Returns the target AMQP message’s body content
Agent
Various — see below
Important Note Agent AMQP functionality is now deprecated and will shortly become unsupported. Any attempt to interact with imp API amqp objects and methods on unregistered development devices or on production devices will generate a runtime error.
If you are using or intend to use Azure IoTHub, we recommend you make use of MQTT instead of AMQP. Please see our Azure IoT Hub integration for more information.
This method returns the body content of the target message. The method will attempt to map AMQP data types to their Squirrel equivalents, but this is not always possible. The AMQP data types which can be converted are as follows:
| AMQP Body Type | AMQP Body Type Notes | Squirrel Data Type |
|---|---|---|
| amqp_NULL_TYPE | The null type, contains no data | Null |
| amqp_BOOLEAN | Boolean true or false | Bool |
| amqp_UBYTE | Unsigned 8-bit integer | Integer |
| amqp_BYTE | Signed 8-bit integer | Integer |
| amqp_USHORT | Unsigned 16-bit integer | Integer |
| amqp_SHORT | Signed 16-bit integer | Integer |
| amqp_UINT | Unsigned 32-bit integer | Integer |
| amqp_INT | Signed 32-bit integer | Integer |
| amqp_ULONG | Unsigned 64-bit integer | Integer |
| amqp_LONG | Signed 64-bit integer | Integer |
| amqp_FLOAT | 32-bit binary floating point | Float |
| amqp_DOUBLE | 64-bit binary floating point | Float |
| amqp_BINARY | Variable length sequence of bytes | Blob |
| amqp_STRING | Variable length UTF8-encoded string | String |
| amqp_SYMBOL | Variable length encoded string | String |
| amqp_ARRAY | A sequence of values of the same type | Array |
| amqp_LIST | A sequence of values, may be of mixed types | Array |
| amqp_MAP | A sequence of key:value pairs, may be of mixed types | Table |
Note 32-bit unsigned integers and all 64-bit values will overflow when converted to Squirrel signed 32-bit integers or floats. This will happen without warning.
The following AMQP body types are not currently supported, and amqpmessage.body() will return a warning string of this kind: "Unhandled message body type <THE_TYPE>":
| AMQP Body Type | AMQP Body Type Notes | Squirrel Data Type |
|---|---|---|
| amqp_CHAR | 2-bit unicode character | None |
| amqp_TIMESTAMP | Signed 64-bit milliseconds since the epoch | None |
| amqp_DECIMAL32 | 32-bit decimal floating point | None |
| amqp_DECIMAL64 | 64-bit decimal floating point | None |
| amqp_DECIMAL128 | 128-bit decimal floating point | None |
| amqp_UUID | 16-byte UUID | None |
| amqp_DESCRIBED | A descriptor and a value | None |
The compound AMQP body types (amqp_ARRAY, amqp_LIST and amqp_MAP) can be nested, and therefore amqpmessage.body() can return either a Squirrel array or a Squirrel table that contains a series of nested arrays and/or tables, plus other data types as appropriate. If unsupported types appear in an amqp_ARRAY, amqp_LIST or amqp_MAP then they will not appear in the corresponding Squirrel table or array. The unsupported entities are omitted — they are not replaced with a warning strings like the one shown above.
In Squirrel, null is not a valid table key, and therefore if the AMQP message contains an amqp_MAP in which an amqp_NULL_TYPE is used as a key, then this slot (ie. both key and value) will be omitted from the Squirrel table returned by amqpmessage.body().
This decoding applies only to incoming messages — the body of an outgoing message is always generated with string data. You can use JSON that has been encoded to send tables and other data structures as strings, but be aware that the AMQP broker you are targeting may expect to receive such structures as native AMQP types, such as amqp_ARRAY or AMQP_MAP, and simple data types as, for example, amqp_INT, amqp_BOOLEAN and amqp_FLOAT.
Note This method cannot be used to update a message; the returned value should be considered read only.