LwM2M Resource Not Accessible on Server

In this tutorial, you'll learn about LwM2M Resource Not Accessible on Server. We cover key concepts, practical examples, and best practices.

The Problem

LwM2M server cannot read or write a specific resource on the client.

Quick Fix

Wrong

// Resource defined but operations not allowed
anjay_resource_create(res, "temperature", 0,
  ANJAY_DM_RESOURCE_OPER_READ);  // Only read allowed```

Server cannot write to temperature resource (write not allowed).

### Right

```cpp
#include <anjay/anjay.h>
#include <anjay/dm.h>

static int temp_get(anjay_t *anjay, const anjay_dm_object_def_t *obj,
                    anjay_iid_t iid, anjay_rid_t rid,
                    anjay_output_buffer_t *buf) {
  float val = 25.5;
  anjay_output_buffer_write_float(buf, val);
  return 0;
}

static const anjay_dm_resource_def_t resources[] = {
  {
    .rid = 0,
    .operations = ANJAY_DM_RESOURCE_OPER_READ |
                  ANJAY_DM_RESOURCE_OPER_WRITE,
    .handler = { .read = temp_get }
  },
  ANJAY_DM_RESOURCE_ARRAY_SENTINEL
};

// Resource supports both read and write operations
anjay_dm_object_register(anjay, obj_def);

Server can both read and write temperature resource. Value updates accepted.

Prevention

LwM2M resources have access permissions: R (Read), W (Write), E (Execute). A resource must declare its supported operations. Write can be single (replace resource) or composite (write multiple resources atomically). The server receives 4.01 (Unauthorized) if trying an unsupported operation. Always set correct operation flags.

DodaTech engineers apply these same patterns across Doda Browser, DodaZIP, and Durga Antivirus Pro for production IoT reliability.

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