diff --git a/apps/er-coap/er-coap-observe.c b/apps/er-coap/er-coap-observe.c
index 710671bff..35ab2ff74 100644
--- a/apps/er-coap/er-coap-observe.c
+++ b/apps/er-coap/er-coap-observe.c
@@ -58,9 +58,9 @@ LIST(observers_list);
 /*---------------------------------------------------------------------------*/
 /*- Internal API ------------------------------------------------------------*/
 /*---------------------------------------------------------------------------*/
-coap_observer_t *
-coap_add_observer(uip_ipaddr_t *addr, uint16_t port, const uint8_t *token,
-                  size_t token_len, const char *uri)
+static coap_observer_t *
+add_observer(uip_ipaddr_t *addr, uint16_t port, const uint8_t *token,
+             size_t token_len, const char *uri, int uri_len)
 {
   /* Remove existing observe relationship, if any. */
   coap_remove_observer_by_uri(addr, port, uri);
@@ -68,7 +68,12 @@ coap_add_observer(uip_ipaddr_t *addr, uint16_t port, const uint8_t *token,
   coap_observer_t *o = memb_alloc(&observers_memb);
 
   if(o) {
-    o->url = uri;
+    int max = sizeof(o->url) - 1;
+    if(max > uri_len) {
+      max = uri_len;
+    }
+    memcpy(o->url, uri, max);
+    o->url[max] = 0;
     uip_ipaddr_copy(&o->addr, addr);
     o->port = port;
     o->token_len = token_len;
@@ -177,18 +182,47 @@ coap_remove_observer_by_mid(uip_ipaddr_t *addr, uint16_t port, uint16_t mid)
 /*---------------------------------------------------------------------------*/
 void
 coap_notify_observers(resource_t *resource)
+{
+  coap_notify_observers_sub(resource, NULL);
+}
+void
+coap_notify_observers_sub(resource_t *resource, const char *subpath)
 {
   /* build notification */
   coap_packet_t notification[1]; /* this way the packet can be treated as pointer as usual */
-  coap_init_message(notification, COAP_TYPE_NON, CONTENT_2_05, 0);
+  coap_packet_t request[1]; /* this way the packet can be treated as pointer as usual */
   coap_observer_t *obs = NULL;
+  int url_len, obs_url_len;
+  char url[COAP_OBSERVER_URL_LEN];
 
-  PRINTF("Observe: Notification from %s\n", resource->url);
+  url_len = strlen(resource->url);
+  strncpy(url, resource->url, COAP_OBSERVER_URL_LEN - 1);
+  if(url_len < COAP_OBSERVER_URL_LEN - 1 && subpath != NULL) {
+    strncpy(&url[url_len], subpath, COAP_OBSERVER_URL_LEN - url_len - 1);
+  }
+  /* Ensure url is null terminated because strncpy does not guarantee this */
+  url[COAP_OBSERVER_URL_LEN - 1] = '\0';
+  /* url now contains the notify URL that needs to match the observer */
+  PRINTF("Observe: Notification from %s\n", url);
+
+  coap_init_message(notification, COAP_TYPE_NON, CONTENT_2_05, 0);
+  /* create a "fake" request for the URI */
+  coap_init_message(request, COAP_TYPE_CON, COAP_GET, 0);
+  coap_set_header_uri_path(request, url);
 
   /* iterate over observers */
+  url_len = strlen(url);
   for(obs = (coap_observer_t *)list_head(observers_list); obs;
       obs = obs->next) {
-    if(obs->url == resource->url) {     /* using RESOURCE url pointer as handle */
+    obs_url_len = strlen(obs->url);
+
+    /* Do a match based on the parent/sub-resource match so that it is
+       possible to do parent-node observe */
+    if((obs_url_len == url_len
+        || (obs_url_len > url_len
+            && (resource->flags & HAS_SUB_RESOURCES)
+            && obs->url[url_len] == '/'))
+       && strncmp(url, obs->url, url_len) == 0) {
       coap_transaction_t *transaction = NULL;
 
       /*TODO implement special transaction for CON, sharing the same buffer to allow for more observers */
@@ -209,7 +243,7 @@ coap_notify_observers(resource_t *resource)
         /* prepare response */
         notification->mid = transaction->mid;
 
-        resource->get_handler(NULL, notification,
+        resource->get_handler(request, notification,
                               transaction->packet + COAP_MAX_HEADER_SIZE,
                               REST_MAX_CHUNK_SIZE, NULL);
 
@@ -237,9 +271,9 @@ coap_observe_handler(resource_t *resource, void *request, void *response)
   if(coap_req->code == COAP_GET && coap_res->code < 128) { /* GET request and response without error code */
     if(IS_OPTION(coap_req, COAP_OPTION_OBSERVE)) {
       if(coap_req->observe == 0) {
-        obs = coap_add_observer(&UIP_IP_BUF->srcipaddr, UIP_UDP_BUF->srcport,
-                                coap_req->token, coap_req->token_len,
-                                resource->url);
+        obs = add_observer(&UIP_IP_BUF->srcipaddr, UIP_UDP_BUF->srcport,
+                           coap_req->token, coap_req->token_len,
+                           coap_req->uri_path, coap_req->uri_path_len);
        if(obs) {
           coap_set_header_observe(coap_res, (obs->obs_counter)++);
           /*
diff --git a/apps/er-coap/er-coap-observe.h b/apps/er-coap/er-coap-observe.h
index 6d0498bb6..4e9644bf0 100644
--- a/apps/er-coap/er-coap-observe.h
+++ b/apps/er-coap/er-coap-observe.h
@@ -43,6 +43,8 @@
 #include "er-coap-transactions.h"
 #include "stimer.h"
 
+#define COAP_OBSERVER_URL_LEN 20
+
 typedef struct coap_observable {
   uint32_t observe_clock;
   struct stimer orphan_timer;
@@ -54,7 +56,7 @@ typedef struct coap_observable {
 typedef struct coap_observer {
   struct coap_observer *next;   /* for LIST */
 
-  const char *url;
+  char url[COAP_OBSERVER_URL_LEN];
   uip_ipaddr_t addr;
   uint16_t port;
   uint8_t token_len;
@@ -68,11 +70,6 @@ typedef struct coap_observer {
 } coap_observer_t;
 
 list_t coap_get_observers(void);
-
-coap_observer_t *coap_add_observer(uip_ipaddr_t *addr, uint16_t port,
-                                   const uint8_t *token, size_t token_len,
-                                   const char *url);
-
 void coap_remove_observer(coap_observer_t *o);
 int coap_remove_observer_by_client(uip_ipaddr_t *addr, uint16_t port);
 int coap_remove_observer_by_token(uip_ipaddr_t *addr, uint16_t port,
@@ -83,6 +80,7 @@ int coap_remove_observer_by_mid(uip_ipaddr_t *addr, uint16_t port,
                                 uint16_t mid);
 
 void coap_notify_observers(resource_t *resource);
+void coap_notify_observers_sub(resource_t *resource, const char *subpath);
 
 void coap_observe_handler(resource_t *resource, void *request,
                           void *response);
diff --git a/apps/er-coap/er-coap-res-well-known-core.c b/apps/er-coap/er-coap-res-well-known-core.c
index e684017cd..ea3b4bbe9 100644
--- a/apps/er-coap/er-coap-res-well-known-core.c
+++ b/apps/er-coap/er-coap-res-well-known-core.c
@@ -124,7 +124,7 @@ well_known_core_get_handler(void *request, void *response, uint8_t *buffer,
           continue;
         }
         end = attrib + strlen(attrib);
-      } else {
+      } else if(resource->attributes != NULL) {
         attrib = strstr(resource->attributes, filter);
         if(attrib == NULL
            || (attrib[strlen(filter)] != '='
@@ -159,8 +159,8 @@ well_known_core_get_handler(void *request, void *response, uint8_t *buffer,
     }
 #endif
 
-    PRINTF("res: /%s (%p)\npos: s%d, o%ld, b%d\n", resource->url, resource,
-           strpos, *offset, bufpos);
+    PRINTF("res: /%s (%p)\npos: s%zu, o%ld, b%zu\n", resource->url, resource,
+           strpos, (long)*offset, bufpos);
 
     if(strpos > 0) {
       ADD_CHAR_IF_POSSIBLE(',');
@@ -170,7 +170,7 @@ well_known_core_get_handler(void *request, void *response, uint8_t *buffer,
     ADD_STRING_IF_POSSIBLE(resource->url, >=);
     ADD_CHAR_IF_POSSIBLE('>');
 
-    if(resource->attributes[0]) {
+    if(resource->attributes != NULL && resource->attributes[0]) {
       ADD_CHAR_IF_POSSIBLE(';');
       ADD_STRING_IF_POSSIBLE(resource->attributes, >);
     }
@@ -183,7 +183,7 @@ well_known_core_get_handler(void *request, void *response, uint8_t *buffer,
   }
 
   if(bufpos > 0) {
-    PRINTF("BUF %d: %.*s\n", bufpos, bufpos, (char *)buffer);
+    PRINTF("BUF %zu: %.*s\n", bufpos, (int)bufpos, (char *)buffer);
 
     coap_set_payload(response, buffer, bufpos);
     coap_set_header_content_format(response, APPLICATION_LINK_FORMAT);
diff --git a/apps/er-coap/er-coap-transactions.c b/apps/er-coap/er-coap-transactions.c
index 7f6537932..3987b4814 100644
--- a/apps/er-coap/er-coap-transactions.c
+++ b/apps/er-coap/er-coap-transactions.c
@@ -113,15 +113,9 @@ coap_send_transaction(coap_transaction_t *t)
                (float)t->retrans_timer.timer.interval / CLOCK_SECOND);
       }
 
-      /*FIXME
-       * Hack: Setting timer for responsible process.
-       * Maybe there is a better way, but avoid posting everything to the process.
-       */
-      struct process *process_actual = PROCESS_CURRENT();
-
-      process_current = transaction_handler_process;
+      PROCESS_CONTEXT_BEGIN(transaction_handler_process);
       etimer_restart(&t->retrans_timer);        /* interval updated above */
-      process_current = process_actual;
+      PROCESS_CONTEXT_END(transaction_handler_process);
 
       t = NULL;
     } else {
diff --git a/apps/er-coap/er-coap.c b/apps/er-coap/er-coap.c
index 34c671623..cdb5ee76a 100644
--- a/apps/er-coap/er-coap.c
+++ b/apps/er-coap/er-coap.c
@@ -113,19 +113,21 @@ coap_set_option_header(unsigned int delta, size_t length, uint8_t *buffer)
 
   buffer[0] = coap_option_nibble(delta) << 4 | coap_option_nibble(length);
 
-  /* avoids code duplication without function overhead */
-  unsigned int *x = &delta;
+  if(delta > 268) {
+    buffer[++written] = ((delta - 269) >> 8) & 0xff;
+    buffer[++written] = (delta - 269) & 0xff;
+  } else if(delta > 12) {
+    buffer[++written] = (delta - 13);
+  }
 
-  do {
-    if(*x > 268) {
-      buffer[++written] = (*x - 269) >> 8;
-      buffer[++written] = (*x - 269);
-    } else if(*x > 12) {
-      buffer[++written] = (*x - 13);
-    }
-  } while(x != &length && (x = &length));
+  if(length > 268) {
+    buffer[++written] = ((length - 269) >> 8) & 0xff;
+    buffer[++written] = (length - 269) & 0xff;
+  } else if(length > 12) {
+    buffer[++written] = (length - 13);
+  }
 
-  PRINTF("WRITTEN %u B opt header\n", 1 + written);
+  PRINTF("WRITTEN %zu B opt header\n", 1 + written);
 
   return ++written;
 }
@@ -148,7 +150,7 @@ coap_serialize_int_option(unsigned int number, unsigned int current_number,
   if(0xFFFFFFFF & value) {
     ++i;
   }
-  PRINTF("OPTION %u (delta %u, len %u)\n", number, number - current_number,
+  PRINTF("OPTION %u (delta %u, len %zu)\n", number, number - current_number,
          i);
 
   i = coap_set_option_header(number - current_number, i, buffer);
@@ -175,8 +177,8 @@ coap_serialize_array_option(unsigned int number, unsigned int current_number,
 {
   size_t i = 0;
 
-  PRINTF("ARRAY type %u, len %u, full [%.*s]\n", number, length, length,
-         array);
+  PRINTF("ARRAY type %u, len %zu, full [%.*s]\n", number, length,
+	 (int)length, array);
 
   if(split_char != '\0') {
     int j;
@@ -185,7 +187,7 @@ coap_serialize_array_option(unsigned int number, unsigned int current_number,
     size_t temp_length;
 
     for(j = 0; j <= length + 1; ++j) {
-      PRINTF("STEP %u/%u (%c)\n", j, length, array[j]);
+      PRINTF("STEP %u/%zu (%c)\n", j, length, array[j]);
       if(array[j] == split_char || j == length) {
         part_end = array + j;
         temp_length = part_end - part_start;
@@ -195,8 +197,8 @@ coap_serialize_array_option(unsigned int number, unsigned int current_number,
         memcpy(&buffer[i], part_start, temp_length);
         i += temp_length;
 
-        PRINTF("OPTION type %u, delta %u, len %u, part [%.*s]\n", number,
-               number - current_number, i, temp_length, part_start);
+        PRINTF("OPTION type %u, delta %u, len %zu, part [%.*s]\n", number,
+               number - current_number, i, (int)temp_length, part_start);
 
         ++j;                    /* skip the splitter */
         current_number = number;
@@ -208,7 +210,7 @@ coap_serialize_array_option(unsigned int number, unsigned int current_number,
     memcpy(&buffer[i], array, length);
     i += length;
 
-    PRINTF("OPTION type %u, delta %u, len %u\n", number,
+    PRINTF("OPTION type %u, delta %u, len %zu\n", number,
            number - current_number, length);
   }
 
@@ -332,7 +334,7 @@ coap_serialize_message(void *packet, uint8_t *buffer)
 
   /* empty packet, dont need to do more stuff */
   if(!coap_pkt->code) {
-    PRINTF("-Done serializing empty message at %p-\n", option);
+    PRINTF("-Done serializing empty message at %p-\n", coap_pkt->buffer);
     return 4;
   }
 
@@ -368,6 +370,7 @@ coap_serialize_message(void *packet, uint8_t *buffer)
                                "Location-Path");
   COAP_SERIALIZE_STRING_OPTION(COAP_OPTION_URI_PATH, uri_path, '/',
                                "Uri-Path");
+  PRINTF("Serialize content format: %d\n", coap_pkt->content_format);
   COAP_SERIALIZE_INT_OPTION(COAP_OPTION_CONTENT_FORMAT, content_format,
                             "Content-Format");
   COAP_SERIALIZE_INT_OPTION(COAP_OPTION_MAX_AGE, max_age, "Max-Age");
@@ -403,8 +406,9 @@ coap_serialize_message(void *packet, uint8_t *buffer)
   }
 
   PRINTF("-Done %u B (header len %u, payload len %u)-\n",
-         coap_pkt->payload_len + option - buffer, option - buffer,
-         coap_pkt->payload_len);
+         (unsigned int)(coap_pkt->payload_len + option - buffer),
+         (unsigned int)(option - buffer),
+         (unsigned int)coap_pkt->payload_len);
 
   PRINTF("Dump [0x%02X %02X %02X %02X  %02X %02X %02X %02X]\n",
          coap_pkt->buffer[0],
@@ -500,25 +504,31 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
     option_length = current_option[0] & 0x0F;
     ++current_option;
 
-    /* avoids code duplication without function overhead */
-    unsigned int *x = &option_delta;
+    if(option_delta == 13) {
+      option_delta += current_option[0];
+      ++current_option;
+    } else if(option_delta == 14) {
+      option_delta += 255;
+      option_delta += current_option[0] << 8;
+      ++current_option;
+      option_delta += current_option[0];
+      ++current_option;
+    }
 
-    do {
-      if(*x == 13) {
-        *x += current_option[0];
-        ++current_option;
-      } else if(*x == 14) {
-        *x += 255;
-        *x += current_option[0] << 8;
-        ++current_option;
-        *x += current_option[0];
-        ++current_option;
-      }
-    } while(x != &option_length && (x = &option_length));
+    if(option_length == 13) {
+      option_length += current_option[0];
+      ++current_option;
+    } else if(option_length == 14) {
+      option_length += 255;
+      option_length += current_option[0] << 8;
+      ++current_option;
+      option_length += current_option[0];
+      ++current_option;
+    }
 
     option_number += option_delta;
 
-    PRINTF("OPTION %u (delta %u, len %u): ", option_number, option_delta,
+    PRINTF("OPTION %u (delta %u, len %zu): ", option_number, option_delta,
            option_length);
 
     SET_OPTION(coap_pkt, option_number);
@@ -532,7 +542,7 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
     case COAP_OPTION_MAX_AGE:
       coap_pkt->max_age = coap_parse_int_option(current_option,
                                                 option_length);
-      PRINTF("Max-Age [%lu]\n", coap_pkt->max_age);
+      PRINTF("Max-Age [%lu]\n", (unsigned long)coap_pkt->max_age);
       break;
     case COAP_OPTION_ETAG:
       coap_pkt->etag_len = MIN(COAP_ETAG_LEN, option_length);
@@ -569,7 +579,7 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
       coap_pkt->proxy_uri = (char *)current_option;
       coap_pkt->proxy_uri_len = option_length;
 #endif
-      PRINTF("Proxy-Uri NOT IMPLEMENTED [%.*s]\n", coap_pkt->proxy_uri_len,
+      PRINTF("Proxy-Uri NOT IMPLEMENTED [%.*s]\n", (int)coap_pkt->proxy_uri_len,
              coap_pkt->proxy_uri);
       coap_error_message = "This is a constrained server (Contiki)";
       return PROXYING_NOT_SUPPORTED_5_05;
@@ -580,7 +590,7 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
       coap_pkt->proxy_scheme_len = option_length;
 #endif
       PRINTF("Proxy-Scheme NOT IMPLEMENTED [%.*s]\n",
-             coap_pkt->proxy_scheme_len, coap_pkt->proxy_scheme);
+             (int)coap_pkt->proxy_scheme_len, coap_pkt->proxy_scheme);
       coap_error_message = "This is a constrained server (Contiki)";
       return PROXYING_NOT_SUPPORTED_5_05;
       break;
@@ -588,7 +598,8 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
     case COAP_OPTION_URI_HOST:
       coap_pkt->uri_host = (char *)current_option;
       coap_pkt->uri_host_len = option_length;
-      PRINTF("Uri-Host [%.*s]\n", coap_pkt->uri_host_len, coap_pkt->uri_host);
+      PRINTF("Uri-Host [%.*s]\n", (int)coap_pkt->uri_host_len,
+	     coap_pkt->uri_host);
       break;
     case COAP_OPTION_URI_PORT:
       coap_pkt->uri_port = coap_parse_int_option(current_option,
@@ -600,14 +611,14 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
       coap_merge_multi_option((char **)&(coap_pkt->uri_path),
                               &(coap_pkt->uri_path_len), current_option,
                               option_length, '/');
-      PRINTF("Uri-Path [%.*s]\n", coap_pkt->uri_path_len, coap_pkt->uri_path);
+      PRINTF("Uri-Path [%.*s]\n", (int)coap_pkt->uri_path_len, coap_pkt->uri_path);
       break;
     case COAP_OPTION_URI_QUERY:
       /* coap_merge_multi_option() operates in-place on the IPBUF, but final packet field should be const string -> cast to string */
       coap_merge_multi_option((char **)&(coap_pkt->uri_query),
                               &(coap_pkt->uri_query_len), current_option,
                               option_length, '&');
-      PRINTF("Uri-Query [%.*s]\n", coap_pkt->uri_query_len,
+      PRINTF("Uri-Query [%.*s]\n", (int)coap_pkt->uri_query_len,
              coap_pkt->uri_query);
       break;
 
@@ -616,7 +627,7 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
       coap_merge_multi_option((char **)&(coap_pkt->location_path),
                               &(coap_pkt->location_path_len), current_option,
                               option_length, '/');
-      PRINTF("Location-Path [%.*s]\n", coap_pkt->location_path_len,
+      PRINTF("Location-Path [%.*s]\n", (int)coap_pkt->location_path_len,
              coap_pkt->location_path);
       break;
     case COAP_OPTION_LOCATION_QUERY:
@@ -624,14 +635,14 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
       coap_merge_multi_option((char **)&(coap_pkt->location_query),
                               &(coap_pkt->location_query_len), current_option,
                               option_length, '&');
-      PRINTF("Location-Query [%.*s]\n", coap_pkt->location_query_len,
+      PRINTF("Location-Query [%.*s]\n", (int)coap_pkt->location_query_len,
              coap_pkt->location_query);
       break;
 
     case COAP_OPTION_OBSERVE:
       coap_pkt->observe = coap_parse_int_option(current_option,
                                                 option_length);
-      PRINTF("Observe [%lu]\n", coap_pkt->observe);
+      PRINTF("Observe [%lu]\n", (unsigned long)coap_pkt->observe);
       break;
     case COAP_OPTION_BLOCK2:
       coap_pkt->block2_num = coap_parse_int_option(current_option,
@@ -641,7 +652,8 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
       coap_pkt->block2_offset = (coap_pkt->block2_num & ~0x0000000F)
         << (coap_pkt->block2_num & 0x07);
       coap_pkt->block2_num >>= 4;
-      PRINTF("Block2 [%lu%s (%u B/blk)]\n", coap_pkt->block2_num,
+      PRINTF("Block2 [%lu%s (%u B/blk)]\n",
+             (unsigned long)coap_pkt->block2_num,
              coap_pkt->block2_more ? "+" : "", coap_pkt->block2_size);
       break;
     case COAP_OPTION_BLOCK1:
@@ -652,16 +664,17 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
       coap_pkt->block1_offset = (coap_pkt->block1_num & ~0x0000000F)
         << (coap_pkt->block1_num & 0x07);
       coap_pkt->block1_num >>= 4;
-      PRINTF("Block1 [%lu%s (%u B/blk)]\n", coap_pkt->block1_num,
+      PRINTF("Block1 [%lu%s (%u B/blk)]\n",
+             (unsigned long)coap_pkt->block1_num,
              coap_pkt->block1_more ? "+" : "", coap_pkt->block1_size);
       break;
     case COAP_OPTION_SIZE2:
       coap_pkt->size2 = coap_parse_int_option(current_option, option_length);
-      PRINTF("Size2 [%lu]\n", coap_pkt->size2);
+      PRINTF("Size2 [%lu]\n", (unsigned long)coap_pkt->size2);
       break;
     case COAP_OPTION_SIZE1:
       coap_pkt->size1 = coap_parse_int_option(current_option, option_length);
-      PRINTF("Size1 [%lu]\n", coap_pkt->size1);
+      PRINTF("Size1 [%lu]\n", (unsigned long)coap_pkt->size1);
       break;
     default:
       PRINTF("unknown (%u)\n", option_number);
@@ -744,7 +757,7 @@ coap_set_header_content_format(void *packet, unsigned int format)
 {
   coap_packet_t *const coap_pkt = (coap_packet_t *)packet;
 
-  coap_pkt->content_format = (coap_content_format_t)format;
+  coap_pkt->content_format = format;
   SET_OPTION(coap_pkt, COAP_OPTION_CONTENT_FORMAT);
   return 1;
 }
@@ -765,7 +778,7 @@ coap_set_header_accept(void *packet, unsigned int accept)
 {
   coap_packet_t *const coap_pkt = (coap_packet_t *)packet;
 
-  coap_pkt->accept = (coap_content_format_t)accept;
+  coap_pkt->accept = accept;
   SET_OPTION(coap_pkt, COAP_OPTION_ACCEPT);
   return 1;
 }
diff --git a/apps/er-coap/er-coap.h b/apps/er-coap/er-coap.h
index 69ea8b363..ccac6d76e 100644
--- a/apps/er-coap/er-coap.h
+++ b/apps/er-coap/er-coap.h
@@ -93,7 +93,7 @@ typedef struct {
 
   uint8_t options[COAP_OPTION_SIZE1 / OPTION_MAP_SIZE + 1]; /* bitmap to check if option is set */
 
-  coap_content_format_t content_format; /* parse options once and store; allows setting options in random order  */
+  uint16_t content_format; /* parse options once and store; allows setting options in random order  */
   uint32_t max_age;
   uint8_t etag_len;
   uint8_t etag[COAP_ETAG_LEN];
@@ -111,7 +111,7 @@ typedef struct {
   size_t uri_path_len;
   const char *uri_path;
   int32_t observe;
-  coap_content_format_t accept;
+  uint16_t accept;
   uint8_t if_match_len;
   uint8_t if_match[COAP_ETAG_LEN];
   uint32_t block2_num;
@@ -135,13 +135,13 @@ typedef struct {
 /* option format serialization */
 #define COAP_SERIALIZE_INT_OPTION(number, field, text) \
   if(IS_OPTION(coap_pkt, number)) { \
-    PRINTF(text " [%u]\n", coap_pkt->field); \
+    PRINTF(text " [%u]\n", (unsigned int)coap_pkt->field);		\
     option += coap_serialize_int_option(number, current_number, option, coap_pkt->field); \
     current_number = number; \
   }
 #define COAP_SERIALIZE_BYTE_OPTION(number, field, text) \
   if(IS_OPTION(coap_pkt, number)) { \
-    PRINTF(text " %u [0x%02X%02X%02X%02X%02X%02X%02X%02X]\n", coap_pkt->field##_len, \
+    PRINTF(text " %u [0x%02X%02X%02X%02X%02X%02X%02X%02X]\n", (unsigned int)coap_pkt->field##_len, \
            coap_pkt->field[0], \
            coap_pkt->field[1], \
            coap_pkt->field[2], \
@@ -156,18 +156,18 @@ typedef struct {
   }
 #define COAP_SERIALIZE_STRING_OPTION(number, field, splitter, text) \
   if(IS_OPTION(coap_pkt, number)) { \
-    PRINTF(text " [%.*s]\n", coap_pkt->field##_len, coap_pkt->field); \
+    PRINTF(text " [%.*s]\n", (int)coap_pkt->field##_len, coap_pkt->field); \
     option += coap_serialize_array_option(number, current_number, option, (uint8_t *)coap_pkt->field, coap_pkt->field##_len, splitter); \
     current_number = number; \
   }
 #define COAP_SERIALIZE_BLOCK_OPTION(number, field, text) \
   if(IS_OPTION(coap_pkt, number)) \
   { \
-    PRINTF(text " [%lu%s (%u B/blk)]\n", coap_pkt->field##_num, coap_pkt->field##_more ? "+" : "", coap_pkt->field##_size); \
+    PRINTF(text " [%lu%s (%u B/blk)]\n", (unsigned long)coap_pkt->field##_num, coap_pkt->field##_more ? "+" : "", coap_pkt->field##_size); \
     uint32_t block = coap_pkt->field##_num << 4; \
     if(coap_pkt->field##_more) { block |= 0x8; } \
     block |= 0xF & coap_log_2(coap_pkt->field##_size / 16); \
-    PRINTF(text " encoded: 0x%lX\n", block); \
+    PRINTF(text " encoded: 0x%lX\n", (unsigned long)block);		\
     option += coap_serialize_int_option(number, current_number, option, block); \
     current_number = number; \
   }
diff --git a/apps/rest-engine/rest-engine.c b/apps/rest-engine/rest-engine.c
index 7eb686d4d..67ac232a2 100644
--- a/apps/rest-engine/rest-engine.c
+++ b/apps/rest-engine/rest-engine.c
@@ -70,6 +70,15 @@ LIST(restful_periodic_services);
 void
 rest_init_engine(void)
 {
+  /* avoid initializing twice */
+  static uint8_t initialized = 0;
+
+  if(initialized) {
+    PRINTF("REST engine process already running - double initialization?\n");
+    return;
+  }
+  initialized = 1;
+
   list_init(restful_services);
 
   REST.set_service_callback(rest_invoke_restful_service);
@@ -124,15 +133,19 @@ rest_invoke_restful_service(void *request, void *response, uint8_t *buffer,
 
   resource_t *resource = NULL;
   const char *url = NULL;
+  int url_len, res_url_len;
 
+  url_len = REST.get_url(request, &url);
   for(resource = (resource_t *)list_head(restful_services);
       resource; resource = resource->next) {
 
     /* if the web service handles that kind of requests and urls matches */
-    if((REST.get_url(request, &url) == strlen(resource->url)
-        || (REST.get_url(request, &url) > strlen(resource->url)
-            && (resource->flags & HAS_SUB_RESOURCES)))
-       && strncmp(resource->url, url, strlen(resource->url)) == 0) {
+    res_url_len = strlen(resource->url);
+    if((url_len == res_url_len
+        || (url_len > res_url_len
+            && (resource->flags & HAS_SUB_RESOURCES)
+            && url[res_url_len] == '/'))
+       && strncmp(resource->url, url, res_url_len) == 0) {
       found = 1;
       rest_resource_flags_t method = REST.get_method_type(request);