Java Glossary

Last updated 1998 June 30 by Roedy Green ©1996-1998 Canadian Mind Products.

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X

X2
3Com and U.S. Robotics' candidate technology for 56 kbps modems. It competes against Rockwell's Kflex56K. The technology is not symmetrical. The ISP needs one kind of modem and the clients another.
X.21
An electrical interface similar to RS-422 with balanced lines. It uses a DB-15 connector. It is common in Europe for attaching digitally to the packet nets services.
X.25
This is a synchronous protocol used by minicomputers to talk to the world wide network of datacommunication computers. X.25 also refers to the global network of computers, Datapac in Canada, Tymnet and TELNET in the USA, Transpac in France etc. In most countries you can tap into this net with a local phone call. This is a separate, more regulated network than the Internet.
X.28
When you call up a PAD computer on the X.25 world wide network, there are a number of things you can change about the way the PAD works. The list of things you can control is described in the X.28 standard.
X.29
When you use the packet net, the remote mainframe you call up can control your local PAD computer. The X.29 standard defines how this is done. For example the mainframe can control whether the PAD should echo back to you the characters you type.
X.3
standard that describes the commands you can send from your computer to control the local X.25 PAD computer when you dial it up. For example you can tell it which characters mean "packet forward" -- this message is ready to send it on its way.
X.32
Synchronous access to the X.25 packet net via dial-up using the X.25 error-correcting protocol.
xbaseJ
a collection of JAVA classes to access dBase III files. Processes DBF, DBT and NDX format files. Also provided with this release is a server class and example code. Examples are written in JAVA and NetRexx. See dBase.
Xelfi
a Java IDE. See IDE.
XML
XML is the Extensible Markup Language, a W3C proposed recommendation. Like HTML, XML is based on SGML, an International Standard (ISO 8879) for creating markup languages. However, while HTML is a single SGML document type, with a fixed set of element type names (AKA "tag names"), XML is a simplified profile of SGML: you can use it to define many different document types, each of which uses its own element type names (instead of HTML's "html", "body", "h1", "ol", etc.). For example, in XML, you can markup an online transaction like this:

<?xml version="1.0" standalone="no"?>
<!DOCTYPE order SYSTEM "order.dtd">
<order>
<invoice-number>12345</invoice-number>
<customer>Wile E. Coyote</customer>
<date>1997-12-14</date>
<item>
<name>Jet-Propelled Roller Skates</name>
<catalog-number>345-678-9</catalog-number>
<quantity>2</quantity>
</item>
<item>
<name>100,000-pound Weight</name>
<catalog-number>987-654-3</catalog-number>
<quantity>1</quantity>
</item>
</order>
See AELfred Alphaworks have written an XML parser in pure Java. See Alphaworks

XMODEM
Ward Christensen's original file transfer protocol. The receiving computer must acknowledge each block before the next block is sent.
XOFF
ASCII character 19 also known as DC3 or Ctrl-S. The character is sometimes used for flow control to mean, "STOP for a while. You are sending me data faster than I can handle it."
XON
ASCII character 17 also known as DC1 or Ctrl-Q. The character is sometimes used for flow control to mean, "send me more data".


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