An AMQP message body can hold binary data using any encoding you like. AMQP also defines its own encoding and types. The AMQP encoding is often used in message bodies because it is supported by AMQP libraries on many languages and platforms. You also need to use the AMQP types to set and examine message properties.
Each type is identified by a proton::type_id.
| C++ type | AMQP type_id | Description |
|---|---|---|
| bool | proton::BOOLEAN | Boolean true or false |
| uint8_t | proton::UBYTE | 8-bit unsigned byte |
| int8_t | proton::BYTE | 8-bit signed byte |
| uint16_t | proton::USHORT | 16-bit unsigned integer |
| int16_t | proton::SHORT | 16-bit signed integer |
| uint32_t | proton::UINT | 32-bit unsigned integer |
| int32_t | proton::INT | 32-bit signed integer |
| uint64_t | proton::ULONG | 64-bit unsigned integer |
| int64_t | proton::LONG | 64-bit signed integer |
| wchar_t | proton::CHAR | 32-bit unicode code point |
| float | proton::FLOAT | 32-bit binary floating point |
| double | proton::DOUBLE | 64-bit binary floating point |
| proton::timestamp | proton::TIMESTAMP | 64-bit signed milliseconds since 00:00:00 (UTC), 1 January 1970. |
| proton::decimal32 | proton::DECIMAL32 | 32-bit decimal floating point |
| proton::decimal64 | proton::DECIMAL64 | 64-bit decimal floating point |
| proton::decimal128 | proton::DECIMAL128 | 128-bit decimal floating point |
| proton::uuid | proton::UUID | 128-bit universally-unique identifier |
| std::string | proton::STRING | UTF-8 encoded Unicode string |
| proton::symbol | proton::SYMBOL | 7-bit ASCII encoded string |
| proton::binary | proton::BINARY | Variable-length binary data |
proton::scalar is a holder that can accept a scalar value of any type.
| C++ type | AMQP type_id | Description |
|---|---|---|
| See below | proton::ARRAY | Sequence of values of the same type |
| See below | proton::LIST | Sequence of values of mixed types |
| See below | proton::MAP | Map of key-value pairs |
proton::value is a holder that can accept any AMQP value, scalar or compound.
proton::ARRAY converts to and from C++ sequences: std::vector, std::deque, std::list, and std::forward_list.
proton::LIST converts to and from sequences of proton::value or proton::scalar, which can hold mixed types of data.
proton::MAP converts to and from std::map, std::unordered_map, and sequences of std::pair.
When decoding, the encoded map types must be convertible to the element type of the C++ sequence or the key-value types of the C++ map. Use proton::value as the element or key-value type to decode any ARRAY, LIST, or MAP.
For example you can decode any AMQP MAP into:
std::map<proton::value, proton::value>
You can decode any AMQP LIST or ARRAY into:
std::vector<proton::value>
You can simply include proton/types.hpp to get all the type definitions and conversions. Alternatively, you can selectively include only what you need:
.hpp files as per the table above.