Qpid Proton C++ API  0.34.0
AMQP and C++ types


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.

Scalar types

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

Holder types

proton::message::body() and other message-related data can contain different types of data at runtime. There are two "holder" types provided to hold runtime typed data:

You can set the value in a holder by assignment, and use the proton::get() and proton::coerce() templates to extract data in a type-safe way. Holders also provide functions to query the type of value they contain.

Compound types

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

A proton::value containing a proton::ARRAY can convert to and from C++ sequences of the corresponding C++ type: 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.

For example, you can decode a message body with any AMQP map as follows.

proton::message m = ...;
std::map<proton::value, proton::value> map;
proton::get(m.body(), map);

You can encode a message body with a map of string keys and uint64_t values like this:

std::unordered_map<std::string, uint64_t> map;
map["foo"] = 123;
m.body() = map;

Include files

proton/types.hpp includes all available type definitions and conversions. Alternatively, you can selectively include the .hpp files you want.