Java Glossary
Last updated by Roedy Green
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X
- 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.
- X.509 v3
- A standard for formatting digital certificates. The standard
allows for additional information to be included in the form of
keyword=value pairs. When the certificate authority signs the
certificate with their private key, they are attesting that all
the information in the certificate is correct. You can check if a
certificate is valid without checking at an online database since
you know the public keys of all the certificate issuing
authorities; they are burned into your browser. However, if you
want to ensure the certificate has not been revoked, you need to
check with the database at the certificate authority's website.
PGP does not use this format. It uses its own simpler one. See
certificates, digital signing, PGP.
- 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.
- 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>
There are some tutorials at Developer Life. 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".