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transport.h

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/* -*- c++ -*- */
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#ifndef MPS_Transport_H
#define MPS_Transport_H

namespace MPS {

/**
 * Represents a method of resolving names for, and connecting to
 * remote objects. Subclasses implement name-resolution and connection
 * facilities according to a particular transport protocol; examples
 * include InetTransport, SleeTransport, and FastmsgTransport. */
class Transport {
private:
  typedef vector<Transport *> transportVec_t;           ///< A list of Transports.
  static transportVec_t allTransports;                  ///< All registered Transports

private:
  string name;                          ///< Registered name of this transport ("inet", "slee", ..)

private:
  /**
   * Locate a Transport by name.
   *
   * @return a pointer to the named Transport.
   * @exception MPSException if the Transport name is not registered. */
  static Transport *findTransport(string const &name);

public:
  /// Register a transport.
  static void registerTransport(Transport *t);

  /**
   * Returns a message source/sink that can be used for communication
   * with the object at the address described by the
   * connectionSpec. Selects an appropriate Transport based on the
   * "transport" field of the Address.
   *
   * @param connectionSpec the address of the remote object
   * @return a connection handle for remote communication, or NULL if
   * none could be created
   * @exception MPSException if the transport name given is not
   * registered */
  static ref<Connection> getConnectionTo(Address const &connectionSpec);

  /**
   * Bind an object server to an interface provided by a transport.
   *
   * @param server the server to bind to the (about-to-be-created) transport-interface
   *
   * @param bindingSpec the suggested resolved name to bind to -
   * should be of the form "mps:transportname" or, if a greater degree
   * of control over the bind is desired,
   * "mps:transportname:param:param:..." (for instance, with the
   * "inet" transport, you use "mps:inet:hostname:portnumber").
   *
   * @return the string of the newly-bound address, or empty-string if the bind failed */
  static string bindServer(Server *server, string const &bindingSpec);

  /**
   * Bind an object server to all available transports that currently
   * do not have a binding for this server.
   *
   * @param server the server to bind */
  static void bindServer(Server *server);

  /**
   * Unbind an object server from an interface provided by a transport.
   *
   * @param server the server to unbind to the (about-to-be-removed) transport-interface
   *
   * @param bindingSpec the suggested resolved name to unbind from - cf. bindServer()
   * @return the string of the newly-unbound address, or empty-string if the unbind failed */
  static string unbindServer(Server *server, string const &bindingSpec);

  /**
   * Unbind a previously-bound server.
   * @param server the server to unbind. */
  static void unbindServer(Server *server);

protected:
  /**
   * For access by subclasses - initialises this class
   *
   * @param _name name to register the transport under
   */
  Transport(string const &_name);

public:
  virtual ~Transport();

  /// Retrieves the transport's registered name.
  string const &getName() const;

protected:
  /**
   * Returns a message source/sink that can be used for communication
   * with the object at the address described by the
   * connectionSpec. The connectionSpec is the broken-down resolved
   * name of the remote object, and <b>must</b> match the address
   * format that this transport expects.
   *
   * @param connectionSpec the address of the remote object
   * @return a connection handle for remote communication, or NULL if
   * none could be created */
  virtual ref<Connection> connectTo(Address const &connectionSpec) = 0;

  /**
   * Attempt to register a server interface for access using this transport.
   *
   * @param server the server to register
   * @param spec the connection specification that the transport may
   * use as a hint in determining the final resolved name to use when
   * binding this object.
   * @return the canonical name of the server-bound-to-this-transport,
   * or "" if binding to this transport fails. */
  virtual string registerServer(Server *server, Address const &spec) = 0;

  /**
   * Attempt to deregister a server interface.
   *
   * @param server the server to deregister
   * @param spec the connection specification that the transport may
   * use as a hint in determining the final resolved name to use when
   * unbinding this object.
   * @return the canonical name of the server-that-was-bound-to-this-transport,
   * or "" if unbinding from this transport fails. */
  virtual string deregisterServer(Server *server, Address const &spec) = 0;
};

}

#endif

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