TCP/IP is the foundation of Unix networking: a mish-mash of networking protocols whose supreme virtue is that they are free and they work. The industry has adapted them to every possible type of hardware platform, creating a world standard. However Microsoft, surprise, surprise, has produced a TCP/IP version for Windows 95 and NT that's just a little incompatible. Windows applications that work with it may not work with third-party versions. So even a major player like Hummingbird is forced to stick with Microsoft's version. Even so, it's a suitable basis on which other protocols can be stacked.
The remote procedure call (rpc) enables one computer to submit a demand to the processor on another and receive a response. Its development, by Sun Microsystems, advanced network computing way beyond the primitive stage of file transfers and print services. Using it, a Windows client and a Unix server can collaborate in the following ways:
- File transfer, across the network from one computer to another, either peer-to-peer or between client and server.
- Remote execution, of commands. One computer's input device can trigger a program to run on another computer's processor and display on the screen of a third (or, more commonly, on the one from which it was launched).
- Remote login, whereby the user treats her computer as a transparent terminal, through which to log into, and execute commands on, a remote computer.
- Remote mount, whereby a disc drive or partition on one computer can be mounted, across the network, so as to behave as if it were locally attached to a remote computer.
- Remote boot, whereby one computer can be booted across the network, even though it has no disc drive of its own.
- Client/server operation, where the Unix host acts as a server. It may, for example, provide access to a database or a computer fax system or Internet service, and the Windows PC acts as the client, providing local data input, display and file access.
- Simple Internet services, such as finger, archie, gopher, veronica and anonymous ftp.
- More complex Internet functions, such as access to the World Wide Web through a locally executed browser.
- X terminal functionality, whereby an X server is run on the PC screen as an alternative to the dedicated X terminals popular on Unix networks.
- Java whereby a diskless client gathers applets from multiple hosts, via an intranet or Internet, and executes them locally.
Quite a variety! Hummingbird's Start menu groups some 40 tasks into logical groups: system admin, host access, remote tools and accessories (this is an improvement over earlier versions which had one, single bloated menu).
On the host
Any interconnection requires some software on both client and server and this can influence an administrator's choice. If you have a single PC, through which you access an array of servers you do not control, then choose a package that requires little modification to the server.
Apart from standard Unix programs, like mountd, nfsd or portmapper, Hummingbird requires only one file on the server: a PCNFS daemon named HCLNFS. Source code is available on the Internet or Hummingbird support will email you a compiled executable. Apart from creating a script to start the daemon at boot time, all the administrator need do is identify, which Unix file systems are to be shared.
File transfer
Of all the file transfer utilities, none has proved so popular and durable as ftp (file transfer protocol). It originated (like much of Unix), from Berkeley, so was implemented as a Unix command: type ftp at the shell prompt and it loads a new, specialist shell, denoted by the > prompt.
The DOS version is identical. You can specify, on the command line, the host to which you wish to connect and you get logged into it, password permitting. Then you issue commands, such as get filename to get a specified file. The early command set was a bit sparse but was extended as it gained popularity. Now, for example, while logged into the remote machine you can type ! followed by a command, to execute a program on the local one.
Most commands now operate at both ends of the link, although the syntax is not always self-explanatory. For example pwd establishes in which directory, on the remote machine, you are working. lcd, with a local directory pathname as an argument, changes you to that local directory and, with no argument, provides the local equivalent of pwd. FTP can transfer files in two different file formats: Ascii (for text files) and Binary (for image and executable files).
Modern commercial users are unwilling to learn a sophisticated command set, preferring to select options from icons and menus. Hummingbird is implemented as a pane, in which file manager windows display. On first launch you get the local file system. From a connection menu you select the remote machine, then log into it, as if you were using remote login software. A second window opens to display the remote file system. You can navigate your way up and down both file trees.
File transfer is accomplished by simple drag and drop: you drag the source file (or multiple selected files) and drop it in the window that represents the target directory. Multiple FTP servers can be accessed during a single FTP session. So a PC client can transfer files between, say, the Unix server on its local ethernet, and the corporate web pages held on a server at Demon Internet.
Any configuration settings made from menus can be saved to a settings file, which can then be used to connect to a host automatically. An FTP server is a remote computer that is running FTP, ie a server implementation of the FTP protocol. The system works both ways; the remote machine can be either source or target. Hummingbird does not enable its FTP server when you install NFS Maestro: you have to configure this and a collection of other daemons, such as telnet.
One of the best features of the Hummingbird suite is automation, via scripts; a technique used extensively in Unix, but barely practised in the Windows world. Automated Hummingbird scripts use an FTP programming interface, and a mini programming language, based upon Basic, with procedures and the ability to pass parameters. This is very convenient for regular, repetitive tasks, such as submitting the day's takings from a book-keeping package on a local PC, to the company server in the head office finance department.
Telnet
Telnet logs you into a remote computer, regardless of whether it is in the same room and linked by ethernet, or 10,000 miles away and connected via X.25 or the Internet. If you only have Microsoft networking on your Windows client you can telnet from it but not into it. However, with Hummingbird's telnet daemon on the PC, you can Telnet into it from the host.
Hummingbird's Telnet implementation on the PC is a graphical version.
Click a Telnet icon on your desktop and you get a window that lists all known hosts on the network. Double-click one of the hosts and a black SCO ANSI terminal emulation window opens, followed shortly after by a login prompt from the remote system. From that moment on, it is as if you were no longer at a PC, but at a terminal to the host. The emulator provides function keys and a choice of terminal emulations, including Wyse 50 and 60, Dec VT 220 and 320 and a bulletin board ANSI emulation.
For each you can choose your font, foreground and background colour, and other matters such as the behaviour of the backspace key and whether characters blink or are underlined in standout mode.
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