CODEX_Quorum::QuorumSystem Class Reference

QuorumSystem is an abstract base class designed to present the basic interface for all quorum systems. More...

#include <QuorumSystem.h>

Inheritance diagram for CODEX_Quorum::QuorumSystem:

[legend]Collaboration diagram for CODEX_Quorum::QuorumSystem:

[legend]List of all members.

Public Member Functions
	QuorumSystem (ResponseTracker *aRT)
	The constructor takes a pointer to a ResponseTracker object, which is used to manage collecting responses to requests that are sent out.
virtual	~QuorumSystem ()
	The destructor frees the memory for the ResponseTracker.
virtual unsigned int	quorumSystemSize ()=0
virtual unsigned int	quorumSize ()=0
virtual unsigned int	faultsTolerated ()=0
virtual bool	broadcastMessage (const Message &msg, ReturnVector &rets, ResponseCallback *cb)=0
	Send a message to all the servers in a QuorumSystem.
virtual bool	unicastMessage (const MessageVector &msgs, ReturnVector &rets, ResponseCallback *cb=0)=0
	Send a server-specific message to each server in a QuorumSystem.
virtual void	poll (MessageDispatcher &requestDispatcher, QuorumDispatcher &responseDispatcher)=0
	Poll the RemoteServer%s for incoming messages, storing or dispatching them as appropriate.
virtual unsigned char *	extractKey (const unsigned char *data)
	Forwards a request to ResponseTracker::extractKey().
virtual bool	keyRegistered (const unsigned char *key)
	Determines whether a key is registered with the ResponseTracker.
Protected Attributes
ResponseTracker *	m_responseTracker
	This is used to match responses to their associated requests.

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Detailed Description

QuorumSystem is an abstract base class designed to present the basic interface for all quorum systems.

Definition at line 78 of file QuorumSystem.h.

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Constructor & Destructor Documentation

CODEX_Quorum::QuorumSystem::QuorumSystem (  ResponseTracker *  aRT  )  [inline]

The constructor takes a pointer to a ResponseTracker object, which is used to manage collecting responses to requests that are sent out. QuorumSystem takes ownership of the ResponseTracker. Definition at line 87 of file QuorumSystem.h. References m_responseTracker.

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Member Function Documentation

virtual bool CODEX_Quorum::QuorumSystem::broadcastMessage (  const Message &  msg, ReturnVector &  rets, ResponseCallback *  cb )  [pure virtual]

Send a message to all the servers in a QuorumSystem. This method only sends messages. It expects the vector rets to be initialized before calling. Repeated calls can be made until sufficient servers have been contacted. The subclass implementation should check the current values of rets before making connections. The message sent is also registered with the ResponseTracker, since broadcasts are generally requests awaiting replies. This can be prevented by passing a 0 callback. It is advisable in cases where the sender is part of the quorum system for there to be distinct outgoing and incoming server identifiers. For example, the first bit of the first byte might flag whether this is a request being sent by the server or a response to a request from the server. This prevents the request from being treated as a response to itself in ResponseTracker. All messages should have identifying information for the initiator of the request and a unique ID for the request. Parameters: msg  A message to broadcast to the QuorumSystem. rets  Vector of RemoteServerReturn%s to the message. cb  If not 0, the request is added to the ResponseTracker using cb as its message callback. This should only be done once for any given request. Returns: true if the broadcast was successfully sent to all servers. Implemented in CODEX_Quorum::StaticByzantineQuorumSystem< N, T >, CODEX_Quorum::StaticByzantineQuorumSystem< nServers, nFaults >, and CODEX_Quorum::StaticByzantineQuorumSystem< 3 *T+1, T >. Referenced by CODEX_Server::SignRequestHandler::handler(), and CODEX_Server::BroadcastRequestHandler::handler().

virtual unsigned int CODEX_Quorum::QuorumSystem::faultsTolerated (   )  [pure virtual]

Returns: The number of faults tolerated by this QuorumSystem. Implemented in CODEX_Quorum::StaticByzantineQuorumSystem< N, T >, CODEX_Quorum::StaticByzantineQuorumSystem< nServers, nFaults >, and CODEX_Quorum::StaticByzantineQuorumSystem< 3 *T+1, T >. Referenced by CODEX_KeyService::DelegateResponseVerifier::handler(), CODEX_KeyService::SignWriteCallback::operator()(), CODEX_KeyService::SignReadCallback::operator()(), CODEX_KeyService::SignCreateCallback::operator()(), and CODEX_KeyService::ClientReadCallback::operator()().

virtual bool CODEX_Quorum::QuorumSystem::keyRegistered (  const unsigned char *  key  )  [inline, virtual]

Determines whether a key is registered with the ResponseTracker. Returns: Whether the key passed in is registered. Definition at line 207 of file QuorumSystem.h. References m_responseTracker. Referenced by CODEX_Server::UnicastRequestHandler::handler(), and CODEX_Server::BroadcastRequestHandler::handler().

virtual void CODEX_Quorum::QuorumSystem::poll (  MessageDispatcher &  requestDispatcher, QuorumDispatcher &  responseDispatcher )  [pure virtual]

Poll the RemoteServer%s for incoming messages, storing or dispatching them as appropriate. A non-blocking select(2) is used to determine if there is incoming data. New requests are dispatched, and responses are stored in a ResponseTracker until a quorum has been received, at which point they too will be dispatched. Parameters: requestDispatcher  Functional object that dispatches new requests responseDispatcher  Functional object that dispatches responses from a quorum Implemented in CODEX_Quorum::StaticByzantineQuorumSystem< N, T >, CODEX_Quorum::StaticByzantineQuorumSystem< nServers, nFaults >, and CODEX_Quorum::StaticByzantineQuorumSystem< 3 *T+1, T >.

virtual unsigned int CODEX_Quorum::QuorumSystem::quorumSize (   )  [pure virtual]

Returns: The size of a quorum for this QuorumSystem. Implemented in CODEX_Quorum::StaticByzantineQuorumSystem< N, T >, CODEX_Quorum::StaticByzantineQuorumSystem< nServers, nFaults >, and CODEX_Quorum::StaticByzantineQuorumSystem< 3 *T+1, T >. Referenced by CODEX_Server::UnicastRequestHandler::handler(), CODEX_Server::SignRequestHandler::handler(), CODEX_APSS::MessageVerifier::handler(), CODEX_KeyService::DelegateResponseVerifier::handler(), CODEX_Server::BroadcastRequestHandler::handler(), CODEX_KeyService::VerifyWriteCallback::operator()(), CODEX_KeyService::SignWriteCallback::operator()(), CODEX_KeyService::SignReadCallback::operator()(), CODEX_KeyService::SignCreateCallback::operator()(), CODEX_KeyService::ClientWriteCallback::operator()(), CODEX_KeyService::ClientReadCallback::operator()(), and CODEX_KeyService::ClientCreateCallback::operator()().

virtual unsigned int CODEX_Quorum::QuorumSystem::quorumSystemSize (   )  [pure virtual]

Returns: The number of servers in this QuorumSystem. Implemented in CODEX_Quorum::StaticByzantineQuorumSystem< N, T >, CODEX_Quorum::StaticByzantineQuorumSystem< nServers, nFaults >, and CODEX_Quorum::StaticByzantineQuorumSystem< 3 *T+1, T >.

virtual bool CODEX_Quorum::QuorumSystem::unicastMessage (  const MessageVector &  msgs, ReturnVector &  rets, ResponseCallback *  cb = 0 )  [pure virtual]

Send a server-specific message to each server in a QuorumSystem. This method only sends messages. It expects the vector rets to be initialized before calling. Repeated calls can be made until sufficient servers have been contacted. The subclass implementation should check the current values of rets before making connections. By default, the message sent is not registered with the ResponseTracker, since unicasts are not generally requests awaiting replies. This behavior can be changed by passing a callback object. It is advisable in cases where the sender is part of the quorum system for there to be distinct outgoing and incoming server identifiers. For example, the first bit of the first byte might flag whether this is a request being sent by the server or a response to a request from the server. This prevents the request from being treated as a response to itself in ResponseTracker. Parameters: msgs  A set of messages to unicast to the servers in the QuorumSystem. rets  Vector of RemoteServerReturn%s to the messages. cb  If not 0, the request is added to the ResponseTracker using cb as its message callback. This should only be done once for any given request. Returns: true if the unicasts were successfully sent to all servers. Implemented in CODEX_Quorum::StaticByzantineQuorumSystem< N, T >, CODEX_Quorum::StaticByzantineQuorumSystem< nServers, nFaults >, and CODEX_Quorum::StaticByzantineQuorumSystem< 3 *T+1, T >. Referenced by CODEX_Server::UnicastRequestHandler::handler().

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The documentation for this class was generated from the following file:

• QuorumSystem.h

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