When a book is not purchased by a library it should be available from one of the co-operating libraries, whenever it is required by its readers. To ensure this, inter – library loan system was introduced by various libraries. It can be successful only if the catalogues of the co-operating libraries are made available amongst themselves. The union catalogue which are prepared on co-operative basis enables this system to work successfully.
Delivery of Books and Newspaper Act 1954
The delivery of Books (Public Libraries) Act, 1954 was enacted by the Government of India in order to promote libraries in India and to encourage scholarship. It is considered necessary to build good libraries and for this purpose, it is desired to acquire not more than four copies of books and other publications in India. One copy of book so acquired will be deposited in the National Library, Calcutta and the remaining three sets will be utilized for important libraries. In this Act, the term “book” includes every volume, part or division of a volume in any language and every sheet of music, map, chart or plan separately printed or lithographed. The Act was amended by the Government to include newspapers in 1956 because the newspapers also contain highly useful nascent information and thought. The public libraries which were granted the privilege of legal deposits by this Act are (1) National Library, Calcutta for the Eastern Region, (2) Central Library, Bombay for Western Region, (3) Connemara Public Library, madras for Southern Region, (4) National Central Library (proposed), Delhi, Northern Region (at present Delhi Public Library).
The Act has made it obligatory for every publisher to deliver at his own cost four copies of the publication to four libraries within thirty days of its publications. The Act provides for penalty upto fifty rupees for contravening this provision or the fine may be equal to the value of the book. Only the conscientious publishers may be sending the books. The unscrupulous may ignore the Act, particularly in case of the books of Arts and science which are highly priced.
Library Association (LA),
The Library Association was founded in 1877 in order to raise the standards of librarianship and to improve service to the public. Its success was reorganized by the granting of Royal Charter in 1898. Her majesty the Queen became patron of the association in 1977, the centenary year. In 1965 the Library Associations moved to Ridgmount Street, London. Today the association has 25,000 members, including nearly 2000 resident outside the United Kingdom. The largest category of membership is from public libraries. Any one join the association, who are interested in the objectives of the association.
The Library Association is highly decentralized body. Twelve geographical branches cover the whole of the United Kingdom. In order to foster work on many aspects of library and the information work, the association has 23 special interest groups. The Association of Assistant Librarians (AAL) originally an independent organization is the largest of all groups, AAL conducts work on all subjects but other groups specialize in some aspects of library work. The Library Association has published hundreds of publications. Today the publishing role is carried out by Library Association Publishing Ltd., a company wholly owned by the Association. The Association also publishes Library Association Record, a monthly. This record helps the members to keep in touch with others and know the development in the profession.
Special Library
A library which is concerned almost exclusively with the literature of a particular subject, or a group of subjects. Special library serves a special clientele located within a single establishment or group and all engaged in working towards one common purpose. It exists to serve the personnel of the parent body and caters to their information needs. The readers of the special library are the scientists, researchers and employees attached to the institution to which the library is attached. Materials collected and kept in such libraries will be special in nature, mainly belonging to the subject area on which the special library is concerned.
In contrast, applications software (also calledend-userprograms) includesdatabaseprograms,word processors, andspreadsheets. Figuratively speaking, applications software sits on top of systems software because it is unable torunwithout the operating system andsystemutilities.
AsystemofInternetserversthatsupportspeciallyformatteddocuments. The documents are formatted in a markup language calledHTML(HyperText Markup Language) that supports links to other documents, as well asgraphics, audio, and videofiles. This means you can jump from one document to another simply byclickingonhot spots. Not all Internet servers are part of the World Wide Web.
TheInternetis a massivenetworkof networks, a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. Information that travels over the Internet does so via a variety of languages known asprotocols.
TheWorld Wide Web, or simplyWeb, is a way of accessing information over the medium of the Internet. It is an information-sharing model that is built on top of the Internet. The Web uses the HTTP protocol, only one of the languages spoken over the Internet, to transmit data. Web services, which use HTTP to allow applications to communicate in order to exchange business logic, use the the Web to share information. The Web also utilizesbrowsers, such asInternet ExplorerorFirefox, to access Web documents calledWeb pagesthat are linked to each other viahyperlinks. Web documents also contain graphics, sounds, text and video.
7.Switching techniques
page number 194(library science unleashed)
8.expert systems
Acomputer applicationthat performs a task that would otherwise be performed by a human expert. For example, there are expertsystemsthat can diagnose human illnesses, make financial forecasts, and schedule routes for delivery vehicles. Some expert systems are designed to take the place of human experts, while others are designed to aid them.
Expert systems are part of a general category of computer applications known asartificial intelligence.To design an expert system, one needs aknowledge engineer,an individual who studies how human experts make decisions and translates the rules into terms that acomputercan understand.
9.electronic mail
page 199(library science unleashed)
10.cpu
Abbreviation forcentralprocessingunit. The CPU is the brain of thecomputer. Sometimes referred to simply as thecentral processor,but more commonly calledprocessor,the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of acomputer system.
Two typical components of a CPU are the following:
An extension tohypertextthat supports linking graphics, sound, and video elements in addition to text elements. TheWorld Wide Webis a partial hypermedia system since is supports graphicalhyperlinksand links to sound and video files. New hypermedia systems under development will allow objects in computervideosto be hyperlinked.
12.Hypertext
A special type ofdatabase system, invented by Ted Nelson in the 1960s, in whichobjects(text, pictures, music,programs, and so on) can be creativelylinkedto each other. When youselectan object, you can see all the other objects that are linked to it. You can move from one object to another even though they might have very different forms.
13.database
Often abbreviatedDB. A collection of information organized in such a way that acomputerprogramcan quicklyselectdesired pieces ofdata. You can think of a database as an electronic filingsystem.
Traditional databases are organized byfields,records, andfiles. A field is a single piece of information; a record is one complete set of fields; and a file is a collection of records. For example, a telephone book is analogous to a file. It contains a list of records, each of which consists of three fields: name, address, and telephone number.
Toaccessinformation from a database, you need adatabase management system (DBMS). This is a collection of programs that enables you to enter, organize, and select data in a database.
15.website
A site (location) on theWorld Wide Web. Each Web site contains ahome page, which is the firstdocumentuserssee when they enter the site. The site might also contain additional documents andfiles. Each site is owned and managed by an individual, company or organization.
Acomputernetworkthat spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. Asystemof LANs connected in this way is called awide-area network (WAN).
There are many different types of LANsEthernetsbeing the most common forPCs. MostApple Macintoshnetworks are based onApple'sAppleTalknetwork system, which is built into Macintosh computers.
The following characteristics differentiate one LAN from another:
·topology:The geometric arrangement of devices on the network. For example, devices can be arranged in a ring or in a straight line.
LANs are capable of transmitting data at very fast rates, much faster than data can be transmitted over a telephone line; but the distances are limited, and there is also a limit on the number of computers that can be attached to a single LAN.
Computers connected to a wide-area network are often connected through public networks, such as the telephone system. They can also be connected throughleased linesor satellites. The largest WAN in existence is theInternet.
HTML defines the structure and layout of a Web document by using a variety oftagsandattributes. The correct structure for an HTML document starts with (enter here what document is about) and ends with . All the information you'd like to include in your Web page fits in between the and tags.
There are hundreds of other tags used to format and layout the information in a Web page. Tags are also used to specify hypertext links. These allow Web developers to direct users to other Web pages with only a click of the mouse on either an image or word(s).
20.Ms office
Office Application software by Microsoft corporation.ncludes word ,excel,powerpoint etc.
21.cd rom technology
page no.11 study material
22.online database
An online database is a database accessible via a network, now generally the internet.
23.bibliographic database
Abibliographicorlibrary databaseis adatabaseofbibliographicrecords. It may be a database containing information aboutbooksand other materials held in a library (e.g. an onlinelibrary catalog, orOPAC) or, as the term is more often used, an electronicindextojournalormagazinearticles, containingcitations,abstractsand often either the full text of the articles indexed, or links to the full text.
Many scientific databases are bibliographic databases, but some are not. WithinChemical Abstracts, for example, there are databases of chemical structures and withinEntrezthere are databases of sequences. Outside of science, the same holds — there are databases of citations to articles in art history journals, and there are databases of images, such asARTstor.
24.search engines
Aprogramthat searches documents for specifiedkeywordsand returns a list of the documents where the keywords were found. Althoughsearch engineis really a general class of programs, the term is often used to specifically describe systems like Google, Alta VistaandExcitethat enable users to search for documents on theWorld Wide WebandUSENETnewsgroups.
Typically, a search engine works by sending out aspiderto fetch as many documents as possible. Another program, called anindexer,then reads these documents and creates anindexbased on the words contained in each document. Each search engine uses aproprietaryalgorithmto create its indices such that, ideally, only meaningful results are returned for each query.
25.OCR
page 27 study material
OR
Often abbreviatedOCR,optical character recognition refers to the branch ofcomputer sciencethat involves readingtextfrom paper and translating the images into a form that thecomputercan manipulate (for example, intoASCIIcodes). An OCRsystemenables you to take a book or a magazine article, feed it directly into an electroniccomputerfile, and then edit the file using a wordprocessor.
All OCR systems include anoptical scannerforreadingtext, and sophisticatedsoftwarefor analyzing images. Most OCR systems use a combination ofhardware(specializedcircuit boards) and software to recognizecharacters, although some inexpensive systems do it entirely through software. Advanced OCR systems can read text in large variety offonts, but they still have difficulty with handwritten text.
The potential of OCR systems is enormous because they enableusersto harness the power of computers toaccessprinteddocuments. OCR is already being used widely in the legal profession, where searches that once required hours or days can now be accomplished in a few seconds.
26.METASEARCH ENGINE
Asearch enginethat queries other search engines and then combines the results that are received from all. In effect, the user is not using just one search engine but a combination of many search engines at once to optimize Web searching. For example,Dogpileis a metasearch engine.
27.ring network
page 92 study material
28.compilers and interpreters
page 56 study mat.
28.algorithm
A formula or set of steps for solving a particular problem. To be an algorithm, a set of rules must be unambiguous and have a clear stopping point. Algorithms can be expressed in anylanguage, fromnatural languageslike English or French toprogramming languageslikeFORTRAN.
We use algorithms every day. For example, a recipe for baking a cake is an algorithm. Mostprograms, with the exception of someartificial intelligenceapplications, consist of algorithms. Inventing elegant algorithms -- algorithms that are simple and require the fewest steps possible -- is one of the principal challenges in programming.
High-level programming languages, while simple compared to human languages, are more complex than the languages thecomputeractually understands, calledmachine languages. Each different type ofCPUhas its own unique machine language.
30.assembly language
Lying between machine languages and high-level languages are languages calledassembly languages. Assembly languages are similar to machine languages, but they are much easier to program in because they allow aprogrammerto substitutenamesfor numbers. Machine languages consist of numbers only.
Lying above high-level languages are languages calledfourth-generation languages(usually abbreviated4GL). 4GLs are far removed from machine languages and represent the class of computer languages closest to human languages.
Regardless of what language you use, you eventually need toconvertyour program into machine language so that the computer can understand it. There are two ways to do this:
Short formodulator-demodulator.A modem is adeviceorprogramthat enables acomputerto transmitdataover, for example, telephone or cable lines. Computer information isstoreddigitally, whereas information transmitted over telephone lines is transmitted in the form ofanalogwaves. A modemconvertsbetween these two forms.
The use ofcomputersto presenttext,graphics,video,animation, and sound in anintegratedway. Long touted as the future revolution in computing, multimediaapplicationswere, until the mid-90s, uncommon due to the expensivehardwarerequired. With increases in performance and decreases in price, however, multimedia is now commonplace. Nearly all PCs are capable of displaying video, though the resolution available depends on the power of the computer's video adapter and CPU.
34.virus
A program or piece ofcodethat is loaded onto yourcomputerwithout your knowledge and runs against your wishes. Viruses can also replicate themselves. Allcomputerviruses are manmade. A simple virus that can make acopyof itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all availablememoryand bring thesystemto a halt. An even more dangerous type of virus is one capable of transmitting itself acrossnetworksand bypassingsecuritysystems.
Since 1987, when a virus infectedARPANET, a large network used by the Defense Department and many universities, manyantivirus programshave become available. Theseprogramsperiodically check yourcomputer systemfor the best-known types of viruses.
Some people distinguish between general viruses andworms.A worm is a special type of virus that can replicate itself and use memory, but cannot attach itself to other programs.
35.boolean logic
Boolean Searching on the Internet
A Primer in Boolean Logic
The Internet is a vast computer database. As such, its contents must be searched according to the rules of computer database searching. Much database searching is based on the principles of Boolean logic. Boolean logic refers to the logical relationship among search terms, and is named for the British-born Irish mathematician George Boole.
On Internet search engines, the options for constructing logical relationships among search terms extend beyond the traditional practice of Boolean searching. This will be covered in the section below,Boolean Searching on the Internet.
Boolean logic consists of three logical operators:
OR
AND
NOT
Each operator can be visually described by using Venn diagrams, as shown below.
OR
college OR university
Query: I would like information about college.
In this search, we will retrieve records in which AT LEAST ONE of the search terms is present. We are searching on the termscollegeand alsouniversitysince documents containing either of these words might be relevant.
This is illustrated by:
othe shaded circle with the wordcollegerepresenting all the records that contain the word "college"
othe shaded circle with the worduniversityrepresenting all the records that contain the word "university"
othe shaded overlap area representing all the records that contain both "college" and "university"
OR logic is most commonly used to search for synonymous terms or concepts.
Here is an example of how OR logic works:
Search terms
Results
college
396,482
university
590,791
college OR university
819,214
OR logic collates the results to retrieve all the unique records containing one term, the other, or both.
Themoreterms or concepts we combine in a search with OR logic, themorerecords we will retrieve.
For example:
Search terms
Results
college
396,482
university
590,791
college OR university
819,214
college OR university OR campus
929,677
AND
poverty AND crime
Query: I'm interested in the relationship between poverty and crime.
In this search, we retrieve records in which BOTH of the search terms are present
This is illustrated by the shaded area overlapping the two circles representing all the records that contain both the word "poverty" and the word "crime"
Notice how we do not retrieve any records with only "poverty" or only "crime"
Here is an example of how AND logic works:
Search terms
Results
poverty
76,342
crime
348,252
poverty AND crime
12,998
Themoreterms or concepts we combine in a search with AND logic, thefewerrecords we will retrieve.
For example:
Search terms
Results
poverty
76,342
crime
348,252
poverty AND crime
12,998
poverty AND crime AND gender
1,220
A few Internet search engines make use of theproximity operatorNEAR. A proximity operator determines the closeness of terms within the text of a source document. NEAR is a restrictive AND. The closeness of the search terms is determined by the particular search engine. Google defaults to proximity searching by default.
NOT
cats NOT dogs
Query: I want information about cats, but I want to avoid anything about dogs.
In this search, we retrieve records in which ONLY ONE of the terms is present
This is illustrated by the shaded area with the wordcatsrepresenting all the records containing the word "cats"
No records are retrieved in which the word "dogs" appears, even if the word "cats" appears there too
Here is an example of how NOT logic works:
Search terms
Results
cats
86,747
dogs
130,424
cats NOT dogs
65,223
NOT logic excludes records from your search results. Be careful when you use NOT: the term you do want may be present in an important way in documents that also contain the word you wish to avoid.
Boolean Searching on the Internet
When you use an Internet search engine, the use of Boolean logic may be manifested in three distinct ways:
Full Boolean logic with the use of the logical operators
Implied Boolean logic with keyword searching
Predetermined language in a user fill-in template
1. Full Boolean logic with the use of the logical operators
Few search engines nowadays offer the option to do full Boolean searching with the use of the Boolean logical operators. It is more common for them to offer simpler methods of constructing search statements, specifically implied Boolean logic and template language. These methods are covered below.
If you want to construct search queries using Boolean logical opeartors, you will need to experiment with search engines and see what happens when you search. You can try some of the search statements shown below.
Examples:
Query: I need information about cats.
Boolean logic: OR
Search: cats OR felines
Query: I'm interested in dyslexia in adults.
Boolean logic: AND
Search: dyslexia AND adults
Query: I'm interested in radiation, but not nuclear radiation.
Boolean logic: NOT
Search: radiation NOT nuclear
Query: I want to learn about cat behavior.
Boolean logic: OR, AND
Search: (cats OR felines) AND behavior
Note: Use of parentheses in this search is known asforcing the order of processing.In this case, we surround the OR words with parentheses so that the search engine will process the two related terms first. Next, the search engine will combine this result with the last part of the search that involves the second concept. Using this method, we are assured that the semantically-related OR terms are kept together as a logical unit.
2. Implied Boolean logic with keyword searching
Keyword searchingrefers to a search type in which you enter terms representing the concepts you wish to retrieve. Boolean operators are not used.
Implied Boolean logicrefers to a search in which symbols are used to represent Boolean logical operators. In this type of search on the Internet, theabsenceof a symbol is also significant, as the space between keywords defaults to either OR logic or AND logic. Nowadays, most search engines default to AND.
Implied Boolean logic has become so common in Web searching that it may be considered a de facto standard.
Examples:
Query: I need information about cats.
Boolean logic: OR
Search:[None]
It is extremely rare for a search engine to interpret the space between keywords as the Boolean OR. Rather, the space between keywords is interpreted as AND. To do an OR search, choose either option #1 above (full Boolean logic) or option #3 below (user fill-in template).
Query: I'm interested in dyslexia in adults.
Boolean logic: AND
Search: +dyslexia +adults
Query: I'm interested in radiation, but not nuclear radiation.
Boolean logic: NOT
Search: radiation -nuclear
Query: I want to learn about cat behavior.
Boolean logic: OR, AND
Search:[none]
Since this query involves an OR search, it cannot be done with keyword searching. To conduct this type of search, choose either option #1 above (full Boolean logic) or option #3 below (user fill-in template).
3. Predetermined language in a user fill-in template
Some search engines offer a search template which allows the user to choose the Boolean operator from a menu. Usually the logical operator is expressed with substitute language rather than with the operator itself.
Examples:
Query: I need information about cats
Boolean logic: OR
Search: Any of these words/Can contain the words/Should contain the words
Query: I'm interested in dyslexia in adults.
Boolean logic: AND
Search: All of these words/Must contain the words
Query: I'm interested in radiation, but not nuclear radiation.
Boolean logic: NOT
Search: Must not contain the words/Should not contain the words
Query: I want to learn about cat behavior.
Boolean logic: OR, AND
Search: Combine options as above if the template allows multiple search statements
Quick Comparison Chart:
Full Boolean vs. Implied Boolean vs. Templates
Full Boolean
Implied Boolean
Template Terminology
OR
college or university
[rarely available] *see note below
any of these words
can contain the words
should contain the words
AND
poverty and crime
+poverty +crime
all of these words
must contain the words
NOT
cats not dogs
cats -dogs
must not contain the words
should not contain the words
NEAR, etc.
cats near dogs
N/A
near
* Most multi-term search statements will resolve to AND logic at search engines that use AND as the default. Nowadays most search engines default to AND. Always play it safe, however, and consult the Help files at each site to find out which logic is the default.
Amarkup languageis anartificial languageusing a set of annotations to text that give instructions regarding the structure of text or how it is to be displayed. Markup languages have been in use for centuries, and in recent years have been used in computer typesetting and word-processing systems.
A well-known example of a markup language in use today in computing isHyperTextMarkup Language (HTML), one of the most used in theWorld Wide Web. HTML follows some of the markup conventions used in the publishing industry in the communication of printed work among authors, editors, and printers.
History
The termmarkupis derived from the traditional publishing practice of"marking up"'amanuscript, which involves adding symbolicprinter's instructions in the margins of a paper manuscript. For centuries, this task was done primarily by skilled typographers known as "markup men"[1]who marked up text to indicate whattypeface, style, and size should be applied to each part, and then passed the manuscript to others fortypesettingby hand. Markup was also commonly applied by editors, proofreaders, publishers, and graphic designers.
The idea ofmarkup languageswas apparently first publicly presented by publishing executiveWilliam W. Tunnicliffeat a conference in 1967, although he preferred to call it"generic coding."In the 1970s, Tunnicliffe led the development of a standard called GenCode for the publishing industry and later was the first chair of theInternational Organization for Standardizationcommittee that createdSGML, the first widely used descriptive markup language. Book designer Stanley Rice published vague speculation along similar lines in the late 1960s.Brian Reid, in his 1980 dissertation atCarnegie Mellon University, developed the theory and a working implementation of descriptive markup in actual use.
However,IBMresearcherCharles Goldfarbis more commonly seen today as the "father" of markup languages. Goldfarb hit upon the basic idea while working on a primitive document management system intended for law firms in 1969, and helped inventIBM GMLlater that same year. GML was first publicly disclosed in 1973.
By 1991, it appeared to many that SGML would be limited to commercial and data-based applications whileWYSIWYGtools (which stored documents in proprietary binary formats) would suffice for otherdocument processingapplications.
The situation changed whenSir Tim Berners-Lee, learning of SGML from co-worker Anders Berglund and others atCERN, used SGML syntax to createHTML. HTML resembles other SGML-based tag languages, although it began as simpler than most and a formal DTD was not developed until later.Steven DeRose[3]argues that HTML's use of descriptive markup (and SGML in particular) was a major factor in the success of the Web, because of the flexibility and extensibility that it enabled (other factors include the notion of URLs and the free distribution of browsers). HTML is quite likely the most used markup language in the world today.
XML (Extensible Markup Language) is a meta markup language that is now widely used. XML was developed by theWorld Wide Web Consortium, in a committee created and chaired byJon Bosak. The main purpose of XML was to simplify SGML by focusing on a particular problem — documents on the Internet.[4]XML remains a meta-language like SGML, allowing users to create any tags needed (hence "extensible") and then describing those tags and their permitted uses.
XML was designed primarily for semi-structured environments such as documents and publications. However, it appeared to strike a happy medium between simplicity and flexibility, and was rapidly adopted for many other uses. XML is now widely used for communicatingdatabetween applications. Like HTML, it can be described as a 'container' language.
Since January 2000 allW3C Recommendationsfor HTML have been based on XML rather than SGML, using the abbreviationXHTML(ExtensibleHyperTextMarkupLanguage). The language specification requires that XHTML Web documents must bewell-formedXML documents – this allows for more rigorous and robust documents while using tags familiar from HTML.
One of the most noticeable differences between HTML and XHTML is the rule thatall tags must be closed: empty HTML tags such as must either beclosedwith a regular end-tag, or replaced by a special form: (the space before the '/' on the end tag is optional, but frequently used because it enables some pre-XML Web browsers, and SGML parsers, to accept the tag). Another is that allattributevalues in tags must be quoted. Finally, all tag and attribute names must be lowercase in order to be valid; HTML, on the other hand, was case-insensitive.
As with just about everything else in the world, there are many different types of databases. There are also different ways to classify these types of databases. Two popular ways to differentiate between databases is by the function of the database and by the data model of the database.
Function:
First, we shall take a look at classifying by the function of the database. There are different databases that are used for different tasks and jobs. The two categories here are analytic databases and operational databases:
Analytic Databases:
Analytic databases, also called On Line Analytical Processing (OLAP), are databases that are primarily used to keep track of statistics. Usually, they are read-only, meaning that you can only retrieve data, but you can't modify the data in any way. They are often used by stores as inventory catalogs. They keep track of the company's sales, and then can be read and analyzed to determine how and when more products are sold. These databases can hold all sorts of descriptive information about the goods stored in a company's inventory.
Operational Databases:
Operational databases, also called On Line Transaction Processing (OLTP), are databases that have a completely different job. These databases, unlike the analytic databases, let you actually change and manipulate the data. While analytic databases only let you view the data, these databases let you modify the data in any way you would like- you can add data, delete data, or even change the data.
Data Model:
Another way of classifying databases is by their data model. So, what's a data model? A data model is the intangible form in which data is stored. It is kind of like the structure of a database, but data models are only a theoretical idea; they are abstract concepts that you cannot touch. Data models are used to describe how the data is stored and retrieved in a database. Now, we will discuss a few of the types of data models.
Flat-file Database Model:
The flat-file data model is generally used by the old paper-based databases. In this system, data was stored in numerous files. However, the files were not linked, so often, data might be repeated in more than one file. This caused everything to be quite redundant. The original "database," flat-file databases inspired scientists to find a way to link files so that they would not be repetitive.
Hierarchical Database Model:
The hierarchical database model took steps to get rid of the repetitiveness of the flat-file database model, but although it was somewhat successful, it did not completely succeed. There is still a level of redundant data in hierarchical databases.
A hierarchical database consists of a series of databases that are grouped together to resemble a family tree:
Each of the boxes in the diagram represents one database. The top database in the hierarchical model is called the "parent" database. The databases under it are called "child" databases. One "parent" can have many "children," but a "child" can only have one "parent." The child databases are all connected to the parent database via links called "pointers."
To get to a child database in the hierarchical database model, you must first go through the parent database, and then through the levels above it. If you have Microsoft Windows, you might realize that this is how Windows Explorer works. First, you open up a file- usually it's "My Computer." Under "My Computer," you can then choose from a list of drives. Pretend you clicked on the "Disk Drive C" icon. Then, under this, you can choose from a series of folders. After opening one folder, you can open another folder, and another, until you reach the file that you want.
Notice in the diagram above how the child databases on the same level are not connected. This presents a problem in the hierarchical database model and makes searching for data extremely difficult. Another problem is that data cannot be entered into the child databases until that field has been added to the parent database. This method was quite inefficient. Thus, although the hierarchical database model reduced some repetitiveness of data, it also presented many new problems.
Network Database Model:
The network database model was designed to help resolve some of the hierarchical database model's problems. For one thing, it allowed for links between the child databases. This no only reduces the chance of redundant data, but also makes searching for data much easier!
Another improvement of the network database model over the hierarchical model is that while in the hierarchical model a child database can only have one parent, in the network model, a child database can have more than one parent!
However, the network database model still had its share of problems. For one thing, it was difficult to execute and maintain. Only database experts could successfully use these databases. It was difficult for the general public to use network databases for real-life applications.
Relational Database Model:
The relational database model came in at full swing during the 1980s. Modeled after the work of Dr. E. F. Codd of IBM, the relational database model is extremely popular because it solved many of the problems displayed in the hierarchical and network database models.
The relational database model is different from the hierarchical and network database models in that there are no "parent" and "child" databases. Rather, all of the databases in the relational database model are equal.
Data can be stored in any number of separate databases. Then, these databases are connected by a "key" field. A key field is a field (in case you don't remember, a field is the columns in the database where the data is stored- see "Parts of a Database" for more details) that is found in all of the databases that are being linked together. All of the databases can be used to hold different types of data. For example, let's pretend that we have an address book, which is a paper-based database. If we were to use the relational database model, then we would store all of the data in separate databases. One database could hold a person's address; another could hold the person's phone number, etc. However, all of the databases might have one field that is the same, like, for example, the person's name.
This makes it easy to search for and extract data from the databases. It is also very efficient and easy to use. No wonder why this database model is so popular!
Object-oriented Databases:
You might realize that databases can not only store text and numeric values, but that there are special databases that can also store photos, sounds, videos, and all sorts of graphics. How is this possible? Well, I can tell you one thing, the old hierarchical, network, and relational databases couldn't store all of these types of data! As a matter of fact, this is where the object-oriented database models come in.
Object-oriented database models let databases store and manipulate not only text, but also sounds, images, and all sorts of media clips! They are extremely useful, but unfortunately, they are large in size and are extremely expensive. Thus, they are only found in large commercial or governmental organizations.
Client/Server Databases
As you probably know, the Internet is one of the most popular usages of a computer. Client/server databases are the databases that you will use for the Internet and for the World Wide Web. The database is left on 24 hours a day, 7 days a week. This is so that users, or clients, can access the web sites or whatever other data is contained in the database at any time they want. This is especially necessary if you want to make the applications available to anybody, anywhere in the world. There is a special type of interface that lets the clients submit certain data requests from the database. Then, the database will handle and process the requests!
4.search strategies
Successful searching combines creative guessing of Uniform Resource Locators (URLs) along with smart use of subject directories and search engines. Here are three general strategies. Before using any of them, be sure to consider what organization might be a likely source for providing the necessary information.
For many sites, do not even bother with a directory or search engines. When you are searching for a specific organization's Web site, first try guessing the central URL for the organization. The following steps may help:
With Netscape and Internet Explorer, leave offhttp://
Try the commonwwwto start the machine address
Use the name, acronym, or brief name of the organization (nra, honda, uwyo) in the middle
Add the appropriate top level domain, most often.com. See acomplete listor try one of the following common endings:
comfor commercial
edufor educational
orgfor other organizations
govfor U.S. federal government
milfor U.S. military
netfor Internet service providers and networks
URL guessing can help in finding pages for URLs that no longer work and links that lead to dead ends. Try chopping off parts of the URL starting on the right-hand side and stopping at every /
Subject directories select and classify resources into subject categories and subcategories. Some include reviews and/or ratings. Access is by keyword search or by browsing the classifications. Use these for finding
Search Engines attempt to find and index as many sites as possible. Search features vary greatly, as does the actual scope, size, and accuracy of the databases. Use these for
Unique Keywords
Combinations of unique keywords
Field searching and limiting
Pages buried deep in a Web site
For a quick overview list of strategies to consider see the list below. It repeats some of what is is in the three above as well as in the online tutorials below.
Determine likely organization with answer
Guess organization's URL before trying search engines
Search for organization URL otherwise
Use "phrase searching" and unique words as much as possible
Use directories (Yahoo!, ODP, LookSmart) for broad, general topics
Use multiple step approach – can be several clicks to an answer
Folders to narrow large search sets: Teoma, WiseNut, Vivisimo, or NLResearch
Try a title field search to focus results more by subject
Use specialized search engines for news, Usenet postings, phone numbers, etc.
This method involves the physical interconnection of two devices. A good example of circuit switching involves the Public phone network. A data example would be the classic A/B switch!
Packet Switching techniques switch packets of data between destinations. Traditionally, this applied to X.25 techniques, but this also applies to TCP/IP and IPX/SPX routers also. Proprietary Frame Relay switches can switch voice signals.
Message Switching techniques were originally used in data communications. An example would be early "store and forward" paper tape relay systems. E-Mail delivery is another example of message switching. In voice systems, you can find Voice Mail delivery systems on the Internet. The classic "forward voice mail" capability in some voice mail systems is another example.
Cell Switching is similar to packet switching, except that the switching does not necessarily occur on packet boundaries. This is ideal for an integrated environment and is found within Cell-based networks, such as ATM. Cell-switching can handle both digital voice and data signals.
An index file can be used to effectively overcome the above mentioned problem, and to speed up the key search as well. The simplest indexing structure is the single-level one: a file whose records are pairs key-pointer, where the pointer is the position in the data file of the record with the given key. Only a subset of data records, evenly spaced along the data file, are indexed, so to mark intervals of data records.
A key search then proceeds as follows: the search key is compared with the index ones to find the highest index key preceding the search one, and a linear search is performed from the record the index key points onward, until the search key is matched or until the record pointed by the next index entry is reached. In spite of the double file access (index + data) needed by this kind of search, the decrease in access time with respect to a sequential file is significant.
Consider, for example, the case of simple linear search on a file with 1,000 records. With the sequential organization, an average of 500 key comparisons are necessary (assuming uniformly distributed search key among the data ones). However, using and evenly spaced index with 100 entries, the number of comparisons is reduced to 50 in the index file plus 50 in the data file: a 5:1 reduction in the number of operations.
This scheme can obviously be hyerarchically extended: an index is a sequential file in itself, amenable to be indexed in turn by a second-level index, and so on, thus exploiting more and more the hyerarchical decomposition of the searches to decrease the access time. Obviously, if the layering of indexes is pushed too far, a point is reached when the advantages of indexing are hampered by the increased storage costs, and by the index access times as well.
9.artificial intelligence
Artificial intelligence(AI) is theintelligenceofmachinesand the branch ofcomputer sciencewhich aims to create it. Major AI textbooks define the field as "the study and design ofintelligent agents,"[1]where anintelligent agentis a system that perceives its environment and takes actions which maximize its chances of success.[2]John McCarthy, who coined the term in 1956,[3]defines it as "the science and engineering of making intelligent machines."[4]
The field was founded on the claim that a central property of human beings, intelligence—thesapienceofHomo sapiens—can be so precisely described that it can be simulated by a machine.[5]This raises philosophical issues about the nature of themindand limits of scientific hubris, issues which have been addressed bymyth,fictionandphilosophysinceantiquity.[6]Artificial intelligence has been the subject of breathtaking optimism,[7]has suffered stunning setbacks[8]and, today, has become an essential part of the technology industry, providing the heavy lifting for many of the most difficult problems in computer science.
The concept of sending electronic text messages between parties in a way analogous to mailing letters or memos predates the creation of the Internet. Even today it can be important to distinguish between Internet and internal e-mail systems. Internet e-mail may travel and be stored unencrypted on many other networks and machines out of both the sender's and the recipient's control. During this time it is quite possible for the content to be read and even tampered with by third parties, if anyone considers it important enough. Purely internal or intranet mail systems, where the information never leaves the corporate or organization's network, are much more secure, although in any organization there will beITand other personnel whose job may involve monitoring, and occasionally accessing, the e-mail of other employees not addressed to them. Today you can send pictures and attach files on e-mail. Most e-mail servers today also feature the ability to send e-mail to multiplee-mail addresses.
E-Mail E-mail is a means or system of transmitting messages electronically. It is any method of creating, transmitting, or storing. E-mails are what allow people to keep in touch with other people in an easy and fast way because of the invention of the Internet. It is a quick way to send a message or document or eve a file or just anything to someone or the other. Not only can the email be sent to one person but it can also be sent to as many people as it is needed to be sent to. If one receives an email that they need to send to others they are able to forward the message to anyone they chose to There are many different types of websites such as Google, yahoo, msn, etc. to create email accounts on. Creating an account in any of these still allows for one to communicate with anyone from any of the different types of accounts. All email accounts created are free and anyone is allowed to create one. E-mails are very secure and private between the sender and recipient and allow for information to be very easily sent and replied to.
The World Wide Web
Many people use the termsInternetandWorld Wide Web(or just theWeb) interchangeably, but, as discussed above, the two terms are notsynonymous.
The World Wide Web is a huge set of interlinkeddocuments,imagesand other resources, linked byhyperlinksandURLs. These hyperlinks and URLs allow theweb serversand other machines that store originals, and cached copies of, these resources to deliver them as required usingHTTP(Hypertext Transfer Protocol). HTTP is only one of the communication protocols used on the Internet.
Web servicesalso use HTTP to allow software systems to communicate in order to share and exchange business logic and data.
Throughkeyword-drivenInternet researchusingsearch engineslikeYahoo!andGoogle, millions of people worldwide have easy, instant access to a vast and diverse amount of online information. Compared toencyclopediasand traditionallibraries, the World Wide Web has enabled a sudden and extreme decentralization of information and data.
Using the Web, it is also easier than ever before for individuals and organisations topublishideas and information to an extremely largeaudience. Anyone can find ways to publish a web page, ablogor build a website for very little initialcost. Publishing and maintaining large, professional websites full of attractive, diverse and up-to-date information is still a difficult and expensive proposition, however.
Many individuals and some companies and groups use "web logs" orblogs, which are largely used as easily updatable online diaries. Some commercial organisations encouragestaffto fill them with advice on their areas of specialization in the hope that visitors will be impressed by the expert knowledge and free information, and be attracted to the corporation as a result. One example of this practice isMicrosoft, whoseproduct developerspublish their personal blogs in order to pique the public's interest in their work.
Collections of personal web pages published by large service providers remain popular, and have become increasingly sophisticated. Whereas operations such asAngelfireandGeoCitieshave existed since the early days of the Web, newer offerings from, for example,FacebookandMySpacecurrently have large followings. These operations often brand themselves associal network servicesrather than simply as web page hosts.
Advertisingon popular web pages can be lucrative, ande-commerceor the sale of products and services directly via the Web continues to grow.
In the early days, web pages were usually created as sets of complete and isolatedHTMLtext files stored on a web server. More recently, websites are more often created usingcontent managementorwikisoftware with, initially, very little content. Contributors to these systems, who may be paid staff, members of a club or other organisation or members of the public, fill underlying databases with content using editing pages designed for that purpose, while casual visitors view and read this content in its final HTML form. There may or may not be editorial, approval and security systems built into the process of taking newly entered content and making it available to the target visitors.
The Internet allows computer users to connect to other computers and information stores easily, wherever they may be across the world. They may do this with or without the use ofsecurity, authentication and encryption technologies, depending on the requirements.
This is encouraging new ways of working from home, collaboration and information sharing in many industries. Anaccountantsitting at home canauditthe books of a company based in another country, on aserversituated in a third country that is remotely maintained by IT specialists in a fourth. These accounts could have been created by home-working bookkeepers, in other remote locations, based on information e-mailed to them from offices all over the world. Some of these things were possible before the widespread use of the Internet, but the cost of privateleased lineswould have made many of them infeasible in practice.
An office worker away from his desk, perhaps on the other side of the world on a business trip or a holiday, can open aremote desktopsession into his normal office PC using a secureVirtual Private Network(VPN) connection via the Internet. This gives the worker complete access to all of his or her normal files and data, including e-mail and other applications, while away from the office.
This concept is also referred to by some network security people as the Virtual Private Nightmare, because it extends the secure perimeter of a corporate network into its employees' homes.
The low cost and nearly instantaneous sharing of ideas, knowledge, and skills has madecollaborativework dramatically easier. Not only can a group cheaply communicate and share ideas, but the wide reach of the Internet allows such groups to easily form in the first place. An example of this is thefree software movement, which has producedLinux,Mozilla Firefox,OpenOffice.orgetc.
Internet "chat", whether in the form ofIRCchat rooms or channels, or viainstant messagingsystems, allow colleagues to stay in touch in a very convenient way when working at their computers during the day. Messages can be exchanged even more quickly and conveniently than via e-mail. Extensions to these systems may allow files to be exchanged, "whiteboard" drawings to be shared or voice and video contact between team members.
Version controlsystems allow collaborating teams to work on shared sets of documents without either accidentally overwriting each other's work or having members wait until they get "sent" documents to be able to make their contributions.
Business and project teams can share calendars as well as documents and other information. Such collaboration occurs in a wide variety of areas including scientific research, software development, conference planning, political activism and creative writing.
Acomputer filecan bee-mailedto customers, colleagues and friends as anattachment. It can be uploaded to awebsiteorFTPserver for easy download by others. It can be put into a "shared location" or onto afile serverfor instant use by colleagues. The load of bulk downloads to many users can be eased by the use of "mirror" servers orpeer-to-peernetworks.
In any of these cases, access to the file may be controlled by userauthentication, the transit of the file over the Internet may be obscured byencryption, and money may change hands for access to the file. The price can be paid by the remote charging of funds from, for example, a credit card whose details are also passed—hopefully fully encrypted—across the Internet. The origin and authenticity of the file received may be checked bydigital signaturesor byMD5or other message digests.
These simple features of the Internet, over a worldwide basis, are changing the production, sale, and distribution of anything that can be reduced to a computer file for transmission. This includes all manner of print publications, software products, news, music, film, video, photography, graphics and the other arts. This in turn has caused seismic shifts in each of the existing industries that previously controlled the production and distribution of these products.
Streaming media
Many existing radio and television broadcasters provide Internet "feeds" of their live audio and video streams (for example, theBBC). They may also allow time-shift viewing or listening such as Preview, Classic Clips and Listen Again features. These providers have been joined by a range of pure Internet "broadcasters" who never had on-air licenses. This means that an Internet-connected device, such as a computer or something more specific, can be used to access on-line media in much the same way as was previously possible only with atelevisionorradioreceiver. The range of material is much wider, frompornographyto highly specialized, technicalwebcasts.Podcastingis a variation on this theme, where—usually audio—material is downloaded and played back on a computer or shifted to aportable media playerto be listened to on the move. These techniques using simple equipment allow anybody, with little censorship or licensing control, to broadcast audio-visual material on a worldwide basis.
Webcamscan be seen as an even lower-budget extension of this phenomenon. While some webcams can give full-frame-rate video, the picture is usually either small or updates slowly. Internet users can watch animals around an African waterhole, ships in thePanama Canal, traffic at a local roundabout or monitor their own premises, live and in real time. Videochat roomsandvideo conferencingare also popular with many uses being found for personal webcams, with and without two-way sound.
YouTubewas founded on 15 February 2005 and is now the leading website for free streaming video with a vast number of users. It uses aflash-based web player to stream and show the video files. Users are able to watch videos without signing up; however, if they do sign up, they are able to upload an unlimited amount of videos and build their own personal profile. YouTube claims that its users watch hundreds of millions, and upload hundreds of thousands, of videos daily.[15]
VoIP stands for Voice-over-Internet Protocol, referring to the protocol that underlies all Internet communication. The idea began in the early 1990s withwalkie-talkie-like voice applications for personal computers. In recent years many VoIP systems have become as easy to use and as convenient as a normal telephone. The benefit is that, as the Internet carries the voice traffic, VoIP can be free or cost much less than a traditional telephone call, especially over long distances and especially for those with always-on Internet connections such ascableorADSL.
VoIP is maturing into a competitive alternative to traditional telephone service. Interoperability between different providers has improved and the ability to call or receive a call from a traditional telephone is available. Simple, inexpensive VoIP network adapters are available that eliminate the need for a personal computer.
Voice quality can still vary from call to call but is often equal to and can even exceed that of traditional calls.
Remaining problems for VoIP includeemergency telephone numberdialling and reliability. Currently, a few VoIP providers provide an emergency service, but it is not universally available. Traditional phones are line-powered and operate during a power failure; VoIP does not do so without abackup power sourcefor the phone equipment and the Internet access devices.
VoIP has also become increasingly popular for gaming applications, as a form of communication between players. Popular VoIP clients for gaming includeVentriloandTeamspeak, and others.PlayStation 3andXbox 360also offer VoIP chat features.
A DBMS is a set ofsoftware programsthat controls theorganization,storage, management, andretrievalofdatain adatabase. DBMS are categorized according to their data structures or types. It is a set of prewritten programs that are used to store, update and retrieve a Database. The DBMS accepts requests for data from the application program and instructs theoperating systemto transfer the appropriate data. When a DBMS is used,information systemscan be changed much more easily as the organization's information requirements change. New categories of data can be added to the database without disruption to the existing system.
Organizations may use one kind of DBMS for daily transaction processing and then move the detail onto another computer that uses another DBMS better suited for random inquiries and analysis. Overall systems design decisions are performed by data administrators and systems analysts. Detailed database design is performed by database administrators.
Database serversare computers that hold the actual databases and run only the DBMS and related software. Database servers are usuallymultiprocessorcomputers, with generous memory andRAIDdisk arrays used for stable storage. Connected to one or more servers via a high-speed channel, hardware database accelerators are also used in large volume transaction processing environments. DBMSs are found at the heart of mostdatabase applications. Sometimes DBMSs are built around a privatemultitaskingkernelwith built-innetworkingsupport although nowadays these functions are left to theoperating system.
IT THEORY
Essays
1.major input/output devices of a computer?
answer:page 26-31(study material)
2.define information technology?explain the application of IT in library and info.centres?(must study question)
answer page 8-14(study material)
3.recent developments in communication media?
4.history of secondary storage media?
Page 33.study material
5.library automation
page 98-101 study material
Always follow 'KISS PRINCIPLE" while answering,ie.."keep it short and simple"...
