At the request of NLM, PSRML is promoting the use of the Internet by Network libraries to connect to the DOCLINE and SERHOLD systems. NLM recently phased out value-added networks and required users to switch to either the FTS2000 number or use the In ternet to access the NLM databases and DOCLINE. Because of the high costs of FTS2000 usage, all of which are absorbed by NLM, Internet access is the preferred method. In order to use these systems over the Internet, you must have a telnet client (softwa re) loaded on your computer before you can open a telnet connection. If you do not know how to do this or how to locate a telnet client to use DOCLINE and SERHOLD over the Internet, this article will provide you with some essential information and refere nces about the telnet protocol to get you started. Telnet clients are available on the Internet in shareware and commercial versions. Your choice of telnet clients depends not only on what type of terminal emulation you need, but also on quality, ease o f use, and availability of features such as printing and saving.
The DOCLINE and SERHOLD systems are both accessed by a basic Internet tool called remote login, or "telnet". Telnet is an abbreviation for Teletype Network, a protocol or set of rules which allows users to login to other computers on the Internet. T elnet is part of a complex set of Internet Protocols that allow computers of different platforms and operating systems (for example: Windows, Macintosh, UNIX) to communicate with each other. This means you can sit at your desktop computer and use your k eyboard to connect to (login) and use a computer located in the next room or on another continent, and access information on that remote computer as if your keyboard were directly connected to it.
Telnet operates in what is called a client/server environment. These terms refer to two pieces of software that must work together in order to make Telnet possible. The client runs on the computer requesting a service or information (this is the com puter you are using); the server runs on the computer providing the service or information. The client and server "talk" to one another over the Internet using a protocol. Telnet requires the use of an external program (known as a client) and may be use d directly or configured to be used with a Web browser (such as Netscape or Microsoft Explorer). Unlike other Internet protocols which are pre-loaded on Web browsers, a user must locate, load, and configure a telnet client to enable a telnet connection t o work (be launched) from a Web browser. Many Internet Service Providers (ISPs) bundle a telnet client with the communications software they provide to subscribers. If your ISP does not include a telnet client, then you will need to obtain and configure a telnet client before you will be able to use DOCLINE or SERHOLD.
An important feature of a telnet program is the ability to emulate or mimic diverse types of terminals. One of the most common types of terminal emulation is VT100, originally made by the Digital Equipment Corporation (DEC). VT100 is basically the s tandard today. In fact, most systems will assume a VT100 connection. VT100 terminal emulation is most often used for library online catalogs and is used for NLM's DOCLINE system.
An older, less common terminal emulation type is 3270. NLM's Online SERHOLD Updating System uses 3270. "3270" refers to a proprietary full screen terminal used by IBM mainframes which is designed to make data entry easier for the user. 3270 termina l emulation uses special purpose keys called programmed function keys (PF keys) which may have special commands tied to them and uses "protected fields" for data entry. Working in 3270 mode involves filling in the blanks on a screen form by moving the cu rsor using PF and "Enter" keys to get work done and clear screens. Not all telnet clients provide 3270 terminal emulation. While most telnet clients can handle VT100 emulations, typically a separate tn3270 client is needed for 3270 emulations.
Well-known shareware telnet clients for Windows machines without tn3270 include EWAN (Emulator Without A Name), NetTerm, and Trumpet Telnet. QWS3270 is a Windows shareware program that is able to handle 3270 emulation. On the Macintosh side, NCSA Te lnet is a popular telnet client but does not have 3270 capability. These telnet clients are available at no cost as shareware on the Internet. Commercial communications programs tend to have full telnet capabilities and include tn3270; a good example is PROCOMM Plus.
Before downloading a telnet client from the Internet, it is best to contact your Internet Service Provider (ISP) and find out which telnet and tn3270 client they support, recommend and provide to their subscribers. It is also important to try to down load the "final version" of an application. Applications that are still being developed and tested are known as beta versions (they are being beta or alpha tested by a group of users who help the creator work out the bugs of the program). Your ISP can h elp you locate an appropriate telnet client and can also walk you through downloading and configuring a telnet client to either function as a separate program or to be used with your Web browser.
If you already have a telnet client, you are ready to begin using DOCLINE. If your client is equipped with a 3270 emulator, you are ready to use both DOCLINE and SERHOLD. To use either of these systems with your Web browser, point to http://medlars.nlm.nih.gov.
Configuring your Web browser to allow or launch a telnet connection is relatively simple. You can either contact your ISP and have them walk you through this process or Netscape users can follow these instructions:
If you are having difficulty connecting to the NLM databases and services, you should begin with your ISP. Contact your ISP and tell them what you need and what you are trying to do. Since your ISP provides you with your Internet connection, they ar e the most familiar with how the applications are configured on your system. This type of technical assistance is covered by the monthly fees you pay your ISP. If your ISP is not available or unable to help you with this, here are two options: 1) you m ay want to consider establishing service with an ISP that provides subscribers convenient access to their technical services (there is a URL for a list of ISPs at the end of this article); and 2) your call is always welcome at the PSRML.
To search for shareware sites, you can use Yahoo or other search engine and search for "telnet shareware" or "tn3270 shareware".