Messages#

constellation::message Namespace#

using constellation::message::AssembledMessage = std::array<std::byte, chirp::CHIRP_MESSAGE_LENGTH>#

CHIRP message assembled to array of bytes

class BaseHeader#
#include <constellation/core/message/BaseHeader.hpp>

Message Header Base Class

Subclassed by constellation::message::CDTP1Message::Header, constellation::message::CMDP1Message::Header, constellation::message::CSCP1Message::Header

Public Functions

virtual ~BaseHeader() = default#
inline constexpr protocol::Protocol getProtocol() const#

Return message protocol

inline std::string_view getSender() const#

Return message sender

inline constexpr std::chrono::system_clock::time_point getTime() const#

Return message time

inline const config::Dictionary &getTags() const#

Return message tags

inline bool hasTag(const std::string &key) const#

Return if message has given tag

template<typename T>
inline T getTag(const std::string &key) const#

Return message tag

inline void setTag(const std::string &key, config::Value value)#

Set message tag

virtual std::string to_string() const#

Convert message header to human readable string

virtual void msgpack_pack(msgpack::packer<msgpack::sbuffer> &msgpack_packer) const#

Pack message header with msgpack

Protected Functions

inline BaseHeader(protocol::Protocol protocol, std::string sender, std::chrono::system_clock::time_point time, config::Dictionary tags = {})#

Construct new message header

Parameters:

  • protocol – Message protocol

  • sender – Sender name

  • time – Message time

  • tags – Message tags (defaults to empty dictionary)

Protected Static Functions

static BaseHeader disassemble(protocol::Protocol protocol, std::span<const std::byte> data)#

Disassemble message from from bytes

Parameters:

  • protocol – Protocol

  • data – View to byte data

class CDTP1Message#
#include <constellation/core/message/CDTP1Message.hpp>

Class representing a CDTP1 message

Public Types

enum class Type : std::uint8_t#

Values:

enumerator DATA#
enumerator BOR#
enumerator EOR#

Public Functions

CDTP1Message(Header header, std::size_t frames = 1)#
Parameters:

  • header – CDTP1 header of the message

  • frames – Number of payload frames to reserve

inline constexpr const Header &getHeader() const#
Returns:

Read-only reference to the CSCP1 header of the message

inline constexpr Header &getHeader()#
Returns:

Reference to the CSCP1 header of the message

inline const std::vector<message::PayloadBuffer> &getPayload() const#
Returns:

Read-only reference to the payload of the message

inline void addPayload(message::PayloadBuffer &&payload)#
Parameters:

payload – Payload buffer containing a payload to be added as ZeroMQ message

inline std::size_t countPayloadFrames() const#
Returns:

Current number of payload frames in this message

zmq::multipart_t assemble()#

Assemble full message to frames for ZeroMQ

This function always moves the payload

Public Static Functions

static CDTP1Message disassemble(zmq::multipart_t &frames)#

Disassemble message from ZeroMQ frames

This function moves the payload frames

class Header : public constellation::message::BaseHeader#

Public Functions

inline Header(std::string sender, std::uint64_t seq, Type type, std::chrono::system_clock::time_point time = std::chrono::system_clock::now(), config::Dictionary tags = {})#
inline constexpr std::uint64_t getSequenceNumber() const#
inline constexpr Type getType() const#
virtual std::string to_string() const final#

Convert message header to human readable string

virtual void msgpack_pack(msgpack::packer<msgpack::sbuffer> &msgpack_packer) const final#

Pack message header with msgpack

Public Static Functions

static Header disassemble(std::span<const std::byte> data)#
class CHIRPMessage#
#include <constellation/core/message/CHIRPMessage.hpp>

CHIRP message

Public Functions

CHIRPMessage(chirp::MessageType type, MD5Hash group_id, MD5Hash host_id, chirp::ServiceIdentifier service_id, utils::Port port)#
Parameters:

  • type – CHIRP message type

  • group_id – Constellation group ID (MD5 Hash of group name)

  • host_id – Constellation host ID (MD5 Hash of host name)

  • service_id – CHIRP service identifier

  • port – Service port

CHIRPMessage(chirp::MessageType type, std::string_view group, std::string_view host, chirp::ServiceIdentifier service_id, utils::Port port)#
Parameters:

  • type – CHIRP message type

  • group – Constellation group name (converted to group ID using MD5Hash)

  • host – Host name (converted to host ID using MD5Hash)

  • service_id – CHIRP service identifier

  • port – Service port

inline constexpr chirp::MessageType getType() const#

Return the message type

inline constexpr MD5Hash getGroupID() const#

Return the group ID of the message

inline constexpr MD5Hash getHostID() const#

Return the host ID of the message

inline constexpr chirp::ServiceIdentifier getServiceIdentifier() const#

Return the service identifier of the message

inline constexpr utils::Port getPort() const#

Return the service port of the message

AssembledMessage assemble() const#

Assemble message to byte array

Public Static Functions

static CHIRPMessage disassemble(std::span<const std::byte> assembled_message)#

Constructor for a CHIRP message from an assembled message

Parameters:

assembled_message – View of assembled message

Throws:

DecodeError – If the message header does not match the CHIRP specification, or if the message has an unknown ServiceIdentifier

class CHP1Message#
#include <constellation/core/message/CHP1Message.hpp>

Class representing a CHP1 message

Public Functions

inline CHP1Message(std::string sender, protocol::CSCP::State state, std::chrono::milliseconds interval, std::chrono::system_clock::time_point time = std::chrono::system_clock::now())#
Parameters:

  • sender – Sender name

  • time – Message time

  • state – State of the sender

  • interval – Time interval until next message is expected

inline constexpr protocol::Protocol getProtocol() const#

Return message protocol

inline std::string_view getSender() const#

Return message sender

inline constexpr std::chrono::system_clock::time_point getTime() const#

Return message time

inline constexpr protocol::CSCP::State getState() const#

Return state of the message

inline constexpr std::chrono::milliseconds getInterval() const#

Return maxima time interval until next message is expected

zmq::multipart_t assemble()#

Assemble full message to frames for ZeroMQ

Public Static Functions

static CHP1Message disassemble(zmq::multipart_t &frames)#

Disassemble message from ZeroMQ frames

This function moves the frames

class CMDP1LogMessage : public constellation::message::CMDP1Message#

Public Functions

CMDP1LogMessage(log::Level level, std::string log_topic, Header header, std::string message)#

Construct a new CMDP1 message for logging

Parameters:

  • level – Log level of the message

  • log_topic – Log topic of the message (can be empty)

  • header – CMDP1 header of the message

  • message – Log message

CMDP1LogMessage(CMDP1Message &&message)#

Construct a CMDP1LogMessage from a decoded CMDP1Message

Throws:

IncorrectMessageType – If the message is not a (valid) log message

inline constexpr log::Level getLogLevel() const#
Returns:

Log level of the message

inline std::string_view getLogTopic() const#
Returns:

Log topic of the message (might be empty)

std::string_view getLogMessage() const#
Returns:

Log message

Public Static Functions

static CMDP1LogMessage disassemble(zmq::multipart_t &frames)#

Disassemble log message from ZeroMQ frames

This function moves the payload.

Throws:
Returns:

New CMDP1LogMessage assembled from ZeroMQ frames

class CMDP1Message#
#include <constellation/core/message/CMDP1Message.hpp>

Class representing a CMDP1 message

Subclassed by constellation::message::CMDP1LogMessage, constellation::message::CMDP1StatMessage

Public Functions

inline constexpr const Header &getHeader() const#
Returns:

Read-only reference to the CMDP1 header of the message

inline constexpr Header &getHeader()#
Returns:

Reference to the CMDP1 header of the message

inline std::string_view getTopic() const#
Returns:

CMDP message topic

bool isLogMessage() const#
Returns:

If the message is a log message

bool isStatMessage() const#
Returns:

If the message is a stat message

zmq::multipart_t assemble()#

Assemble full message to frames for ZeroMQ

This function moves the payload.

Returns:

Message assembled to ZeroMQ frames

Public Static Functions

static CMDP1Message disassemble(zmq::multipart_t &frames)#

Disassemble message from ZeroMQ frames

This function moves the payload.

Throws:

MessageDecodingError – If the message is not a valid CMDP1 message

Returns:

New CMDP1Message assembled from ZeroMQ frames

Protected Functions

CMDP1Message(std::string topic, Header header, message::PayloadBuffer &&payload)#

Construct a new CMDP1 message with payload

Parameters:

  • topic – Topic of the message

  • header – Header of the message

  • payload – Payload of the message

inline const message::PayloadBuffer &get_payload() const#
Returns:

Message payload

Protected Static Functions

static log::Level get_log_level_from_topic(std::string_view topic)#

Extract the log level from CMDP1 message topic

Parameters:

topic – Topic of the message

Throws:

MessageDecodingError – If not a valid log level

class Header : public constellation::message::BaseHeader#
#include <constellation/core/message/CMDP1Message.hpp>

CMDP1 Header

Public Functions

inline Header(std::string sender, std::chrono::system_clock::time_point time = std::chrono::system_clock::now())#

Public Static Functions

static inline Header disassemble(std::span<const std::byte> data)#
class CMDP1StatMessage : public constellation::message::CMDP1Message#

Public Functions

CMDP1StatMessage(std::string topic, Header header, std::shared_ptr<metrics::Metric> metric)#

Construct a new CMDP1 message for metrics

Note

The message payload will be create immediately from the current value

Parameters:

  • topic – Topic of the statistics metric message

  • header – CMDP1 header of the message

  • metric – The metric to be sent

CMDP1StatMessage(CMDP1Message &&message)#

Construct a CMDP1StatMessage from a decoded CMDP1Message

Throws:

IncorrectMessageType – If the message is not a (valid) metrics message

inline std::shared_ptr<metrics::Metric> getMetric() const#
Returns:

Metric value and type

Public Static Functions

static CMDP1StatMessage disassemble(zmq::multipart_t &frames)#

Disassemble stats message from ZeroMQ frames

This function moves the payload.

Throws:
Returns:

New CMDP1StatMessage assembled from ZeroMQ frames

class CSCP1Message#
#include <constellation/core/message/CSCP1Message.hpp>

Class representing a CSCP1 message

Public Types

enum class Type : std::uint8_t#

Enum describing the type of CSCP1 message

Values:

enumerator REQUEST#

Request with a command

enumerator SUCCESS#

Command is being executed

enumerator NOTIMPLEMENTED#

Command is valid but not implemented

enumerator INCOMPLETE#

Command is valid but mandatory payload information is missing or incorrectly formatted

enumerator INVALID#

Command is invalid for the current state

enumerator UNKNOWN#

Command is entirely unknown

enumerator ERROR#

Previously received message is invalid

Public Functions

CSCP1Message(Header header, std::pair<Type, std::string> verb)#
Parameters:

  • header – CSCP1 header of the message

  • verb – Message verb containing the type and the command/reply string

inline constexpr const Header &getHeader() const#
Returns:

Read-only reference to the CSCP1 header of the message

inline constexpr Header &getHeader()#
Returns:

Reference to the CSCP1 header of the message

inline std::pair<Type, std::string_view> getVerb() const#
Returns:

Message verb containing the type and the command/reply string

inline const message::PayloadBuffer &getPayload() const#
Returns:

Message payload

inline bool hasPayload() const#
Returns:

True if message has payload

inline void addPayload(message::PayloadBuffer &&payload)#
Parameters:

payload – Payload buffer containing the payload to be added as ZeroMQ message

zmq::multipart_t assemble(bool keep_payload = false)#

Assemble full message to frames for ZeroMQ

Parameters:

keep_payload – If true, the payload is kept such that the message can be send again

Returns:

Message assembled to ZeroMQ frames

Public Static Functions

static CSCP1Message disassemble(zmq::multipart_t &frames)#

Disassemble message from ZeroMQ frames

This function moves the payload frame if there is one.

Throws:

TODO –

Returns:

New CSCP1Message assembled from ZeroMQ frames

class Header : public constellation::message::BaseHeader#
#include <constellation/core/message/CSCP1Message.hpp>

CSCP1 Header

Public Functions

inline Header(std::string sender, std::chrono::system_clock::time_point time = std::chrono::system_clock::now(), config::Dictionary tags = {})#

Public Static Functions

static inline Header disassemble(std::span<const std::byte> data)#
class IncorrectMessageType : public constellation::utils::RuntimeError#
#include <constellation/core/message/exceptions.hpp>

Incorrect message type.

The message type does not match the requested operation

Public Functions

inline explicit IncorrectMessageType(std::string_view why)#
class InvalidProtocolError : public constellation::message::MessageDecodingError#
#include <constellation/core/message/exceptions.hpp>

Invalid protocol identifier.

The message identifier does not represent a valid or known protocol identifier

Public Functions

inline explicit InvalidProtocolError(const std::string &protocol)#
class MD5Hash : public std::array<std::uint8_t, 16>#
#include <constellation/core/message/CHIRPMessage.hpp>

MD5 hash stored as array with 16 bytes

Public Functions

constexpr MD5Hash() = default#
MD5Hash(std::string_view string)#

Construct MD5 hash from a string

Parameters:

string – String from which to create the MD5 hash

std::string to_string() const#

Convert MD5 hash to an human readable string

Returns:

String containing a lowercase hex representation of the MD5 hash

bool operator<(const MD5Hash &other) const#
class MessageDecodingError : public constellation::utils::RuntimeError#
#include <constellation/core/message/exceptions.hpp>

Error in decoding the message.

The message cannot be correctly decoded because the format does not adhere to protocol.

Subclassed by constellation::message::InvalidProtocolError, constellation::message::UnexpectedProtocolError

Public Functions

inline explicit MessageDecodingError(const std::string &reason)#

Protected Functions

MessageDecodingError() = default#
class PayloadBuffer#
#include <constellation/core/message/PayloadBuffer.hpp>

Buffer holding an arbitrary object that can be turned into a zmq::message_t

This buffer takes ownership of an arbitrary object that owns some memory. The buffer stores the object in an std::any and memory range owned by the object in a span. The buffer features manual memory management to allow for zero-copy message transport with ZeroMQ.

To make the zero-copy mechanism work, the std::any is allocated via new on the heap. This allows to pass a free function to ZeroMQ, which deallocates the std::any via delete. However, to avoid that the std::any is deleted when the buffer goes out of scope, the buffer has to be released. This simply means that it resets the pointer to the std::any such that it does not get deleted in the destructor of the buffer.

Public Functions

template<typename T, typename F>
inline PayloadBuffer(T &&t, F f)#

Construct buffer given by moving an arbitrary object.

Note

If T doesn’t construct nicely to an std::any, one possibility is moving it into an std::shared_ptr

Parameters:

  • t – L-Value Reference of object T to move into the buffer

  • f – Function F that takes a reference of T and returns an std::span<std::byte>

inline PayloadBuffer(zmq::message_t &&msg)#

Specialized constructor for zmq::message_t

inline PayloadBuffer(msgpack::sbuffer &&buf)#

Specialized constructor for msgpack::sbuffer

template<typename R>
inline PayloadBuffer(R &&range)#

Specialized constructor for non-const ranges.

PayloadBuffer() = default#

Default constructor (empty payload)

inline ~PayloadBuffer()#

Destructor deleting the std::any

inline PayloadBuffer(PayloadBuffer &&other) noexcept#

Move constructor taking over other pointer and releasing other buffer.

inline PayloadBuffer &operator=(PayloadBuffer &&other) noexcept#

Move assignment freeing the buffer, taking over other pointer and releasing other buffer.

inline constexpr std::span<const std::byte> span() const#

Read-only access to the data in the buffer.

Returns:

Constant span of the data

inline constexpr std::span<std::byte> span()#

Write access to the data in the buffer.

Returns:

Non-constant span of the data

inline constexpr bool empty() const#

Check if the payload is empty.

Returns:

If the span is empty

inline std::string_view to_string_view() const#

Interpret data as string.

Note

This function does not ensure that the data in the buffer is actually a string

Returns:

String of the content in the buffer

inline zmq::message_t to_zmq_msg_copy() const#

Create a ZeroMQ message by copying the buffer.

Returns:

ZeroMQ message with a copy of the data in the buffer

inline zmq::message_t to_zmq_msg_release()#

Create a ZeroMQ message for zero-copy transport.

Note

The buffer will be released after this function, meaning that the buffer cannot be used anymore

Returns:

ZeroMQ message owning the data in the buffer

class UnexpectedProtocolError : public constellation::message::MessageDecodingError#
#include <constellation/core/message/exceptions.hpp>

Unexpected protocol identifier.

The protocol identifier of the message does not match the expected protocol

Public Functions

inline explicit UnexpectedProtocolError(protocol::Protocol prot_recv, protocol::Protocol prot_exp)#
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