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NAME

       globus_gass_transfer_protocol - Protocol Modules

        - Protocol Implementation API.

SYNOPSIS

   Data Structures
       struct globus_gass_transfer_request_proto_s
           Protocol module request handling structure.
       struct globus_gass_transfer_listener_proto_s
           Protocol module listener handling structure.
       struct globus_gass_transfer_proto_descriptor_t
           Protocol module descriptor structure.

   Typedefs
       typedef struct globus_gass_transfer_request_proto_s globus_gass_transfer_request_proto_t
       typedef struct globus_gass_transfer_listener_proto_s globus_gass_transfer_listener_proto_t
       typedef void(* globus_gass_transfer_proto_send_t) (globus_gass_transfer_request_proto_t
           *proto, globus_gass_transfer_request_t request, globus_byte_t *bytes, globus_size_t
           bytes_length, globus_bool_t last_data)
       typedef void(* globus_gass_transfer_proto_receive_t) (globus_gass_transfer_request_proto_t
           *proto, globus_gass_transfer_request_t request, globus_byte_t *bytes, globus_size_t
           bytes_length, globus_size_t wait_for_length)
       typedef void(* globus_gass_transfer_proto_func_t) (globus_gass_transfer_request_proto_t
           *proto, globus_gass_transfer_request_t request)
       typedef void(* globus_gass_transfer_proto_new_request_t) (globus_gass_transfer_request_t
           request, globus_gass_transfer_requestattr_t *attr)
       typedef int(* globus_gass_transfer_proto_create_listener_t)
           (globus_gass_transfer_listener_t listener, globus_gass_transfer_listenerattr_t *attr,
           char *scheme, char **base_url, globus_gass_transfer_listener_proto_t **proto)
       typedef void(* globus_gass_transfer_proto_listener_t)
           (globus_gass_transfer_listener_proto_t *proto, globus_gass_transfer_listener_t
           listener)
       typedef globus_object_t *(* globus_gass_transfer_proto_new_attr_t) (char *url_scheme)
       typedef void(* globus_gass_transfer_proto_accept_t) (globus_gass_transfer_listener_proto_t
           *proto, globus_gass_transfer_listener_t listener, globus_gass_transfer_request_t
           request, globus_gass_transfer_requestattr_t *attr)

   Functions
       void globus_gass_transfer_proto_send_complete (globus_gass_transfer_request_t request,
           globus_byte_t *bytes, globus_size_t nbytes, globus_bool_t failed, globus_bool_t
           last_data)
       void globus_gass_transfer_proto_receive_complete (globus_gass_transfer_request_t request,
           globus_byte_t *bytes, globus_size_t nbytes, globus_bool_t failed, globus_bool_t
           last_data)
       void globus_gass_transfer_proto_listener_ready (globus_gass_transfer_listener_t listener)
       int globus_gass_transfer_proto_register_protocol (globus_gass_transfer_proto_descriptor_t
           *proto_desc)
       int globus_gass_transfer_proto_unregister_protocol
           (globus_gass_transfer_proto_descriptor_t *proto_desc)
       void globus_gass_transfer_proto_request_ready (globus_gass_transfer_request_t request,
           globus_gass_transfer_request_proto_t *proto)
       void globus_gass_transfer_proto_new_listener_request (globus_gass_transfer_listener_t
           listener, globus_gass_transfer_request_t request, globus_gass_transfer_request_proto_t
           *proto)
       void globus_gass_transfer_proto_request_denied (globus_gass_transfer_request_t request,
           int reason, char *message)
       void globus_gass_transfer_proto_request_referred (globus_gass_transfer_request_t request,
           char **url, globus_size_t num_urls)

Detailed Description

       Protocol Implementation API.

       Protocol Modules

       The GASS Protocol Module API is designed to make it possible to extend the GASS client and
       server APIs to support additional protocols without making any changes to the core of the
       GASS implementation. GASS protocol modules are intended to to handle protocol-specific
       connection and data handling. The GASS Transfer library includes protocol modules which
       implement the HTTP, HTTPS, FTP, and GSI-FTP protocols.

       Every protocol module implementation must include the following header file:

       #include "globus_gass_transfer_proto.h"

       To implement a protocol module, one must create a globus_gass_transfer_proto_descriptor_t
       structure which indicates what the protocol module is able to do. This structure contains
       the URL scheme which the protocol module supports, and function pointers which indicate
       what type of operations (client or server) that the module implements. To implement a
       client-side protocol module, the new_requestattr and new_request fields must be set to the
       protocol module's implementations of those functions. To implement a server-side protocol
       module, the new_listenerattr and new_listener functions must be set to the protocol
       module's implementations of those functions.

       A protocol module implementor registers a protocol module with the GASS Transfer library
       by calling the function globus_gass_transfer_proto_register_protocol(), and unregisters
       the module by calling globus_gass_transfer_proto_unregister_protocol(). This functions
       must be called after the GLOBUS_GASS_TRANSFER_MODULE has already been activated. Once
       registered, applications may use URLs of the scheme type provided by the protocol module
       for the standard client or server operations.

Typedef Documentation

   typedef struct globus_gass_transfer_listener_proto_s globus_gass_transfer_listener_proto_t
       Protocol module listener handling structure.

       See also
           globus_gass_transfer_listener_proto_s

   typedef void(* globus_gass_transfer_proto_accept_t) (globus_gass_transfer_listener_proto_t
       *proto, globus_gass_transfer_listener_t listener, globus_gass_transfer_request_t request,
       globus_gass_transfer_requestattr_t *attr)
       Protocol module implementation function type for server request parsing.

       Function pointers of this type are associated with the
       globus_gass_transfer_listener_proto_t associated with a particular listener handle. They
       are called when a server implementation wants to accept a new connection from the
       listener. A new request is generated based on the protocol-specific request done on the
       new connection.

       The new request will be created with the attributes specified in the attr parameter. Once
       the protocol module has parsed the request, it must call
       globus_gass_transfer_proto_new_listener_request() to let the server implementation decide
       how to process this request.

       The protocol module should update the request to indicate the type of operation being
       requested, the size of the file (if applicable), and the identity of the client (if
       applicable).

       Parameters
           proto The protocol specific listener data structure associated with the listener
           handle.
           listener The listener handle which the user requested the listen on.
           request The new request handle.
           attr The request attribute set to be used when processing this request.

   typedef int(* globus_gass_transfer_proto_create_listener_t) (globus_gass_transfer_listener_t
       listener, globus_gass_transfer_listenerattr_t *attr, char *scheme, char **base_url,
       globus_gass_transfer_listener_proto_t **proto)
       Protocol module implementation function type for new server listeners.

       A function pointer of this type is associated with the
       globus_gass_transfer_proto_descriptor_t for a particular protocol module's implementation.
       It is called when the server has called globus_gass_transfer_create_listener().

       Parameters
           listener The listener handle to associate with the new proto created by the protocol
           module.
           attr A protocol-specific attribute set, created by calling the protocol module's
           new_listenerattr function pointer.
           scheme The URL scheme that the server has requested for the new listener. This will be
           one the scheme associated with a particular protocol module.
           base_url A pointer to be set the value of the base url of this listener. For most
           protocols, this will contain the scheme, hostname, and port number of the listener.
           This string must be allocated using one of the memory allocators defined in the
           globus_common library. It will be freed by the GASS Transfer library when the listener
           is closed.
           proto A pointer to be set to a new globus_gass_transfer_listener_proto_t which will be
           associated with this listener. This must be allocated by the protocol module using one
           of the memory allocators defined in the globus_common library. It will be freed by the
           GASS Transfer library when the listener is closed.

       Returns
           A GASS error value, or GLOBUS_SUCCESS.

   typedef void(* globus_gass_transfer_proto_func_t) (globus_gass_transfer_request_proto_t
       *proto, globus_gass_transfer_request_t request)
       Protocol module implementation function type.

       Function pointers of this type are associated with the
       globus_gass_transfer_request_proto_t associated with a particular request handle. They are
       called when certain functions which modify the status of a request have been called by a
       client or server.

       A function of this type is used for the fail, deny, refer, authorize, and destroy fields
       of the globus_gass_transfer_request_proto_t. A protocol module can query the request
       handle to determine the status and, if applicable, denial reasons if necessary.

       Parameters
           proto The protocol module's request handler.
           request The request handle.

   typedef void(* globus_gass_transfer_proto_listener_t) (globus_gass_transfer_listener_proto_t
       *proto, globus_gass_transfer_listener_t listener)
       Protocol module implementation function type for server operations.

       Function pointers of this type are associated with the
       globus_gass_transfer_listener_proto_t associated with a particular listener handle. They
       are called when a server implementation wants to close the listener, listen for new
       connections, or destroy the listener.

       Parameters
           proto The protocol-specific implementation of the
           globus_gass_transfer_listener_proto_t for a particular listener.
           listener The listener handle associated with the proto.

       See also
           globus_gass_transfer_proto_create_listener_t

   typedef globus_object_t *(* globus_gass_transfer_proto_new_attr_t) (char *url_scheme)
       Protocol module implementation function type for attribute creation.

       A function pointer of this type is associated with the
       globus_gass_transfer_proto_descriptor_t defining a protocol module. It is called when a
       client requests a new request attribute set be created for a URL scheme handled by a
       protocol module. The function implementation must create a new request attribute usable by
       the protocol.

       The returned attribute must be a globus object which inherits from one of the base
       attributes defined in the GASS Transfer API. A client or server operation will use a
       request attribute generated by this function when creating a new
       globus_gass_transfer_request_proto_t to handle a request.

       Parameters
           url_scheme The URL scheme that the request attribute should be compatible with.

       Returns
           A globus_object_t-based request attribute.

       See also
           globus_gass_transfer_proto_new_request_t, globus_gass_transfer_proto_accept_t

   typedef void(* globus_gass_transfer_proto_new_request_t) (globus_gass_transfer_request_t
       request, globus_gass_transfer_requestattr_t *attr)
       Protocol module implementation function type for new client requests.

       A function pointer of this type is associated with the
       globus_gass_transfer_proto_descriptor_t for a particular protocol module's implementation.
       It is called when the client has begun a file transfer request by calling one of the
       functions in the '@ref globus_gass_transfer_client' section of this manual.

       When this function is called for a protocol module, the module should query the request
       handle to determine the URL which is being requested by the client, and the operation
       being done on that URL. The protocol module should initiate the request, and once it has
       determined that it has been authorized, denied, or referred, one of
       globus_gass_transfer_proto_request_ready(), globus_gass_transfer_proto_request_denied(),
       or globus_gass_transfer_proto_request_referred() must be called.

       Parameters
           request The request handle containing the information about the request.
           attr A protocol-specific attribute set, created by calling the protocol module's
           new_requestattr function pointer.

   typedef void(* globus_gass_transfer_proto_receive_t) (globus_gass_transfer_request_proto_t
       *proto, globus_gass_transfer_request_t request, globus_byte_t *bytes, globus_size_t
       bytes_length, globus_size_t wait_for_length)
       Protocol module function type to handle receiving data.

       A function pointer of this type is associated with the
       globus_gass_transfer_request_proto_t associated with a request handle. It is called when
       client or server has registered a bytes array for receiving from the client or server
       which is handling the request. The GASS Transfer Library will only pass one bytes array to
       the protocol module for processing per request at any given time.

       Once the protocol module has processed the array, it must call
       globus_gass_transfer_proto_receive_complete() to let the GASS Transfer library continue to
       process the request.

       Parameters
           proto The protocol module's request handler.
           request The request handle with which this block of bytes is associated.
           bytes The user-supplied byte array containing the data associated with the request.
           bytes_length The length of the bytes array.
           wait_for_length The minimum amount of data to receive before calling
           globus_gass_transfer_proto_receive_complete() for the request. The GASS Transfer
           protocol module may call that function with a smaller value for the amount received if
           EOF has been reached.

       See also
           globus_gass_transfer_receive_bytes()

   typedef void(* globus_gass_transfer_proto_send_t) (globus_gass_transfer_request_proto_t
       *proto, globus_gass_transfer_request_t request, globus_byte_t *bytes, globus_size_t
       bytes_length, globus_bool_t last_data)
       Protocol module function type to handle sending data.

       A function pointer of this type is associated with the
       globus_gass_transfer_request_proto_t associated with a request handle. It is called when
       client or server has registered a bytes array for sending to the client or server which is
       handling the request. The GASS Transfer Library will only pass one bytes array to the
       protocol module for processing per request at any given time.

       Once the protocol module has processed the array, it must call
       globus_gass_transfer_proto_send_complete() to let the GASS Transfer library continue to
       process the request.

       Parameters
           proto The protocol module's request handler.
           request The request handle with which this block of bytes is associated.
           bytes The user-supplied byte array containing the data associated with the request.
           bytes_length The length of the bytes array.
           last_data A flag to indicate whether this is the final block of data for the request.
           If this is true, then the callback function will be delayed until the server
           acknowledges that the file has been completely received.

       See also
           globus_gass_transfer_send_bytes()

   typedef struct globus_gass_transfer_request_proto_s globus_gass_transfer_request_proto_t
       Protocol module request handling structure.

       See also
           globus_gass_transfer_request_proto_s

Function Documentation

   void globus_gass_transfer_proto_listener_ready (globus_gass_transfer_listener_t listener)
       Server listener ready.

       This function notifies the GASS Transfer Library that the protocol module has decided that
       a new request can be accepted on this particular listener. It must only be called after
       the GASS Transfer Library has called the listen function in a
       globus_gass_transfer_listener_proto_t protocol module-specific listener structure.

       Parameters
           listener The listener handle which is now ready for accepting a new connection.

   void globus_gass_transfer_proto_new_listener_request (globus_gass_transfer_listener_t
       listener, globus_gass_transfer_request_t request, globus_gass_transfer_request_proto_t *
       proto)
       New listener request.

       This function notifies the GASS Transfer Library that new request generated by a server
       calling the globus_gass_transfer_register_accept() function has begun processing in a
       protocol module, and that protocol module is now ready to send or receive data to handle
       this request.

       Parameters
           listener The listener handle used to accept this request.
           request The request handle used for this request. This was created by the user calling
           one of the functions in the '@ref
                  globus_gass_transfer_client' section of this manual.
           proto The protocol-module specific request structure. This structure contains a set of
           function pointers to allow GASS to continue to process this request.

   void globus_gass_transfer_proto_receive_complete (globus_gass_transfer_request_t request,
       globus_byte_t * bytes, globus_size_t nbytes, globus_bool_t failed, globus_bool_t
       last_data)
       Data receive complete.

       A protocol module must call this function once a byte range registered for receive via the
       protocol module's recv_buffer method has been completely processed. This function is
       called for protocol modules implementing either server or client functionality.

       Parameters
           request The request handle associated with this byte array.
           bytes The byte array which was received into. This should be the same as the pointer
           passed in the send_buffer method.
           nbytes The number of bytes which were sent from this byte array. This may be different
           than length passed to the send_buffer method if an error occurred or EOF was reached
           while receiving the data.
           failed A boolean indicating whether this byte range was successfully received or not.
           This should be set to GLOBUS_TRUE if either a protocol error or a user-generated abort
           has occurred while processing the byte range. If this is set to GLOBUS_TRUE, then the
           last_data parameter must also be set to GLOBUS_TRUE.
           last_data A boolean indicating whether this byte range was the final one which can be
           processed for this request. This should be set to GLOBUS_TRUE if an error occurred
           while processing this byte range, and user-generated abort occurred, or this is the
           final byte range in the data transfer.

       See also
           globus_gass_transfer_send_bytes()

   int globus_gass_transfer_proto_register_protocol (globus_gass_transfer_proto_descriptor_t *
       proto_desc)
       Register protocol.

       This function registers a protocol module handler with the GASS Transfer library. If this
       succeeds, then users of the library may use the URLs with the protocol scheme implemented
       by this module descriptor in GASS Transfer operations.

       Parameters
           proto_desc The protocol module descriptor. See the '@ref
                  globus_gass_transfer_protocol' section of the manual for information on this
           structure.

       Return values
           GLOBUS_SUCCESS The protocol module was successfully registered with GASS.
           GLOBUS_GASS_TRANSFER_ERROR_NULL_POINTER The proto_desc parameter was GLOBUS_NULL.
           GLOBUS_GASS_TRANSFER_ERROR_ALREADY_REGISTERED A protocol module has already been
           registered with GASS to handle this URL scheme.

   void globus_gass_transfer_proto_request_denied (globus_gass_transfer_request_t request, int
       reason, char * message)
       Request denied.

       This function notifies the GASS Transfer Library that new request generated by a client
       calling one of the functions in the '@ref globus_gass_transfer_client' section of the
       manual has been denied by the server, and so cannot be processed by the protocol module.

       Parameters
           request The request handle used for this request. This was created by the user calling
           one of the functions in the '@ref
                  globus_gass_transfer_client' section of this manual.
           reason A protocol-specific reason code.
           message A string containing a message describing why the request was denied. The GASS
           Transfer library is responsible for freeing this message. It must be allocated using
           one of the memory allocators defined in the Globus Common Library.

       See also
           globus_gass_transfer_proto_request_ready(),
           globus_gass_transfer_proto_request_referred()

   void globus_gass_transfer_proto_request_ready (globus_gass_transfer_request_t request,
       globus_gass_transfer_request_proto_t * proto)
       Request ready.

       This function notifies the GASS Transfer Library that new request generated by a client
       has begun processing in a protocol module, and that protocol module is now ready to send
       or receive data to handle this request.

       Parameters
           request The request handle used for this request. This was created by the user calling
           one of the functions in the '@ref
                  globus_gass_transfer_client' section of this manual.
           proto The protocol-module specific request structure. This structure contains a set of
           function pointers to allow GASS to continue to process this request.

       See also
           globus_gass_transfer_proto_request_referred(),
           globus_gass_transfer_proto_request_denied()

   void globus_gass_transfer_proto_request_referred (globus_gass_transfer_request_t request, char
       ** url, globus_size_t num_urls)
       Request referred.

       This function notifies the GASS Transfer Library that new request generated by a client
       calling one of the functions in the '@ref globus_gass_transfer_client' section of the
       manual has been referred to another URL by the server, and so processing has stopped.

       Parameters
           request The request handle used for this request. This was created by the user calling
           one of the functions in the '@ref
                  globus_gass_transfer_client' section of this manual.
           url An array of url strings containing alternate locations for this file. The GASS
           transfer library is responsible for freeing this array. It must be allocated using one
           of the memory allocators defined in the Globus Common Library.
           num_urls The length of the url array.

       See also
           globus_gass_transfer_proto_request_ready(),
           globus_gass_transfer_proto_request_denied(),
           globus_gass_transfer_proto_request_referred()

   void globus_gass_transfer_proto_send_complete (globus_gass_transfer_request_t request,
       globus_byte_t * bytes, globus_size_t nbytes, globus_bool_t failed, globus_bool_t
       last_data)
       Data send complete.

       A protocol module must call this function once a byte range registered for sending via the
       protocol module's send_buffer method has been completely processed. This function is
       called for protocol modules implementing either server or client functionality.

       Parameters
           request The request handle associated with this byte array.
           bytes The byte array which was sent. This should be the same as the pointer passed in
           the send_buffer method.
           nbytes The number of bytes which were sent from this byte array. This may be different
           than length passed to the send_buffer method if an error occurred.
           failed A boolean indicating whether this byte range was successfully sent or not. This
           should be set to GLOBUS_TRUE if either a protocol error or a user-generated abort has
           occurred while processing the byte range. If this is set to GLOBUS_TRUE, then the
           last_data parameter must also be set to GLOBUS_TRUE.
           last_data A boolean indicating whether this byte range was the final one which can be
           processed for this request. This should be set to GLOBUS_TRUE if an error occurred
           while processing this byte range, and user-generated abort occurred, or this is the
           final byte range in the data transfer.

       See also
           globus_gass_transfer_send_bytes()

   int globus_gass_transfer_proto_unregister_protocol (globus_gass_transfer_proto_descriptor_t *
       proto_desc)
       Unregister protocol.

       This function unregisters a protocol module handler from the GASS Transfer library. If
       this succeeds, then users of the library may no longer user URLs with the protocol scheme
       implemented by this module descriptor in GASS Transfer operations.

       Parameters
           proto_desc The protocol module descriptor. See the '@ref
                  globus_gass_transfer_protocol' section of the manual for information on this
           structure.

       Return values
           GLOBUS_SUCCESS The protocol module was successfully registered with GASS.
           GLOBUS_GASS_TRANSFER_ERROR_NULL_POINTER The proto_desc parameter was GLOBUS_NULL.
           GLOBUS_GASS_TRANSFER_ERROR_INVALID_USE A protocol module has not been registered with
           GASS to handle this URL scheme.

Author

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