+XBT_PUBLIC(size_t) sg_host_extension_create(void(*deleter)(void*));
+XBT_PUBLIC(void*) sg_host_extension_get(sg_host_t host, size_t rank);
+XBT_PUBLIC(sg_host_t) sg_host_by_name(const char *name);
+XBT_PUBLIC(const char*) sg_host_get_name(sg_host_t host);
+XBT_PUBLIC(xbt_dynar_t) sg_hosts_as_dynar();
+
+// ========== User Data ==============
+XBT_PUBLIC(void*) sg_host_user(sg_host_t host);
+XBT_PUBLIC(void) sg_host_user_set(sg_host_t host, void* userdata);
+XBT_PUBLIC(void) sg_host_user_destroy(sg_host_t host);
+
+// ========= storage related functions ============
+XBT_PUBLIC(xbt_dict_t) sg_host_get_mounted_storage_list(sg_host_t host);
+XBT_PUBLIC(xbt_dynar_t) sg_host_get_attached_storage_list(sg_host_t host);
+// =========== user-level functions ===============
+XBT_PUBLIC(double) sg_host_speed(sg_host_t host);
+XBT_PUBLIC(double) sg_host_get_available_speed(sg_host_t host);
+
+XBT_PUBLIC(int) sg_host_get_nb_pstates(sg_host_t host);
+XBT_PUBLIC(int) sg_host_get_pstate(sg_host_t host);
+XBT_PUBLIC(void) sg_host_set_pstate(sg_host_t host,int pstate);
+XBT_PUBLIC(xbt_dict_t) sg_host_get_properties(sg_host_t host);
+XBT_PUBLIC(const char*) sg_host_get_property_value(sg_host_t host, const char* name);
+XBT_PUBLIC(void) sg_host_route(sg_host_t from, sg_host_t to, xbt_dynar_t links);
+XBT_PUBLIC(double) sg_host_route_latency(sg_host_t from, sg_host_t to);
+XBT_PUBLIC(double) sg_host_route_bandwidth(sg_host_t from, sg_host_t to);
+XBT_PUBLIC(void) sg_host_dump(sg_host_t ws);