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Full Discussion: Sockets and File descriptors
Top Forums Programming Sockets and File descriptors Post 92437 by gstlouis on Sunday 11th of December 2005 11:56:24 AM
Old 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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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)
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