not support these additional capabilities.   FTP uses TELNET services to set up a connection between the FTP   Client and FTP Server.  A three-digit reply code followed by   explanatory text indicates the status of the preceding request and   provides diagnostic information explaining each transaction.   FTAM relies on the Association Control Service Element (ACSE) to   start and stop the network for network file interaction.  Generally,   the ASCE establishes the application association and related   application context needed to support the FTAM protocol.   The FTAM protocol is modularized so as to keep the allowable number   of actions in any particular state relatively small.  There are many   more possible sequences of FTP operations than possible sequences of   FTAM operations [NIST86].   Because FTAM is more robust than FTP, FTAM allows greater flexibility   for conveying information about files.  FTAM deals only with aspects   of application processes, and leaves data representation and data   management facilities to other OSI service elements.   In contrast to the Client/Server model present in the FTP scheme,   FTAM is based on the Initiator/Responder model.  The key distinctionMindel & Slaski                                                [Page 19]RFC 1415             FTP-FTAM Gateway Specification         January 1993   is that once the FTAM Initiator has established a connection with a   remote host, either the Initiator or Responder can request services   of the other.  In the FTP realm, the Client both initiates a   connection and requests all services.   The FTP Client knows the real properties of the remote host   filesystem.  FTAM, in contrast, embraces a conceptual model of a   filesystem, labeled a virtual filestore model.  The virtual filestore   is a collection of files, each of which has a name that uniquely   identifies it.  Each file has a set of attributes, such as ownership   information and contents, which is the data associated with the file.   One file attribute is the <Contents Type> of the file, typically of   value "FTAM-1", "FTAM-3", or "NBS-9".  The FTAM Initiator only knows   the properties of the corresponding Responder and virtual filestore,   not the real properties of the filesystem on the remote host.7.1. Loss of Functionality   As happens whenever two dissimilar protocols, or languages for that   matter, are translated, some loss of functionality is inevitable.   With reference to the FTP-FTAM gateway, several of the most blatant   losses of functionality are:        1. Diagnostics passed between protocols may not be precisely           translated.        2. The FTAM partial file (record) transfer may not be           supported.        3. Some FTAM attributes are not supported by FTP.   The primary goal of the gateway protocol mappings are to minimize   this loss of functionality. As this gateway specification and   subsequent implementations evolve, means to partially overcome loss   of functionality may become more obvious.  For example, the gateway   may be able to emulate file record transfers between FTAM Initiators   and FTP Servers.8. Mapping of Protocol Functions and Representations   The mappings presented are based upon the FTAM protocol   implementation as defined in Stable Implementation Agreements for   Open Systems Interconnection Protocols:  Part 9 - FTAM Phase 2,   produced by the March 1992 Open Systems Environment Implementors'   Workshop [NIST92], and in [ISO8571-1], [ISO8571-2],[ISO8571-   3],[ISO8571-4], and [ISO8571-5].  The FTP protocol as defined in   Request for Comments [RFC959].   The mappings are strongly influenced   by the work of M. A. Wallace et. al. at NIST [NIST86] and John ScottMindel & Slaski                                                [Page 20]RFC 1415             FTP-FTAM Gateway Specification         January 1993   at MITRE [MITRE87].   A key goal of the mappings presented in this document is to minimize   the loss of functionality between the two protocols.  The specific   approach taken to implement the mappings is left to the discretion of   the gateway implementor.  The focus of the protocol function and   representation mappings is on non-error encumbered processing.  The   mapping of diagnostic and error messages is treated separately in   section 9.   At a minimum, the FTAM implementation in the FTP-FTAM gateway support   for Implementation Profiles T1 (Simple File Transfer) and M1   (Management), as defined in [NIST92], is required.  These   Implementation Profiles correspond to the A/111 and A/13 Profiles of   Standards Promotion and Application Group in Europe, respectively   [NIST92].   At a minimum, the gateway support for the following is required:      ASCII and 8 bit binary file types.  It should also support FTP      File Stream Mode.      The following FTAM document types: FTAM-1 (unstructured text      file), FTAM-3 (unstructured binary file), and NBS-9 (set of      directory entries).   POSIX file naming and organization conventions are assumed in these   mappings; i.e., files in the systems are assumed to be organized in a   hierarchical structure in which all of the non-terminal nodes are   directories and all of the terminal nodes are any other type of file.   The following terminology is used in the mapping specifications:      argument .......FTP Service Command argument, as used in [RFC959].      parameter ......FTAM Service Primitive parameters and attributes,                      as enumerated in Tables 6, 50, and 51 of [ISO8571-                      3].   The following notation is used in the mapping specifications:      Arguments and parameters are enclosed in angle brackets; e.g.,      <Action Result>      Values of arguments and parameters are enclosed in quotation      marks; e.g., "Success"Mindel & Slaski                                                [Page 21]RFC 1415             FTP-FTAM Gateway Specification         January 1993      FTP Service Commands and FTAM Primitives are in uppercase; e.g., F-      INITIALIZE8.1.  FTP-Initiated Gateway Service   The protocol mapping between FTP and FTAM may be one-to-zero (i.e.,   not mappable), one-to-one, or one-to-many.   The general steps taken by the FTP-FTAM gateway to provide the FTP-   Initiated service are:        1. Accept an FTP Client request at the FTP Server side of the           gateway service.        2. Map the request to the (set of) corresponding FTAM           Initiator function(s).        3. Acting as an FTAM Initiator, send the FTAM Initiator           function(s) to the FTAM Responder.        4. Accept information returned to the FTAM Initiator side of           the gateway.  This information originated at the FTAM           Responder.        5. Map this returned information to the protocol form           understood by the FTP Server side of the gateway.        6. Send this returned information from the FTP Server side of           the gateway to the FTP Client.   For each FTP protocol function, the FTAM protocol functions required   to map it are identified:   FTP       FTAM   ------------------------------------------------------------------   ABOR      F-BEGIN-GROUP, F-CANCEL, F-CLOSE, F-DESELECT, F-END-GROUP   ACCT      F-INITIALIZE,   ALLO      none   APPE      F-BEGIN-GROUP, F-CLOSE, F-CREATE, F-DATA, F-DATA-END, F-             DESELECT, F-END-GROUP, F-OPEN, F-READ-ATTRIBUTES, F-SELECT,             F-TRANSFER-END, F-WRITE   CDUP      F-BEGIN-GROUP, F-DESELECT, F-END-GROUP, F-SELECTMindel & Slaski                                                [Page 22]RFC 1415             FTP-FTAM Gateway Specification         January 1993   CWD       F-BEGIN-GROUP, F-END-GROUP, F-DESELECT, F-SELECT   DELE      F-BEGIN-GROUP, F-DELETE, F-END-GROUP, F-SELECT   HELP      none   LIST      F-BEGIN-GROUP, F-CLOSE, F-DATA, F-DATA-END, F-DESELECT, F-             END-GROUP, F-OPEN, F-READ, F-READ-ATTRIBUTES, F-SELECT, F-             TRANSFER-END   MKD       none   MODE      none   NLST      F-BEGIN-GROUP, F-CLOSE, F-DATA, F-DATA-END, F-DESELECT, F-             END-GROUP, F-OPEN, F-READ, F-SELECT, F-TRANSFER-END   NOOP      none   PASS      F-INITIALIZE   PASV      none   PORT      none   PWD       F-BEGIN-GROUP, F-DESELECT, F-END-GROUP, F-READ-ATTRIBUTES,             F-SELECT   QUIT      F-P-ABORT or F-U-ABORT, F-TERMINATE   REIN      F-BEGIN-GROUP, F-CANCEL, F-CLOSE, F-DESELECT, F-END-GROUP   REST      F-CHECK, F-RESTART   RETR      F-BEGIN-GROUP, F-CLOSE, F-DATA, F-DATA-END, F-DESELECT, F-             END-GROUP, F-OPEN, F-READ, F-SELECT, F-TRANSFER-END   RMD       none   RNFR      F-BEGIN-GROUP, F-DESELECT, F-END-GROUP, F-SELECT   RNTO      F-BEGIN-GROUP, F-CHANGE-ATTRIBUTES, F-DESELECT, F-END-             GROUP, F-SELECT   SITE      F-INITIALIZE   SMNT      noneMindel & Slaski                                                [Page 23]RFC 1415             FTP-FTAM Gateway Specification         January 1993   STAT      none   STOR      F-BEGIN-GROUP,F-CLOSE, F-CREATE, F-DATA, F-DATA-END, F-             DESELECT, F-END-GROUP, F-OPEN, F-READ-ATTRIBUTES, F-SELECT,             F-TRANSFER-END, F-WRITE   STOU      F-BEGIN-GROUP, F-CLOSE, F-CREATE, F-DATA, F-DATA-END, F-             DESELECT, F-END-GROUP, F-OPEN, F-READ-ATTRIBUTES, F-SELECT,             F-TRANSFER-END, F-WRITE   STRU      none   TYPE      none   USER      F-INITIALIZE   The remainder of this section presents detailed mapping procedures   for each of the FTP protocol functions.  Gateway support for these   mappings is required.8.1.1. ABOR        1. Send F-CANCEL to FTAM Responder.        2. Send the following grouped request to the FTAM Responder.           F-BEGIN-GROUP           F-CLOSE           F-DESELECT           F-END-GROUP        3. Translate FTAM Responder <Action Result> and <Diagnostic>           parameters to equivalent FTP reply code(s) and send reply           codes to FTP Client.        4. Translate FTP Client reply codes to equivalent FTAM <Action           Result> and <Diagnostic> parameters and send parameters to           FTAM Responder.8.1.2. ACCT        1. Set <Account> parameter value for issuing F-INITIALIZE to           FTAM Responder.        2. If <Called Presentation Address>, <Initiator Identity>, and           <Filestore Password> parameters are available, attempt           connection with FTAM Responder;           Otherwise wait for additional ACCT commands.        3. Translate FTAM Responder <Action Result> and <Diagnostic>           parameters to equivalent FTP reply code(s) and send reply           codes to FTP Client.        4. Translate FTP Client reply codes to equivalent FTAM <Action           Result> and <Diagnostic> parameters and send parameters toMindel & Slaski                                                [Page 24]RFC 1415             FTP-FTAM Gateway Specification         January 1993           FTAM Responder.        Note:        a. The ACCT command will be effective with the next PASS           command.8.1.3. ALLO        1. Return a 200 reply code to FTP Client.8.1.4. APPE        1. Save current pathname by appending saved CWD string with           <pathname> argument.  If no saved CWD string, proceed to           step 12.        2. Send the following grouped request to FTAM Responder.            F-BEGIN-GROUP            F-SELECT            F-READ-ATTRIBUTES                Save <Contents Type> parameter value            F-DESELECT            F-END-GROUP        3. If the <Contents Type> parameter value returned with the           F-READ-ATTRIBUTES has a value of "NBS-9", proceed to step           12.        4. Send the following grouped request to the FTAM responder.            F-BEGIN-GROUP            F-CREATE                Set the <Override> parameter in the F-CREATE to                "Select Old File".            F-OPEN            F-END-GROUP        5. If the file existed, set the <Contents Type> parameter in           the F-CREATE to match that returned by the