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Digital Library
INTRODUCTION
Many terms are defined at different times to represent the concept of a library without books, libraries having information in a computer-readable format, or having access to information in digitized or digital format. The terms which are hip at different times include a paperless library, electronic library, virtual library, library borderless, and more recently, digital library. The term digital library, on one hand, is employed to ask a system or applications whose function is chiefly to increase electronic access to material available during a conventional library to a foreign user. On the opposite hand, it’s wont to describe both commercial and academic systems designed to enable electronic access to an outsized corpus of electronic documents to authorized users. The term digital library may mean various things to different people and it is often used frequently one or more of the following:
• Contents of documents are created or converted to computer processible form for online access;
• Digital access to material already existed within traditional library collections be provided, i.e. libraries of the scanned image, images of photographic or printed texts, digital video segments;
• Online databases and CD-ROM information products, particularly those with multimedia or interactive video components or those, which contain complete contents of books or other publications;
• Digital audio, video clips or full-length movies;
• Database, including library catalog accessible through the Internet;
• memory devices on which information repositories reside, like an optical disk, jukeboxes, CD-ROM / DVD-ROM towers, etc.;
the sole thing common about the range of products and services mentioned above is their being “digital” or “digitized”. The relatively recent use of the term “digital library” is often traced to the “Digital Library Initiatives” funded by the National Science Foundation (NSF), the Advanced Research Projects Agency (ARPA), and thus the National Aeronautics and Space Administration (NASA) within us. In 1994, these agencies granted 24.4 million US dollars to 6 universities within the US for digital library research impelled by the sudden explosive growth of the web and web technology. The term was quickly adopted by the pc scientists, librarians et al.
A digital library isn’t merely a set of electronic information; it’s an organized system of digitized information that will function as an upscale resource for its user community. The library and knowledge science community treats digital libraries as a “logical extension and augmentation of physical libraries within the electronic information society” (Marchionini, 1998). They extend and augment their physical counterparts by extending existing resources and services and enable the development of the latest possibilities for information access and retrieval (Fox, 1998).
The terms digital libraries and electronic libraries are wiles used interchangeably and synonymously, the term “virtual library” or “library without walls” usually refers to the meta resources or subject portals that reach virtual accessibility of digital collections from several diverse sources without the users every knowing where the resource actually resides. The virtual library could potentially be enormous, linking huge collections from all around the globe, or it might be very small, consisting of a couple of hundred links to digital resources maintained by a private. The concept of “Hybrid Library” (Rusbridge, 1998) reflects the realities being faced by libraries as they plan to integrate electronic resources acquired on CD-ROM or other media or electronic access that they buy with the digital collections produced in-house. The hybrid library is in a continuum between the traditional and digital library, where electronic and paper-based information sources are used alongside one another
DEFINITIONS OF DIGITAL LIBRARY
Terence R. Smith (1997), defined digital libraries as “controlled collections of data-bearing objects (IBOs) that are in digital form which could also be organized, accessed, evaluated, and employed by means of a heterogeneous and extensible set of distributed services that are supported by digital technology.”
Clifford Lynch (1995), a well-known expert on digital libraries and new technologies, defined a digital library as a “system providing a community of users with coherent access to an outsized, organized repository of data and knowledge. The digital library isn’t only one entity, but multiple sources seamlessly integrated.”
The Association of Research Libraries (Waters, 1998), one among the leaders in collaborative digitization programs within the US, assigns the subsequent tenets to a digital library:
The Digital Library isn’t one entity;
The digital library requires technology to link the resources of many;
These linkages between many digital libraries and knowledge services are transparent to end-users; Universal access to the digital libraries and knowledge services is that the goal; and
Digital Library collections aren’t limited to documents surrogates, they also include digital artifacts that can’t be represented or distributed in printed formats.
Michael Lesk, who predicts that half the materials accessed in major libraries are going to be digital by the early 21st century (Lesk, 1997), offers the subsequent definition for the digital libraries:” Digital libraries are organized collections of digital information. They combine the structuring and gathering of data, 6 which libraries and archives have always done, with the digital representation that computers have made possible. Digital information is often accessed rapidly around the world, copies for preservation without error, stored compactly, and searched very quickly…. a real digital library also provides the principles governing what’s included and the way the gathering is organized” (Lesk, 1997).
Basically, digital libraries provide organized and structured access to information contents during a distributed environment and assist users in searching evaluating, and utilizing resources regardless of their format. Digital libraries combine collection and expertise during a seamless interface, and therefore, require specialized staff to pick, organize, evaluate, interpret, offer intellectual access, preserve the integrity and make sure the persistence over time of digital works in order that they’re readily and economically available to be used by an outlined community or set of communities (Waters, 1992).
CHARACTERISTICS OF DIGITAL LIBRARY
Following are the characteristics of the digital library:
• A digital library isn’t one entity, it’s going to also provide access to digital material and resources from outside the particular confines of anybody digital library;
• Digital libraries include all the processes and services offered by traditional libraries though these processes will need to be revised to accommodate differences between digital and paper media;
• Digital libraries are the digital counterparts of traditional libraries and include both electronic (digital) also as print and other (e.g. audio, video, graphics, animation, etc.) material;
• Digital libraries support quick and efficient access to an outsized number of distributed but interlinked information sources that are seamlessly integrated;
• A digital library owns and controls the information; it provides access to information, not just tips that could it;
• A digital library features a unified organizational structure with consistent points for accessing the data;
• Digital libraries have collections that
(a) are large and persist over time;
(b) are well-organized and managed;
(c) contain many formats;
(d) contain objects and not just their representations;
(e) contain objects which will be otherwise unobtainable; and
(f) contain some objects that are digital by origin;
The World Wide Web (WWW) or the online may be a collection of several thousand documents and is taken into account as a digital library by many of us. the online is that the means by which most digital libraries are accessed. However but it’s not a digital library itself, although it’s several features of a digital library. The web, unlike a digital library, is an unorganized collection of documents, many of them having ephemeral information that doesn’t have any durability or lasting value.
Presently digital libraries are built around Internet and web technologies with electronic journals as their building blocks. While the web is the carrier and provides the contents delivery mechanism, the online provides the tools and techniques for content publishing, hosting, and accessing. The increasing popularity of the Internet and developments in web technologies are a catalyst to the concept of the digital library. Further, the availability of computing power that permits multiprocessing, multitasking, parallel consultation, and parallel knowledge navigation, put together, creates a semblance of AI and interactively necessary for developing a digital library. the arrival of the World Wide Web (WWW), its ever-increasing usage, and highly evolved browsers have paved the way for the creation of a worldwide digital library.
COMPONENTS OF A DIGITAL LIBRARY
The digital library resources and services require an excellent deal of the latest infrastructural components that aren’t available off-the-shelf as packaged solutions. There are not any turnkey, monolithic systems available for digital libraries, instead digital libraries are collections of disparate systems and resources connected through a network, and integrated within one interface, currently the online interface. The use of open architecture and standard protocols, however, make it possible that pieces of required infrastructure, be it hardware, software, or accessories, are gathered from different vendors within the marketplace and integrated to construct a working environment. Several components required for establishing digital libraries would be internal to the institutions, but several others would be distributed across the web, owned and controlled by an outsized number of independent players. The task of building a digital library, therefore, requires an excellent deal of integration of varied components (Flecker, D. 2000). Components required for a digital library can broadly be divided into the subsequent five categories and are as under:
• Collection Infrastructure
• Access Infrastructure
• Computer and Network Infrastructure
• Digital Resource Organization
• Manpower Training
INFORMATION RETRIEVAL IN DIGITAL LIBRARY
A typical digital library implementation may employ a spread of data retrieval techniques including metadata searching, full-text document searching, and content searching, or a combination of two or all of them. Information retrieval is formed simpler and user-friendly by preprocessing digital documents to extract additional metadata before storing them during a database. The database is then configured to get indices from selected fields including author(s), titles, abstracts, etc. or it’s going to even be configured to get indices from the full-text articles with a pre-defined stop-word list. The success of data retrieval are often measured in terms of the percentage of relevant “Contents” or “Table of Contents” (ToC) primarily extend a browsing interface to the users although search also can be restricted to the ToC during a digital library implementation.
a) Meta Resources, Portal, or Knowledge Gateways: The meta resources or portal sites or subject gateways redirect a user to the location holding the first material.
b) Computer and Network Infrastructure A typical digital library during a distributed client-server environment consists of hardware and software components at the server’s side also as at the client’s side. Clients are machines that are used for accessing the digital library by users while the server hosts databases, digital objects, browse, and search interfaces to facilitate its access.
Server-side Hardware Components: Servers are the guts of a digital library. Servers for digital library implementation got to be computationally powerful, have adequate main memory (RAM) to handle the expected work, have an outsized amount of secure disc storage for the database (s) and digital objects, and have good communication capabilities. A digital library may have a variety of specialized servers for various tasks so on distribute the workload onto different servers. it might require one or more library server(s) to host indices and databases and one or more object server(s) to store digital objects and other multimedia objects. However, for a smaller library, many distinct activities are often performed on one server. it’s important that the server is scalable (such as Sun Enterprise Server) in order that additional storage, processing power, or networking capabilities are often added whenever required.
Input Devices: Image-based digital library implementation require input devices like scanners, digital cameras, video cameras, and PhotoCD systems. an outsized range of choices is available for these image capturing devices. Scanners are available altogether sizes and shapes. Flatbed scanners or digital cameras mounted on book cradle are more suitable for libraries.
Storage Devices: Since digital libraries require large amounts of storage, particular attention must tend to the storage solution. Digital library collections that are overlarge to store entirely on a disk use hierarchical storage mechanisms(HSM). In an HSM, the foremost frequently used data is kept on fast disks, while less frequently used data is kept in near-line like an automated(robotic) tape library. An HSM can automatically migrate data from tape to disk and vice-versa, as needed. Intelligent storage networks and snap-servers are now available during which the physical storage devices are intelligently controlled and made available to a variety of servers. Although hard disk (fixed and removable) solutions are increasingly available at a reasonable cost, optical storage devices including WORM, CD-R, CD-ROM, DVD-ROM, or opto-magnetic devices in standalone or networked mode, are attractive alternatives for long-term storage of digital information. Optical drives record information by writing data onto the disc with a beam. The media offer enormous storage capabilities. variety of RAID (Redundant Array of cheap Disks) models also is available for greater security and performance. The RAID technology distributes the info across a variety of disks in a way that albeit one or more disks fail, the system would still function while the failed component is replaced.
Communication Devices: Setting-up a digital library requires network and communication equipment like communication switches, routers, hubs, repeaters, modems, and other items required during a Local Area Network. These hardware and software items are required for setting-up any network and aren’t specific to a digital library.
Server-side Software Components: A typical digital library requires a variety of software packages to handle its highly diversified resources, activities, and services. Different software packages are required to handle different components and activities of a digital library.
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Uniform Resource Name (URN): maybe a development of the web Engineering Task Force (IETF). A URN isn’t a naming scheme in itself, but a framework for outlining identifiers. They contain a naming authority identifier ( a central authority given the task of assigning identifiers) and an object identifier (assigned by the central authority). Like PURLs, URNs must be resolved, through a database or other such system, into actual URLs. Unlike PURLs, however, a URN is often resolved into quite one URL, like one for every of several different formats.
Digital Object Identifier (DOI): is an initiative by the Association of yank Publishers and therefore the Corporation for National Research Initiatives (CNRI) designed to supply a way by which digital objects are often reliably identified and accessed. The CNRI Handle System, which underlies DOI, maybe a system that resolves digital identifiers into the knowledge required to locate and access a digital object. the most impetus of the DOI system is to supply publishers with a way by which the property rights issues related to their materials are often managed. The DOI System consists of the subsequent four components:
• Enumeration: assigning an alphanumeric string to the digital object that the DOI identifies;
•Description: creating an outline (“metadata”) of the entity that has been identified with a DOI;
•Resolution: making the identifier “actionable” by providing information about what the DOI should resolve to, and therefore the technology to deliver the services that this will provide to users.
•Policies: the principles that govern the operation of the system
Online Database Connectivity (ODBC): Html, the de facto language of the online, doesn’t offer much interactivity essential during a digital library implementation. Restrictions inherent within the current www protocol are overcome by employing back-end databases to retrieve information in response to queries from users or queries embedded as links. Methods used for providing connectivity to a database with the online are described below:
ODBC Drivers: Online database connectivity provides a consistent thanks to access databases that compliant drivers are written. The ODBC drivers are readily available for well-known electronic database systems. Working with ODBC gives access to the widest sort of system. The technology is now available to make sites on-the-fly to get data dynamically obtained from a database like Oracle 7, Microsoft Access, In magic, BASIC+, etc. ODBC drivers for important databases are already in-built in major operating systems.
Common Gateway Interface (CGI): A CGI script is a particularly powerful feature to realize browser and server interaction. A CGI script may be a program that runs on an internet server. It is a link between the online server and a few other programs ( a database) running on the server. the online interfaces can now be designed to question databases, receive results, and display them to the users. The program is persisted in the online server and activated within the online page in conjunction with HTML “forms” for query formulations by using CGI scripts.
Java Database Connectivity (JDBC): Java applets aren’t used only for creating visual effects and animations; Database access is another popular application where Java applets are used. Java applets are client-end applications that get automatically transmitted to the client’s PC over the web. Java Database Connectivity (JDBC) may be a programming interface, which allows applets to speak with database systems through Servlets during a three-tier architecture. The applets interact with the server, which successively, interact with the database layer. In response, the server receives data from the database layer and sends the results back to the client. Java is extremely significant since it makes the WWW truly interactive by incorporating applications that will be programmed, run online, and distributed in a simple, safe, and portable manner. Java also provides an extensible method to handle internally new data types and protocols. Libsys features a Java client to supply web-based connectivity of Libsys.
Uniform Resource Characteristics or Metadata in Digital Libraries: The digital objects got to be identified, described, stored, and disseminated so on serving their purpose. Stored in digital repositories, digital objects must have their unique identifications or names which will be used for his or her retrieval. Uniform Resource Characteristics (URC) or metadata, as more popularly known, provide metadata or meta-information about an object, and is analogous to bibliographic records.
Manpower Training
The digital libraries, on the one hand, are almost like physical libraries, they involve equivalent problems with selection, evaluation, access, housing, preservation, and providing user assistance. However, on the opposite hand, digital objects are very different from physical objects in some ways. a special set of data and skills are required to handle them. In a nutshell, digital libraries need digital librarians to manage them. Since digital libraries and digital objects are new, such skills are hard to seek out. A key component of building a digital library is to create a team with understanding and expertise in various areas relevant to digital resources. things warrants library and knowledge science professionals to perform a paradigm shift to satisfy the challenge. The paradigm shift involves the introduction of those technologies within the libraries and to coach the prevailing and potential humanistic discipline professionals in their use.
Skills required for Digital Manpower:
Digital Libraries are amongst the foremost complex and advanced sort of information systems. The digital library development requires in-depth knowledge of digital document imaging, distributed management, hypertext, information retrieval, enforcement of property rights, integration of multimedia information services, management and organization of the multilingual collection, information mining, electronic reference service, electronic document delivery, and selective dissemination of data.
GLOSSARY
Digital Library: Library with both digital collection and traditional, fixed media collection. It also includes digital materials that exist outside the physical and administrative bounds of anybody’s digital library.
Digital Collection: It stands for texts, images, databases, files, etc. during a digital format. The objects during a digital collection are often either digitized or born-digital.
Digitization: it’s the method of converting print information and other media information of the prevailing collection to digital form. it’s the conversion of any fixed or analog media, like books, journal articles, photos, paintings, microforms, etc., into electronic form through scanning or actually even rekeying.
Metadata: it’s the info that describes the content and attributes of any particular item. it’s the key to resource discovery and therefore the use of any document. The cataloguing record (i.e. bibliographical record) is an example of metadata.
Scanners: it’s a tool wont to capture a digital image from an analog media like the printed page or a microfiche/ microfilm at a predefined resolution.
Scanning: the method of acquisition of a bitmap through its original which will be a text, photograph, manuscript, etc., into the pc using a bitmap scanner. a picture is read or scanned at a predefined resolution and dynamic range.
REFERENCES & FURTHER READINGS
Vijay Lakshmi and Jindal, S C eds. Digital Libraries: problems with the digital library environment. Delhi,
Isha Books, 2004. Gary Cleveland. Digital libraries: definitions, issues, and challenges. http://www.ifla.org/archive/udt/op/udtop8/udt-op8.pdf
