Browse Prior Art Database

Methodology for Serializing Asynchronous Network Requests Over Multiple Paths

IP.com Disclosure Number: IPCOM000103621D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 6 page(s) / 301K

Publishing Venue

IBM

Related People

Jones, D: AUTHOR [+2]

Abstract

This article describes how the Workstation LAN File Services/VM (WLFS) product maintains the correct order of processing for client requests using the Server Message Block (SMB) format that are multiplexed to the host from the OS/2* LAN Server Front End Processor, while still allowing maximum efficiency in the use of host communications links and storage on the host and front end server.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 21% of the total text.

Methodology for Serializing Asynchronous Network Requests Over Multiple Paths

       This article describes how the Workstation LAN File
Services/VM (WLFS) product maintains the correct order of processing
for client requests using the Server Message Block (SMB) format that
are multiplexed to the host from the OS/2* LAN Server Front End
Processor, while still allowing maximum efficiency in the use of host
communications links and storage on the host and front end server.

      In the WLFS product, SMB-based clients (clients using the
Server Message Block protocol to access remote services from a
Server) are handled by the host server through an enhanced OS/2 LAN
Server Front End Processor.  This front end server handles the
NetBIOS LAN communications and can provide file and other services to
clients from local disks and devices as it normally does.
Additionally, with the WLFS enhancements, it will serve as a pipeline
and filter for client requests for host file services.

      The SMB protocol has 3 important features for this discussion,
one of which is a function of the NetBIOS communications protocol
that the client and server use to carry the SMB file service
protocol.
  1.  NetBIOS sessions
  2.  negotiated buffer sizes
  3.  large block transfer protocols (sometimes known as Raw
protocols)

      In order to use the SMB protocol to request remote file
services from a server, the client first establishes a NetBIOS
session with the server.  This NetBIOS session is a full-duplex
communication link between the client and the server.  The NetBIOS
Session is dedicated to the client for as long as it remains open and
active.  The server, therefore, knows which client has sent it a
request by which session presents the request.

      The SMB protocol has rules for negotiating a maximum buffer
size that the client can send to the server, and that the server can
send to the client.  The usual size is 4096 plus approximately 100
bytes for additional header space.  This means that, for example, the
client cannot normally write more than approximately 4000 bytes of
data to a file on the server per SMB request, nor can the client
request to read more than approximately 4000 bytes of data from a
file on the server per SMB request.  This allows the server to
efficiently pre-allocate memory for use in receiving client requests
and sending responses to clients.

      The large block or Raw protocols provide a way to increase the
efficiency of normal client-server requests by increasing the amount
of data that can be transferred between the client and server with
each network operation.  This is because it takes very nearly the
same network overhead to send 4K of data as it does to send 64K of
data.

      There are 2 raw protocols, Raw Read and Raw Write.  They work
because there is a dedicated session between each client and the
server, so that no routing information is needed once the correct
session to...