.TH "globus_xio_udp_driver_io" 3 "Tue Jul 5 2022" "Version 6.6" "globus_xio" \" -*- nroff -*-
.ad l
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.SH NAME
globus_xio_udp_driver_io \- Reading/Writing
.PP
 \- Reading/Writing\&.  

.SH SYNOPSIS
.br
.PP
.SH "Detailed Description"
.PP 
Reading/Writing\&. 

\fBglobus_xio_register_read()\fP semantics:
.PP
If the waitforbytes parameter is greater than zero, the read will happen asynchronously and be completed when at least waitforbytes has been read/written\&.
.PP
If the waitforbytes parameter is equal to zero, one of the following alternative behaviors occur:
.PP
If the length of the buffer is > 0 the read happens synchronously\&. If the user is using one of the blocking xio calls, no internal callback will occur\&.
.PP
If the length of the buffer is also 0, the call behaves like an asynchronous notification of data ready to be read\&. ie, an asynchronous select()\&.
.PP
In any case, when an error occurs before the waitforbytes request has been met, the outgoing nbytes is set to the amount of data actually read before the error occurred\&.
.PP
If the handle is not connected, the user should pass in a data descriptor\&. After the read, this data_descriptor will contain the contact string of the sender\&. The user can either get this contact string with \fBGLOBUS_XIO_UDP_GET_CONTACT\fP or pass the data descriptor directly to \fBglobus_xio_register_write()\fP to send a message back to the sender\&.
.PP
Also, if the handle is not connected, the waitforbytes should probably be 1 to guarantee that only one packet is received and the sender contact isn't overwritten by multiple packets from different senders\&.
.PP
\fBglobus_xio_register_write()\fP semantics:
.PP
When performing a write, exactly one UDP packet is sent of the entire buffer length\&. The waitforbytes parameter is ignored\&. If the entire buffer can not be written, a \fBGLOBUS_XIO_UDP_ERROR_SHORT_WRITE\fP error will be returned with nbytes set to the number of bytes actually sent\&.
.PP
If the handle is not 'connected', a contact string must be set in the data descriptor to \fBglobus_xio_register_write()\fP\&. This can either be done explicitly with \fBGLOBUS_XIO_UDP_SET_CONTACT\fP or implicitly by passing in a data descriptor received from \fBglobus_xio_register_read()\fP\&.
.PP
The udp write semantics are always synchronous\&. No blocking or internal callback will occur when using \fBglobus_xio_write()\fP\&. 
.SH "Author"
.PP 
Generated automatically by Doxygen for globus_xio from the source code\&.