12-11-2005
Sockets and File descriptors
I am in a Systems programming class this semester, and our current project is to write a program utilizing sockets and fork. For the project, I decided to make my own instant messaging program. I have the code completed, but I have a problem that keeps old clients from communicating with new clients. The way it is currently set up has 2 programs, a client and a server. The server is always running. Each time a client connects, it forks off a child process to handle communication with that client, then the parent goes back to listening for new clients. On the client side, a connection to the server is made and communication is done with its associated server child process. Each time the server forks, it passes the updated table of file descriptors to its new child. However, child processes that already exist don't have record of the new file descriptor, which keeps them from being able to communicate to other users.
Take this example. Client A signs on. Then Client B. Client B can send messages to Client A, but Client A cannot send messages to client B because Client B signed on after client A, so he doesn't have the file descriptor for B. Client C then signs on. He can communicate with A and B because he has a current list of file descriptors for the users. But B cannot communicate with C and A can't communicate with either. I obviously would like all clients to communicate with one another no matter when they signed on.
Essentially, I would like a way to update file descriptors on all of the children each time a new client signs on. But that may not be the best solution to the problem. All I really need is a way for clients to communicate no matter when they signed on and without creating a seperate socket between each client. Any ideas?
Thanks for your help.
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LEARN ABOUT DEBIAN
rt::client::rest::exception
RT::Client::REST::Exception(3pm) User Contributed Perl Documentation RT::Client::REST::Exception(3pm)
NAME
RT::Client::REST::Exception -- exceptions thrown by RT::Client::REST methods.
DESCRIPTION
These are exceptions that are thrown by various RT::Client::REST methods.
EXCEPTION HIERARCHY
RT::Client::REST::Exception
This exception is virtual -- it is never thrown. It is used to group all the exceptions in this category.
RT::Client::REST::OddNumberOfArgumentsException
This means that the method you called wants key-value pairs.
RT::Client::REST::InvaildObjectTypeException
Thrown when you specify an invalid type to "show()", "edit()", or "search()" methods.
RT::Client::REST::RequiredAttributeUnsetException
An operation failed because a required attribute was not set in the object.
RT::Client::REST::MalformedRTResponseException
RT server sent response that we cannot parse. This may very well mean a bug in this client, so if you get this exception, some debug
information mailed to the author would be appreciated.
RT::Client::REST::InvalidParameterValueException
Invalid value for comments, link types, object IDs, etc.
RT::Client::REST::CannotReadAttachmentException
Cannot read attachment (thrown from methods "comment()" and "correspond").
RT::Client::REST::RTException
This is a virtual exception and is never thrown. It is used to group exceptions thrown because RT server returns an error.
RT::Client::REST::ObjectNotFoundException
One or more of the specified objects was not found.
RT::Client::REST::AuthenticationFailureException
Incorrect username or password.
RT::Client::REST::UpdateException
This is a virtual exception. It is used to group exceptions thrown when RT server returns an error trying to update an object.
RT::Client::REST::CouldNotSetAttributeException
For one or another reason, attribute could not be updated with the new value.
RT::Client::REST::InvalidEmailAddressException
Invalid e-mail address specified.
RT::Client::REST::AlreadyCurrentValueException
The attribute you are trying to update already has this value. I do not know why RT insists on treating this as an exception, but
since it does so, so should the client. You can probably safely catch and throw away this exception in your code.
RT::Client::REST::ImmutableFieldException
Trying to update an immutable field (such as "last_updated", for example).
RT::Client::REST::IllegalValueException
Illegal value for attribute was specified.
RT::Client::REST::UnknownCustomFieldException
Unknown custom field was specified in the request.
RT::Client::REST::InvalidQueryException
Server could not parse the search query.
RT::Client::REST::UnauthorizedActionException
You are not authorized to perform this action.
RT::Client::REST::AlreadyTicketOwnerException
The owner you are trying to assign to a ticket is already the owner. This exception is usually thrown by methods "take()", "untake",
and "steal", if the operation is a noop.
RT::Client::REST::RequestTimedOutException
Request timed out.
RT::Client::REST::UnknownRTException
Some other RT exception that the driver cannot recognize.
METHODS
_get_exception_class
Figure out exception class based on content returned by RT.
_rt_content_to_exception
Translate error string returned by RT server into an exception object ready to be thrown.
SEE ALSO
Exception::Class, RT::Client::REST.
AUTHOR
Dmitri Tikhonov <dtikhonov@yahoo.com>
perl v5.14.2 2011-12-27 RT::Client::REST::Exception(3pm)