A database (DB) system is a computer-based record keeping system used to record and maintain certain types of information that have a significant value to some organization. A DB is a repository of stored data, which in general is both integrated and shared. Between the physical database and the users of the system is a layer of software, usually called the database management system (DBMS). All requests from the users to access the DB are handled by the DBMS.
When trying to organize the data and information within an organization, the DB helps the user in entering, storing, and retrieving it, and when trying to integrate all or part of the information of the enterprise the DB becomes a key player. Normally, within the DB, information is organized into data elements, fields, records, and files. In a system such as a hospital information system (HIS), a patient name is a data element or a field; a record could be related to that patient's visit on a particular date (e.g., date, diagnoses, treatments, charges, medications, tests) at a particular time; and a file would contain all the information from all the visits for that patient. An HIS DB will include not only patient files, but it could also have accounting information related to charges, inventory, payroll, and personnel records. With DB systems, different people can have access to different parts of the system, so, for example, not all personnel employees will have access to laboratory results.
The DBMS organization and definition of the contents of the individual data elements, fields, records, and files are provided via a machine-readable definition called "schema." This creates an independence of physical location from logical location of the content of a DB. The DBMS not only "manages the DB" but also allows for entering, editing, and retrieving results. The DBMS helps with the integration of data coming from multiple sources. The user can also access and retrieve specific types of information via queries.
A DB provides an organization with centralized control of its operational data. Some of the advantages of having centralized (versus distributed) control of the data are:
•Redundancies can be reduced.
•Inconsistencies can be avoided.
•Data can be shared.
•Standards can be enforced.
•Privacy, confidentiality, authenticity, and security restrictions can be applied.
•Integrity can be maintained.
•Conflicting requirements (among users) can be balanced (for the enterprise).
•Data is easier to support (the single repository, the application, and the endusers).
Due to technological advancements, databases today are much more complex than a few decades ago. They contain "multimedia" information, such as text, graphics, scanned images from documents, clinical images from all modalities (X-rays, ultra-sound, MRI, CT scan), still and dynamic studies, and sound. When doing population studies, the creation of data "warehouses" is necessary, and data "mining" techniques are used to extrapolate results. In public health, the data needed for a study can reside in a small computer, in a local area network (LAN), or in a wide area network (WAN). In order to use information that is geographically distributed (and/or with distributed users) it is important to learn techniques for data integration and data communications. Because of the continuing fusion of computers and communications, this is the fastest changing area within information technology.
Internet and the World Wide Web
There is little historical precedent for the swift and dramatic growth of the Internet, which was originally a limited scientific communication network developed by the U.S. government to facilitate cooperation among federal researchers and the university research community. With its rapid adoption by the private sector, the Internet has remained an important research tool, and it is also becoming a vital ingredient in maintaining and increasing the scientific and commercial leadership of the United States. In the twenty-first century, the Internet will provide a powerful and versatile environment for business, education, culture, entertainment, health care and public health. Sight, sound, and even touch will be integrated through powerful computers, displays, and networks. People will use this environment to work, study, bank, shop, entertain, visit with each other, and communicate with their health care providers. Whether at the office, at home, or traveling, the environment and its interface will be largely the same, and security, reliability, and privacy will be built in. Benefits of this dramatically different environment will include a more agile economy, improved health care (particularly in rural areas), less stress on ecosystems, easy access to lifelong and distance learning, a greater choice of places to live and work, and more opportunities to participate in the community, the nation, and the world.
Internet and WWW Acronyms. People that communicate with each other electronically may not have the same "platform." "Cross-platform" means that people do not have to use the same kind of operating system to access files on a remote system. In order to access the Web there are two basic mechanisms: (1) using the telephone system to link to another computer or network that is connected to the Internet, and (2) connecting to a network; and from there into the Internet. An Internet service provider (ISP) may be required to access the Internet. An important factor regarding Internet access is bandwidth, which determines how much data a connection can accommodate and the speed at which data can be accessed.
Information on the Web is generally written in Hypertext Markup Language (HTML), which is a text-based markup language that describes the structure of a Web document's content and some of its properties. It can also be viewed as a way of representing text and linking it to other resources, such as multimedia files, graphic files, still or dynamic images files, and sound files. HTML contains the information or text to be displayed and the control needed for its display or playback.
Navigation Tools. Prior to the use of Web browsers, there were several Internet navigation tools that required more user expertise than the modern browser, including:
•File Transfer Protocol (FTP), a cross-platform protocol for transferring files to and from computers anywhere on the Internet.
•Gopher, a tool for browsing files on the Internet.
•Usenet, a worldwide messaging system through which anyone can read and post articles to a group of individuals who share the same interests.
•Wide Area Information Server (WAIS), one of a handful of Internet search tools that can be spread across the network to scour multiple archives and handle multiple data formats.
•Hyperlink (also called link), a pointer— from text, from a picture or a graphic, or from an image map—to a page or file on the World Wide Web; hyperlinks are the primary way to navigate between Web pages and among Web sites.
Today, a Web browser is the main piece of software required by the end user to find information through Internet. Some of the most popular browsers are: Lynx, Mosaic, Netscape Navigator/Communicator, and Internet Explorer. Lynx is a text-only Web browser; it cannot display graphical or multimedia elements. Mosaic, a graphical Web browser, was the first "full-featured" graphical browser for the Web. It was developed by a team of programmers at the National Center for Supercomputing Applications (NCSA). One of these programmers, Marc Andreesen, later formed Netscape. Netscape Navigator/Communicator is one of the most popular Web browsers. Internet Explorer is Microsoft's Web browser.
Web Resources. A Uniform Resource Locator (URL) is a Web resource that describes the protocols needed to access a particular resource or site on the Web, and then point to the resource's Internet location. URLs are, in short, used to locate information on the Web.
Normally the URL is composed of six parts:
1.The protocol or data source (i.e., ftp://, gopher://, news://, telnet://, WAIS://, http://)
2.The domain name (for the Web server where the desired information resides)
3.The port address
4.The directory path (location of the Web page in the Web server's file system)
5.The object name
6.The spot (precise location within the file)
Protocols are the rules and formats that govern the methods by which computers communicate over a network. Protocols link clients and servers together and handle requests and responses, including making a connection, making a request, and the closing of the connection. Transmission Control Protocol/Internet Protocol (TCP/IP) is the full set of standard protocols used on the Internet. Hypertext Transfer Protocol (HTTP) is an Internet protocol specifically for the World Wide Web. It provides a way for Web clients and servers to communicate primarily through the exchange of messages.
Multipurpose Internet Mail Extension (MIME) is a technique designed to insert attachments within individual e-mail files. MIME allows a Web server to deliver multiple forms of data to the user in a single transfer. Also, when creating a Web page, it could include text files as well as nontext files, such as sound, graphics, still images, and videos.
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