diff --git a/src/Test.java b/src/Test.java
deleted file mode 100644
index 0fcdc57..0000000
--- a/src/Test.java
+++ /dev/null
@@ -1,13 +0,0 @@
-import org.pEp.jniadapter.*;
-
-public class Test {
-    public static void main(String[] args) {
-        try (Engine pEp = new Engine()) {
-            // using pEp engine
-        }
-        catch (pEpException e) {
-
-        }
-    }
-}
-
diff --git a/src/gen_cpp_Message.ysl2 b/src/gen_cpp_Message.ysl2
index 342ddb7..c7160c7 100644
--- a/src/gen_cpp_Message.ysl2
+++ b/src/gen_cpp_Message.ysl2
@@ -3,7 +3,7 @@ include yslt.yml2
 tstylesheet {
     include ./types_c.ysl2
 
-    template "/namespace[@name='pEp']" apply "struct|interface", 0;
+    template "/namespace[@name='pEp']" apply "struct", 0;
 
     template "struct" {
         const "jname" call "CamelCase" with "text", "@name";
@@ -11,6 +11,7 @@ tstylesheet {
         document("org_pEp_jniadapter_{$jname}.cc", "text")
         ||
         #include <exception>
+        #include <new>
         #include <stdint.h>
         #include <assert.h>
         #include <pEp/«@name».h>
@@ -18,74 +19,112 @@ tstylesheet {
         #include "jniutils.hh"
         #include "org_pEp_jniadapter_«$jname».h"
 
+        using namespace std;
+
+        namespace pEp {
+            namespace JNIAdapter {
+                static ::«@name» *«@name»_ptr(JNIEnv *env, jobject me) {
+                    jfieldID handle;
+
+                    try {
+                        handle = getFieldID(env, "org/pEp/jniadapter/«$jname»", "handle", "J");
+                    }
+                    catch (std::exception& ex) {
+                        assert(0);
+                        return NULL;
+                    }
+
+                    return (::«@name» *) (intptr_t) (int64_t) env->GetLongField(me, handle);
+                }
+            };
+        };
+
+        extern "C" {
+
         using namespace pEp::JNIAdapter;
 
         JNIEXPORT jlong JNICALL
                 Java_org_pEp_jniadapter_«$jname»_init(JNIEnv *env, jobject obj) {
             ::«@name» * _obj = ::new_«@name»(PEP_dir_incoming);
-            // BUG: test for out of memory missing
+            if (!_obj) {
+                outOfMemory(env);
+                return (jlong) 0;
+            }
             return (jlong) (int64_t) (intptr_t) _obj;
         }
 
         JNIEXPORT void JNICALL
                 Java_org_pEp_jniadapter_«$jname»_release(JNIEnv *env, jobject obj, jlong value) {
-            ::«@name» *_obj = (::«@name» *) (intptr_t) (int64_t) value;
-            ::free_«@name»(_obj);
-        }
-
-        static ::«@name» *ptr(JNIEnv *env, jobject me) {
-            jfieldID handle;
-
-            try {
-                handle = getFieldID(env, "org/pEp/jniadapter/«$jname»", "handle", "J");
-            }
-            catch (std::exception& ex) {
-                assert(0);
-                return NULL;
+            if (value) {
+                ::«@name» *_obj = (::«@name» *) (intptr_t) (int64_t) value;
+                ::free_«@name»(_obj);
             }
-
-            return (::«@name» *) (intptr_t) (int64_t) env->GetLongField(me, handle);
         }
 
-        `` apply "*[name(.)!='enum']", 0, mode=entry with "class" call "CamelCase" with "text", "@name";
-        ||
-    }
-
-    template "interface" {
-        const "jname" call "CamelCase" with "text", "@name";
-
-        document("org_pEp_jniadapter_{$jname}.cc", "text")
-        ||
-        #include "org_pEp_jniadapter_«$jname».h"
+        `` apply "*[name(.)!='enum']", 0, mode=entry with "name", "@name", with "class" call "CamelCase" with "text", "@name";
+        } // extern "C"
 
         ||
     }
 
     template "*", mode=entry {
+        param "name";
         param "class";
-        const "_class" call "lcase" with "text", "$class";
         const "ctype" call "toC" with "type", "name(.)";
         const "jname" call "CamelCase" with "text", "name(*[1])";
         const "cname" call "lcase" with "text", "name(*[1])";
+        const "type", "name(.)";
 
         ||
-        JNIEXPORT jobject JNICALL
+        JNIEXPORT `call "jni_type" with "type", "name(.)"` JNICALL
                 Java_org_pEp_jniadapter_«$class»_get«$jname»(JNIEnv *env, jobject obj) {
-            «$_class» *_obj = ptr(env, obj);
-            jobject result = NULL;
-
-            _obj->«$cname»;
-            return result;
+            «$name» *_obj = «$name»_ptr(env, obj);
+        ||
+        choose {
+            when "../enum[@name=$type]"
+                |> return (jint) _obj->«$cname»;
+            otherwise
+                |> return from_«$type»(env, _obj->«$cname»);
+        }
+        ||
         }
 
         JNIEXPORT void JNICALL
-                Java_org_pEp_jniadapter_Message_set«$jname»(JNIEnv *env, jobject obj, jobject value) {
-            «$_class» *_obj = ptr(env, obj);   
-            «$ctype» *_value;
-            _obj->«$cname»;
+                Java_org_pEp_jniadapter_Message_set«$jname»(JNIEnv *env, jobject obj, `call "jni_type" with "type", "name(.)"` value) {
+            «$name» *_obj = «$name»_ptr(env, obj);   
+        ||
+        choose {
+            when "../enum[@name=$type]"
+                |> _obj->«$cname» = («$ctype») (int) value;
+            when "$type = 'string'" {
+                |> free(_obj->«$cname»);
+                |> _obj->«$cname» = to_«$type»(env, value);
+            }
+            otherwise {
+                const "free" choose {
+                    when "$ctype = 'pEp_identity'" > identity
+                    when "contains($ctype, '_t')" value "substring-before($ctype, '_t')";
+                    otherwise value "$ctype";
+                }
+
+                |> free_«$free»(_obj->«$cname»);
+                |> _obj->«$cname» = to_«$type»(env, value);
+            }
+        }
+        ||
         }
 
         ||
     }
+
+    function "jni_type" {
+        param "type";
+
+        choose {
+            when "../enum[@name=$type]" > jint
+            when "$type = 'string'" > jbyteArray
+            otherwise > jobject
+        }
+    }
 }
 
diff --git a/src/jniutils.cc b/src/jniutils.cc
index fda43df..5113bbf 100644
--- a/src/jniutils.cc
+++ b/src/jniutils.cc
@@ -7,24 +7,31 @@
 
 namespace pEp {
     namespace JNIAdapter {
-        jfieldID getFieldID(
-                JNIEnv *env,
-                const char *classname,
-                const char *fieldname,
-                const char *signature
-            )
+        jclass findClass(JNIEnv *env, const char *classname)
         {
-            jclass engine = env->FindClass(classname);
-            assert(engine);
+            jclass clazz = env->FindClass(classname);
+            assert(clazz);
 
-            if (engine == NULL) {
+            if (clazz == NULL) {
                 jclass ex = env->FindClass("java/lang/NoClassDefFoundError");
                 assert(ex);
                 env->ThrowNew(ex, classname);
                 throw std::bad_cast();
             }
+            
+            return clazz;
+        }
 
-            jfieldID field = env->GetFieldID(engine, fieldname, signature);
+        jfieldID getFieldID(
+                JNIEnv *env,
+                const char *classname,
+                const char *fieldname,
+                const char *signature
+            )
+        {
+            jclass clazz = findClass(env, classname);
+
+            jfieldID field = env->GetFieldID(clazz, fieldname, signature);
             assert(field);
 
             if (field == NULL) {
@@ -36,6 +43,75 @@ namespace pEp {
 
             return field;
         }
+
+        jlong callLongMethod(
+                JNIEnv *env,
+                jobject obj,
+                const char *methodname
+            )
+        {
+            jclass clazz = env->GetObjectClass(obj);
+            assert(clazz);
+
+            jmethodID method = env->GetMethodID(clazz, methodname, "()J");
+            if (method == NULL) {
+                jclass ex = env->FindClass("java/lang/NoSuchMethodError");
+                assert(ex);
+                env->ThrowNew(ex, methodname);
+                throw std::invalid_argument(std::string(methodname));
+            }
+
+            return env->CallLongMethod(obj, method);
+        }
+
+        jint outOfMemory(JNIEnv *env)
+        {
+            jclass ex;
+            const char *ex_name = "java/lang/OutOfMemoryError";
+
+            ex = env->FindClass(ex_name);
+            assert(ex);
+            return env->ThrowNew(ex, ex_name);
+        }
+
+        jbyteArray from_string(JNIEnv *env, const char *str)
+        {
+            if (str && str[0]) {
+                bool isCopy;
+                jbyteArray _str = NewByteArray(env, strlen(str));
+                jbyte *b = GetByteArrayElements(env, str, &isCopy);
+                strcpy((char *)b, str);
+                ReleaseByteArrayElements(env, str, b, 0);
+                return _str;
+            }
+            else {
+                return NewByteArray(env, 0);
+            }
+        }
+
+        char *to_string(JNIEnv *env, jbyteArray str)
+        {
+            bool isCopy;
+            jbyte *b = GetByteArrayElements(env, str, &isCopy);
+            char *_str = strndup((char *)b, (size_t)GetArrayLength(env, str));
+            ReleaseByteArrayElements(env, str, b, JNI_ABORT);
+            return _str;
+        }
+
+        jobject from_timestamp(JNIEnv *env, timestamp *ts)
+        {
+            time_t t = timegm(ts);
+            jclass clazz = findClass(env, "java/util/Date");
+            jmethodID constructor = env->GetMethodID(clazz, "<init>", "(J)V");
+            assert(constructor);
+            return env->NewObject(clazz, constructor, (jlong) t);
+        }
+
+        timestamp *to_timestamp(JNIEnv *env, jobject date)
+        {
+            time_t t = (time_t) callLongMethod(env, date, "getTime");
+            return new_timestamp(t);
+        }
     };
 };
 
diff --git a/src/jniutils.hh b/src/jniutils.hh
index 34de343..a672c8d 100644
--- a/src/jniutils.hh
+++ b/src/jniutils.hh
@@ -4,12 +4,43 @@
 
 namespace pEp {
     namespace JNIAdapter {
+        jclass findClass(JNIEnv *env, const char *classname);
+
         jfieldID getFieldID(
                 JNIEnv *env,
                 const char *classname,
                 const char *fieldname,
                 const char *signature
             );
+
+        jlong callLongMethod(
+                JNIEnv *env,
+                jobject obj,
+                const char *methodname
+            );
+
+        jint outOfMemory(JNIEnv *env);
+
+        jbyteArray from_string(JNIEnv *env, const char *str);
+        char *to_string(JNIEnv *env, jbyteArray str);
+
+        jobject from_stringlist(JNIEnv *env, stringlist_t *sl);
+        stringlist_t *to_stringlist(JNIEnv *env, jobject sl);
+
+        jobject from_stringpairlist(JNIEnv *env, stringpair_list_t *sl);
+        stringpair_list_t *to_stringpairlist(JNIEnv *env, jobject sl);
+
+        jobject from_timestamp(JNIEnv *env, timestamp *ts);
+        timestamp *to_timestamp(JNIEnv *env, jobject date);
+
+        jobject from_identity(JNIEnv *env, pEp_identity *ident);
+        pEp_identity *to_identity(JNIEnv *env, jobject ident);
+
+        jobject from_identitylist(JNIEnv *env, identity_list *il);
+        identity_list *to_identitylist(JNIEnv *env, jobject il);
+
+        jobject from_bloblist(JNIEnv *env, bloblist_t *bl);
+        bloblist_t *to_bloblist(JNIEnv *env, jobject bl);
     };
 };