diff --git a/co_sim_io/c/co_sim_io_c.cpp b/co_sim_io/c/co_sim_io_c.cpp
index 9cee1c3e..feb6d2fc 100644
--- a/co_sim_io/c/co_sim_io_c.cpp
+++ b/co_sim_io/c/co_sim_io_c.cpp
@@ -15,6 +15,7 @@ extern "C" {
 #include "co_sim_io_c.h"
 }
 #include "../co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 namespace {
     // get C Info from C++ Info
diff --git a/co_sim_io/impl/Threads.h b/co_sim_io/impl/Threads.h
new file mode 100644
index 00000000..59b18bb4
--- /dev/null
+++ b/co_sim_io/impl/Threads.h
@@ -0,0 +1,199 @@
+#ifndef THREADS_H_
+#define THREADS_H_
+
+////////////////////////////////////////////////////////////////////////////////
+// macro DEFAULT_THREADING
+// Selects the default threading model for certain components of Loki
+// If you don't define it, it defaults to single-threaded
+// All classes in Loki have configurable threading model; DEFAULT_THREADING
+// affects only default template arguments
+////////////////////////////////////////////////////////////////////////////////
+
+// Last update: June 20, 2001
+
+#ifndef DEFAULT_THREADING
+#define DEFAULT_THREADING /**/ ::Loki::SingleThreaded
+#endif
+
+namespace Loki
+{
+////////////////////////////////////////////////////////////////////////////////
+// class template SingleThreaded
+// Implementation of the ThreadingModel policy used by various classes
+// Implements a single-threaded model; no synchronization
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class Host>
+    class SingleThreaded
+    {
+    public:
+        struct Lock
+        {
+            Lock() {}
+            explicit Lock(const SingleThreaded&) {}
+        };
+
+        typedef Host VolatileType;
+
+        typedef int IntType;
+
+        static IntType AtomicAdd(volatile IntType& lval, IntType val)
+        { return lval += val; }
+
+        static IntType AtomicSubtract(volatile IntType& lval, IntType val)
+        { return lval -= val; }
+
+        static IntType AtomicMultiply(volatile IntType& lval, IntType val)
+        { return lval *= val; }
+
+        static IntType AtomicDivide(volatile IntType& lval, IntType val)
+        { return lval /= val; }
+
+        static IntType AtomicIncrement(volatile IntType& lval)
+        { return ++lval; }
+
+        static IntType AtomicDecrement(volatile IntType& lval)
+        { return --lval; }
+
+        static void AtomicAssign(volatile IntType & lval, IntType val)
+        { lval = val; }
+
+        static void AtomicAssign(IntType & lval, volatile IntType & val)
+        { lval = val; }
+    };
+
+#ifdef _WINDOWS_
+
+////////////////////////////////////////////////////////////////////////////////
+// class template ObjectLevelLockable
+// Implementation of the ThreadingModel policy used by various classes
+// Implements a object-level locking scheme
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class Host>
+    class ObjectLevelLockable
+    {
+        mutable CRITICAL_SECTION mtx_;
+
+    public:
+        ObjectLevelLockable()
+        {
+            ::InitializeCriticalSection(&mtx_);
+        }
+
+        ~ObjectLevelLockable()
+        {
+            ::DeleteCriticalSection(&mtx_);
+        }
+
+        class Lock;
+        friend class Lock;
+
+        class Lock
+        {
+            ObjectLevelLockable const& host_;
+
+            Lock(const Lock&);
+            Lock& operator=(const Lock&);
+        public:
+
+            explicit Lock(const ObjectLevelLockable& host) : host_(host)
+            {
+                ::EnterCriticalSection(&host_.mtx_);
+            }
+
+            ~Lock()
+            {
+                ::LeaveCriticalSection(&host_.mtx_);
+            }
+        };
+
+        typedef volatile Host VolatileType;
+
+        typedef LONG IntType;
+
+        static IntType AtomicIncrement(volatile IntType& lval)
+        { return InterlockedIncrement(&const_cast<IntType&>(lval)); }
+
+        static IntType AtomicDecrement(volatile IntType& lval)
+        { return InterlockedDecrement(&const_cast<IntType&>(lval)); }
+
+        static void AtomicAssign(volatile IntType& lval, IntType val)
+        { InterlockedExchange(&const_cast<IntType&>(lval), val); }
+
+        static void AtomicAssign(IntType& lval, volatile IntType& val)
+        { InterlockedExchange(&lval, val); }
+    };
+
+    template <class Host>
+    class ClassLevelLockable
+    {
+        struct Initializer
+        {
+            CRITICAL_SECTION mtx_;
+
+            Initializer()
+            {
+                ::InitializeCriticalSection(&mtx_);
+            }
+            ~Initializer()
+            {
+                ::DeleteCriticalSection(&mtx_);
+            }
+        };
+
+        static Initializer initializer_;
+
+    public:
+        class Lock;
+        friend class Lock;
+
+        class Lock
+        {
+            Lock(const Lock&);
+            Lock& operator=(const Lock&);
+        public:
+            Lock()
+            {
+                ::EnterCriticalSection(&initializer_.mtx_);
+            }
+            explicit Lock(const ClassLevelLockable&)
+            {
+                ::EnterCriticalSection(&initializer_.mtx_);
+            }
+            ~Lock()
+            {
+                ::LeaveCriticalSection(&initializer_.mtx_);
+            }
+        };
+
+        typedef volatile Host VolatileType;
+
+        typedef LONG IntType;
+
+        static IntType AtomicIncrement(volatile IntType& lval)
+        { return InterlockedIncrement(&const_cast<IntType&>(lval)); }
+
+        static IntType AtomicDecrement(volatile IntType& lval)
+        { return InterlockedDecrement(&const_cast<IntType&>(lval)); }
+
+        static void AtomicAssign(volatile IntType& lval, IntType val)
+        { InterlockedExchange(&const_cast<IntType&>(lval), val); }
+
+        static void AtomicAssign(IntType& lval, volatile IntType& val)
+        { InterlockedExchange(&lval, val); }
+    };
+
+    template <class Host>
+    typename ClassLevelLockable<Host>::Initializer
+    ClassLevelLockable<Host>::initializer_;
+
+#endif
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Change log:
+// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
+////////////////////////////////////////////////////////////////////////////////
+
+#endif
diff --git a/co_sim_io/impl/co_sim_io_impl.hpp b/co_sim_io/impl/co_sim_io_impl.hpp
index 279a4943..dbf2d86e 100644
--- a/co_sim_io/impl/co_sim_io_impl.hpp
+++ b/co_sim_io/impl/co_sim_io_impl.hpp
@@ -26,21 +26,84 @@ This file contains the implementation of the functions defined in "co_sim_io.hpp
 #include "utilities.hpp"
 #include "version.hpp"
 
+#include "singleton.h"
+
+using maptype = std::unordered_map<std::string, std::unique_ptr<CoSimIO::Internals::Connection>>;
+
+extern maptype registry_map;
+
+#define DEFINE_SINGLETON_MAIN( ) maptype registry_map
+
 namespace CoSimIO {
 
 namespace Internals {
-// TODO make sure this is unique even across compilation units (test somehow)
-static std::unordered_map<std::string, std::unique_ptr<Connection>> s_co_sim_connections;
 
-static bool HasIO(const std::string& rConnectionName)
+template <typename T>
+class Singleton
+{
+public:
+    static T& getInstance()
+    {
+        if (!m_instance) {
+            m_instance = CoSimIO::make_unique<T>();
+        }
+        return *m_instance;
+    }
+
+private:
+    static std::unique_ptr<T> m_instance;
+};
+
+template<typename T>
+std::unique_ptr<T> Singleton<T>::m_instance = nullptr;
+
+template<typename T>
+class Singleton2 {
+public:
+    static T& Instance();
+
+    Singleton2(const Singleton2&) = delete;
+    Singleton2& operator= (const Singleton2) = delete;
+
+protected:
+    Singleton2() {}
+};
+
+template<typename T>
+T& Singleton2<T>::Instance()
 {
-    return s_co_sim_connections.find(rConnectionName) != s_co_sim_connections.end();
+// #ifdef CO_SIM_IO_EXTERN
+//     extern T t;
+// #else
+    static T t;
+// #endif
+    return t;
 }
 
-static Connection& GetConnection(const std::string& rConnectionName)
+// using maptype = std::unordered_map<std::string, std::unique_ptr<Connection>>;
+
+// typedef Loki::SingletonHolder<maptype> SingleA;
+
+// // this function makes sure that the registry works correctly also across translation units / libraries
+// // inline std::unordered_map<std::string, std::unique_ptr<Connection>>& GetRegistry()
+// // {
+// //     static std::unordered_map<std::string, std::unique_ptr<Connection>> s_co_sim_connections;
+// //     return s_co_sim_connections;
+// // }
+
+// using CoSimIOSingletonType = Singleton2<maptype>;
+
+// extern maptype registry_map;
+
+inline bool HasIO(const std::string& rConnectionName)
+{
+    return registry_map.find(rConnectionName) != registry_map.end();
+}
+
+inline Connection& GetConnection(const std::string& rConnectionName)
 {
     CO_SIM_IO_ERROR_IF_NOT(HasIO(rConnectionName)) << "Trying to use connection \"" << rConnectionName << "\" which does not exist!" << std::endl;
-    return *s_co_sim_connections.at(rConnectionName);
+    return *registry_map.at(rConnectionName);
 }
 
 } // namespace Internals
@@ -81,7 +144,7 @@ inline Info Connect(const Info& I_Settings)
 
     CO_SIM_IO_ERROR_IF(HasIO(connection_name)) << "A connection from \"" << my_name << "\" to \"" << connect_to << "\"already exists!" << std::endl;
 
-    s_co_sim_connections[connection_name] = std::unique_ptr<Connection>(new Connection(I_Settings));
+    registry_map[connection_name] = std::unique_ptr<Connection>(new Connection(I_Settings));
 
     auto info = GetConnection(connection_name).Connect(I_Settings);
     info.Set<std::string>("connection_name", connection_name);
@@ -96,7 +159,7 @@ inline Info Disconnect(const Info& I_Info)
     CO_SIM_IO_ERROR_IF_NOT(HasIO(connection_name)) << "Trying to disconnect connection \"" << connection_name << "\" which does not exist!" << std::endl;
 
     auto info = GetConnection(connection_name).Disconnect(I_Info);
-    s_co_sim_connections.erase(connection_name);
+    registry_map.erase(connection_name);
 
     return info;
 }
@@ -214,4 +277,6 @@ inline Info Register(
 
 } // namespace CoSimIO
 
+
+
 #endif // CO_SIM_IO_IMPL_INCLUDED
diff --git a/co_sim_io/impl/singleton.h b/co_sim_io/impl/singleton.h
new file mode 100644
index 00000000..f0ba8795
--- /dev/null
+++ b/co_sim_io/impl/singleton.h
@@ -0,0 +1,464 @@
+////////////////////////////////////////////////////////////////////////////////
+// The Loki Library
+// Copyright (c) 2001 by Andrei Alexandrescu
+// This code accompanies the book:
+// Alexandrescu, Andrei. "Modern C++ Design: Generic Programming and Design
+//     Patterns Applied". Copyright (c) 2001. Addison-Wesley.
+// Permission to use, copy, modify, distribute and sell this software for any
+//     purpose is hereby granted without fee, provided that the above copyright
+//     notice appear in all copies and that both that copyright notice and this
+//     permission notice appear in supporting documentation.
+// The author or Addison-Wesley Longman make no representations about the
+//     suitability of this software for any purpose. It is provided "as is"
+//     without express or implied warranty.
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef SINGLETON_INC_
+#define SINGLETON_INC_
+
+#include "Threads.h"
+#include <algorithm>
+#include <stdexcept>
+#include <cassert>
+#include <cstdlib>
+#include <new>
+
+#ifdef _MSC_VER
+#define C_CALLING_CONVENTION_QUALIFIER __cdecl
+#else
+#define C_CALLING_CONVENTION_QUALIFIER
+#endif
+
+namespace Loki
+{
+    typedef void (C_CALLING_CONVENTION_QUALIFIER *atexit_pfn_t)();
+
+    namespace Private
+    {
+////////////////////////////////////////////////////////////////////////////////
+// class LifetimeTracker
+// Helper class for SetLongevity
+////////////////////////////////////////////////////////////////////////////////
+
+        class LifetimeTracker
+        {
+        public:
+            LifetimeTracker(unsigned int x) : longevity_(x)
+            {}
+
+            virtual ~LifetimeTracker() = 0;
+
+            static bool Compare(const LifetimeTracker* lhs,
+                const LifetimeTracker* rhs)
+            {
+                return lhs->longevity_ < rhs->longevity_;
+            }
+
+        private:
+            unsigned int longevity_;
+        };
+
+        // Definition required
+        inline LifetimeTracker::~LifetimeTracker() {}
+
+        // Helper data
+        typedef LifetimeTracker** TrackerArray;
+        extern TrackerArray pTrackerArray;
+        extern unsigned int elements;
+
+        // Helper destroyer function
+        template <typename T>
+        struct Deleter
+        {
+            static void Delete(T* pObj)
+            { delete pObj; }
+        };
+
+        // Concrete lifetime tracker for objects of type T
+        template <typename T, typename Destroyer>
+        class ConcreteLifetimeTracker : public LifetimeTracker
+        {
+        public:
+            ConcreteLifetimeTracker(T* p,unsigned int longevity, Destroyer d)
+                : LifetimeTracker(longevity)
+                , pTracked_(p)
+                , destroyer_(d)
+            {}
+
+            ~ConcreteLifetimeTracker()
+            { destroyer_(pTracked_); }
+
+        private:
+            T* pTracked_;
+            Destroyer destroyer_;
+        };
+
+        void C_CALLING_CONVENTION_QUALIFIER AtExitFn(); // declaration needed below
+    } // namespace Private
+
+////////////////////////////////////////////////////////////////////////////////
+// function template SetLongevity
+// Assigns an object a longevity; ensures ordered destructions of objects
+//     registered thusly during the exit sequence of the application
+////////////////////////////////////////////////////////////////////////////////
+
+    template <typename T, typename Destroyer>
+    void SetLongevity(T* pDynObject, unsigned int longevity,
+        Destroyer d = Private::Deleter<T>::Delete)
+    {
+        using namespace Private;
+
+        TrackerArray pNewArray = static_cast<TrackerArray>(
+                std::realloc(pTrackerArray,
+                    sizeof(*pTrackerArray) * (elements + 1)));
+        if (!pNewArray) throw std::bad_alloc();
+
+        // Delayed assignment for exception safety
+        pTrackerArray = pNewArray;
+
+        LifetimeTracker* p = new ConcreteLifetimeTracker<T, Destroyer>(
+            pDynObject, longevity, d);
+
+        // Insert a pointer to the object into the queue
+        TrackerArray pos = std::upper_bound(
+            pTrackerArray,
+            pTrackerArray + elements,
+            p,
+            LifetimeTracker::Compare);
+        std::copy_backward(
+            pos,
+            pTrackerArray + elements,
+            pTrackerArray + elements + 1);
+        *pos = p;
+        ++elements;
+
+        // Register a call to AtExitFn
+        std::atexit(Private::AtExitFn);
+    }
+
+////////////////////////////////////////////////////////////////////////////////
+// class template CreateUsingNew
+// Implementation of the CreationPolicy used by SingletonHolder
+// Creates objects using a straight call to the new operator
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class T> struct CreateUsingNew
+    {
+        static T* Create()
+        { return new T; }
+
+        static void Destroy(T* p)
+        { delete p; }
+    };
+
+////////////////////////////////////////////////////////////////////////////////
+// class template CreateUsingNew
+// Implementation of the CreationPolicy used by SingletonHolder
+// Creates objects using a call to std::malloc, followed by a call to the
+//     placement new operator
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class T> struct CreateUsingMalloc
+    {
+        static T* Create()
+        {
+            void* p = std::malloc(sizeof(T));
+            if (!p) return 0;
+            return new(p) T;
+        }
+
+        static void Destroy(T* p)
+        {
+            p->~T();
+            std::free(p);
+        }
+    };
+
+////////////////////////////////////////////////////////////////////////////////
+// class template CreateStatic
+// Implementation of the CreationPolicy used by SingletonHolder
+// Creates an object in static memory
+// Implementation is slightly nonportable because it uses the MaxAlign trick
+//     (an union of all types to ensure proper memory alignment). This trick is
+//     nonportable in theory but highly portable in practice.
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class T> struct CreateStatic
+    {
+#if defined(_MSC_VER) && _MSC_VER >= 1300
+#pragma warning( push )
+ // alignment of a member was sensitive to packing
+#pragma warning( disable : 4121 )
+#endif // _MSC_VER
+        union MaxAlign
+        {
+            char t_[sizeof(T)];
+            short int shortInt_;
+            int int_;
+            long int longInt_;
+            float float_;
+            double double_;
+            long double longDouble_;
+            struct Test;
+            int Test::* pMember_;
+            int (Test::*pMemberFn_)(int);
+        };
+#if defined(_MSC_VER) && _MSC_VER >= 1300
+#pragma warning( pop )
+#endif // _MSC_VER
+
+        static T* Create()
+        {
+            static MaxAlign staticMemory_;
+            return new(&staticMemory_) T;
+        }
+
+        static void Destroy(T* p)
+        {
+            p->~T();
+        }
+    };
+
+////////////////////////////////////////////////////////////////////////////////
+// class template DefaultLifetime
+// Implementation of the LifetimePolicy used by SingletonHolder
+// Schedules an object's destruction as per C++ rules
+// Forwards to std::atexit
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class T>
+    struct DefaultLifetime
+    {
+        static void ScheduleDestruction(T*, atexit_pfn_t pFun)
+        { std::atexit(pFun); }
+
+        static void OnDeadReference()
+        { throw std::logic_error("Dead Reference Detected"); }
+    };
+
+////////////////////////////////////////////////////////////////////////////////
+// class template PhoenixSingleton
+// Implementation of the LifetimePolicy used by SingletonHolder
+// Schedules an object's destruction as per C++ rules, and it allows object
+//    recreation by not throwing an exception from OnDeadReference
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class T>
+    class PhoenixSingleton
+    {
+    public:
+        static void ScheduleDestruction(T*, atexit_pfn_t pFun)
+        {
+#ifndef ATEXIT_FIXED
+            if (!destroyedOnce_)
+#endif
+                std::atexit(pFun);
+        }
+
+        static void OnDeadReference()
+        {
+#ifndef ATEXIT_FIXED
+            destroyedOnce_ = true;
+#endif
+        }
+
+    private:
+#ifndef ATEXIT_FIXED
+        static bool destroyedOnce_;
+#endif
+    };
+
+#ifndef ATEXIT_FIXED
+    template <class T> bool PhoenixSingleton<T>::destroyedOnce_ = false;
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+// class template Adapter
+// Helper for SingletonWithLongevity below
+////////////////////////////////////////////////////////////////////////////////
+
+    namespace Private
+    {
+        template <class T>
+        struct Adapter
+        {
+            void operator()(T*) { return pFun_(); }
+            atexit_pfn_t pFun_;
+        };
+    }
+
+////////////////////////////////////////////////////////////////////////////////
+// class template SingletonWithLongevity
+// Implementation of the LifetimePolicy used by SingletonHolder
+// Schedules an object's destruction in order of their longevities
+// Assumes a visible function GetLongevity(T*) that returns the longevity of the
+//     object
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class T>
+    class SingletonWithLongevity
+    {
+    public:
+        static void ScheduleDestruction(T* pObj, atexit_pfn_t pFun)
+        {
+            Private::Adapter<T> adapter = { pFun };
+            SetLongevity(pObj, GetLongevity(pObj), adapter);
+        }
+
+        static void OnDeadReference()
+        { throw std::logic_error("Dead Reference Detected"); }
+    };
+
+////////////////////////////////////////////////////////////////////////////////
+// class template NoDestroy
+// Implementation of the LifetimePolicy used by SingletonHolder
+// Never destroys the object
+////////////////////////////////////////////////////////////////////////////////
+
+    template <class T>
+    struct NoDestroy
+    {
+        static void ScheduleDestruction(T*, atexit_pfn_t pFun)
+        {}
+
+        static void OnDeadReference()
+        {}
+    };
+
+////////////////////////////////////////////////////////////////////////////////
+// class template SingletonHolder
+// Provides Singleton amenities for a type T
+// To protect that type from spurious instantiations, you have to protect it
+//     yourself.
+////////////////////////////////////////////////////////////////////////////////
+
+    template
+    <
+        typename T,
+        template <class> class CreationPolicy = CreateUsingNew,
+        template <class> class LifetimePolicy = DefaultLifetime,
+        template <class> class ThreadingModel = SingleThreaded
+    >
+    class SingletonHolder
+    {
+    public:
+        static T& Instance();
+
+    private:
+        // Helpers
+        static void MakeInstance();
+        static void C_CALLING_CONVENTION_QUALIFIER DestroySingleton();
+
+        // Protection
+        SingletonHolder();
+
+        // Data
+        typedef typename ThreadingModel<T*>::VolatileType PtrInstanceType;
+        static PtrInstanceType pInstance_;
+        static bool destroyed_;
+    };
+
+////////////////////////////////////////////////////////////////////////////////
+// SingletonHolder's data
+////////////////////////////////////////////////////////////////////////////////
+
+    template
+    <
+        class T,
+        template <class> class C,
+        template <class> class L,
+        template <class> class M
+    >
+    typename SingletonHolder<T, C, L, M>::PtrInstanceType
+        SingletonHolder<T, C, L, M>::pInstance_;
+
+    template
+    <
+        class T,
+        template <class> class C,
+        template <class> class L,
+        template <class> class M
+    >
+    bool SingletonHolder<T, C, L, M>::destroyed_;
+
+////////////////////////////////////////////////////////////////////////////////
+// SingletonHolder::Instance
+////////////////////////////////////////////////////////////////////////////////
+
+    template
+    <
+        class T,
+        template <class> class CreationPolicy,
+        template <class> class LifetimePolicy,
+        template <class> class ThreadingModel
+    >
+    inline T& SingletonHolder<T, CreationPolicy,
+        LifetimePolicy, ThreadingModel>::Instance()
+    {
+        if (!pInstance_)
+        {
+            MakeInstance();
+        }
+        return *pInstance_;
+    }
+
+////////////////////////////////////////////////////////////////////////////////
+// SingletonHolder::MakeInstance (helper for Instance)
+////////////////////////////////////////////////////////////////////////////////
+
+    template
+    <
+        class T,
+        template <class> class CreationPolicy,
+        template <class> class LifetimePolicy,
+        template <class> class ThreadingModel
+    >
+    void SingletonHolder<T, CreationPolicy,
+        LifetimePolicy, ThreadingModel>::MakeInstance()
+    {
+        typename ThreadingModel<T>::Lock guard;
+        (void)guard;
+
+        if (!pInstance_)
+        {
+            if (destroyed_)
+            {
+                LifetimePolicy<T>::OnDeadReference();
+                destroyed_ = false;
+            }
+            pInstance_ = CreationPolicy<T>::Create();
+            LifetimePolicy<T>::ScheduleDestruction(pInstance_,
+                &DestroySingleton);
+        }
+    }
+
+    template
+    <
+        class T,
+        template <class> class CreationPolicy,
+        template <class> class L,
+        template <class> class M
+    >
+    void C_CALLING_CONVENTION_QUALIFIER
+    SingletonHolder<T, CreationPolicy, L, M>::DestroySingleton()
+    {
+        assert(!destroyed_);
+        CreationPolicy<T>::Destroy(pInstance_);
+        pInstance_ = 0;
+        destroyed_ = true;
+    }
+} // namespace Loki
+
+////////////////////////////////////////////////////////////////////////////////
+// Change log:
+// May 21, 2001: Correct the volatile qualifier - credit due to Darin Adler
+// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
+// January 08, 2002: Fixed bug in call to realloc - credit due to Nigel Gent and
+//      Eike Petersen
+// March 08, 2002: moved the assignment to pTrackerArray in SetLongevity to fix
+//      exception safety issue. Credit due to Kari Hoijarvi
+// May 09, 2002: Fixed bug in Compare that caused longevities to act backwards.
+//      Credit due to Scott McDonald.
+////////////////////////////////////////////////////////////////////////////////
+
+#endif // SINGLETON_INC_
diff --git a/co_sim_io/python/co_sim_io_python.cpp b/co_sim_io/python/co_sim_io_python.cpp
index 683b6457..09bfd063 100644
--- a/co_sim_io/python/co_sim_io_python.cpp
+++ b/co_sim_io/python/co_sim_io_python.cpp
@@ -31,6 +31,7 @@ PYBIND11_DECLARE_HOLDER_TYPE(T, CoSimIO::intrusive_ptr<T>)
 
 // CoSimIO includes
 #include "../co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 #include "info_to_python.hpp"
 #include "model_part_to_python.hpp"
 #include "vector_to_python.hpp"
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index e7da9d50..e1d65d40 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -31,6 +31,9 @@ if (CO_SIM_IO_ENABLE_MPI)
 
 endif()
 
+# singleton tests
+add_subdirectory(co_sim_io/impl/singleton_tests)
+
 ### C++ tests ###
 function(add_cpp_executable TEST_SOURCE_FILE)
     get_filename_component(TEST_FILENAME ${TEST_SOURCE_FILE} NAME)
diff --git a/tests/co_sim_io/impl/singleton_tests/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/CMakeLists.txt
new file mode 100644
index 00000000..7bd6b431
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/CMakeLists.txt
@@ -0,0 +1,18 @@
+include_directories( ${CMAKE_SOURCE_DIR}/co_sim_io )
+
+add_executable ( main_singleton_partner main_partner.cpp )
+install( TARGETS main_singleton_partner DESTINATION ${CMAKE_SOURCE_DIR}/bin/singleton_tests )
+set_target_properties( main_singleton_partner PROPERTIES
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED YES
+    CXX_EXTENSIONS NO
+)
+
+# add_subdirectory(scenario_1)
+# add_subdirectory(scenario_2)
+# add_subdirectory(scenario_3)
+# add_subdirectory(scenario_4)
+# add_subdirectory(scenario_5)
+# add_subdirectory(scenario_6)
+# add_subdirectory(source)
+add_subdirectory(source_cosimio)
diff --git a/tests/co_sim_io/impl/singleton_tests/main_partner.cpp b/tests/co_sim_io/impl/singleton_tests/main_partner.cpp
new file mode 100644
index 00000000..da7a3c71
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/main_partner.cpp
@@ -0,0 +1,42 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// CoSimulation includes
+#include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
+
+#define COSIMIO_CHECK_EQUAL(a, b)                                \
+    if (a != b) {                                                \
+        std::cout << "in line " << __LINE__ << " : " << a        \
+                  << " is not equal to " << b << std::endl;      \
+        return 1;                                                \
+    }
+
+int main()
+{
+    CoSimIO::Info settings;
+    settings.Set("my_name", "singleton_tester_partner");
+    settings.Set("connect_to",    "singleton_tester");
+    settings.Set("echo_level", 1);
+    settings.Set("version", "1.25");
+
+    auto info = CoSimIO::Connect(settings);
+    COSIMIO_CHECK_EQUAL(info.Get<int>("connection_status"), CoSimIO::ConnectionStatus::Connected);
+    const std::string connection_name = info.Get<std::string>("connection_name");
+
+    CoSimIO::Info disconnect_settings;
+    disconnect_settings.Set("connection_name", connection_name);
+    info = CoSimIO::Disconnect(disconnect_settings); // disconnect afterwards
+    COSIMIO_CHECK_EQUAL(info.Get<int>("connection_status"), CoSimIO::ConnectionStatus::Disconnected);
+
+    return 0;
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_1/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/scenario_1/CMakeLists.txt
new file mode 100644
index 00000000..fdfbe567
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_1/CMakeLists.txt
@@ -0,0 +1,15 @@
+include_directories( ${CMAKE_SOURCE_DIR}/co_sim_io )
+
+add_library(singleton_tests_scenario_1_ext_lib SHARED ext_lib.cpp )
+install( TARGETS singleton_tests_scenario_1_ext_lib DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_executable ( main_scenario_1 main.cpp )
+target_link_libraries( main_scenario_1 singleton_tests_scenario_1_ext_lib )
+install( TARGETS main_scenario_1 DESTINATION ${CMAKE_SOURCE_DIR}/bin/singleton_tests/scenario_1/ )
+set_target_properties( main_scenario_1 PROPERTIES
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED YES
+    CXX_EXTENSIONS NO
+)
+
+add_test(NAME singleton_tests_scenario_1 COMMAND sh ../../../../run.sh $<TARGET_FILE:main_scenario_1>  $<TARGET_FILE:main_singleton_partner>)
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_1/ext_lib.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_1/ext_lib.cpp
new file mode 100644
index 00000000..1ed94749
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_1/ext_lib.cpp
@@ -0,0 +1,21 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
+#include "ext_lib.hpp"
+
+bool CheckExtLibHasConnection(const std::string& ConnectionName)
+{
+    return CoSimIO::Internals::HasIO(ConnectionName);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_1/ext_lib.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_1/ext_lib.hpp
new file mode 100644
index 00000000..3840e405
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_1/ext_lib.hpp
@@ -0,0 +1,16 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+bool CheckExtLibHasConnection(const std::string& ConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_1/main.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_1/main.cpp
new file mode 100644
index 00000000..f12ed3af
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_1/main.cpp
@@ -0,0 +1,58 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+/*
+Testing if the CoSimIO can be safely included in complex libraries
+In this scenario the CoSimIO is included in the main executable
+and in the external library
+Connecting and disconnecting is done in the main executable
+*/
+
+// CoSimulation includes
+#include "co_sim_io.hpp"
+#include "ext_lib.hpp"
+
+#define COSIMIO_CHECK_EQUAL(a, b)                                \
+    if (a != b) {                                                \
+        std::cout << "in line " << __LINE__ << " : " << a        \
+                  << " is not equal to " << b << std::endl;      \
+        return 1;                                                \
+    }
+
+#define COSIMIO_CHECK_True(a)                                    \
+    if (!a) {                                                    \
+        std::cout << "in line " << __LINE__ << " : "             \
+                  << "false is not true" << std::endl;           \
+        return 1;                                                \
+    }
+
+int main()
+{
+    CoSimIO::Info settings;
+    settings.Set("my_name",    "singleton_tester");
+    settings.Set("connect_to", "singleton_tester_partner");
+    settings.Set("echo_level", 1);
+    settings.Set("version", "1.25");
+
+    auto info = CoSimIO::Connect(settings);
+    COSIMIO_CHECK_EQUAL(info.Get<int>("connection_status"), CoSimIO::ConnectionStatus::Connected);
+    const std::string connection_name = info.Get<std::string>("connection_name");
+
+    COSIMIO_CHECK_True(CheckExtLibHasConnection(connection_name));
+
+    CoSimIO::Info disconnect_settings;
+    disconnect_settings.Set("connection_name", connection_name);
+    info = CoSimIO::Disconnect(disconnect_settings); // disconnect afterwards
+    COSIMIO_CHECK_EQUAL(info.Get<int>("connection_status"), CoSimIO::ConnectionStatus::Disconnected);
+
+    return 0;
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_2/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/scenario_2/CMakeLists.txt
new file mode 100644
index 00000000..fe8810ec
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_2/CMakeLists.txt
@@ -0,0 +1,15 @@
+include_directories( ${CMAKE_SOURCE_DIR}/co_sim_io )
+
+add_library(singleton_tests_scenario_2_ext_lib SHARED ext_lib.cpp )
+install( TARGETS singleton_tests_scenario_2_ext_lib DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_executable ( main_scenario_2 main.cpp )
+target_link_libraries( main_scenario_2 singleton_tests_scenario_2_ext_lib )
+install( TARGETS main_scenario_2 DESTINATION ${CMAKE_SOURCE_DIR}/bin/singleton_tests/scenario_2/ )
+set_target_properties( main_scenario_2 PROPERTIES
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED YES
+    CXX_EXTENSIONS NO
+)
+
+add_test(NAME singleton_tests_scenario_2 COMMAND sh ../../../../run.sh $<TARGET_FILE:main_scenario_2>  $<TARGET_FILE:main_singleton_partner>)
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_2/ext_lib.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_2/ext_lib.cpp
new file mode 100644
index 00000000..cd5614e7
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_2/ext_lib.cpp
@@ -0,0 +1,35 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
+#include "ext_lib.hpp"
+
+std::string ConnectToCoSimIO()
+{
+    CoSimIO::Info settings;
+    settings.Set("my_name",    "singleton_tester");
+    settings.Set("connect_to", "singleton_tester_partner");
+    settings.Set("echo_level", 1);
+    settings.Set("version", "1.25");
+
+    auto info = CoSimIO::Connect(settings);
+    return info.Get<std::string>("connection_name");
+}
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName)
+{
+    CoSimIO::Info disconnect_settings;
+    disconnect_settings.Set("connection_name", rConnectionName);
+    CoSimIO::Disconnect(disconnect_settings);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_2/ext_lib.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_2/ext_lib.hpp
new file mode 100644
index 00000000..2ec1c264
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_2/ext_lib.hpp
@@ -0,0 +1,18 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+std::string ConnectToCoSimIO();
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_2/main.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_2/main.cpp
new file mode 100644
index 00000000..46e9a5f0
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_2/main.cpp
@@ -0,0 +1,40 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+/*
+Testing if the CoSimIO can be safely included in complex libraries
+In this scenario the CoSimIO is included in the main executable
+and in the external library
+Connecting and disconnecting is done in the external library
+*/
+
+// CoSimulation includes
+#include "co_sim_io.hpp"
+#include "ext_lib.hpp"
+
+#define COSIMIO_CHECK_True(a)                                    \
+    if (!a) {                                                    \
+        std::cout << "in line " << __LINE__ << " : "             \
+                  << "false is not true" << std::endl;           \
+        return 1;                                                \
+    }
+
+int main()
+{
+    const std::string connection_name = ConnectToCoSimIO();
+
+    COSIMIO_CHECK_True(CoSimIO::Internals::HasIO(connection_name));
+
+    DisconnectFromCoSimIO(connection_name);
+
+    return 0;
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_3/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/scenario_3/CMakeLists.txt
new file mode 100644
index 00000000..54bedfed
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_3/CMakeLists.txt
@@ -0,0 +1,15 @@
+include_directories( ${CMAKE_SOURCE_DIR}/co_sim_io )
+
+add_library(singleton_tests_scenario_3_ext_lib SHARED ext_lib.cpp )
+install( TARGETS singleton_tests_scenario_3_ext_lib DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_executable ( main_scenario_3 main.cpp )
+target_link_libraries( main_scenario_3 singleton_tests_scenario_3_ext_lib )
+install( TARGETS main_scenario_3 DESTINATION ${CMAKE_SOURCE_DIR}/bin/singleton_tests/scenario_3/ )
+set_target_properties( main_scenario_3 PROPERTIES
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED YES
+    CXX_EXTENSIONS NO
+)
+
+add_test(NAME singleton_tests_scenario_3 COMMAND sh ../../../../run.sh $<TARGET_FILE:main_scenario_3>  $<TARGET_FILE:main_singleton_partner>)
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_3/ext_lib.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_3/ext_lib.cpp
new file mode 100644
index 00000000..7bf50de6
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_3/ext_lib.cpp
@@ -0,0 +1,26 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+#include "ext_lib.hpp"
+
+std::string ConnectToCoSimIO(CoSimIO::Info& rSettings)
+{
+    auto info = CoSimIO::Connect(rSettings);
+    return info.Get<std::string>("connection_name");
+}
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName)
+{
+    CoSimIO::Info disconnect_settings;
+    disconnect_settings.Set("connection_name", rConnectionName);
+    CoSimIO::Disconnect(disconnect_settings);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_3/ext_lib.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_3/ext_lib.hpp
new file mode 100644
index 00000000..1835147f
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_3/ext_lib.hpp
@@ -0,0 +1,22 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+// Project includes
+#include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
+
+std::string ConnectToCoSimIO(CoSimIO::Info& rSettings);
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_3/main.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_3/main.cpp
new file mode 100644
index 00000000..b889f6e2
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_3/main.cpp
@@ -0,0 +1,48 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+/*
+Testing if the CoSimIO can be safely included in complex libraries
+In this scenario the CoSimIO is included in the main executable
+and in the external library
+Connecting and disconnecting is done in the external library
+Difference to scenario 2: The CoSimIO is also included in the
+header of the ext library
+*/
+
+// CoSimulation includes
+#include "co_sim_io.hpp"
+#include "ext_lib.hpp"
+
+#define COSIMIO_CHECK_True(a)                                    \
+    if (!a) {                                                    \
+        std::cout << "in line " << __LINE__ << " : "             \
+                  << "false is not true" << std::endl;           \
+        return 1;                                                \
+    }
+
+int main()
+{
+    CoSimIO::Info settings;
+    settings.Set("my_name",    "singleton_tester");
+    settings.Set("connect_to", "singleton_tester_partner");
+    settings.Set("echo_level", 1);
+    settings.Set("version", "1.25");
+
+    const std::string connection_name = ConnectToCoSimIO(settings);
+
+    COSIMIO_CHECK_True(CoSimIO::Internals::HasIO(connection_name));
+
+    DisconnectFromCoSimIO(connection_name);
+
+    return 0;
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_4/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/scenario_4/CMakeLists.txt
new file mode 100644
index 00000000..0e083f6a
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_4/CMakeLists.txt
@@ -0,0 +1,18 @@
+include_directories( ${CMAKE_SOURCE_DIR}/co_sim_io )
+
+add_library(singleton_tests_scenario_4_ext_lib_1 SHARED ext_lib_1.cpp )
+install( TARGETS singleton_tests_scenario_4_ext_lib_1 DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_library(singleton_tests_scenario_4_ext_lib_2 SHARED ext_lib_2.cpp )
+install( TARGETS singleton_tests_scenario_4_ext_lib_2 DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_executable ( main_scenario_4 main.cpp )
+target_link_libraries( main_scenario_4 singleton_tests_scenario_4_ext_lib_1 singleton_tests_scenario_4_ext_lib_2 )
+install( TARGETS main_scenario_4 DESTINATION ${CMAKE_SOURCE_DIR}/bin/singleton_tests/scenario_4/ )
+set_target_properties( main_scenario_4 PROPERTIES
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED YES
+    CXX_EXTENSIONS NO
+)
+
+add_test(NAME singleton_tests_scenario_4 COMMAND sh ../../../../run.sh $<TARGET_FILE:main_scenario_4>  $<TARGET_FILE:main_singleton_partner>)
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_1.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_1.cpp
new file mode 100644
index 00000000..29b4b0f4
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_1.cpp
@@ -0,0 +1,35 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
+#include "ext_lib_1.hpp"
+
+std::string ConnectToCoSimIO()
+{
+    CoSimIO::Info settings;
+    settings.Set("my_name",    "singleton_tester");
+    settings.Set("connect_to", "singleton_tester_partner");
+    settings.Set("echo_level", 1);
+    settings.Set("version", "1.25");
+
+    auto info = CoSimIO::Connect(settings);
+    return info.Get<std::string>("connection_name");
+}
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName)
+{
+    CoSimIO::Info disconnect_settings;
+    disconnect_settings.Set("connection_name", rConnectionName);
+    CoSimIO::Disconnect(disconnect_settings);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_1.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_1.hpp
new file mode 100644
index 00000000..2ec1c264
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_1.hpp
@@ -0,0 +1,18 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+std::string ConnectToCoSimIO();
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_2.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_2.cpp
new file mode 100644
index 00000000..c0169725
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_2.cpp
@@ -0,0 +1,20 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+#include "ext_lib_2.hpp"
+
+bool ExtLib2HasIO(const std::string& rConnectionName)
+{
+    return CoSimIO::Internals::HasIO(rConnectionName);
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_2.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_2.hpp
new file mode 100644
index 00000000..9eb89cc1
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_4/ext_lib_2.hpp
@@ -0,0 +1,16 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+bool ExtLib2HasIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_4/main.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_4/main.cpp
new file mode 100644
index 00000000..ea39b5c3
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_4/main.cpp
@@ -0,0 +1,43 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+/*
+Testing if the CoSimIO can be safely included in complex libraries
+In this scenario the CoSimIO is included in the main executable
+and in the external library
+Connecting and disconnecting is done in the external library 1
+The it is checked if the connection is also available in library 2
+*/
+
+// CoSimulation includes
+#include "co_sim_io.hpp"
+#include "ext_lib_1.hpp"
+#include "ext_lib_2.hpp"
+
+#define COSIMIO_CHECK_True(a)                                    \
+    if (!a) {                                                    \
+        std::cout << "in line " << __LINE__ << " : "             \
+                  << "false is not true" << std::endl;           \
+        return 1;                                                \
+    }
+
+int main()
+{
+    const std::string connection_name = ConnectToCoSimIO();
+
+    COSIMIO_CHECK_True(CoSimIO::Internals::HasIO(connection_name));
+    COSIMIO_CHECK_True(ExtLib2HasIO(connection_name));
+
+    DisconnectFromCoSimIO(connection_name);
+
+    return 0;
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_5/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/scenario_5/CMakeLists.txt
new file mode 100644
index 00000000..a08e7233
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_5/CMakeLists.txt
@@ -0,0 +1,18 @@
+include_directories( ${CMAKE_SOURCE_DIR}/co_sim_io )
+
+add_library(singleton_tests_scenario_5_ext_lib_1 SHARED ext_lib_1.cpp )
+install( TARGETS singleton_tests_scenario_5_ext_lib_1 DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_library(singleton_tests_scenario_5_ext_lib_2 SHARED ext_lib_2.cpp )
+install( TARGETS singleton_tests_scenario_5_ext_lib_2 DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_executable ( main_scenario_5 main.cpp )
+target_link_libraries( main_scenario_5 singleton_tests_scenario_5_ext_lib_1 singleton_tests_scenario_5_ext_lib_2 )
+install( TARGETS main_scenario_5 DESTINATION ${CMAKE_SOURCE_DIR}/bin/singleton_tests/scenario_5/ )
+set_target_properties( main_scenario_5 PROPERTIES
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED YES
+    CXX_EXTENSIONS NO
+)
+
+add_test(NAME singleton_tests_scenario_5 COMMAND sh ../../../../run.sh $<TARGET_FILE:main_scenario_5>  $<TARGET_FILE:main_singleton_partner>)
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_1.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_1.cpp
new file mode 100644
index 00000000..29b4b0f4
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_1.cpp
@@ -0,0 +1,35 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
+#include "ext_lib_1.hpp"
+
+std::string ConnectToCoSimIO()
+{
+    CoSimIO::Info settings;
+    settings.Set("my_name",    "singleton_tester");
+    settings.Set("connect_to", "singleton_tester_partner");
+    settings.Set("echo_level", 1);
+    settings.Set("version", "1.25");
+
+    auto info = CoSimIO::Connect(settings);
+    return info.Get<std::string>("connection_name");
+}
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName)
+{
+    CoSimIO::Info disconnect_settings;
+    disconnect_settings.Set("connection_name", rConnectionName);
+    CoSimIO::Disconnect(disconnect_settings);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_1.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_1.hpp
new file mode 100644
index 00000000..2ec1c264
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_1.hpp
@@ -0,0 +1,18 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+std::string ConnectToCoSimIO();
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_2.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_2.cpp
new file mode 100644
index 00000000..c0169725
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_2.cpp
@@ -0,0 +1,20 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+#include "ext_lib_2.hpp"
+
+bool ExtLib2HasIO(const std::string& rConnectionName)
+{
+    return CoSimIO::Internals::HasIO(rConnectionName);
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_2.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_2.hpp
new file mode 100644
index 00000000..9eb89cc1
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_5/ext_lib_2.hpp
@@ -0,0 +1,16 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+bool ExtLib2HasIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_5/main.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_5/main.cpp
new file mode 100644
index 00000000..d0a7edfe
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_5/main.cpp
@@ -0,0 +1,45 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+/*
+Testing if the CoSimIO can be safely included in complex libraries
+In this scenario the CoSimIO is included in the main executable
+and in the external library
+Connecting and disconnecting is done in the external library 1
+The it is checked if the connection is also available in library 2
+Difference to scenario 4 is that the main doesn't include CoSimIO
+*/
+
+// System includes
+#include <iostream>
+
+// CoSimulation includes
+#include "ext_lib_1.hpp"
+#include "ext_lib_2.hpp"
+
+#define COSIMIO_CHECK_True(a)                                    \
+    if (!a) {                                                    \
+        std::cout << "in line " << __LINE__ << " : "             \
+                  << "false is not true" << std::endl;           \
+        return 1;                                                \
+    }
+
+int main()
+{
+    const std::string connection_name = ConnectToCoSimIO();
+
+    COSIMIO_CHECK_True(ExtLib2HasIO(connection_name));
+
+    DisconnectFromCoSimIO(connection_name);
+
+    return 0;
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/scenario_6/CMakeLists.txt
new file mode 100644
index 00000000..762e1f4f
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/CMakeLists.txt
@@ -0,0 +1,18 @@
+include_directories( ${CMAKE_SOURCE_DIR}/co_sim_io )
+
+add_library(singleton_tests_scenario_6_ext_lib_1 SHARED ext_lib_11.cpp ext_lib_12.cpp ext_lib_13.cpp )
+install( TARGETS singleton_tests_scenario_6_ext_lib_1 DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_library(singleton_tests_scenario_6_ext_lib_2 SHARED ext_lib_2.cpp )
+install( TARGETS singleton_tests_scenario_6_ext_lib_2 DESTINATION ${CMAKE_SOURCE_DIR}/bin )
+
+add_executable ( main_scenario_6 main.cpp )
+target_link_libraries( main_scenario_6 singleton_tests_scenario_6_ext_lib_1 singleton_tests_scenario_6_ext_lib_2 )
+install( TARGETS main_scenario_6 DESTINATION ${CMAKE_SOURCE_DIR}/bin/singleton_tests/scenario_6/ )
+set_target_properties( main_scenario_6 PROPERTIES
+    CXX_STANDARD 11
+    CXX_STANDARD_REQUIRED YES
+    CXX_EXTENSIONS NO
+)
+
+add_test(NAME singleton_tests_scenario_6 COMMAND sh ../../../../run.sh $<TARGET_FILE:main_scenario_6>  $<TARGET_FILE:main_singleton_partner>)
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_1.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_1.hpp
new file mode 100644
index 00000000..d9af0acf
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_1.hpp
@@ -0,0 +1,20 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+std::string ConnectToCoSimIO();
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName);
+
+bool ExtLib1HasIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_11.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_11.cpp
new file mode 100644
index 00000000..02f65418
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_11.cpp
@@ -0,0 +1,34 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+#include "ext_lib_1.hpp"
+
+std::string ConnectToCoSimIO()
+{
+    CoSimIO::Info settings;
+    settings.Set("my_name",    "singleton_tester");
+    settings.Set("connect_to", "singleton_tester_partner");
+    settings.Set("echo_level", 1);
+    settings.Set("version", "1.25");
+
+    auto info = CoSimIO::Connect(settings);
+    return info.Get<std::string>("connection_name");
+}
+
+void DisconnectFromCoSimIO(const std::string& rConnectionName)
+{
+    CoSimIO::Info disconnect_settings;
+    disconnect_settings.Set("connection_name", rConnectionName);
+    CoSimIO::Disconnect(disconnect_settings);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_12.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_12.cpp
new file mode 100644
index 00000000..d13ee2e2
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_12.cpp
@@ -0,0 +1,20 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+#include "ext_lib_1.hpp"
+
+bool ExtLib1HasIO(const std::string& rConnectionName)
+{
+    return CoSimIO::Internals::HasIO(rConnectionName);
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_13.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_13.cpp
new file mode 100644
index 00000000..207495c5
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_13.cpp
@@ -0,0 +1,20 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+#include "ext_lib_13.hpp"
+
+bool ExtLib13HasIO(const std::string& rConnectionName)
+{
+    return CoSimIO::Internals::HasIO(rConnectionName);
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_13.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_13.hpp
new file mode 100644
index 00000000..dabcf604
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_13.hpp
@@ -0,0 +1,16 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+bool ExtLib13HasIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_2.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_2.cpp
new file mode 100644
index 00000000..59d8e07f
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_2.cpp
@@ -0,0 +1,21 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// Project includes
+#include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
+#include "ext_lib_2.hpp"
+
+bool ExtLib2HasIO(const std::string& rConnectionName)
+{
+    return CoSimIO::Internals::HasIO(rConnectionName);
+}
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_2.hpp b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_2.hpp
new file mode 100644
index 00000000..9eb89cc1
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/ext_lib_2.hpp
@@ -0,0 +1,16 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+// System includes
+#include <string>
+
+bool ExtLib2HasIO(const std::string& rConnectionName);
diff --git a/tests/co_sim_io/impl/singleton_tests/scenario_6/main.cpp b/tests/co_sim_io/impl/singleton_tests/scenario_6/main.cpp
new file mode 100644
index 00000000..ce5079b7
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/scenario_6/main.cpp
@@ -0,0 +1,46 @@
+//     ______     _____ _           ________
+//    / ____/___ / ___/(_)___ ___  /  _/ __ |
+//   / /   / __ \\__ \/ / __ `__ \ / // / / /
+//  / /___/ /_/ /__/ / / / / / / // // /_/ /
+//  \____/\____/____/_/_/ /_/ /_/___/\____/
+//  Kratos CoSimulationApplication
+//
+//  License:         BSD License, see license.txt
+//
+//  Main authors:    Philipp Bucher (https://github.com/philbucher)
+//
+
+/*
+Testing if the CoSimIO can be safely included in complex libraries
+In this scenario the CoSimIO is included in the main executable
+and in the external library
+This is a more elaborate example with a more complex structure
+*/
+
+// System includes
+#include <iostream>
+
+// CoSimulation includes
+#include "ext_lib_1.hpp"
+#include "ext_lib_13.hpp"
+#include "ext_lib_2.hpp"
+
+#define COSIMIO_CHECK_True(a)                                    \
+    if (!a) {                                                    \
+        std::cout << "in line " << __LINE__ << " : "             \
+                  << "false is not true" << std::endl;           \
+        return 1;                                                \
+    }
+
+int main()
+{
+    const std::string connection_name = ConnectToCoSimIO();
+
+    COSIMIO_CHECK_True(ExtLib1HasIO(connection_name));
+    COSIMIO_CHECK_True(ExtLib13HasIO(connection_name));
+    COSIMIO_CHECK_True(ExtLib2HasIO(connection_name));
+
+    DisconnectFromCoSimIO(connection_name);
+
+    return 0;
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/source/CMakeLists.txt
new file mode 100644
index 00000000..8b00449b
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/CMakeLists.txt
@@ -0,0 +1,18 @@
+
+cmake_minimum_required( VERSION 3.12 )
+
+project( test LANGUAGES CXX )
+
+set( WINDOWS_EXPORT_ALL_SYMBOLS ON )
+
+add_library( library1 lib1/lib1source1.cpp lib1/lib1source2.cpp lib1/lib1header.hpp )
+add_library( library2 lib2/lib2source1.cpp lib2/lib2source2.cpp lib2/lib2header.hpp )
+
+target_include_directories( library1 PUBLIC . lib1 )
+target_include_directories( library2 PUBLIC . lib2 )
+
+add_executable( exe main.cpp )
+
+target_link_libraries( exe library1 library2 )
+
+add_test(singleton_philipp exe)
diff --git a/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1header.hpp b/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1header.hpp
new file mode 100644
index 00000000..6da90601
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1header.hpp
@@ -0,0 +1,2 @@
+void lib1function1( );
+void lib1function2( );
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1source1.cpp b/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1source1.cpp
new file mode 100644
index 00000000..5b300717
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1source1.cpp
@@ -0,0 +1,9 @@
+#include "lib1header.hpp"
+#include "singleheader.hpp"
+
+#include <iostream>
+
+void lib1function2( )
+{
+    singleton.increment( );
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1source2.cpp b/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1source2.cpp
new file mode 100644
index 00000000..f8e8c44a
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/lib1/lib1source2.cpp
@@ -0,0 +1,7 @@
+#include "lib1header.hpp"
+#include "singleheader.hpp"
+
+void lib1function1( )
+{
+    singleton.increment( );
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2header.hpp b/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2header.hpp
new file mode 100644
index 00000000..00fd131b
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2header.hpp
@@ -0,0 +1,2 @@
+void lib2function1( );
+void lib2function2( );
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2source1.cpp b/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2source1.cpp
new file mode 100644
index 00000000..4a4feef7
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2source1.cpp
@@ -0,0 +1,9 @@
+#include "lib2header.hpp"
+#include "singleheader.hpp"
+
+#include <iostream>
+
+void lib2function2( )
+{
+    singleton.increment( );
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2source2.cpp b/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2source2.cpp
new file mode 100644
index 00000000..8829c945
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/lib2/lib2source2.cpp
@@ -0,0 +1,7 @@
+#include "lib2header.hpp"
+#include "singleheader.hpp"
+
+void lib2function1( )
+{
+    singleton.increment( );
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source/main.cpp b/tests/co_sim_io/impl/singleton_tests/source/main.cpp
new file mode 100644
index 00000000..bb054c49
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/main.cpp
@@ -0,0 +1,30 @@
+#include <iostream>
+#include "lib1header.hpp"
+#include "lib2header.hpp"
+
+#include "singleheader.hpp"
+
+DEFINE_SINGLETON_MAIN( );
+
+int main( )
+{
+    lib1function1( );
+    lib2function1( );
+
+    singleton.increment( );
+
+    lib1function2( );
+    lib2function2( );
+
+    lib1function1( );
+    lib2function1( );
+
+    singleton.increment( );
+
+    lib1function2( );
+    lib2function2( );
+
+    std::cout << "Final count: " << singleton.count( ) << std::endl;
+
+    return singleton.count( ) != 10;
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source/singleheader.hpp b/tests/co_sim_io/impl/singleton_tests/source/singleheader.hpp
new file mode 100644
index 00000000..5e9cbaf8
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source/singleheader.hpp
@@ -0,0 +1,22 @@
+class Singleton
+{
+    int count_;
+
+public:
+    Singleton( ) : count_( 0 ) { }
+
+    void increment( )
+    {
+        count_++;
+    }
+
+    int count( )
+    {
+        return count_;
+    }
+};
+
+extern Singleton singleton;
+
+#define DEFINE_SINGLETON_MAIN( ) Singleton singleton
+
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/CMakeLists.txt b/tests/co_sim_io/impl/singleton_tests/source_cosimio/CMakeLists.txt
new file mode 100644
index 00000000..8b00449b
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/CMakeLists.txt
@@ -0,0 +1,18 @@
+
+cmake_minimum_required( VERSION 3.12 )
+
+project( test LANGUAGES CXX )
+
+set( WINDOWS_EXPORT_ALL_SYMBOLS ON )
+
+add_library( library1 lib1/lib1source1.cpp lib1/lib1source2.cpp lib1/lib1header.hpp )
+add_library( library2 lib2/lib2source1.cpp lib2/lib2source2.cpp lib2/lib2header.hpp )
+
+target_include_directories( library1 PUBLIC . lib1 )
+target_include_directories( library2 PUBLIC . lib2 )
+
+add_executable( exe main.cpp )
+
+target_link_libraries( exe library1 library2 )
+
+add_test(singleton_philipp exe)
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1header.hpp b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1header.hpp
new file mode 100644
index 00000000..6da90601
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1header.hpp
@@ -0,0 +1,2 @@
+void lib1function1( );
+void lib1function2( );
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1source1.cpp b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1source1.cpp
new file mode 100644
index 00000000..ebcaddeb
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1source1.cpp
@@ -0,0 +1,10 @@
+#include "lib1header.hpp"
+#include "co_sim_io.hpp"
+
+#include <iostream>
+
+void lib1function2( )
+{
+    CoSimIO::Info info;
+    CoSimIO::Connect(info);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1source2.cpp b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1source2.cpp
new file mode 100644
index 00000000..0c3bb0ad
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib1/lib1source2.cpp
@@ -0,0 +1,8 @@
+#include "lib1header.hpp"
+#include "co_sim_io.hpp"
+
+void lib1function1( )
+{
+    CoSimIO::Info info;
+    CoSimIO::Connect(info);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2header.hpp b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2header.hpp
new file mode 100644
index 00000000..00fd131b
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2header.hpp
@@ -0,0 +1,2 @@
+void lib2function1( );
+void lib2function2( );
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2source1.cpp b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2source1.cpp
new file mode 100644
index 00000000..695e26a6
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2source1.cpp
@@ -0,0 +1,10 @@
+#include "lib2header.hpp"
+#include "co_sim_io.hpp"
+
+#include <iostream>
+
+void lib2function2( )
+{
+    CoSimIO::Info info;
+    CoSimIO::Connect(info);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2source2.cpp b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2source2.cpp
new file mode 100644
index 00000000..37eaf2e8
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/lib2/lib2source2.cpp
@@ -0,0 +1,8 @@
+#include "lib2header.hpp"
+#include "co_sim_io.hpp"
+
+void lib2function1( )
+{
+    CoSimIO::Info info;
+    CoSimIO::Connect(info);
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/main.cpp b/tests/co_sim_io/impl/singleton_tests/source_cosimio/main.cpp
new file mode 100644
index 00000000..131d58b5
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/main.cpp
@@ -0,0 +1,32 @@
+#include <iostream>
+#include "lib1header.hpp"
+#include "lib2header.hpp"
+
+#include "co_sim_io.hpp"
+
+DEFINE_SINGLETON_MAIN( );
+
+int main( )
+{
+    CoSimIO::Info info;
+    CoSimIO::Connect(info);
+    // lib1function1( );
+    // lib2function1( );
+
+    // singleton.increment( );
+
+    // lib1function2( );
+    // lib2function2( );
+
+    // lib1function1( );
+    // lib2function1( );
+
+    // singleton.increment( );
+
+    // lib1function2( );
+    // lib2function2( );
+
+    // std::cout << "Final count: " << singleton.count( ) << std::endl;
+
+    // return singleton.count( ) != 10;
+}
\ No newline at end of file
diff --git a/tests/co_sim_io/impl/singleton_tests/source_cosimio/singleheader.hpp b/tests/co_sim_io/impl/singleton_tests/source_cosimio/singleheader.hpp
new file mode 100644
index 00000000..5e9cbaf8
--- /dev/null
+++ b/tests/co_sim_io/impl/singleton_tests/source_cosimio/singleheader.hpp
@@ -0,0 +1,22 @@
+class Singleton
+{
+    int count_;
+
+public:
+    Singleton( ) : count_( 0 ) { }
+
+    void increment( )
+    {
+        count_++;
+    }
+
+    int count( )
+    {
+        return count_;
+    }
+};
+
+extern Singleton singleton;
+
+#define DEFINE_SINGLETON_MAIN( ) Singleton singleton
+
diff --git a/tests/co_sim_io/impl/test_include_co_sim_io_1.cpp b/tests/co_sim_io/impl/test_include_co_sim_io_1.cpp
index 987a51ef..3d5b516a 100644
--- a/tests/co_sim_io/impl/test_include_co_sim_io_1.cpp
+++ b/tests/co_sim_io/impl/test_include_co_sim_io_1.cpp
@@ -17,3 +17,4 @@ the "other" file that includes CoSimIO is "test_include_co_sim_io_2.cpp"
 
 // Project includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
diff --git a/tests/integration_tutorials/cpp/connect_disconnect_a.cpp b/tests/integration_tutorials/cpp/connect_disconnect_a.cpp
index e29b88ea..24449e62 100644
--- a/tests/integration_tutorials/cpp/connect_disconnect_a.cpp
+++ b/tests/integration_tutorials/cpp/connect_disconnect_a.cpp
@@ -12,6 +12,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/connect_disconnect_b.cpp b/tests/integration_tutorials/cpp/connect_disconnect_b.cpp
index 4596b41d..555f8562 100644
--- a/tests/integration_tutorials/cpp/connect_disconnect_b.cpp
+++ b/tests/integration_tutorials/cpp/connect_disconnect_b.cpp
@@ -12,6 +12,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/data_exchange.cpp b/tests/integration_tutorials/cpp/data_exchange.cpp
index e0f7360a..c843f49c 100644
--- a/tests/integration_tutorials/cpp/data_exchange.cpp
+++ b/tests/integration_tutorials/cpp/data_exchange.cpp
@@ -15,6 +15,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/export_data.cpp b/tests/integration_tutorials/cpp/export_data.cpp
index 442b500a..8dfb1e6d 100644
--- a/tests/integration_tutorials/cpp/export_data.cpp
+++ b/tests/integration_tutorials/cpp/export_data.cpp
@@ -12,6 +12,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/export_info.cpp b/tests/integration_tutorials/cpp/export_info.cpp
index 4e1f97ac..c0072a85 100644
--- a/tests/integration_tutorials/cpp/export_info.cpp
+++ b/tests/integration_tutorials/cpp/export_info.cpp
@@ -12,6 +12,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/export_mesh.cpp b/tests/integration_tutorials/cpp/export_mesh.cpp
index d683059d..27c82f0c 100644
--- a/tests/integration_tutorials/cpp/export_mesh.cpp
+++ b/tests/integration_tutorials/cpp/export_mesh.cpp
@@ -16,6 +16,7 @@
 
 // Project includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/hello.cpp b/tests/integration_tutorials/cpp/hello.cpp
index 39d091ec..89e4f894 100644
--- a/tests/integration_tutorials/cpp/hello.cpp
+++ b/tests/integration_tutorials/cpp/hello.cpp
@@ -12,6 +12,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/import_data.cpp b/tests/integration_tutorials/cpp/import_data.cpp
index be0e1159..1aeec29c 100644
--- a/tests/integration_tutorials/cpp/import_data.cpp
+++ b/tests/integration_tutorials/cpp/import_data.cpp
@@ -12,6 +12,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/import_info.cpp b/tests/integration_tutorials/cpp/import_info.cpp
index fe64abb8..785a6955 100644
--- a/tests/integration_tutorials/cpp/import_info.cpp
+++ b/tests/integration_tutorials/cpp/import_info.cpp
@@ -12,6 +12,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/import_mesh.cpp b/tests/integration_tutorials/cpp/import_mesh.cpp
index 213941a5..4a855f09 100644
--- a/tests/integration_tutorials/cpp/import_mesh.cpp
+++ b/tests/integration_tutorials/cpp/import_mesh.cpp
@@ -16,6 +16,7 @@
 
 // Project includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/mesh_exchange.cpp b/tests/integration_tutorials/cpp/mesh_exchange.cpp
index 7a5f1e7f..6c88f92c 100644
--- a/tests/integration_tutorials/cpp/mesh_exchange.cpp
+++ b/tests/integration_tutorials/cpp/mesh_exchange.cpp
@@ -15,6 +15,7 @@
 
 // CoSimulation includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/mpi/connect_disconnect_mpi_a.cpp b/tests/integration_tutorials/cpp/mpi/connect_disconnect_mpi_a.cpp
index 28971df3..b49c4cbe 100644
--- a/tests/integration_tutorials/cpp/mpi/connect_disconnect_mpi_a.cpp
+++ b/tests/integration_tutorials/cpp/mpi/connect_disconnect_mpi_a.cpp
@@ -15,6 +15,7 @@
 
 // CoSimulation includes
 #include "co_sim_io_mpi.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/mpi/connect_disconnect_mpi_b.cpp b/tests/integration_tutorials/cpp/mpi/connect_disconnect_mpi_b.cpp
index ab8dba4e..c5823383 100644
--- a/tests/integration_tutorials/cpp/mpi/connect_disconnect_mpi_b.cpp
+++ b/tests/integration_tutorials/cpp/mpi/connect_disconnect_mpi_b.cpp
@@ -15,6 +15,7 @@
 
 // CoSimulation includes
 #include "co_sim_io_mpi.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/run.cpp b/tests/integration_tutorials/cpp/run.cpp
index 22de9ecb..fb3706ff 100644
--- a/tests/integration_tutorials/cpp/run.cpp
+++ b/tests/integration_tutorials/cpp/run.cpp
@@ -12,6 +12,7 @@
 
 // Project includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_EQUAL(a, b)                                \
     if (a != b) {                                                \
diff --git a/tests/integration_tutorials/cpp/runner.cpp b/tests/integration_tutorials/cpp/runner.cpp
index fdfc7544..d182a66b 100644
--- a/tests/integration_tutorials/cpp/runner.cpp
+++ b/tests/integration_tutorials/cpp/runner.cpp
@@ -12,6 +12,7 @@
 
 // Project includes
 #include "co_sim_io.hpp"
+DEFINE_SINGLETON_MAIN( );
 
 #define COSIMIO_CHECK_TRUE(a)                               \
     if (!(a)) {                                             \