Monday, June 22, 2009

Wide Area Information Servers


Wide Area Information Servers or WAIS is a client-server text searching system that uses the ANSI Standard Z39.50 Information Retrieval Service Definition and Protocol Specifications for Library Application (Z39.50:1988) to search index databases on remote computers. It was developed in the late 1980s as a project of Thinking Machines, Apple Computer, Dow Jones, and KPMG Peat Marwick.

WAIS did not adhere to either the standard or its OSI framework (adopting instead TCP/IP) but created a unique protocol inspired by Z39.50:1988.

The WAIS protocol and servers were primarily promoted by Thinking Machines Corporation of Cambridge, Massachusetts. Thinking Machines produced WAIS servers which ran on their massively parallel CM-2 (connection machine) and SPARC-based CM-5 MP supercomputers. WAIS clients were developed for various operating systems including Windows, Macintosh, NeXT and UNIX. TMC, however, released a free open source version of WAIS to run on Unix in 1991.

Inspired by the WAIS project on full text databases and emerging SGML projects Z39.50 version 2 or Z39.50:1992 was released. Unlike its 1988 predecessor it was a compatible superset of the ISO 10162/10163 work that had been done internationally.

With the advent of Z39.50:1992, the termination of support for the free WAIS from Thinking Machines and the establishment of WAIS Inc as a commercial venture (their WAIS was written to use the Fulcrum fulltext engine), the U.S. National Science Foundation funded CNIDR to create a clearinghouse of information related to Internet search and discovery systems and to promote open source and standards. CNIDR created a new freely available open-source WAIS. This created first the freeWAIS package based on the wais-8-b5 codebase implemented by Thinking Machines Corp and then a wholly new software suite Isite based upon Z39.50:1992 with Isearch as its full text search engine.

Ulrich Pfeifer and Norbert Gövert of the computer science department of the University of Dortmund took the CNIDR freeWAIS code and extended it to become freeWAIS-sf: sf means structured fields and indicated its main improvement. Ulrich Pfeifer rewrote freeWAIS-sf in Perl where it became WAIT.

Thursday, June 4, 2009

Server Message Block

In computer networking, Server Message Block (SMB) operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an authenticated Inter-process communication mechanism. Most usage of SMB involves computers running Microsoft Windows, where it is often known as "Microsoft Windows Network".

When discussing SMB, one should distinguish:

* the SMB protocol
* the SMB services that run on the protocol
* NetBIOS
* the DCE/RPC services that use SMB as an authenticated Inter-process communication channel (over named pipes)
* the "Network Neighborhood" protocols which primarily (but not exclusively) run as datagram services directly on the NetBIOS transport

Monday, June 1, 2009

Smokeless Tobacco

Many people who chew tobacco or dip snuff think it's safer than smoking. But you don't have to smoke tobacco for it to be dangerous. Chewing or dipping carries risks like

* Cancer of the mouth
* Decay of exposed tooth roots
* Pulling away of the gums from the teeth
* White patches or red sores in the mouth that can turn to cancer

Recent research shows the dangers of smokeless tobacco may go beyond the mouth. It might also play a role in other cancers, heart disease and stroke.

Smokeless tobacco contains more nicotine than cigarettes. Nicotine is a highly additive drug that makes it hard to stop using tobacco once you start. Having a quit date and a quitting plan can help you stop successfully.