Using libHexabus (0.6.0 or later)

Packet handling

Since every interaction in and with a Hexabus network hinges on the packets, packet handling will be discussed first.

Valid Hexabus packets are represented in a class hierarchy.

Every valid Hexabus packet on the wire has a representation in this class hierarchy, with the obvious equivalences of hexabus packet type identifiers and classes in this hierarchy. Packets are visitable, and a visitor interface for all valid packet types is provided, as will be explained in greater detail lateron. All classes live in the namespace hexabus, which will be elided for brevity.

class Packet

Base class for all packets in libhexabus. Provides two accessors: uint8_t type(), which returns the type code of the packet on the network, and uint8_t flags(), which contains the flags of the packet. Provides the abstract bast void accept(PacketVisitor&), making all packets visitable.

class ErrorPacket : Packet

Represents an error packet (packet type HXB_PTYPE_ERROR). Provides one extra accessor: uint8_t code(), which contains the error code received with the packet.

Provides a constructor ErrorPacket(uint8_t code, uint8_t flags = 0).

class EIDPacket : Packet

Base class for all packets with EID information. Provides one extra accessor: uint32_t eid(), which contains the EID sent with the packet.

class QueryPacket : EIDPacket

Represents a direct query (packet type HXB_PTYPE_QUERY).

Provides a constructor QueryPacket(uint32_t eid, uint8_t flags = 0).

class EndpointQueryPacket : EIDPacket

Represents an endpoint query (packet type HXB_PTYPE_EPQUERY).

Provides a constructor EndpointQueryPacket(uint32_t eid, uint8_t flags = 0).

class TypedPacket : EIDPacket

Represents a packet with contents of some specified type. Provides one extra accessor: uint8_t datatype(), which contains the hexabus datatype identifier. This value can be any of the valid HXB_DTYPE_* values.

template class ValuePacket<TValue> : TypedPacket

Represents a packet that contains a value. Provides on extra accessor: TValue value(), which contains the value of the packet. Valid template parameters for TValue, with the equivalent hexabus datatype identifiers, are:

Type	Hexabus type code	Notes
bool	HXB_DTYPE_BOOL
uint8_t	HXB_DTYPE_UINT8
uint32_t	HXB_DTYPE_UINT32
float	HXB_DTYPE_FLOAT
boost::posix_time::ptime	HXB_DTYPE_DATETIME
boost::posix_time::time_duration	HXB_DTYPE_TIMESTAMP
std::string	HXB_DTYPE_128STRING	Strings longer than 127 characters will be rejected
std::vector<char>	HXB_DTYPE_66BYTES	Vectors longer than 66 bytes will be rejected, shorter vector will be zero-padded

Please note that this class cannot be instantiated with parameters of TValue not listed above. Attempting to instantiate anyway will result in a compile-time assertion.

template class InfoPacket<TValue> : ValuePacket<TValue>

Represents an info packet (packet type HXB_PTYPE_INFO).

Valid instantiatons (as defined by ValuePacket) provide a constructor InfoPacket(uint32_t eid, const TValue& value, uint8_t flags = 0).

template class WritePacket<TValue> : ValuePacket<TValue>

Represents a write packet (packet type HXB_PTYPE_WRITE).

Valid instantiatons (as defined by ValuePacket) provide a constructor WritePacket(uint32_t eid, const TValue& value, uint8_t flags = 0).

class EndpointInfoPacket : ValuePacket<std::string>

Represents an endpoint info packet (packet type HXB_PTYPE_EPINFO). Note that, according to the hexabus packet format, the datatype member of this class need not correlate with the actual value. In fact, the datatype member contains the data type of the endpoint, while value contains a textual description of the endpoint.

Provides a constructor EndpointInfoPacket(uint32_t eid, uint8_t datatype, const std::string& value, uint8_t flags = 0).