BRACKENRIDGE@C.ISI.EDU (Billy) (11/23/87)
Does anybody have any idea how to get a redirector? or a redirector specification? A redirector is part of MS-DOS (or perhaps MS-NET) that sits between the file system and the network. It looks at DOS file calls at the file handle level and calls either the disk driver or net driver as appropriate. Redirectors are sold by Microsoft and Locus. Neither company acknowledges that they sell such a beast. As far as I can tell Locus doesn't acknowledge that they sell anything! I have used the redirector with 3Comm 3+, Apollo token net card (a really nice but expensive system), and Sun's PC-NFS. The first two products (and I believe Novell) use the Microsoft redirector. The Sun product uses the Locus redirector. The tricky part of the redirector is that it handles the DOS 3.x access privilege bits and advisory file locking system calls over a distributed file system. Of course I am a clever programmer and could reverse engineer the functionality (probably without disassembling the code) if necessary. This doesn't do me a lot of good. The object of the game is to be compatible with everyone else. Currently I am using the Sun PC-NFS developers toolkit (sockets Yuch!!!) to talk appletalk protocols encapsulated in UDP datagrams. Currently I interface at the virtual disk level because I know how to do it. I'd like to be able to interface at the redirector level, so I can mount Apple File System (AFS) volumes concurrently with NFS volumes and provide all the good stuff like file access control and file locking. Nobody at Locus or Microsoft seems willing to sell a redirector or let loose specifications? Anybody know what the story is here? Note in response to Phil Karn's comment about DOS tasking: Your package is really neat and is a mind warper to people who believe IP/TCP protocols are too complicated to do on a PC or that MS-DOS can't do two things at once, but it isn't the only way to do things. Some of us have more limited goals that we have to supply to users who are used to the DOS they know and loathe. A resident package such as the FTP's 2.0 package with a non sockets truly asynchronous buffered interface is real useful to the rest of us. Try doing a compile over the Sun NFS system. It is a sockets blocking interface and it sucks performance wise. Every net transaction is a complete block. I am running on a 10 Mhz AST premium with megabytes of EEMS memory. I'd like to use some of it to buffer network disk I/O and boost performance but can't with the demented sockets interface. With the FTP interface I can do that and open up mail and other connections as well. This is enough of a step in the right direction to provide useful products people want in the existing DOS environment. -------
backman@interlan.UUCP (Larry Backman) (11/27/87)
In article <8711231334.aa19994@Louie.UDEL.EDU> BRACKENRIDGE@C.ISI.EDU (Billy) writes: >Does anybody have any idea how to get a redirector? or a redirector >specification? > >A redirector is part of MS-DOS (or perhaps MS-NET) that sits between >the file system and the network. It looks at DOS file calls at the file >handle level and calls either the disk driver or net driver as >appropriate. I don't know about Microsoft or Locus, but the Novell redirector (net3.com) is a resident program that traps all sorts of things (INT 21 etc.). It is based on something called Netware Core Protocol (NCP), a request/response protocol between workstation and server. DOS requests, open a file, for instance are intercepted, and translated as needed into NCP before being xmitted to the server. The NCP spec. is available from Novell for a price. It may not be exactly what you are loking for, but you certainly can figue out how a rediector is implemented from it! >IP/TCP protocols are too complicated to do on a PC or that MS-DOS >can't do two things at once, but it isn't the only way to do things. >Some of us have more limited goals that we have to supply to users >who are used to the DOS they know and loathe. Right on! I agree, DOS stinks, but 20 zillion users out there is a big target marketplace. We could all agree that its too hard to do comms. under DOS, but meanwhile, since there's an incredible demand for various comms. rpoducts, some enterprising person will come along and build products irregardless. I know I'd rather be involved in building product for a superseller O.S. that has extreme limitations, than to sit on the sidelines watching someone else build those products. I've been playing DOS since 82, have built 3 separate comms product lines, async file xfer, SNA 3270/3770, and TCP gateway products. Each was/ or is a good product, that works well within its environment despite the O.S.'s shortcomings. I've also built product under UNIX and VMS with tons of system calls, multi-tasking support, signals, virtual memory, etc. I hate to admit it, but ...sh.. DOS is more fun! Larry Backman Micom - dio DJeis
jonm@killer.UUCP (11/30/87)
In article <8711231334.aa19994@Louie.UDEL.EDU>, BRACKENRIDGE@C.ISI.EDU (Billy) writes: > Does anybody have any idea how to get a redirector? or a redirector > specification? > > A redirector is part of MS-DOS (or perhaps MS-NET) that sits between > the file system and the network. It looks at DOS file calls at the file > handle level and calls either the disk driver or net driver as > appropriate. > > Redirectors are sold by Microsoft and Locus. Neither company acknowledges > that they sell such a beast. As far as I can tell Locus doesn't acknowledge > that they sell anything! > The redirector from Microsoft is indeed a part of MS-NET. It is not as far as I know available separately, but is part of an OEM package for licensing MS-NET. 3com, ATT, Xerox, and of course IBM PC networks use the MS-NET Redirector as the basis for their client-side interface. The MS-NET Redirector is tightly coupled to MS-DOS 3.1 (or later) and handles all system calls which require remote access. The DOS-to-redirector interface is not publicly documented (even to OEM's). The redirector-to- NETBIOS interface is via software interrupt 5CH and uses a published protocol called SMB (server message block) to interact with a server. There are some additional MS-DOS system calls which are available only if the redirector is installed. The calls deal with naming and device redirection management. Some other system calls have additional "modes" or options if the redirector is installed. Third party redirectors, such as from Novell or Banyan, usually provide these MS-DOS extensions by intercepting system call requests. In that case, there is no DOS-to-redirector interface since DOS does not "see" the system call request. The redirector- to-network interface is usually proprietary,-- as is the client/server protocol. NETBIOS compatibility is a separate issue, but many non-MS-NET network systems provide some level of compatibility. I doubt that either Microsoft or any other network system vendor will be interested in selling and/or publishing specifications for their redirector unless you are prepared to license/OEM their system. JonM