Mojo Example that demos the difference between providing and requesting an interface

examples/indirect_service/indirect_integer_service.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "examples/indirect_service/indirect_service_demo.mojom.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/public/cpp/application/application_connection.h"
+#include "mojo/public/cpp/application/application_delegate.h"
+#include "mojo/public/cpp/application/application_runner.h"
+#include "mojo/public/cpp/application/interface_factory_impl.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace mojo {
+namespace examples {
+
+class IndirectIntegerServiceImpl :
+    public InterfaceImpl<IndirectIntegerService>, public IntegerService {
+ public:
+  IndirectIntegerServiceImpl() {}
+
+  ~IndirectIntegerServiceImpl() override {
+   for (auto itr = bindings_.begin(); itr < bindings_.end(); itr++)
+     delete *itr;
+  }
+
+  // IndirectIntegerService
+
+  void Set(IntegerServicePtr service) override {
+    integer_service_ = service.Pass();
+  }
+
+  void Get(InterfaceRequest<IntegerService> service) override {
+    bindings_.push_back(new Binding<IntegerService>(this, service.Pass()));
+  }
+
+  // IntegerService
+
+  void Increment(const Callback<void(int32_t)>& callback) override {
+    if (integer_service_.get())
+      integer_service_->Increment(callback);
+  }
+
+private:
+  IntegerServicePtr integer_service_;
+  std::vector<Binding<IntegerService>*> bindings_;
+};
+
+class IndirectIntegerServiceAppDelegate : public ApplicationDelegate {
+ public:
+  bool ConfigureIncomingConnection(
+      ApplicationConnection* connection) override {
+    connection->AddService(&indirect_integer_service_factory_);
+    return true;
+  }
+
+ private:
+  InterfaceFactoryImpl<IndirectIntegerServiceImpl>
+      indirect_integer_service_factory_;
+};
+
+}  // namespace examples
+}  // namespace mojo
+
+MojoResult MojoMain(MojoHandle shell_handle) {
+  mojo::ApplicationRunner runner(
+      new mojo::examples::IndirectIntegerServiceAppDelegate);
+  return runner.Run(shell_handle);
+}
+