The Online World - Odd de Presno (top 10 non fiction books of all time TXT) 📗

other services.) Sending binary files in uuencoded form has weaknesses. One is the lack of automatic error correction when sending/receiving e- mail. Noise on the line can easily distort the picture. File size is another problem. UUENCODEing typically increases file sizes by almost one third. Some mailbox systems restrict the length of individual messages that you can receive, and the file may just be too big. If the uuencoded file gets too big, some services can (or will by default) split it up in parts and then sent separately. Tons of uuencoded public domain and shareware programs are available for retrieval by ordinary email.

FTP by email

While some services accept commands like GET KIDART ART019 by email, this is not so with the many so-called FTP libraries. Many of them can only be accessed by FTP.

Services exist that will do FTP transfers by email for those not having access to the FTP command. The most popular is at DEC Corporate Research in the U.S. For more information, write a message to one of the following addresses: ftpmail@decwrl.dec.com ftpmail@cs.uow.edu.au

In the TEXT of your message, put the word "HELP".

FTPMAIL lets you uuencode binary files for transfers. It can split large files up into several messages, thus helping you around local restrictions on the size of each incoming mail message.

Chapter 13: Cheaper and better communication

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Packet data services and data transportation services like Tymnet Outdial, Infonet, Internet, and PC Pursuit may help keep costs down. About reducing the cost of using mailing lists.

Many users access online services by calling them directly. A lot pay extra for long distance calls to other cities and countries, even when this means inferior transmission quality (like when noise characters degrade the data).

Others investigate other routings for their data. One option is the packet data networks. Most countries have Public Data Networks (PDNs) operated by local telecommunications authorities. These services are often cheaper than direct calls for some applications, but more expensive for others. Before using a packet data network, you'll need to establish a "Network User Identification" (NUI) with the PDN carrier. You must also know the Network User Address (NUA) of the hosts that you want to access. In Scandinavia, the local PDNs are called Datapak. They can be accessed by direct local calls or through leased lines. To personal users, direct calls are least expensive. A leased line may be cost efficient when the daily volume is high, like in a company. When you communicate with online services through a PDN, the latter will split your data and bundle it in standard envelopes or 'packets'. Each packet is marked with a code and sent out into the data stream. Based on this code, the packet is routed from computer center to computer center until it reaches its final destination. There, the information will be reassembled into its original form before being handed over to a user or online service. It is almost like traveling by train. The price per packet or traveler is lower than what it costs to rent the whole train for your trip. National telecommunications monopolies were the first to offer packet data services. Their rates were moderately lower than for long distance calls, but it was hard to find the relationship between real costs and prices. This is still the situation in many countries. Throughout the world, efforts to privatize nationwide phone networks continue. In many countries, this has given us some interesting competitors offering attractive rates for similar services. Their rates differ considerably from country to country, as does the quality of transmissions. The advantage of using packet data also varies considerably, by application and by country. The best routing for retrieval of online news may be impossibly expensive for chats or complex online jobs. We can offer no hard rules of thumb, except this: Compare rates regularly!

What is cheapest?

Some networks charge by the hour, while others charge by volume (number of characters transferred per minute).

When volume is low, your best bet is to use network services with a low price per minute and high prices for volume. When volume is high, you may be better off using those charging by the minute. To estimate costs reliably, you'll need statistics. Since your usage probably differs from what others do, start accumulating experience data now. Like this: On services only charging for connect time ------------------------------------------ Capture trip information to a log file. Register the following information: * number of minutes connected * modem speed * number of characters transmitted. Some communication programs can do this automatically for you. On services charging for time and volume ---------------------------------------- Log the following information: * number of minutes connected * modem speed * number of segments or packets (measurements of volume)

You need this to estimate the average volume of data transferred by minute. Here are some general experiences and hints:

Long streams of data without stops are cheaper through services that only charge by the minute. Retrieving software is a typical high volume application. Trips that include navigation from conference to conference, with a little bit of up- and downloading here and there, make the average transfer speed fall dramatically. It's like driving through a big city at 150 kilometers per hour. Red lights will reduce the average speed considerably. The actual transferred volume of text per minute will differ from place to place (geographically), and often also from call to call. It depends on factors like: * How fast you can enter commands and how much time you spend staring at the display before pressing keys, * How long it takes for an online service to react to your commands. For example, the response time on CompuServe at 04:00 GMT on a Friday morning (it is evening in the U.S.) is much worse than at 10:30 GMT on a Sunday morning. Then, most users are asleep. * The load on your packet data network while you use the service (or the amount of noise and retransmission, when calling direct), * The type of modem you are using (speed, level of MNP), * The number of commands you (or your scripts) have to enter during your online visit. An increase in the number of commands, reduces the average transfer speed. * The amount of transfer overhead for color and screen handling (like, VT-100 codes) that is transferred with your text. * Your use of menus and help texts while online, or whether you come as "expert" with a minimum of prompts. It's impossible to calculate the practical effects of these items. You will just have to bear them in mind when estimating typical jobs, measuring speeds, calculating costs, and comparing networks. Finding the optimal network for our needs, will take time, but is well worth the effort. I think the figures may surprise you. The network services in this chapter will often give you better quality transfers than a direct call. On the other hand, calling direct may give more characters transferred per minute. The average speed tends to drop dramatically when using a packet data service.

Using national packet data services

Most commercial online services can be reached through national PDNs, but you may have problems finding the correct NUA (Network User Address) to get there. Few PDNs have a directory of available "electronic telephone numbers" for you to consult.

The Norwegian PDN, Datapak, used to be my only alternative for access to foreign online services, and I thought that the cost was acceptable. Not so anymore. My applications require that data be pumped back and forth at maximum speed. On network services charging by a combination of volume and time, 80 percent of my costs are typically for volume, while 20 percent is for connect time. When I log out after a successful visit to CompuServe through Datapak, the two services give me similar reports:

Thank you for using CompuServe!

Off at 10:11 EST 24-Nov-87 Connect time = 0:15

CLR PAD (00) 00:00:14:55 537 75

The last line comes from Datapak. It tells that I have received 537 segments and sent 75.

The "Segment" is Datapak's volume measure. A segment contains up to sixty-four characters and/or carriage returns. The price is calculated accordingly. At today's prices, Datapak is still my cheapest alternative calling CompuServe for chats. I use Datapak when connecting to TWICS in Tokyo, as the only alternative today is direct calls at a prohibitive cost. Once i-Com (see below) starts offering outdial to Japan, I expect this service to be substantially cheaper. The slower your modem speed, the more attractive is Datapak compared with direct calls. To get access to a national PDN, you must have a user identification and a password. (Getting temporary access to PDN services while traveling abroad is often hard and expensive.)

| Note: If you have access to a national PDN, but need |

| information about PDNs in other countries, try Hostess, the |

| Global Network Service's information service from British |

| Telecom in England. The NUA is 02342 1920101013 (02342 is |

| the Data Network Identifier Code section of the address.) |

| Username or password is not required to use this service. |

Outdial through PC Pursuit

Sprintnet (formerly GTE Telenet) lets American users call bulletin boards in North America at lower rates through their PC Pursuit service.

They pay a modest subscription to call a local number for access to PC Pursuit. Once connected, they can enter an electronic phone-number to connect to a so-called 'outdial modem' in another city. Once connected to the outdial modem, they can give it dialing commands and have it call any local number. This way, they can use PC Pursuit to call an online service in the area, or the private modem of a friend. We call PC Pursuit an Outdial service. Such services normally offer lower rates for access to remote bulletin boards than what it costs to call by long distance. Besides, they reduce the chances for noise on the line.

Outdial through i-Com

i-Com offers outdial to North American online services by reselling capacity from Tymnet's network (owned by British Telecommunications PLC).

In the United States, Galaxy Telecomm Corp. offers a similar service under the name Starlink. Outdial to numbers in Japan and Europe is planned. i-Com markets its services to users in Europe and Japan, and have local access in Brussels, Paris, Lyon, Milano, the Hague, Eindhoven, Zurich, Geneva, London, Belfast, Birmingham, Bristol, Cambridge, Edinburgh, Leeds, Frankfurt, Cologne, Munich, Madrid, Stockholm, Copenhagen, and more. The basic fee for access to the service is US$25.00 per hour (1992). You don't pay volume charges. The monthly subscription fee is US$8.00. You can pay using VISA or MasterCard/Eurocard. In Norway, I have used i-Com to connect to The Well in San Francisco, MetaNet in Virginia, EXEC-PC in Wisconsin, and SciLink in Toronto, Canada. At the time, i-Com was cheaper than direct calls and Datapak for access to these services. While an ID on your local PDN is only valid in your area or country, your i-Com ID can be used all over the world including several cities in North America. Once your plane has landed in Milano,