CORBA 2.6.1 Programmer's Guide for C++

Implement the method, or
Use the corresponding protocol-specific method from the event framework APIs for the Guardian file system (defined in gfsehoss.h) or
TCP/IP sockets (defined in
sockeh.h).
Event Framework Messages and Message Data Descriptors
The Fw_MD and Fw_Message classes provide methods to assemble and disassemble messages for use by event handlers and event-handler
users. These classes are defined in the header file
message.h.
Class Fw_MD
The Fw_MD, or framework message data descriptor, class provides an abstraction for a single segment of data and a get/put recycling factory.
Fw_MD objects can be written to and read from, and can be combined to form an abstract message (Fw_Message object). The message data
descriptor object allows a long message to be transmitted and received in fragments. See also
Transfer Event Handler and Event-Handler User.
Class Fw_Message
The Fw_Message, or framework message, class provides an abstraction for a complete message and a get/put recycling factory. Messages can
be written to and read from, and are implemented as a list of
Fw_MD objects. See also Transfer Event Handler and Event-Handler User.
Guardian File-System Event Handlers and Event-Handler Users (Class
NSDEFw_GFS)
The NSDEFw_GFS class enables legacy wrappers to use the Guardian file-system and context-sensitive Pathsend interfaces. This class is defined
in the header file
gfsehoss.h.
This class implements client, server, and listener event handlers that use the Guardian file-system protocol in a specific way. If your legacy
clients or servers vary from the semantics provided by this class, you will need to write your own event handlers.
NSDEFw_GFS consists of the following four main subclasses:
NSDEFw_GFS::Client
NSDEFw_GFS::Receive_EH
NSDEFw_GFS::Listener
NSDEFw_GFS::Server
Within these subclasses, hashable abstractions are provided for Guardian file-system addresses. A get/put recycling factory is also included.
Class NSDEFw_GFS::Client
The NSDEFw_GFS::Client class provides classes and methods to support Guardian file-system style communication with a legacy server. It
defines a server's file-system address, an event for tracking I/O completions, and an event handler that uses this address and event to provide
an Fw_Client_EH implementation.
Class NSDEFw_GFS::Receive_EH
The NSDEFw_GFS::Receive_EH class extends the subclass NSDEFw_GFS::Client::EH to provide a $RECEIVE handler, and translates the
semantics of the Guardian READUPDATE, RECEIVEINFO, and REPLY procedures into an asynchronous Guardian file-system listener and
server event-management facility.
Listeners and servers register interest in I/O events associated with their addresses. When READUPDATE produces a message for an
interested party,
Receive_EH packages the message in an appropriate event and delivers the event. Replying to an event invokes REPLY.
Class NSDEFw_GFS::Listener
The NSDEFw_GFS::Listener class provides classes and methods needed by a listener event handler that performs Guardian file-system style
communication with a legacy client in cooperation with a server event handler. It defines a hashable address abstraction used by listeners to
distinguish themselves by subdevice, an event passed from a Receive_EH object upon receipt of an OPEN message, and an event handler that
uses the address abstraction and event to provide an
Fw_Listener_EH implementation.
Class NSDEFw_GFS::Server
The NSDEFw_GFS::Server class provides classes and methods needed by a server event handler that performs Guardian file-system style
communication with a legacy client in cooperation with a listener event handler. It defines a hashable address abstraction used to uniquely
identify a connection, an event passed from a Receive_EH object, and an event handler that uses the address abstraction and event to provide
an
Fw_Server_EH implementation.
Events are generated by the
Receive_EH object upon receipt of WRITE, READ, WRITEREAD, and CLOSE messages. The associated data
fields are populated with data from READUPDATE and RECEIVEINFO.
TS/MP Event Handlers and Event-Handler Users (Class NSDEFw_GCF)
The NSDEFw_GCF class, in the gcfehoss.h header file, builds upon components of the NSDEFw_GFS class and implements a TS/MP specialization of
the Guardian file system. The
NSDEFw_GCF
class is intended primarily for internal use by NonStop CORBA.