diff --git a/include/App/app.h b/include/App/app.h
index 16334d8..2c19e70 100644
--- a/include/App/app.h
+++ b/include/App/app.h
@@ -21,6 +21,8 @@
 
 /* App */
 /* types */
+typedef struct _App App;
+
 typedef struct _AppMessage AppMessage;
 
 #endif /* !LIBAPP_APP_APP_H */
diff --git a/include/App/appclient.h b/include/App/appclient.h
index ea3c19b..62b1b98 100644
--- a/include/App/appclient.h
+++ b/include/App/appclient.h
@@ -21,6 +21,7 @@
 # include <stdint.h>
 # include <System/event.h>
 # include <System/variable.h>
+# include "app.h"
 
 
 /* AppClient */
@@ -29,9 +30,9 @@ typedef struct _AppClient AppClient;
 
 
 /* functions */
-AppClient * appclient_new(char const * app, char const * name);
-AppClient * appclient_new_event(char const * app, char const * name,
-		Event * event);
+AppClient * appclient_new(App * self, char const * app, char const * name);
+AppClient * appclient_new_event(App * self, char const * app,
+		char const * name, Event * event);
 void appclient_delete(AppClient * appclient);
 
 /* useful */
diff --git a/include/App/appserver.h b/include/App/appserver.h
index f7d0244..800a335 100644
--- a/include/App/appserver.h
+++ b/include/App/appserver.h
@@ -19,6 +19,7 @@
 # define LIBAPP_APP_APPSERVER_H
 
 # include <System/event.h>
+# include "app.h"
 
 
 /* AppServer */
@@ -36,10 +37,10 @@ typedef struct _AppServer AppServer;
 
 
 /* functions */
-AppServer * appserver_new(AppServerOptions options, char const * app,
-		char const * name);
-AppServer * appserver_new_event(AppServerOptions options, char const * app,
-		char const * name, Event * event);
+AppServer * appserver_new(App * self, AppServerOptions options,
+		char const * app, char const * name);
+AppServer * appserver_new_event(App * self, AppServerOptions options,
+		char const * app, char const * name, Event * event);
 void appserver_delete(AppServer * appserver);
 
 /* accessors */
diff --git a/src/appclient.c b/src/appclient.c
index 77c7feb..fa56f6d 100644
--- a/src/appclient.c
+++ b/src/appclient.c
@@ -33,6 +33,7 @@
 /* types */
 struct _AppClient
 {
+	App * app;
 	AppInterface * interface;
 	Event * event;
 	int event_free;
@@ -50,15 +51,15 @@ static int _appclient_helper_message(void * data, AppTransport * transport,
 /* public */
 /* functions */
 /* appclient_new */
-AppClient * appclient_new(char const * app, char const * name)
+AppClient * appclient_new(App * self, char const * app, char const * name)
 {
-	return appclient_new_event(app, name, NULL);
+	return appclient_new_event(self, app, name, NULL);
 }
 
 
 /* appclient_new_event */
-AppClient * appclient_new_event(char const * app, char const * name,
-		Event * event)
+AppClient * appclient_new_event(App * self, char const * app,
+		char const * name, Event * event)
 {
 	AppClient * appclient;
 
@@ -68,6 +69,7 @@ AppClient * appclient_new_event(char const * app, char const * name,
 #endif
 	if((appclient = object_new(sizeof(*appclient))) == NULL)
 		return NULL;
+	appclient->app = self;
 	appclient->interface = appinterface_new(app);
 	appclient->helper.data = appclient;
 	appclient->helper.message = _appclient_helper_message;
@@ -121,7 +123,8 @@ int appclient_call(AppClient * appclient,
 	va_list ap;
 
 	va_start(ap, method);
-	ret = appinterface_callv(appclient->interface, result, method, ap);
+	ret = appinterface_callv(appclient->interface, appclient->app, result,
+			method, ap);
 	va_end(ap);
 	return ret;
 }
@@ -145,8 +148,8 @@ int appclient_call_variable(AppClient * appclient,
 	for(i = 0; i < cnt; i++)
 		argv[i] = va_arg(ap, Variable *);
 	va_end(ap);
-	ret = appinterface_call_variablev(appclient->interface, result, method,
-			cnt, argv);
+	ret = appinterface_call_variablev(appclient->interface, appclient->app,
+			result, method, cnt, argv);
 	free(argv);
 	return ret;
 }
diff --git a/src/appinterface.c b/src/appinterface.c
index 307444e..01e329f 100644
--- a/src/appinterface.c
+++ b/src/appinterface.c
@@ -80,7 +80,7 @@ typedef struct _AppInterfaceCall
 	AppInterfaceCallArg type;
 	AppInterfaceCallArg * args;
 	size_t args_cnt;
-	void * func;
+	void * (*func)(void *);
 } AppInterfaceCall;
 
 struct _AppInterface
@@ -387,7 +387,7 @@ int appinterface_get_args_count(AppInterface * appinterface, size_t * count,
 
 /* useful */
 /* appinterface_callv */
-int appinterface_callv(AppInterface * appinterface, void ** result,
+int appinterface_callv(AppInterface * appinterface, App * app, void ** result,
 		char const * method, va_list args)
 {
 	int ret;
@@ -401,8 +401,9 @@ int appinterface_callv(AppInterface * appinterface, void ** result,
 		r = NULL;
 	else if((r = variable_new(call->type.type, NULL)) == NULL)
 		return -1;
-	if((ret = marshall_call(call->type.type, r, call->func, call->args_cnt,
-					NULL)) == 0 && r != NULL)
+	if((ret = marshall_call(app, call->type.type, r, call->func,
+					call->args_cnt, NULL)) == 0
+			&& r != NULL)
 	{
 		if(result != NULL)
 			/* XXX return 0 anyway? */
@@ -414,8 +415,9 @@ int appinterface_callv(AppInterface * appinterface, void ** result,
 
 
 /* appinterface_call_variablev */
-int appinterface_call_variablev(AppInterface * appinterface, Variable * result,
-		char const * method, size_t argc, Variable ** argv)
+int appinterface_call_variablev(AppInterface * appinterface, App * app,
+		Variable * result, char const * method,
+		size_t argc, Variable ** argv)
 {
 	AppInterfaceCall * call;
 
@@ -424,7 +426,8 @@ int appinterface_call_variablev(AppInterface * appinterface, Variable * result,
 	if(argc != call->args_cnt)
 		return -1;
 	/* FIXME implement argv */
-	return marshall_call(call->type.type, result, call->func, argc, NULL);
+	return marshall_call(app, call->type.type, result, call->func, argc,
+			NULL);
 }
 
 
diff --git a/src/appinterface.h b/src/appinterface.h
index 74cca41..5dd3898 100644
--- a/src/appinterface.h
+++ b/src/appinterface.h
@@ -41,9 +41,10 @@ int appinterface_get_args_count(AppInterface * appinterface, size_t * count,
 		char const * function);
 
 /* useful */
-int appinterface_callv(AppInterface * appinterface, void ** result,
+int appinterface_callv(AppInterface * appinterface, App * app, void ** result,
 		char const * method, va_list args);
-int appinterface_call_variablev(AppInterface * appinterface, Variable * result,
-		char const * method, size_t argc, Variable ** argv);
+int appinterface_call_variablev(AppInterface * appinterface, App * app,
+		Variable * result, char const * method,
+		size_t argc, Variable ** argv);
 
 #endif /* !LIBAPP_APPINTERFACE_H */
diff --git a/src/appserver.c b/src/appserver.c
index 255dbc4..cbfbe65 100644
--- a/src/appserver.c
+++ b/src/appserver.c
@@ -36,6 +36,8 @@
 /* types */
 struct _AppServer
 {
+	App * app;
+	AppServerOptions options;
 	AppInterface * interface;
 	Event * event;
 	int event_free;
@@ -53,21 +55,23 @@ static int _appserver_helper_message(void * data, AppTransport * transport,
 /* public */
 /* functions */
 /* appserver_new */
-AppServer * appserver_new(AppServerOptions options, const char * app,
-		char const * name)
+AppServer * appserver_new(App * self, AppServerOptions options,
+		const char * app, char const * name)
 {
-	return appserver_new_event(options, app, name, NULL);
+	return appserver_new_event(self, options, app, name, NULL);
 }
 
 
 /* appserver_new_event */
-AppServer * appserver_new_event(AppServerOptions options, char const * app,
-		char const * name, Event * event)
+AppServer * appserver_new_event(App * self, AppServerOptions options,
+		char const * app, char const * name, Event * event)
 {
 	AppServer * appserver;
 
 	if((appserver = object_new(sizeof(*appserver))) == NULL)
 		return NULL;
+	appserver->app = self;
+	appserver->options = options;
 	appserver->interface = appinterface_new_server(app);
 	appserver->helper.data = appserver;
 	appserver->helper.message = _appserver_helper_message;
@@ -162,8 +166,8 @@ static int _helper_message_call(AppServer * appserver, AppTransport * transport,
 	if(!appinterface_can_call(appserver->interface, name, method))
 		/* XXX report errors */
 		return -1;
-	ret = appinterface_call_variablev(appserver->interface, result, method,
-			0, NULL);
+	ret = appinterface_call_variablev(appserver->interface, appserver->app,
+			result, method, 0, NULL);
 	if(result != NULL)
 		variable_delete(result);
 	return ret;
diff --git a/src/apptransport.c b/src/apptransport.c
index cebec3c..3dddeaa 100644
--- a/src/apptransport.c
+++ b/src/apptransport.c
@@ -286,7 +286,7 @@ String * apptransport_lookup(char const * app)
 		error_set_code(1, "%s: %s", app, "Could not lookup");
 		return NULL;
 	}
-	if((appclient = appclient_new(session, NULL)) == NULL)
+	if((appclient = appclient_new(NULL, session, NULL)) == NULL)
 		return NULL;
 	appclient_call(appclient, (void **)&name, "lookup", app);
 	appclient_delete(appclient);
@@ -317,13 +317,14 @@ int apptransport_server_register(AppTransport * transport, char const * app)
 {
 	int ret;
 	int res = -1;
+	const char session[] = "Session";
 
 	if(transport->mode != ATM_SERVER)
 		return -error_set_code(1, "%s",
 				"Only servers can register to sessions");
 	if(transport->appclient != NULL)
 		appclient_delete(transport->appclient);
-	if((transport->appclient = appclient_new("Session", NULL)) == NULL)
+	if((transport->appclient = appclient_new(NULL, session, NULL)) == NULL)
 		return -1;
 	ret = appclient_call(transport->appclient, (void **)&res, "register",
 			app, transport->name);
diff --git a/src/marshall.c b/src/marshall.c
index e0c49ef..15b0325 100644
--- a/src/marshall.c
+++ b/src/marshall.c
@@ -24,35 +24,37 @@
 /* Marshall */
 /* public */
 /* functions */
-static int _call0(VariableType type, Variable * result, void * func);
+static int _call0(App * app, VariableType type, Variable * result,
+		void * (*func)(void *));
 
-int marshall_call(VariableType type, Variable * result, void * func,
-		size_t argc, Variable ** argv)
+int marshall_call(App * app, VariableType type, Variable * result,
+		void * (*func)(void *), size_t argc, Variable ** argv)
 {
 	if(argc == 0)
-		return _call0(type, result, func);
+		return _call0(app, type, result, func);
 	/* FIXME implement */
 	return -1;
 }
 
-static int _call0(VariableType type, Variable * result, void * func)
+static int _call0(App * app, VariableType type, Variable * result,
+		void * (*func)(void *))
 {
 	int ret = 0;
 	union
 	{
 		void * call;
-		void (*call_null)(void);
-		uint8_t (*call_bool)(void);
-		int8_t (*call_i8)(void);
-		uint8_t (*call_u8)(void);
-		int16_t (*call_i16)(void);
-		uint16_t (*call_u16)(void);
-		int32_t (*call_i32)(void);
-		uint32_t (*call_u32)(void);
-		int32_t (*call_i64)(void);
-		uint32_t (*call_u64)(void);
-		float (*call_f)(void);
-		double (*call_d)(void);
+		void (*call_null)(void *);
+		uint8_t (*call_bool)(void *);
+		int8_t (*call_i8)(void *);
+		uint8_t (*call_u8)(void *);
+		int16_t (*call_i16)(void *);
+		uint16_t (*call_u16)(void *);
+		int32_t (*call_i32)(void *);
+		uint32_t (*call_u32)(void *);
+		int32_t (*call_i64)(void *);
+		uint32_t (*call_u64)(void *);
+		float (*call_f)(void *);
+		double (*call_d)(void *);
 	} f;
 	union
 	{
@@ -74,60 +76,60 @@ static int _call0(VariableType type, Variable * result, void * func)
 	switch(type)
 	{
 		case VT_NULL:
-			f.call_null();
+			f.call_null(app);
 			break;
 		case VT_BOOL:
-			res.b = (f.call_bool() != 0) ? 1 : 0;
+			res.b = (f.call_bool(app) != 0) ? 1 : 0;
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.b);
 			break;
 		case VT_INT8:
-			res.i8 = f.call_i8();
+			res.i8 = f.call_i8(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.i8);
 			break;
 		case VT_UINT8:
-			res.u8 = f.call_u8();
+			res.u8 = f.call_u8(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.u8);
 			break;
 		case VT_INT16:
-			res.i16 = f.call_i16();
+			res.i16 = f.call_i16(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.i16);
 			break;
 		case VT_UINT16:
-			res.u16 = f.call_u16();
+			res.u16 = f.call_u16(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.u16);
 			break;
 		case VT_INT32:
-			res.i32 = f.call_i32();
+			res.i32 = f.call_i32(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.i32);
 			break;
 		case VT_UINT32:
-			res.u32 = f.call_u32();
+			res.u32 = f.call_u32(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.u32);
 			break;
 		case VT_INT64:
-			res.i64 = f.call_i64();
+			res.i64 = f.call_i64(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.i64);
 			break;
 		case VT_UINT64:
-			res.u64 = f.call_u64();
+			res.u64 = f.call_u64(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.u64);
 			break;
 		case VT_FLOAT:
-			res.f = f.call_f();
+			res.f = f.call_f(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.f);
 			break;
 		case VT_DOUBLE:
-			res.d = f.call_d();
+			res.d = f.call_d(app);
 			if(result != NULL)
 				ret = variable_set_from(result, type, &res.d);
 			break;
diff --git a/src/marshall.h b/src/marshall.h
index 4292c04..f8492b1 100644
--- a/src/marshall.h
+++ b/src/marshall.h
@@ -19,11 +19,12 @@
 # define LIBAPP_MARSHALL_H
 
 # include <System/variable.h>
+# include "App/app.h"
 
 
 /* Marshall */
 /* functions */
-int marshall_call(VariableType type, Variable * result, void * func,
-		size_t argc, Variable ** argv);
+int marshall_call(App * app, VariableType type, Variable * result,
+		void * (*func)(void *), size_t argc, Variable ** argv);
 
 #endif /* !LIBAPP_MARSHALL_H */
diff --git a/tests/appclient.c b/tests/appclient.c
index b4d2232..00db12c 100644
--- a/tests/appclient.c
+++ b/tests/appclient.c
@@ -52,7 +52,7 @@ int main(int argc, char * argv[])
 			default:
 				return _usage();
 		}
-	if((appclient = appclient_new(app, name)) == NULL)
+	if((appclient = appclient_new(NULL, app, name)) == NULL)
 	{
 		error_print("appclient");
 		return 2;
diff --git a/tests/appserver.c b/tests/appserver.c
index def7e5e..8d9a78f 100644
--- a/tests/appserver.c
+++ b/tests/appserver.c
@@ -53,7 +53,7 @@ int main(int argc, char * argv[])
 			default:
 				return _usage();
 		}
-	if((appserver = appserver_new(0, app, name)) == NULL)
+	if((appserver = appserver_new(NULL, 0, app, name)) == NULL)
 	{
 		error_print("appserver");
 		return 2;
diff --git a/tools/appbroker.c b/tools/appbroker.c
index 5574a36..8f1dc1b 100644
--- a/tools/appbroker.c
+++ b/tools/appbroker.c
@@ -112,7 +112,7 @@ static int _appbroker_foreach_call(char const * key, Hash * value, void * data)
 	if((p = hash_get(value, "ret")) == NULL)
 		p = "void";
 	fprintf(appbroker->fp, "%s%s%s%s%s%s", p, " ", appbroker->prefix, "_",
-			key, "(AppServerClient * client");
+			key, "(App * app, AppServerClient * client");
 	for(i = 0; i < APPSERVER_MAX_ARGUMENTS; i++)
 	{
 		snprintf(buf, sizeof(buf), "arg%d", i + 1);
diff --git a/tools/appclient.c b/tools/appclient.c
index 4cda9e4..ed1c7e5 100644
--- a/tools/appclient.c
+++ b/tools/appclient.c
@@ -74,7 +74,7 @@ static int _appclient(int verbose, char const * app, char const * name,
 	fprintf(stderr, "DEBUG: %s(%d, %s, %s, %p, %zu)\n", __func__, verbose,
 			hostname, service, (void *)calls, calls_cnt);
 #endif
-	if((ac = appclient_new(app, name)) == NULL)
+	if((ac = appclient_new(NULL, app, name)) == NULL)
 		return _error(PROGNAME, 1);
 	if(verbose != 0)
 		puts("Connected.");