diff --git a/qse/include/qse/http/httpd.h b/qse/include/qse/http/httpd.h
index 332a4262..3f8763ca 100644
--- a/qse/include/qse/http/httpd.h
+++ b/qse/include/qse/http/httpd.h
@@ -341,20 +341,15 @@ struct qse_httpd_task_trigger_t
 
 struct qse_httpd_task_t
 {
-	/* == PUBLIC  == */
-
 	/* you must not call another entask functions from within 
 	 * an initailizer. you can call entask functions from within 
 	 * a finalizer and a main function. */
-	qse_httpd_task_init_t    init;
-	qse_httpd_task_fini_t    fini;
-	qse_httpd_task_main_t    main;
-	qse_httpd_task_trigger_t trigger[QSE_HTTPD_TASK_TRIGGER_MAX];
-	void*                    ctx;
 
-	/* == PRIVATE  == */
-	qse_httpd_task_t*     prev;
-	qse_httpd_task_t*     next;
+	qse_httpd_task_init_t    init;  /**< [IN] initializer */
+	qse_httpd_task_fini_t    fini;  /**< [IN] finalizer */
+	qse_httpd_task_main_t    main;  /**< [IN] main task function */
+	qse_httpd_task_trigger_t trigger[QSE_HTTPD_TASK_TRIGGER_MAX];
+	void*                    ctx;   /**< [IN OUT] user-defined data */
 };
 
 enum qse_httpd_mate_type_t 
@@ -721,7 +716,10 @@ QSE_EXPORT const qse_mchar_t* qse_httpd_fmtgmtimetobb (
 	int                idx
 );
 
-#define qse_httpd_gettaskxtn(httpd,task) ((void*)(task+1))
+QSE_EXPORT void* qse_httpd_gettaskxtn (
+	qse_httpd_t*            httpd,
+	qse_httpd_task_t*       task
+);
 
 QSE_EXPORT qse_httpd_task_t* qse_httpd_entask (
 	qse_httpd_t*            httpd,
diff --git a/qse/lib/http/httpd.c b/qse/lib/http/httpd.c
index 537e76c2..57cefe05 100644
--- a/qse/lib/http/httpd.c
+++ b/qse/lib/http/httpd.c
@@ -252,13 +252,14 @@ qse_mchar_t* qse_httpd_strntombsdup (qse_httpd_t* httpd, const qse_char_t* str,
 
 /* --------------------------------------------------- */
 
-static qse_httpd_task_t* enqueue_task (
+static qse_httpd_real_task_t* enqueue_task (
 	qse_httpd_t* httpd, qse_httpd_client_t* client, 
 	qse_httpd_task_t* pred, const qse_httpd_task_t* task,
 	qse_size_t xtnsize)
 {
-	qse_httpd_task_t* new_task;
-
+	qse_httpd_real_task_t* new_task;
+	qse_httpd_real_task_t* real_pred;
+	
 /* TODO: limit check 
 	if (client->task.count >= httpd->limit.client_task_queue)
 	{
@@ -266,17 +267,17 @@ static qse_httpd_task_t* enqueue_task (
 		return -1;
 	}
 */
-	new_task = (qse_httpd_task_t*)
+	new_task = (qse_httpd_real_task_t*)
 		qse_httpd_allocmem (httpd, QSE_SIZEOF(*new_task) + xtnsize);
 	if (new_task == QSE_NULL) return QSE_NULL;
 
 	QSE_MEMSET (new_task, 0, QSE_SIZEOF(*new_task) + xtnsize);
-	*new_task = *task;
+	new_task->core = *task;
 
-	if (new_task->init)
+	if (new_task->core.init)
 	{
 		httpd->errnum = QSE_HTTPD_ENOERR;
-		if (new_task->init (httpd, client, new_task) <= -1)
+		if (new_task->core.init (httpd, client, (qse_httpd_task_t*)new_task) <= -1)
 		{
 			if (httpd->errnum == QSE_HTTPD_ENOERR) 
 				httpd->errnum = QSE_HTTPD_ETASK;
@@ -285,25 +286,26 @@ static qse_httpd_task_t* enqueue_task (
 		}
 	}
 
+	real_pred = (qse_httpd_real_task_t*)pred;
 	if (pred)
 	{
-		new_task->next = pred->next;
-		new_task->prev = pred;
+		new_task->next = real_pred->next;
+		new_task->prev = real_pred;
 
-		if (pred->next) pred->next->prev = new_task;
-		else client->task.tail = new_task;
-		pred->next = new_task;
+		if (real_pred->next) real_pred->next->prev = new_task;
+		else client->task.tail = (qse_httpd_task_t*)new_task;
+		real_pred->next = new_task;
 	}
 	else
 	{
 		new_task->next = QSE_NULL;
-		new_task->prev = client->task.tail;
+		new_task->prev = (qse_httpd_real_task_t*)client->task.tail;
 
 		if (client->task.tail) 
-			client->task.tail->next = new_task;
+			((qse_httpd_real_task_t*)client->task.tail)->next = new_task;
 		else 
-			client->task.head = new_task;
-		client->task.tail = new_task;
+			client->task.head = (qse_httpd_task_t*)new_task;
+		client->task.tail = (qse_httpd_task_t*)new_task;
 	}
 	client->task.count++;
 
@@ -313,7 +315,7 @@ static qse_httpd_task_t* enqueue_task (
 static QSE_INLINE int dequeue_task (
 	qse_httpd_t* httpd, qse_httpd_client_t* client)
 {
-	qse_httpd_task_t* task;
+	qse_httpd_real_task_t* task;
 	qse_size_t i;
 
 	if (client->task.count <= 0) return -1;
@@ -321,11 +323,11 @@ static QSE_INLINE int dequeue_task (
 	task = client->task.head;
 
 	/* clear task triggers from mux if they are registered */
-	for (i = 0; i < QSE_COUNTOF(task->trigger); i++)
+	for (i = 0; i < QSE_COUNTOF(task->core.trigger); i++)
 	{
 		if (client->status & CLIENT_TASK_TRIGGER_IN_MUX(i))
 		{
-			httpd->opt.scb.mux.delhnd (httpd, httpd->mux, task->trigger[i].handle);
+			httpd->opt.scb.mux.delhnd (httpd, httpd->mux, task->core.trigger[i].handle);
 			client->status &= ~CLIENT_TASK_TRIGGER_IN_MUX(i);
 		}
 	}
@@ -340,11 +342,11 @@ static QSE_INLINE int dequeue_task (
 	else
 	{
 		task->next->prev = QSE_NULL;
-		client->task.head = task->next;
+		client->task.head = (qse_httpd_task_t*)task->next;
 	}
 	client->task.count--;
 
-	if (task->fini) task->fini (httpd, client, task);
+	if (task->core.fini) task->core.fini (httpd, client, task);
 	qse_httpd_freemem (httpd, task);
 
 	return 0;
@@ -1189,12 +1191,17 @@ static void purge_idle_clients (qse_httpd_t* httpd)
 /* TODO: */
 }
 
+void* qse_httpd_gettaskxtn (qse_httpd_t* httpd, qse_httpd_task_t* task)
+{
+	return (void*)((qse_httpd_real_task_t*)task + 1);
+}
+
 qse_httpd_task_t* qse_httpd_entask (
 	qse_httpd_t* httpd, qse_httpd_client_t* client, 
 	qse_httpd_task_t* pred, const qse_httpd_task_t* task,
 	qse_size_t xtnsize)
 {
-	qse_httpd_task_t* new_task;
+	qse_httpd_real_task_t* new_task;
 
 	if (client->status & CLIENT_BAD) return QSE_NULL;
 
@@ -1227,7 +1234,7 @@ qse_printf (QSE_T("MUX ADDHND CLIENT RW(ENTASK) %d\n"), client->handle.i);
 		client->status |= CLIENT_HANDLE_IN_MUX; /* READ | WRITE */
 	}
 
-	return new_task;
+	return (qse_httpd_task_t*)new_task;
 }
 
 static int dispatch_mux (
diff --git a/qse/lib/http/httpd.h b/qse/lib/http/httpd.h
index ab9b2103..3ea4026e 100644
--- a/qse/lib/http/httpd.h
+++ b/qse/lib/http/httpd.h
@@ -80,6 +80,17 @@ struct qse_httpd_t
 	void* mux;
 };
 
+/* qse_httpd_real_task_t is a private type to hide some private fields
+ * from being exposed by qse_httpd_task_t. 
+ */
+typedef struct qse_httpd_real_task_t qse_httpd_real_task_t;
+
+struct qse_httpd_real_task_t
+{
+	qse_httpd_task_t core;
+	qse_httpd_real_task_t* prev;
+	qse_httpd_real_task_t* next;
+};
 
 #define MAX_SEND_SIZE 4096
 
@@ -119,19 +130,19 @@ void qse_httpd_fini (
 qse_httpd_task_t* qse_httpd_entask_err (
 	qse_httpd_t* httpd,
 	qse_httpd_client_t* client,
-     qse_httpd_task_t* pred,
+	qse_httpd_task_t* pred,
 	int code,
 	qse_http_method_t method,
-     const qse_http_version_t* version,
+	const qse_http_version_t* version,
 	int keepalive
 );
 
 qse_httpd_task_t* qse_httpd_entask_nomod (
 	qse_httpd_t* httpd,
 	qse_httpd_client_t* client,
-     qse_httpd_task_t* pred,
-     qse_http_method_t method,
-     const qse_http_version_t* version,
+	qse_httpd_task_t* pred,
+	qse_http_method_t method,
+	const qse_http_version_t* version,
 	int keepalive
 );