/src/backends/ocl/goclbackend.hpp
+++ b/modules/gapi/src/backends/ocl/goclbackend.hpp
@@ -17,8 +17,7 @@
 #include "opencv2/gapi/gproto.hpp"
 #include "opencv2/gapi/ocl/goclkernel.hpp"
 
-
-#include "api/gapi_priv.hpp"
+#include "api/gorigin.hpp"
 #include "backends/common/gbackend.hpp"
 #include "compiler/gislandmodel.hpp"
 
diff --git a/modules/gapi/src/compiler/gcompiler.cpp b/modules/gapi/src/compiler/gcompiler.cpp
index a814b915cf..0418b995f4 100644
--- a/modules/gapi/src/compiler/gcompiler.cpp
+++ b/modules/gapi/src/compiler/gcompiler.cpp
@@ -21,7 +21,7 @@
 #include "api/gnode_priv.hpp"   // FIXME: why it is here?
 #include "api/gproto_priv.hpp"  // FIXME: why it is here?
 #include "api/gcall_priv.hpp"   // FIXME: why it is here?
-#include "api/gapi_priv.hpp"    // FIXME: why it is here?
+
 #include "api/gbackend_priv.hpp" // Backend basic API (newInstance, etc)
 
 #include "compiler/gmodel.hpp"
diff --git a/modules/gapi/src/compiler/gmodel.cpp b/modules/gapi/src/compiler/gmodel.cpp
index c804671134..92ffb2d670 100644
--- a/modules/gapi/src/compiler/gmodel.cpp
+++ b/modules/gapi/src/compiler/gmodel.cpp
@@ -18,6 +18,8 @@
 #include "api/gnode_priv.hpp"
 #include "compiler/gobjref.hpp"
 #include "compiler/gmodel.hpp"
+#include "api/gorigin.hpp"
+#include "compiler/gmodel_priv.hpp"
 
 namespace cv { namespace gimpl {
 
@@ -34,9 +36,9 @@ ade::NodeHandle GModel::mkOpNode(GModel::Graph &g, const GKernel &k, const std::
 
 ade::NodeHandle GModel::mkDataNode(GModel::Graph &g, const GOrigin& origin)
 {
-    ade::NodeHandle op_h = g.createNode();
+    ade::NodeHandle data_h = g.createNode();
     const auto id = g.metadata().get<DataObjectCounter>().GetNewId(origin.shape);
-    g.metadata(op_h).set(NodeType{NodeType::DATA});
+    g.metadata(data_h).set(NodeType{NodeType::DATA});
 
     GMetaArg meta;
     Data::Storage storage = Data::Storage::INTERNAL; // By default, all objects are marked INTERNAL
@@ -46,10 +48,24 @@ ade::NodeHandle GModel::mkDataNode(GModel::Graph &g, const GOrigin& origin)
         auto value = value_of(origin);
         meta       = descr_of(value);
         storage    = Data::Storage::CONST;
-        g.metadata(op_h).set(ConstValue{value});
+        g.metadata(data_h).set(ConstValue{value});
     }
-    g.metadata(op_h).set(Data{origin.shape, id, meta, origin.ctor, storage});
-    return op_h;
+    g.metadata(data_h).set(Data{origin.shape, id, meta, origin.ctor, storage});
+    return data_h;
+}
+
+ade::NodeHandle GModel::mkDataNode(GModel::Graph &g, const GShape shape)
+{
+    ade::NodeHandle data_h = g.createNode();
+    g.metadata(data_h).set(NodeType{NodeType::DATA});
+
+    const auto id = g.metadata().get<DataObjectCounter>().GetNewId(shape);
+    GMetaArg meta;
+    HostCtor ctor;
+    Data::Storage storage = Data::Storage::INTERNAL; // By default, all objects are marked INTERNAL
+
+    g.metadata(data_h).set(Data{shape, id, meta, ctor, storage});
+    return data_h;
 }
 
 void GModel::linkIn(Graph &g, ade::NodeHandle opH, ade::NodeHandle objH, std::size_t in_port)
@@ -169,7 +185,7 @@ void GModel::log(Graph &g, ade::EdgeHandle eh, std::string &&msg, ade::NodeHandl
     }
 }
 
-ade::NodeHandle GModel::detail::dataNodeOf(const ConstGraph &g, const GOrigin &origin)
+ade::NodeHandle GModel::detail::dataNodeOf(const ConstLayoutGraph &g, const GOrigin &origin)
 {
     // FIXME: Does it still work with graph transformations, e.g. redirectWriter()??
     return g.metadata().get<Layout>().object_nodes.at(origin);
diff --git a/modules/gapi/src/compiler/gmodel.hpp b/modules/gapi/src/compiler/gmodel.hpp
index a9c3308d12..dfe65a1e83 100644
--- a/modules/gapi/src/compiler/gmodel.hpp
+++ b/modules/gapi/src/compiler/gmodel.hpp
@@ -24,9 +24,6 @@
 
 #include "opencv2/gapi/garg.hpp"
 #include "opencv2/gapi/gkernel.hpp"
-#include "api/gapi_priv.hpp"   // GShape
-#include "api/gproto_priv.hpp" // origin_of
-#include "backends/common/gbackend.hpp"
 
 #include "compiler/gobjref.hpp"
 #include "compiler/gislandmodel.hpp"
@@ -121,16 +118,6 @@ struct Journal
     std::vector<std::string> messages;
 };
 
-// The mapping between user-side GMat/GScalar/... objects
-// and its  appropriate nodes. Can be stored in graph optionally
-// (NOT used by any compiler or backends, introspection purposes
-// only)
-struct Layout
-{
-    static const char *name() { return "Layout"; }
-    GOriginMap<ade::NodeHandle> object_nodes;
-};
-
 // Unique data object counter (per-type)
 class DataObjectCounter
 {
@@ -170,7 +157,6 @@ namespace GModel
         , Journal
         , ade::passes::TopologicalSortData
         , DataObjectCounter
-        , Layout
         , IslandModel
         , ActiveBackends
         >;
@@ -189,59 +175,46 @@ namespace GModel
         , Journal
         , ade::passes::TopologicalSortData
         , DataObjectCounter
-        , Layout
         , IslandModel
         , ActiveBackends
         >;
 
+    // FIXME:
+    // Export a single class, not a bunch of functions inside a namespace
+
     // User should initialize graph before using it
     // GAPI_EXPORTS for tests
     GAPI_EXPORTS void init (Graph& g);
 
-    ade::NodeHandle mkOpNode(Graph &g, const GKernel &k, const std::vector<GArg>& args, const std::string &island);
+    GAPI_EXPORTS ade::NodeHandle mkOpNode(Graph &g, const GKernel &k, const std::vector<GArg>& args, const std::string &island);
 
-    // FIXME: change it to take GMeta instead of GShape?
-    ade::NodeHandle mkDataNode(Graph &g, const GOrigin& origin);
+    GAPI_EXPORTS ade::NodeHandle mkDataNode(Graph &g, const GShape shape);
 
     // Adds a string message to a node. Any node can be subject of log, messages then
     // appear in the dumped .dot file.x
-    void log(Graph &g, ade::NodeHandle op, std::string &&message, ade::NodeHandle updater = ade::NodeHandle());
-    void log(Graph &g, ade::EdgeHandle op, std::string &&message, ade::NodeHandle updater = ade::NodeHandle());
+    GAPI_EXPORTS void log(Graph &g, ade::NodeHandle op, std::string &&message, ade::NodeHandle updater = ade::NodeHandle());
+    GAPI_EXPORTS void log(Graph &g, ade::EdgeHandle op, std::string &&message, ade::NodeHandle updater = ade::NodeHandle());
 
-    void linkIn   (Graph &g, ade::NodeHandle op,     ade::NodeHandle obj, std::size_t in_port);
-    void linkOut  (Graph &g, ade::NodeHandle op,     ade::NodeHandle obj, std::size_t out_port);
+    GAPI_EXPORTS void linkIn   (Graph &g, ade::NodeHandle op,     ade::NodeHandle obj, std::size_t in_port);
+    GAPI_EXPORTS void linkOut  (Graph &g, ade::NodeHandle op,     ade::NodeHandle obj, std::size_t out_port);
 
-    // FIXME: Align this GModel API properly, it is a mess now
-    namespace detail
-    {
-        // FIXME: GAPI_EXPORTS only because of tests!!!
-        GAPI_EXPORTS ade::NodeHandle dataNodeOf(const ConstGraph& g, const GOrigin &origin);
-    }
-    template<typename T> inline ade::NodeHandle dataNodeOf(const ConstGraph& g, T &&t)
-    {
-        return detail::dataNodeOf(g, cv::gimpl::proto::origin_of(GProtoArg{t}));
-    }
+    GAPI_EXPORTS void redirectReaders(Graph &g, ade::NodeHandle from, ade::NodeHandle to);
+    GAPI_EXPORTS void redirectWriter (Graph &g, ade::NodeHandle from, ade::NodeHandle to);
 
-    void linkIn   (Graph &g, ade::NodeHandle op,     ade::NodeHandle obj, std::size_t in_port);
-    void linkOut  (Graph &g, ade::NodeHandle op,     ade::NodeHandle obj, std::size_t out_port);
-
-    void redirectReaders(Graph &g, ade::NodeHandle from, ade::NodeHandle to);
-    void redirectWriter (Graph &g, ade::NodeHandle from, ade::NodeHandle to);
-
-    std::vector<ade::NodeHandle> orderedInputs (Graph &g, ade::NodeHandle nh);
-    std::vector<ade::NodeHandle> orderedOutputs(Graph &g, ade::NodeHandle nh);
+    GAPI_EXPORTS std::vector<ade::NodeHandle> orderedInputs (Graph &g, ade::NodeHandle nh);
+    GAPI_EXPORTS std::vector<ade::NodeHandle> orderedOutputs(Graph &g, ade::NodeHandle nh);
 
     // Returns input meta array for given op node
     // Array is sparse, as metadata for non-gapi input objects is empty
     // TODO:
     // Cover with tests!!
-    GMetaArgs collectInputMeta(GModel::ConstGraph cg, ade::NodeHandle node);
-    GMetaArgs collectOutputMeta(GModel::ConstGraph cg, ade::NodeHandle node);
+    GAPI_EXPORTS GMetaArgs collectInputMeta(GModel::ConstGraph cg, ade::NodeHandle node);
+    GAPI_EXPORTS GMetaArgs collectOutputMeta(GModel::ConstGraph cg, ade::NodeHandle node);
 
-    ade::EdgeHandle getInEdgeByPort(const GModel::ConstGraph& cg, const ade::NodeHandle& nh, std::size_t in_port);
+    GAPI_EXPORTS ade::EdgeHandle getInEdgeByPort(const GModel::ConstGraph& cg, const ade::NodeHandle& nh, std::size_t in_port);
 
     // Returns true if the given backend participates in the execution
-    bool isActive(const GModel::Graph &cg, const cv::gapi::GBackend &backend);
+    GAPI_EXPORTS bool isActive(const GModel::Graph &cg, const cv::gapi::GBackend &backend);
 } // namespace GModel
 
 
diff --git a/modules/gapi/src/compiler/gmodel_priv.hpp b/modules/gapi/src/compiler/gmodel_priv.hpp
new file mode 100644
index 0000000000..3a3b444b8a
--- /dev/null
+++ b/modules/gapi/src/compiler/gmodel_priv.hpp
@@ -0,0 +1,51 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+//
+// Copyright (C) 2019 Intel Corporation
+
+#ifndef OPENCV_GAPI_GMODEL_PRIV_HPP
+#define OPENCV_GAPI_GMODEL_PRIV_HPP
+
+#include <ade/graph.hpp>
+#include "compiler/gmodel.hpp"
+#include "api/gproto_priv.hpp" // origin_of
+
+namespace cv { namespace gimpl {
+
+// The mapping between user-side GMat/GScalar/... objects
+// and its  appropriate nodes. Can be stored in graph optionally
+// (NOT used by any compiler or backends, introspection purposes
+// only)
+struct Layout
+{
+    static const char *name() { return "Layout"; }
+    GOriginMap<ade::NodeHandle> object_nodes;
+};
+
+namespace GModel {
+
+using LayoutGraph = ade::TypedGraph
+    < Layout
+    >;
+
+using ConstLayoutGraph = ade::ConstTypedGraph
+    < Layout
+    >;
+
+    ade::NodeHandle mkDataNode(Graph &g, const GOrigin& origin);
+
+namespace detail
+{
+    // FIXME: GAPI_EXPORTS only because of tests!!!
+    GAPI_EXPORTS ade::NodeHandle dataNodeOf(const ConstLayoutGraph& g, const GOrigin &origin);
+}
+
+template<typename T> inline ade::NodeHandle dataNodeOf(const ConstLayoutGraph& g, T &&t)
+{
+    return detail::dataNodeOf(g, cv::gimpl::proto::origin_of(GProtoArg{t}));
+}
+
+}}}
+
+#endif // OPENCV_GAPI_GMODEL_PRIV_HPP
diff --git a/modules/gapi/src/compiler/gmodelbuilder.cpp b/modules/gapi/src/compiler/gmodelbuilder.cpp
index 7eb2ecf2c0..180bbe1ad2 100644
--- a/modules/gapi/src/compiler/gmodelbuilder.cpp
+++ b/modules/gapi/src/compiler/gmodelbuilder.cpp
@@ -21,12 +21,13 @@
 
 #include <ade/util/zip_range.hpp>   // util::indexed
 
-#include "api/gapi_priv.hpp"    // GOrigin
+#include "api/gorigin.hpp"
 #include "api/gproto_priv.hpp"  // descriptor_of and other GProtoArg-related
 #include "api/gcall_priv.hpp"
 #include "api/gnode_priv.hpp"
 
 #include "compiler/gmodelbuilder.hpp"
+#include "compiler/gmodel_priv.hpp"
 
 namespace {
 
@@ -187,7 +188,7 @@ cv::gimpl::Unrolled cv::gimpl::unrollExpr(const GProtoArgs &ins,
 
 
 cv::gimpl::GModelBuilder::GModelBuilder(ade::Graph &g)
-    : m_g(g)
+    : m_g(g), m_gm(g)
 {
 }
 
@@ -212,7 +213,7 @@ cv::gimpl::GModelBuilder::put(const GProtoArgs &ins, const GProtoArgs &outs)
             if (proto::is_dynamic(in_arg))
             {
                 ade::NodeHandle data_h = put_DataNode(proto::origin_of(in_arg));
-                cv::gimpl::GModel::linkIn(m_g, call_h, data_h, in_port);
+                cv::gimpl::GModel::linkIn(m_gm, call_h, data_h, in_port);
             }
         }
     }
@@ -228,7 +229,7 @@ cv::gimpl::GModelBuilder::put(const GProtoArgs &ins, const GProtoArgs &outs)
         if (prod.shape() == cv::GNode::NodeShape::CALL)
         {
             ade::NodeHandle call_h = put_OpNode(prod);
-            cv::gimpl::GModel::linkOut(m_g, call_h, data_h, origin.port);
+            cv::gimpl::GModel::linkOut(m_gm, call_h, data_h, origin.port);
         }
     }
 
@@ -236,16 +237,17 @@ cv::gimpl::GModelBuilder::put(const GProtoArgs &ins, const GProtoArgs &outs)
     for (const auto &arg : ins)
     {
         ade::NodeHandle nh = put_DataNode(proto::origin_of(arg));
-        m_g.metadata(nh).get<Data>().storage = Data::Storage::INPUT;
+        m_gm.metadata(nh).get<Data>().storage = Data::Storage::INPUT;
     }
     for (const auto &arg : outs)
     {
         ade::NodeHandle nh = put_DataNode(proto::origin_of(arg));
-        m_g.metadata(nh).get<Data>().storage = Data::Storage::OUTPUT;
+        m_gm.metadata(nh).get<Data>().storage = Data::Storage::OUTPUT;
     }
 
     // And, finally, store data object layout in meta
-    m_g.metadata().set(Layout{m_graph_data});
+    GModel::LayoutGraph lg(m_g);
+    lg.metadata().set(Layout{m_graph_data});
 
     // After graph is generated, specify which data objects are actually
     // computation entry/exit points.
@@ -262,7 +264,7 @@ cv::gimpl::GModelBuilder::put(const GProtoArgs &ins, const GProtoArgs &outs)
         for (const auto &arg : proto)
         {
             ade::NodeHandle nh = put_DataNode(proto::origin_of(arg));
-            const auto &desc = m_g.metadata(nh).get<Data>();
+            const auto &desc = m_gm.metadata(nh).get<Data>();
             //These extra empty {} are to please GCC (-Wmissing-field-initializers)
             slots.first.push_back(RcDesc{desc.rc, desc.shape, {}});
             slots.second.push_back(nh);
@@ -284,7 +286,7 @@ ade::NodeHandle cv::gimpl::GModelBuilder::put_OpNode(const cv::GNode &node)
     {
         GAPI_Assert(node.shape() == GNode::NodeShape::CALL);
         const auto &call_p = node.call().priv();
-        auto nh = cv::gimpl::GModel::mkOpNode(m_g, call_p.m_k, call_p.m_args, node_p.m_island);
+        auto nh = cv::gimpl::GModel::mkOpNode(m_gm, call_p.m_k, call_p.m_args, node_p.m_island);
         m_graph_ops[&node_p] = nh;
         return nh;
     }
@@ -297,7 +299,7 @@ ade::NodeHandle cv::gimpl::GModelBuilder::put_DataNode(const GOrigin &origin)
     const auto it = m_graph_data.find(origin);
     if (it == m_graph_data.end())
     {
-        auto nh = cv::gimpl::GModel::mkDataNode(m_g, origin);
+        auto nh = cv::gimpl::GModel::mkDataNode(m_gm, origin);
         m_graph_data[origin] = nh;
         return nh;
     }
diff --git a/modules/gapi/src/compiler/gmodelbuilder.hpp b/modules/gapi/src/compiler/gmodelbuilder.hpp
index ce12c7e11b..2d06000617 100644
--- a/modules/gapi/src/compiler/gmodelbuilder.hpp
+++ b/modules/gapi/src/compiler/gmodelbuilder.hpp
@@ -14,7 +14,7 @@
 #include "opencv2/gapi/gproto.hpp"
 #include "opencv2/gapi/gcall.hpp"
 
-#include "api/gapi_priv.hpp"
+#include "api/gorigin.hpp"
 #include "api/gnode.hpp"
 #include "compiler/gmodel.hpp"
 
@@ -44,7 +44,8 @@ GAPI_EXPORTS Unrolled unrollExpr(const GProtoArgs &ins, const GProtoArgs &outs);
 // FIXME: GAPI_EXPORTS only because of tests!!!
 class GAPI_EXPORTS GModelBuilder
 {
-    GModel::Graph m_g;
+    ade::Graph &m_g;
+    GModel::Graph m_gm;
 
     // Mappings of G-API user framework entities to ADE node handles
     std::unordered_map<const cv::GNode::Priv*, ade::NodeHandle> m_graph_ops;
diff --git a/modules/gapi/src/compiler/gobjref.hpp b/modules/gapi/src/compiler/gobjref.hpp
index be365c90e4..bcc5047d8e 100644
--- a/modules/gapi/src/compiler/gobjref.hpp
+++ b/modules/gapi/src/compiler/gobjref.hpp
@@ -5,19 +5,31 @@
 // Copyright (C) 2018 Intel Corporation
 
 
-#ifndef OPENCV_GAPI_GMATREF_HPP
-#define OPENCV_GAPI_GMATREF_HPP
+#ifndef OPENCV_GAPI_GOBJREF_HPP
+#define OPENCV_GAPI_GOBJREF_HPP
 
 #include "opencv2/gapi/util/variant.hpp"
 #include "opencv2/gapi/garg.hpp"
 
-#include "api/gapi_priv.hpp" // GShape, HostCtor
-
 namespace cv
 {
 
 namespace gimpl
 {
+    // Union type for various user-defined type constructors (GArray<T>, etc)
+    // FIXME: Replace construct-only API with a more generic one
+    //    (probably with bits of introspection)
+    // Not required for non-user-defined types (GMat, GScalar, etc)
+    using HostCtor = util::variant
+    < util::monostate
+    , detail::ConstructVec
+    >;
+
+    using ConstVal = util::variant
+    < util::monostate
+    , cv::gapi::own::Scalar
+    >;
+
     struct RcDesc
     {
         int      id;      // id is unique but local to shape
@@ -47,4 +59,4 @@ namespace detail
 
 } // cv
 
-#endif // OPENCV_GAPI_GMATREF_HPP
+#endif // OPENCV_GAPI_GOBJREF_HPP
diff --git a/modules/gapi/src/compiler/passes/dump_dot.cpp b/modules/gapi/src/compiler/passes/dump_dot.cpp
index 8741089ba2..89020d19b5 100644
--- a/modules/gapi/src/compiler/passes/dump_dot.cpp
+++ b/modules/gapi/src/compiler/passes/dump_dot.cpp
@@ -10,6 +10,7 @@
 #include <iostream>                              // cout
 #include <sstream>                               // stringstream
 #include <fstream>                               // ofstream
+#include <map>
 
 #include <ade/passes/check_cycles.hpp>
 
diff --git a/modules/gapi/src/compiler/passes/kernels.cpp b/modules/gapi/src/compiler/passes/kernels.cpp
index 1df311295f..0feb7b1b15 100644
--- a/modules/gapi/src/compiler/passes/kernels.cpp
+++ b/modules/gapi/src/compiler/passes/kernels.cpp
@@ -20,6 +20,7 @@
 #include "backends/common/gbackend.hpp"
 #include "compiler/gmodelbuilder.hpp"
 #include "logger.hpp"    // GAPI_LOG
+#include "api/gproto_priv.hpp" // is_dynamic, rewrap
 
 namespace
 {
diff --git a/modules/gapi/test/internal/gapi_int_island_fusion_tests.cpp b/modules/gapi/test/internal/gapi_int_island_fusion_tests.cpp
index 33f0eebefe..6cfd5d3bd1 100644
--- a/modules/gapi/test/internal/gapi_int_island_fusion_tests.cpp
+++ b/modules/gapi/test/internal/gapi_int_island_fusion_tests.cpp
@@ -10,9 +10,9 @@
 
 #include "../gapi_mock_kernels.hpp"
 
-#include "compiler/gmodel.hpp"
 #include "compiler/gislandmodel.hpp"
 #include "compiler/gcompiler.hpp"
+#include "compiler/gmodel_priv.hpp"
 
 namespace opencv_test
 {
@@ -44,10 +44,11 @@ TEST(IslandFusion, TwoOps_OneIsland)
 
     // Inspect the graph and verify the islands configuration
     cv::gimpl::GModel::ConstGraph gm(*graph);
+    cv::gimpl::GModel::ConstLayoutGraph glm(*graph);
 
-    auto in_nh  = cv::gimpl::GModel::dataNodeOf(gm, in);
-    auto tmp_nh = cv::gimpl::GModel::dataNodeOf(gm, tmp0);
-    auto out_nh = cv::gimpl::GModel::dataNodeOf(gm, out);
+    auto in_nh  = cv::gimpl::GModel::dataNodeOf(glm, in);
+    auto tmp_nh = cv::gimpl::GModel::dataNodeOf(glm, tmp0);
+    auto out_nh = cv::gimpl::GModel::dataNodeOf(glm, out);
 
     // in/out mats shouldn't be assigned to any Island
     EXPECT_FALSE(gm.metadata(in_nh ).contains<cv::gimpl::Island>());
diff --git a/modules/gapi/test/internal/gapi_int_island_tests.cpp b/modules/gapi/test/internal/gapi_int_island_tests.cpp
index 06a5b8c7dd..7da1670ecc 100644
--- a/modules/gapi/test/internal/gapi_int_island_tests.cpp
+++ b/modules/gapi/test/internal/gapi_int_island_tests.cpp
@@ -9,6 +9,7 @@
 
 #include "compiler/gmodel.hpp"
 #include "compiler/gcompiled_priv.hpp"
+#include "compiler/gmodel_priv.hpp"
 
 namespace opencv_test
 {