KEY TO SUCCESS

ECHO SERVER

2009-05-28T07:35:00.000-07:00

import java.io.*;

import java.net.*;

/**

This program implements a simple server that listens to

port 8189 and echoes back all client input.

public class EchoServer

{

public static void main(String[] args )

{

try

{

// establish server socket

ServerSocket s = new ServerSocket(8189);

// wait for client connection

Socket incoming = s.accept( );

BufferedReader in = new BufferedReader

(new InputStreamReader(incoming.getInputStream()));

PrintWriter out = new PrintWriter

(incoming.getOutputStream(), true /* autoFlush */);

out.println( "Hello! Enter BYE to exit." );

// echo client input

while (true)

{

String line = in.readLine();

if (line == null) break;

else

{

out.println("Echo: " + line);

if (line.trim().equals("BYE"))

break;

}

incoming.close();

}

catch (Exception e)

{

e.printStackTrace();

}

അഡോബെFLEX

2009-05-23T20:53:00.000-07:00

Adobe Flex is a software development kit released by Adobe Systems for the development and deployment of cross-platform rich Internet applications based on the Adobe Flash platform. Flex applications can be written using Adobe Flash Builder or by using the freely available Flex compiler from Adobe.
The initial release in March 2004 by Macromedia included a software development kit, an IDE, and a J2EE integration application known as Flex Data Services. Since Adobe acquired Macromedia in 2005, subsequent releases of Flex no longer require a license for Flex Data Services, which has become a separate product rebranded as LiveCycle Data Services.
In February 2008, Adobe released the Flex 3 SDK under the open source Mozilla Public License. Adobe Flash Player, the runtime on which Flex applications are viewed, and Adobe Flex Builder, the IDE built on the open source Eclipse platform and used to build Flex applications, remain proprietary.
അഡോബെ

FINGER PRINT

2009-05-03T07:18:00.000-07:00

A fingerprint is an impression of the friction ridges on all parts of the finger.^[1] A friction ridge is a raised portion of the epidermis on the palmar (palm) or digits (fingers and toes) or plantar (sole) skin, consisting of one or more connected ridge units of friction ridge skin.^[1] These are sometimes known as "dermal ridges" or "dermal papillae". These ridges assist in gripping objects and may also serve to amplify vibrations triggered when fingertips brush across an uneven surface, better transmitting the signals to sensory nerves involved in fine texture perception.^[2]

Fingerprints may be deposited in natural secretions from the eccrine glands present in friction ridge skin (secretions consisting primarily of water) or they may be made by ink or other contaminants transferred from the peaks of friction skin ridges to a relatively smooth surface such as a fingerprint card.^[3] The term fingerprint normally refers to impressions transferred from the pad on the last joint of fingers and thumbs, though fingerprint cards also typically record portions of lower joint areas of the fingers (which are also u

Fingerprints as used for identification

Fingerprint identification (sometimes referred to as dactyloscopy^[4]) or palm print identification is the process of comparing questioned and known friction skin ridge impressions (see Minutiae) from fingers or palms or even toes to determine if the impressions are from the same finger or palm. The flexibility of friction ridge skin means that no two finger or palm prints are ever exactly alike (never identical in every detail), even two impressions recorded immediately after each other. Fingerprint identification (also referred to as individualization) occurs when an expert (or an expert computer system operating under threshold scoring rules) determines that two friction ridge impressions originated from the same finger or palm (or toe, sole) to the exclusion of all others.

A known print is the intentional recording of the friction ridges, usually with black printers ink rolled across a contrasting white background, typically a white card. Friction ridges can also be recorded digitally using a technique called Live-Scan. A latent print is the chance reproduction of the friction ridges deposited on the surface of an item. Latent prints are often fragmentary and may require chemical methods, powder, or alternative light sources in order to be visualized.

When friction ridges come in contact with a surface that is receptive to a print, material on the ridges, such as perspiration, oil, grease, ink, etc. can be transferred to the item. The factors which affect friction ridge impressions are numerous, thereby requiring examiners to undergo extensive and objective study in order to be trained to competency. Pliability of the skin, deposition pressure, slippage, the matrix, the surface, and the development medium are just some of the various factors which can cause a latent print to appear differently from the known recording of the same friction ridges. Indeed, the conditions of friction ridge deposition are unique and never duplicated. This is another reason why extensive and objective study is necessary for examiners to achieve competency.

[edit]Fingerprint types

[edit]Latent prints

Although the word latent means hidden or invisible, in modern usage for forensic science the term latent prints means any chance of accidental impression left by friction ridge skin on a surface, regardless of whether it is visible or invisible at the time of deposition. Electronic, chemical and physical processing techniques permit visualization of invisible latent print residue whether they are from natural secretions of the eccrine glands present on friction ridge skin (which produce palmar sweat, consisting primarily of water with various salts and organic compounds in solution), or whether the impression is in a contaminant such as motor oil, blood, paint, ink, etc.

Latent prints may exhibit only a small portion of the surface of the finger and may be smudged, distorted, overlapping, or any combination, depending on how they were deposited. For these reasons, latent prints are an “inevitable source of error in making comparisons,” as they generally “contain less clarity, less content, and less undistorted information than a fingerprint taken under controlled conditions, and much, much less detail compared to the actual patterns of ridges and grooves of a finger.”^[5]

[edit]Patent prints

These are friction ridge impressions of unknown origins which are obvious to the human eye and are caused by a transfer of foreign material on the finger, onto a surface. Because they are already visible they need no enhancement, and are generally photographed instead of being lifted in the same manner as latent prints.^{[citation needed]} Finger deposits can include materials such as ink, dirt, or blood onto a surface.

[edit]Plastic prints

A plastic print is a friction ridge impression from a finger or palm (or toe/foot) deposited in a material that retains the shape of the ridge detail.^[6]Commonly encountered examples are melted candle wax, putty removed from the perimeter of window panes and thick grease deposits on car parts. Such prints are already visible and need no enhancement, but investigators must not overlook the potential that invisible latent prints deposited by accomplices may also be on such surfaces. After photographically recording such prints, attempts should be made to develop other non-plastic impressions deposited at natural finger/palm secretions (eccrine gland secretions) or contaminates.

[edit]Fingerprint capture and detection

[edit]Livescan devices

A fingerprint scanner in Tel Aviv, Israel.

Fingerprint image acquisition is considered the most critical step of an automated fingerprint authentication system, as it determines the final fingerprint image quality, which has drastic effects on the overall system performance. There are different types of fingerprint readers on the market, but the basic idea behind each capture approach is to measure in some way the physical difference between ridges and valleys. All the proposed methods can be grouped in two major families: solid-state fingerprint readers and optical fingerprint readers. The procedure for capturing a fingerprint using a sensor consists of rolling or touching with the finger onto a sensing area, which according to the physical principle in use (capacitive, optical, thermal, acoustic, etc.) captures the difference between valleys and ridges. When a finger touches or rolls onto a surface, the elastic skin deforms. The quantity and direction of the pressure applied by the user, the skin conditions and the projection of an irregular 3D object (the finger) onto a 2D flat plane introduce distortions, noise and inconsistencies in the captured fingerprint image. These problems result in inconsistent, irreproducible and non-uniform contacts^{[citation needed]} and, during each acquisition, their effects on the same fingerprint results are different and uncontrollable. The representation of the same fingerprint changes every time the finger is placed on the sensor platen, increasing the complexity of the fingerprint matching, impairing the system performance, and consequently limiting the widespread use of this biometric technology.

[edit]Methods of Fingerprint Detection

Since the late nineteenth century, fingerprint identification methods have been used by police agencies around the world to identify both suspected criminals as well as the victims of crime. The basis of the traditional fingerprinting technique is simple. The skin on the palmar surface of the hands and feet forms ridges, so-called papillary ridges, in patterns that are unique to each individual and which do not change over time. Even identical twins (who share their DNA) do not have identical fingerprints. Fingerprints on surfaces may be described as patent or latent. Patent fingerprints are left when a substance (such as paint, oil or blood) is transferred from the finger to a surface and are easily photographed without further processing. Latent fingerprints, in contrast, occur when the natural secretions of the skin are deposited on a surface through fingertip contact, and are usually not readily visible. The best way to render latent fingerprints visible, so that they can be photographed, is complex and depends, for example, on the type of surface involved. It is generally necessary to use a ‘developer’, usually a powder or chemical reagent, to produce a high degree of visual contrast between the ridge patterns and the surface on which the fingerprint was left.

Developing agents depend on the presence of organic materials or inorganic salts for their effectiveness although the water deposited may also take a key role. Fingerprints are typically formed from the aqueous based secretions of the eccrine glands of the fingers and palms with additional material from sebaceous glands primarily from the forehead. The latter contamination results from the common human behaviors of touching the face and hair.

The resulting latent fingerprints consist usually of a substantial proportion of water with small traces of amino acids, chlorides etc mixed with a fatty, sebaceous component which contains a number of fatty acids, triglycerides etc Detection of the small proportion of reactive organic material such as urea and amino acids is far from easy.

Crime scene fingerprints may be detected by simple powders, or some chemicals applied at the crime scene; or more complex, usually chemical techniques applied in specialist laboratories to appropriate articles removed from the crime scene. With advances in these more sophisticated techniques some of the more advanced crime scene investigation services from around the world are now reporting that 50% or more of the total crime scene fingerprints result from these laboratory based techniques

Although there are hundreds of reported techniques for fingerprint detection many are only of academic interest and there are only around 20 really effective methods which are currently in use in the more advanced fingerprint laboratories around the world. Some of these techniques such as Ninhydrin, Diazofluorenone, and Vacuum Metal Deposition show quite surprising sensitivity and are used operationally to great effect. Some fingerprint reagents are specific, for example Ninhydrin or Diazo-fluorenone reacting with amino acids. Others such as ethyl cyanoacrylate polymerisation, work apparently by water based catalysis and polymer growth. Vacuum metal deposition using gold and zinc has been shown to be non-specific but detect fat layers as thin as one molecule. More mundane methods such as application of fine powders work by adhesion to sebaceous deposits and possibly aqueous deposits for fresh fingerprints. The aqueous component whilst initially sometimes making up over 90% of the weight of the fingerprint can evaporate quite quickly and most may be gone in after 24 hours. After work by Duff and Menzel on the use of Argon Ion lasers for fingerprint detection a wide range of fluorescence techniques have been introduced, primarily for the enhancement of chemically developed fingerprints but also some detection of inherent fluorescence of the latent fingerprints. The most comprehensive manual of operational methods of fingerprint development is published by the UK Home Office Scientific Development Branch http://scienceandresearch.homeoffice.gov.uk/hosdb/fingerprints-footwear-marks/ and is used widely around the world.

The International Fingerprint Research Group (IFRG) which meets biennially, consisting of members of the leading fingerprint research groups from Europe, the US, Canada, Australia and Israel leads the way in the development, assessment and implementation of new techniques for operational fingerprint detection.

One problem is the fact that the organic component of any deposited material is readily destroyed by heat, such as occurs when a gun is fired or a bomb is detonated, when the temperature may reach as high as 500°C. In contrast, the non-volatile, inorganic component of eccrine secretion remains intact even when exposed to temperatures as high as 600°C.

Within the Materials Research Centre, University of Swansea, UK [3], University of Swansea, UK, Professor Neil McMurray and Dr Geraint Williams have developed a technique that enables fingerprints to be visualised on metallic and electrically conductive surfaces without the need to develop the prints first. The technique involves the use of an instrument called a scanning Kelvin probe (SKP), which measures the voltage, or electrical potential, at pre-set intervals over the surface of an object on which a fingerprint may have been deposited. These measurements can then be mapped to produce an image of the fingerprint. A higher resolution image can be obtained by increasing the number of points sampled, but at the expense of the time taken for the process. A sampling frequency of 20 points per mm is high enough to visualise a fingerprint in sufficient detail for identification purposes and produces a voltage map in 2–3 hours. So far the technique has been shown to work effectively on a wide range of forensically important metal surfaces including iron, steel and aluminum. While initial experiments were performed on planar, i.e. flat, surfaces, the technique has been further developed to cope with severely non-planar surfaces, such as the warped cylindrical surface of fired cartridge cases. The very latest research from the department has found that physically removing a fingerprint from a metal surface, e.g. by rubbing with a tissue, does not necessarily result in the loss of all fingerprint information. The reason for this is that the differences in potential that are the basis of the visualisation are caused by the interaction of inorganic salts in the fingerprint deposit and the metal surface and begin to occur as soon as the finger comes into contact with the metal, resulting in the formation of metal – ion complexes that cannot easily be removed.

Bullet casing with an applied fingerprint

Scanning Kelvin Probe scan of the same casing with the fingerprint clearly detected. The Kelvin probe can easily cope with the 3D curvature of the bullet casing increasing the versatility of the technique.

Currently, in crime scene investigations, a decision has to be made at an early stage whether to attempt to retrieve fingerprints through the use of developers or whether to swab surfaces in an attempt to salvage material for DNA fingerprinting. The two processes are mutually incompatible, as fingerprint developers destroy material that could potentially be used for DNA analysis, and swabbing is likely to make fingerprint identification impossible.

The application of the new SKP fingerprinting technique, which is non-contact and does not require the use of developers, has the potential to allow fingerprints to be retrieved while still leaving intact any material that could subsequently be subjected to DNA analysis. The University of Swansea group hope to have a forensically usable prototype in the near future and it is intended that eventually the instrument will be manufactured in sufficiently large numbers that it will be widely used by forensic teams on the frontline.

There has recently been significant worldwide interest in the technique with articles appearing in/on BBC.co.uk[4], Sky News[5] [6], S4C news, The Daily Mail, FHM magazine, AOL, Yahoo news, Telegraph.co.uk, The Hindu, Taipei times, Sydney Morning Herald, San Francisco Gate, The Mercury (South Africa), Brisbane Courier Mail and many others. There has also been significant interest from the Home Office and a number of different police forces across the UK.

More information about the technique has been published in a number of scientific journals[7] [8].

[edit]Classifying fingerprints

Before computerization replaced manual filing systems in large fingerprint operations, manual fingerprint classification systems were used to categorize fingerprints based on general ridge formations (such as the presence or absence of circular patterns in various fingers), thus permitting filing and retrieval of paper records in large collections based on friction ridge patterns independent of name, birth date and other biographic data that persons may misrepresent. The most popular ten-print classification systems include the Roscher system, the Vucetich system, and the Henry Classification System. Of these systems, the Roscher system was developed in Germany and implemented in bothGermany and Japan, the Vucetich system was developed in Argentina and implemented throughout South America, and the Henry system was developed in India and implemented in most English-speaking countries.^[7]

In the Henry system of classification, there are three basic fingerprint patterns: Arch, Loop and Whorl.^[8] There are also more complex classification systems that further break down patterns to plain arches or tented arches.^[7] Loops may be radial or ulnar, depending on the side of the hand the tail points towards. Whorls also have sub-group classifications including plain whorls, accidental whorls, double loop whorls, peacock's eye, accidental, composite, and central pocket loop whorls.^[7]

Arch

Loop
(Right Loop)

Whorl

Arch
(Tented Arch)

[edit]Footprints

Friction ridge skin present on the soles of the feet and toes (plantar surfaces) is as unique as ridge detail on the fingers and palms (palmar surfaces). When recovered at crime scenes or on items of evidence, sole and toe impressions are used in the same manner as finger and palm prints to effect identifications. Footprint (toe and sole friction ridge skin) evidence has been admitted in U.S. courts since 1934 (People v. Les, 267 Michigan 648, 255 NW 407).

Footprints of infants, along with thumb or index finger prints of mothers, are still commonly recorded in hospitals to assist in verifying the identity of infants. Often, the only identifiable ridge detail in such impressions is from the large toe or adjacent to the large toe, due to the difficulty of recording such fine detail. When legible ridge detail is lacking, DNA is normally effective (except in instances of chimaerism) for indirectly identifying infants by confirming maternity and paternity of an infant's parents.

It is not uncommon for military records of flight personnel to include bare foot inked impressions. Friction ridge skin protected inside flight boots tends to survive the trauma of a plane crash (and accompanying fire) better than fingers. Even though the U.S. Armed Forces DNA Identification Laboratory (AFDIL) stores refrigerated DNA samples from all current active duty and reserve personnel, almost all casualty identifications are effected using fingerprints from military ID card records (live scan fingerprints are recorded at the time such cards are issued). When friction ridge skin is not available from deceased military personnel, DNA and dental records are used to confirm identity.

[edit]Lifestyle information

The secretions, skin oils and dead cells in the fingerprint contain residues of various chemicals and their metabolites present in the body. These can be detected and used for forensic purposes. For example the fingerprints of tobacco smokers contain traces of cotinine, a nicotinemetabolite; they also contain traces of nicotine itself; however that may be ambiguous as its presence may be caused by mere contact of the finger with a tobacco product. By treating the fingerprint with gold nanoparticles with attached cotinine antibodies, and then subsequently with fluorescent agent attached to cotinine antibody antibodies, a fingerprint of a smoker becomes fluorescent; non-smoker's fingerprint stays dark. The same approach is investigated to be used for identifying heavy coffee drinkers, cannabis smokers, and users of various other drugs. [9][10]

[edit]U.S. databases and compression

The FBI manages a fingerprint identification system and database called IAFIS, which currently holds the fingerprints and criminal records of over fifty-one million criminal record subjects, and over 1.5 million civil (non-criminal) fingerprint records. U.S. Visit currently holds a repository of over 50 million persons, primarily in the form of two-finger records (by 2008, U.S. Visit is transforming to a system recording FBI-standard tenprint records).

Most American law enforcement agencies use Wavelet Scalar Quantization (WSQ), a wavelet-based system for efficient storage of compressed fingerprint images at 500 pixels per inch (ppi). WSQ was developed by the FBI, the Los Alamos National Lab, and the National Institute for Standards and Technology (NIST). For fingerprints recorded at 1000 ppi spatial resolution, law enforcement (including the FBI) uses JPEG 2000instead of WSQ.

[edit]History and validity

[edit]History of fingerprinting for identification

Fingerprinting clerks, Los Angeles Police Department, 1928

Fingerprints have been found on ancient Babylonian clay tablets, seals, and pottery^[9]^[10]^[11]^[12]. They have also been found on the walls of Egyptian tombs and on Minoan, Greek, and Chinese pottery — as well as on bricks and tiles in Babylon and Rome. Some of these fingerprints were deposited unintentionally by workers during fabrication; sometimes the fingerprints served as decoration. However, on some pottery, fingerprints were impressed so deeply that they were likely intended to serve as the equivalent of a brand label.

Fingerprints were also used as substitutes for signatures. In Babylon from 1885-1913 B.C.E., in order to protect against forgery, parties to a legal contract impressed their fingerprints into the clay tablet on which the contract had been written. By 246 B.C.E., Chinese officials impressed their fingerprints in clay seals, which were used to seal documents. With the advent of silk and paper in China, parties to a legal contract impressed their handprints on the document. Sometime before 851 C.E., an Arab merchant in China, Abu Zayd Hasan, witnessed Chinese merchants using fingerprints to authenticate loans.^[13] By 702 C.E., Japan had adopted the Chinese practice of sealing contracts with fingerprints.

Although the ancient peoples probably did not realize that fingerprints could identify individuals,^[14] references from the age of the Babylonian king Hammurabi (1792-1750 B.C.E.) indicate that law officials fingerprinted people who had been arrested.^[15] In China around 300 C.E. handprints were used as evidence in a trial for theft. In 650 C.E., the Chinese historian Kia Kung-Yen remarked that fingerprints could be used as a means of authentication.^[16] In his Jami al-Tawarikh [Universal History], Persian official and physician Rashid-al-Din Hamadani (a.k.a. "Rashideddin") (1247-1318) comments on the Chinese practice of identifying people via their fingerprints: "Experience shows that no two individuals have fingers exactly alike."^[17]Supposedly, in Persia at this time, government documents were authenticated with thumbprints.^[18]

A list of significant modern dates documenting the use of fingerprints for positive identification are as follows^[19]:

1684: Nehemiah Grew (1641-1712, English physician, botanist, and microscopist) published the first paper on the ridge structure of skin of the fingers and palms.^[20] In 1685, Govard Bidloo (1649-1713, Dutch physician)^[21] and Marcello Malpighi (1628-1694, Italian physician)^[22]published books on anatomy which also illustrated the ridge structure of the fingers.
1788: Johann Christoph Andreas Mayer^[23] (1747-1801, German anatomist) recognized that fingerprints are unique to each individual.^[24]
1823: Jan Evangelista Purkyně, a professor of anatomy at the University of Breslau, published his thesis discussing 9 fingerprint patterns, but he did not mention the use of fingerprints to identify persons.^[25]
1853: Georg von Meissner (1829-1905, German anatomist) studied friction ridges.^[26]
1858: Sir William James Herschel (1833-1918, English magistrate) initiated fingerprinting in India.^[27]
1880: Dr Henry Faulds published his first paper on the subject in the scientific journal Nature in 1880.^[28] Returning to the UK in 1886, he offered the concept to the Metropolitan Police in London but it was dismissed.^[29]^[30]
1892: Sir Francis Galton published a detailed statistical model of fingerprint analysis and identification and encouraged its use in forensic science in his book Finger Prints.^[31]
1892: Juan Vucetich, an Argentine police officer who had been studying Galton pattern types for a year, made the first criminal fingerprint identification. He successfully proved Francisca Rojas guilty of murder after showing that the bloody fingerprint found at the crime scene was hers, and could only be hers.
1897: The world's first Fingerprint Bureau opened in Calcutta (Kolkata), India after the Council of the Governor General approved a committee report (on 12 June 1897) that fingerprints should be used for classification of criminal records. Working in the Calcutta Anthropometric Bureau (before it became the Fingerprint Bureau) were Azizul Haque and Hem Chandra Bose. Haque and Bose were the Indian fingerprint experts credited with primary development of the fingerprint classification system eventually named after their supervisor, Sir Edward Richard Henry.^[32]^[33]
1901: The first United Kingdom Fingerprint Bureau was founded in Scotland Yard. The Henry Classification System, devised by Sir Edward Richard Henry with the help of Haque and Bose was accepted in England and Wales.
1902: Dr. Henry P. DeForrest used fingerprinting in the New York Civil Service.
1906: New York City Police Department Deputy Commissioner Joseph A. Faurot introduced fingerprinting of criminals to the United States.

[edit]Validity of fingerprinting for identification

The validity of forensic fingerprint evidence has recently been challenged by academics, judges and the media. While fingerprint identification was an improvement over earlier anthropometric systems, the subjective nature of matching, despite a very low error rate, has made this forensic practice controversial. ^[34]

Certain specific criticisms are now being accepted by some leaders of the forensic fingerprint community, providing an incentive to improve training and procedures. Glenn Langenburg who is a Forensic Scientist, Latent Print Examiner for the Minnesota Bureau of Criminal Apprehension, is such an individual, having written an article that responds to the most active academic critics.

[edit]Criticism

The words "reliability" and "validity" have specific meanings to the scientific community. Reliability means successive tests bring the same results. Validity means that the results accurately reflect the external criteria being measured.

Although experts are often more comfortable relying on their instincts, this reliance does not always translate into superior predictive ability. For example, in the popular Analysis, Comparison, Evaluation, and Verification (ACE-V) paradigm for fingerprint identification, the verification stage, in which a second examiner confirms the assessment of the original examiner, may increase the consistency of the assessments. But while the verification stage has implications for the reliability of latent print comparisons, it does not assure their validity.(pp 12)^[5]

The few tests of validity of forensic fingerprinting have not been supportive of the method:

Despite the absence of objective standards, scientific validation, and adequate statistical studies, a natural question to ask is how well fingerprint examiners actually perform. Proficiency tests do not validate a procedure per se, but they can provide some insight into error rates. In 1995, the Collaborative Testing Service (CTS) administered a proficiency test that, for the first time, was “designed, assembled, and reviewed” by the International Association for Identification (IAI).The results were disappointing. Four suspect cards with prints of all ten fingers were provided together with seven latents. Of 156 people taking the test, only 68 (44%) correctly classified all seven latents. Overall, the tests contained a total of 48 incorrect identifications. David Grieve, the editor of the Journal of Forensic Identification, describes the reaction of the forensic community to the results of the CTS test as ranging from “shock to disbelief,” and added:
Errors of this magnitude within a discipline singularly admired and respected for its touted absolute certainty as an identification process have produced chilling and mind- numbing realities. Thirty-four participants, an incredible 22% of those involved, substituted presumed but false certainty for truth. By any measure, this represents a profile of practice that is unacceptable and thus demands positive action by the entire community.
What is striking about these comments is that they do not come from a critic of the fingerprint community, but from the editor of one of its premier publications.(pp25)^[5]

[edit]Defense

Fingerprints collected at a crime scene, or on items of evidence from a crime, can be used in forensic science to identify suspects, victims and other persons who touched a surface. Fingerprint identification emerged as an important system within police agencies in the late 19th century, when it replaced anthropometric measurements as a more reliable method for identifying persons having a prior record, often under an alias name, in a criminal record repository.^[4]

The science of fingerprint identification can assert its standing amongst forensic sciences for many reasons, including the following:

Has served all governments worldwide during the past 100 years to provide accurate identification of criminals. No two fingerprints have ever been found identical in many billions of human and automated computer comparisons. Fingerprints are the very basis for criminal history foundation at every police agency.^[4]
Established the first forensic professional organization, the International Association for Identification (IAI), in 1915.^[35]
Established the first professional certification program for forensic scientists, the IAI's Certified Latent Print Examiner program (in 1977), issuing certification to those meeting stringent criteria and revoking certification for serious errors such as erroneous identifications.^[36]
Remains the most commonly used forensic evidence worldwide — in most jurisdictions fingerprint examination cases match or outnumber all other forensic examination casework combined.
Continues to expand as the premier method for identifying persons, with tens of thousands of persons added to fingerprint repositories daily in America alone — far outdistancing similar databases in growth.
Is claimed to outperform DNA and all other human identification systems (fingerprints are said to solve ten times more unknown suspect cases than DNA in most jurisdictions).
Fingerprint identification was the first forensic discipline (in 1977) to formally institute a professional certification program for individual experts, including a procedure for decertifying those making errors. Other forensic disciplines later followed suit in establishing certification programs whereby certification could be revoked for error.^[36]

Fingerprint identification effects far more positive identifications of persons worldwide daily than any other human identification procedure. Some of the discontent over fingerprint evidence may be due to the desire to push the conclusiveness of fingerprint examinations to the same level of certitude as that of DNA analysis. DNA is probability-based inasmuch as an individual is genetically half from the mother's contribution and half from the father's contribution. These genetic contributions are passed down from generation to generation. While pattern type (arch, loops, and whorls) may be inherited, the details of the friction ridges are not. For example, it cannot be concluded that a person inherited a certain bifurcation from their mother and an ending ridge from their father as the development of these features are completely random. Further, fingerprints as an analogy of uniqueness has been widely scientifically accepted. For example, chemists often use the term "fingerprint region" to describe an area of a chemical that can be used to identify it.

Another criticism sometimes leveled at fingerprint practice is that it is a "closed discipline". However, practitioners in the scientific community are generally specialized and may not extend to other areas of science; in this respect, fingerprint scientists are no different from the rest of the scientific community. The fingerprint community asserts that it maintains the need for objectivity and continued research in the area of friction ridge analysis.

[edit]Errors in identification or processing

Below are cases of errors in fingerprint identification; however, some cases involved misfiling of fingerprints or suspect profiling which slanted interpretation, rather than faults by objective matches from fingerprint search technology.

[edit]William West

A story that some regard as apocryphal circulates about events occurring in the early 20th century when a man was spotted in the incoming prisoner line at the U.S. Penitentiary in Leavenworth, Kansas by a guard who recognized him and thought he was already in the prison population. Upon examination, the incoming prisoner claimed to be named Will West, while the existing prisoner was named William West. According to their Bertillon measurements, they were essentially indistinguishable. Only their fingerprints could readily identify them, and the Bertillon Method was discredited.

There is evidence that men named Will and William West were both imprisoned in the Federal Penitentiary in Leavenworth, Kansas, between 1903 and 1909. However, the details of the case are suspicious, especially since they differ between retells, and the story did not appear in print until 1918. Today, people familiar with the story differ on whether the story was accurate, a case of people (possibly separated twins) who bore a striking resemblance, a case of known twins, or complete fiction. The story of Will West is mentioned on page 167 of Forensic Uses of Digital Imaging by John C. Russ, with mug shots of "the two Will Wests" on page 168.

It should be noted that the West case is not a case of fingerprint error, but an error in the method of anthropometry, which the fingerprint science replaced.

[edit]Brandon Mayfield and Madrid bombing

Error in identification: Brandon Mayfield is an Oregon lawyer who was identified as a participant in the Madrid bombing based on a so-called fingerprint match by the FBI.^[37] The FBI Latent Print Unit ran the print collected in Madrid and reported a match against one of 20 fingerprint candidates returned in a search response from their IAFIS — Integrated Automated Fingerprint Identification System. The FBI initially called the match "100 percent positive" and an "absolutely incontrovertible match". The Spanish National Police examiners concluded the prints did not match Mayfield, and after two weeks identified another man who matched. The FBI acknowledged the error, and a judge released Mayfield after two weeks in May 2004.^[37] In January of 2006, a U.S. Justice Department report was released which faulted the FBI for sloppy work but exonerated them of more serious allegations. The report found that misidentification was due to misapplication of methodology by the examiners involved: Mayfield is an American-born convert^[37] to Islam and his wife is an Egyptian immigrant,^[37] not factors that affect fingerprint search technology.

On 29 November 2006, the FBI agreed to pay Brandon Mayfield the sum of US$2 million.^[37] The judicial settlement allows Mayfield to continue a suit regarding certain other government practices surrounding his arrest and detention. The formal apology stated that the FBI, which erroneously linked him to the 2004 Madrid bombing through a fingerprinting mistake, had taken steps to "ensure that what happened to Mr. Mayfield and the Mayfield family does not happen again."^[37]

[edit]René Ramón Sánchez

Error in "Clerical" processing. René Ramón Sánchez, a legal Dominican Republic immigrant was booked on a DUI charge on July 15, 1995. He had his fingerprints affixed on a card containing the name, Social Security number and other data for Leo Rosario, who was being processed at the same time. Leo Rosario was arrested for selling cocaine to an undercover police officer. In August of 1998, Sanchez was stopped again by police officers, for DUI in Manhattan. René was then identified as Leo Rosario on October 11, 2000, while returning from a visit to relatives in the Dominican Republic. He was arrested at Kennedy International Airport. Even though he did not match the physical description of Rosario, the fingerprints were considered more reliable.^[38]

[edit]Shirley McKie

Error in identification. Shirley McKie was a police detective in 1997 when she was accused of leaving her thumb print inside a house inKilmarnock, Scotland where Marion Ross had been murdered. Although detective constable McKie denied having been inside the house, she was arrested in a dawn raid the following year and charged with perjury. The only evidence was the thumb print allegedly found at the murder scene. Two American experts testified on her behalf at her trial in May 1999 and she was found not guilty. The Scottish Criminal Record Office(SCRO) would not admit any error, but Scottish first minister Jack McConnell later said there had been an "honest mistake".

On February 7, 2006, McKie was awarded £750,000 in compensation from the Scottish Executive and the SCRO.[11] Controversy continues to surround the McKie case with calls for the resignations of Scottish ministers and for either a public or a judicial inquiry into the matter.[12]

[edit]Stephan Cowans

Error in identification. Stephan Cowans (d. 2007-10-25)^[39] was convicted of attempted murder in 1997 after he was accused of the shooting of apolice officer while fleeing a robbery in Roxbury, Massachusetts. He was implicated in the crime by the testimony of two witnesses, one of whom was the victim. The other evidence was a fingerprint on a glass mug that the assailant drank water from, and experts testified that the fingerprint belonged to him. He was found guilty and sent to prison with a sentence of 35 years. While in prison he earned money cleaning up biohazards until he could afford to have the evidence tested for DNA. The DNA did not match his, but he had already served six years in prison before he was released.

[edit]Privacy issues

[edit]Fingerprinting of children

Further information: Biometrics in schools

Various schools have implemented fingerprint locks or registered children's fingerprints. This happened in the United Kingdom (fingerprint lock in the Holland Park School in London,^[40] databases, etc.),^[41] in Belgium (école Marie-José in Liège^[42]^[43]), in France, in Italy, etc. The NGOPrivacy International has alerted that tens of thousands of UK school children were being fingerprinted by schools, often without the knowledge or consent of their parents.^[44] In 2002, the supplier Micro Librarian Systems, which use a technology similar to US prisons and German military, estimated that 350 schools through-out Britain were using such systems, to replace library cards.^[44] In 2007, it is estimated that 3 500 schools (ten times more) are using such systems.^[45] Under the Data Protection Act (DPA), schools in the UK do not have to ask parental consent for such practices. Parents opposed to such practices may only bring individual complaints against schools.^[46]

In Belgium, this practice gave rise to a question in Parliament on February 6, 2007 by Michel de La Motte (Humanist Democratic Centre) to the Education Minister Marie Arena, who replied that they were legal insofar as the school did not use them for external purposes nor to survey the private life of children.^[47] Such practices have also been used in France (Angers, Carqueiranne college in the Var — the latter won the Big Brother Award of 2005, etc.) although the CNIL, official organisation in charge of protection of privacy, has declared them "disproportionate."^[48]

In March 2007, the British government was considering fingerprinting of children aged 11 to 15 as part of new passport and ID card (the latter having been recently implemented in the UK), also lifting opposition for privacy concerns. All fingerprints taken would be cross-checked against prints from 900,000 unsolved crimes. Shadow Home secretary David Davis called the plan "sinister."^[45]

Recently, serious concerns about the security implications of using conventional biometric templates in schools have been raised by a number of leading IT security experts, including Kim Cameron, architect of identity and access in the connected systems division at Microsoft, who cites research by Cavoukian and Stoianov^[49] to back up his assertion that "it is absolutely premature to begin using 'conventional biometrics' in schools".

Biometric vendors claim benefits to schools such as improved reading skills, decreased wait times in lunch lines and increased revenues.^[50]They do not cite independent research to support this. Educationalist Dr Sandra Leaton Gray of Homerton College, Cambridge stated in early 2007 that "I have not been able to find a single piece of published research which suggests that the use of biometrics in schools promotes healthy eating or improves reading skills amongst children... There is absolutely no evidence for such claims".

The Ottawa Police in Canada advised parents who fear that their children may be kidnapped to have their fingerprints taken.^[51]

[edit]Other uses

[edit]Locks and other applications

In the 2000s, electronic fingerprint readers have been introduced for security applications such as identification of computer users (log-in authentication). However, early devices have been discovered to be vulnerable to quite simple methods of deception, such as fake fingerprints cast in gels. In 2006, fingerprint sensors gained popularity in the notebook PC market. Built-in sensors in ThinkPads, VAIO laptops, and others also double as motion detectors for document scrolling, like the scroll wheel.

Another recent use of fingerprints in a day-to-day setting has been the increasing reliance on biometrics in schools where fingerprints and, to a lesser extent, iris scans are used to validate electronic registration, cashless catering, and library access. This practice is particularly widespread in the UK, where more than 3500 schools currently use such technology, though it is also starting to be adopted in some states in the US.

[edit]Fingerprints in other species

Some other animals, including many primates, koalas, and fishers have their own unique prints.^[52] According to one study, even with an electron microscope, it can be quite difficult to distinguish between the fingerprints of a koala and a human.^[53]

[edit]Fingerprinting in fiction

The 1985 Granada TV adoption of The Adventure of the Final Problem, an 1893 Sherlock Holmes short story set in 1891, has a plot hole in Holmes's use of the Bertillon criminal ID system, in which he uses fingerprints to trap Moriarty's agents and recover the Mona Lisa. The real Bertillon system did not use fingerprints. Bertillon added four spaces for fingerprints on his identification cards by 1900 because of fingerprinting's growing popularity, but the identification cards were still organized based on anthropometric measurements.
In The Norwood Builder, an 1903 Sherlock Holmes short story set in 1894, the discovery of a bloody fingerprint helps Holmes expose the real criminal and free his client.

WEB APPLICATION DEVOLOPMENT

2009-04-29T08:28:00.000-07:00

MODULE II

1. What is JUnit

JUnit is an open source testing framework that is used to develop and execute unit tests in Java. It was written by Erich Gamma, one of four notable authors, who wrote the classic book Design Patterns; and Kent Beck, who has also written extensively about object development and first described the eXtreme Programming (XP) software development process.

JUnit features include:

• Assertions for testing expected results

• Test fixtures for sharing common test data

• Test suites for easily organizing and running tests

• Graphical and textual test runners

2. What is a test case

A test case is a class which holds a number of test methods. For example if you want to test some methods of a class Book you create a class BookTest which extends the JUnit TestCase class and place your test methods in there.

3. How you write and run a simple test

i. Create a subclass of TestCase:

public class BookTest extends TestCase{

//..

}

ii. Write a test method to assert expected results on the object under test:

public void testCollection() {

Collection collection = new ArrayList();

assertTrue(collection.isEmpty());

}

iii. Write a suite() method that uses reflection to dynamically create a test suite containing all the testXXX() methods:

public static Test suite(){

return new TestSuite(BookTest.class);

}

iv. Activate the JUnit view in Eclipse (Window > Show View > Other.. > Java > JUnit).

v. Right click on the subclass of TestCase and choose Run > JUnit Test to run the test.

4. What is test fixture

A test fixture is useful if you have two or more tests for a common set of objects. Using a test fixture avoids duplicating the test code necessary to initialize and cleanup those common objects for each test.

To create a test fixture, define a setUp() method that initializes common object and a tearDown() method to cleanup those objects. The JUnit framework automatically invokes the setUp() method before a each test is run and the tearDown() method after each test is run.

The following test uses a test fixture:

public class BookTest2 extends TestCase {

private Collection collection;

protected void setUp() {

collection = new ArrayList();

}

protected void tearDown() {

collection.clear();

}

public void testEmptyCollection(){

assertTrue(collection.isEmpty());

}

5. Dynamic and static way of running single tests

JUnit supports two ways (static and dynamic) of running single tests.

In static way you override the runTest() method inherited form TestCase class and all the desired test case. A convenient way to do this is with an anonymous inner class.

Note: Each test must be given a name, so you can identify it if it fails.

TestCase test = new BookTest("equals test") {

public void runTest() {

testEquals();

}

};

The dynamic way to create a test case to be run uses reflection to implement runTest. It assumes the name of the test is the name of the test case method to invoke. It dynamically finds and invokes the test method. The dynamic way is more compact to write but it is less static type safe. An error in the name of the test case goes unnoticed until you run it and get a NoSuchMethodException. We leave the choice of which to use up to you.

TestCast test = new BookTest("testEquals");

6. What is a TestSuite

If you have two tests and you'll run them together you could run the tests one at a time yourself, but you would quickly grow tired of that. Instead, JUnit provides an object TestSuite which runs any number of test cases together. The suite method is like a main method that is specialized to run tests.

Create a suite and add each test case you want to execute:

public static void suite(){

TestSuite suite = new TestSuite();

suite.addTest(new BookTest("testEquals"));

suite.addTest(new BookTest("testBookAdd"));

return suite;

}

Since JUnit 2.0 there is an even simpler way to create a test suite, which holds all testXXX() methods. You only pass the class with the tests to a TestSuite and it extracts the test methods automatically.

Note: If you use this way to create a TestSuite all test methods will be added. If you do not want all

test methods in the TestSuite use the normal way to create it.

Example:

public static void suite(){

return new TestSuite(BookTest.class);

}

****A little example****(pls try it in eclipse)

Create a new Java project named JUnitExample.

Add a package de.laliluna.tutorial.junitexample where you place the example classes and a package test.laliluna.tutorial.junitexample where you place your test classes.

The class Book

Ø Create a new class Book in the package de.laliluna.tutorial.junitexample.

Ø Add two properties title of type String and price of type double.

Ø Add a constructor to set the two properties.

Ø Provide a getter- and setter-method for each of them.

Ø Add a method trunk for a method equals(Object object) which checks if the object is an instance of the class Book and the values of the object are equal. The method return a boolean value.

Ø Note: Do not write the logic of the equals(..) method, we do it after finish creating the test method.

The following source code shows the class Book.

public class Book {

private String title;

private double price;

/**

* Constructor

* @param title

* @param price

public Book(String title,

double price) {

this.title = title;

this.price = price;

}

/**

* Check if an object is an instance of book

* and the values of title and price are equal

* then return true, otherwise return false

public boolean equals(Object object) {

return false;

}

public double getPrice() {

return price;

}

public void setPrice(double price) {

this.price = price;

}

public String getTitle() {

return title;

}

public void setTitle(String title) {

this.title = title;

}

The test case BookTest

§ Create a new test case BookTest in the package test.laliluna.tutorial.junitexample

§ Right click on the package and choose New > JUnit Test Case.

§ In the wizard choose the methods stubs setUp(), tearDown() and constructor().

The following source code shows the class BookTest

public class BookTest extends TestCase {

/**

* setUp() method that initializes common objects

protected void setUp() throws Exception {

super.setUp();

}

/**

* tearDown() method that cleanup the common objects

protected void tearDown() throws Exception {

super.tearDown();

}

/**

* Constructor for BookTest.

* @param name

public BookTest(String name) {

super(name);

}

Now we want to write a test for the equals(..) method of the class Book. We provide three private properties, book1, book2 and book3 of type Book.

private Book book1;

private Book book2;

private Book book3;

Within the setUp() method we initializes the three properties with some values. Property book1 and book3 are the same.

protected void setUp() throws Exception {

super.setUp();

book1 = new Book("ES", 12.99);

book2 = new Book("The Gate", 11.99);

book3 = new Book("ES", 12.99);

}

Within the tearDown() method we cleanup the properties:

protected void tearDown() throws Exception {

super.tearDown();

book1 = null;

book2 = null;

book3 = null;

}

Now, add a test method testEquals() to the test case. Within the method we use the assertFalse() method of the JUnit framework to test if the return-value of the equals(..) method is false, because book1 and book2 are not the same. If the return-value is false the logic of the equals() method is correct, otherwise there is a logical problem while comparing the objects. We want to test if the method compares the objects correctly by using the assertTrue() method. Book1 and Book3 are the same, because both are an instance of the class Book and have the same values.

The following source code shows the testEquals() method:

public void testEquals(){

assertFalse(book2.equals(book1));

assertTrue(book1.equals(book1));

}

Writing the logic of the equals() method

We have finished the test and now we can add the logic to the equals() method stub. Open the class Book and add the logic to the equals() method. First we check if the object given by the method is an instance of Book. Then compare the properties title and price, if they are equal return true.

public boolean equals(Object object) {

if (object instanceof Book) {

Book book = (Book) object;

return getTitle().equals(book.getTitle())

&& getPrice() == book.getPrice();

}

return false;

}

Create the suite() method

In order to run the test method testEquals() add a method suite() to the class BookTest.

Within the method create a new instance of TestSuite and use the method addTest(..) to add a

test. Here we use the dynamically way to add a test to a TestSuite.

The method looks like the follows:

public static Test suite(){

TestSuite suite = new TestSuite();

suite.addTest(new BookTest("testEquals"));

return suite;

}

Run the test

After finishing all test methods we want to run the JUnit test case. Right mouse button on the class BookTest and choose Run As > JUnit Test.

On the JUnit view (Menu Windows -> show view) of Eclipse you can see how many runs, errors and failures occurred.

7. Explain WebSphere Test Environment benefits

a. Standalone all-in-one testing.

b. No dependency on WebSphere Application Server installation or availability.

c. No dependency on an external database even when entity bean support is required.

d. Provides the ability to debug running server-side code.

e. Supports configuring multiple Web applications.

f. Supports multiple servers that can be configured and run at the same time.

g. Provides access to the profiling feature that is available in the Application Developer.

h. Provides the ability to version Server Tools server configurations.

i. Provides an EJB test client.

j. Provides access to the WebSphere Application Server Administration Client.

8. What is Unit testing

Unit tests are informal tests that are generally executed by the developers of the application code. They are often quite low-level in nature, and test the behavior of individual software components such as individual Java classes, servlets or EJBs.

9. Write a short note on Benefits of a unit testing framework

Ø Making it easier to write tests

Ø Making it easier to run tests

Ø Making it easier to rerun a test after a change

Ø Consistency: Because every developer is using the same framework, all of your unit tests will work in the same way, can be managed in the same way, and report results in the same format.

Ø Maintenance: Because a framework has already been developed and is probably already in use in a number of projects you spend less time maintaining your testing code.

Ø Ramp-up time: If you select a popular testing framework, you may find that new developers coming into your team are already familiar with the tools and concepts involved.

Ø Automation: A framework may offer the ability to run tests unattended, perhaps as part of a daily or nightly build.

Reference :

Chapter 20 Testing Web Applications

Software Engineering: A Practitioner’s Approach, 6th edition by Roger S. Pressman

DS QUESTIONS

2009-04-29T08:27:00.000-07:00

Transparency issues associated with DS
Explain Tunneling with example
Why architecture models is important in the DS design
Why threads are important for DS
IP multicasting suffer omission failure, how
How objects are communicated in the DS
Discuss each of tasks of encapsulation, concurrent processing, protection, name resolution in the case of an Operating system
What are the characteristics of a distributed file system
Explain some limitations of flat transaction
Explain sequential consistency
What is middleware? What do we expect it to solve? Illustrate with CORBA
Diff b/w bridge, router & gateway
Why heterogeneity unavoidable in many DS
Why is there no explicit data typing CORBA CDR
Main characteristics of distributed event based system
Compare monolithic kernels and micro kernels
Compare serialized invocation and concurrent invocation
Explain flat file service operations
Explain two phase commit protocol
Explain deadlocks in a DS with examples
Give four examples of resources to be shared in DS
What is meant by internetworking? What are the main issues in internet working
Why is scalability an important feature in the design of a DS
What are the major issues associated relating to UDP datagram communication
Compare may be invocation semantics and at-least-once invocation semantics in RMI invocation
Explain how the OS help the middleware layer to provide efficient remote invocation mechanisms
Explain how public key cryptography can be used for DS
Explain how transparency is major requirement in DS
What is nested transactions and what is their role in a DS
How replication enhance the service in DS
Define DS
What is resource sharing and its importance
Explain the relevance of internet protocol in DS
What is API for internet protocol
How IPC achieved in a time-sharing system
Explain the features of a DS
What is multicast address allocation
Explain concurrency control
What is fragmentation and replication in distributed system
Define fault-tolerant service
Main difficulties in the design and construction of distributed system
Three eg of DS
Short note on resource management in DS
Various types of Network
Event ordering
Why stateless servers used in the distributed applications
Location transparency ,eg
Essential properties of required for transaction
Problems associated with file replication

Essay

Module 1

Major issues in the design of DS
Event ordering in DS, eg
Illustrate the function of each layer in a protocol suite
Describe client-server model
Design requirements for DS
Compare synchronous and Asynchronous DS
Diff failures in DS
Explain IP version 6. How this migrate from IP 4
Compare the main features of TCP and UDP
Explain routing using an algorithm
Openness of the computer system is a major characteristics in DS design why
Major n/w issues for a DS design
The address resolution module is responsible for address converting ,how
Explain tunneling in n/w system
How internetworking can be done? eg
How communication is done in Mobile IP
Explain the features of a DS
Architectural model and functional model differ
Major diff b/w network OS and distributed OS
Explain various classes of distributed topologies
Explain workstation server model and processor pool model in distributed systems
Explain the following n/w protocols : CSMA/CD , Token Ring

Module 2

1. How can we implement group communication

2. What are the advantages of using multicasting faculty in a DS

3. Briefly explain multicast address allocation for temporary and permanent groups

4. How garbage collection is done in DS

5. Explain OS layer

6. How the security techniques can be implemented in DS

7. How thread can be used in client and server process

8. How remote object referenced in languages such as CORBA and JAVA

9. Explain events and notifications with eg

10. Explain external data representation and marshalling with eg

11. Explain the OS architecture

12. The thread operation are most significant in cost explain. Do page fault present a problem for user level thread implementation

13. Briefly explain the IPC in an operating system

14. Explain major design issues for RNI

15. Describe a scenario in which a client could receive a replay from an earlier call

16. Define the semantics for and design a protocol for a group form of request replay interaction, for eg using IP multicast

17. Explain the security policy in multiuser OS

18. Describe any security policy with eg

19. Discuss extended data representation and marshalling

20. Explain relative advantage of using and multiple servers for implementing service

21. What are threads and process? Explain the issues in designing a “Thread Package”

22. Explain the term “Process Migration” and its advantages

23. Short notes on: One-to-many communication, Process and Threads

24. Explain the protection models

25. Explain the concepts of security and integrity

26. Explain how RFC is implementation.

27.

Module 3

1. Explain major design requirement of distributed file system

2. Compare nested and flat distribution model

3. Explain system model

4. Explain the enhancements in AFS

5. Nested transactions

6. ACID properties

7. Optimistic concurrency control and timestamps

8. Compare sun network file system and Andrew file system

9. Explain concurrency control in DS

10. Explain Group communication

11. Explain fault-tolerant service in DS

12. Why should UFIDs be unique across all possible file system? How is uniqueness for UFIDs ensured?

13. Which features of the AFS design make it more scalable than NFS? What are the limits on its scalability?

14. Explain SUN Network file system and its enhancements

15. Compare linearizability and sequential consistency and why the latter is more practical to implement

16. Explain DS using two phase locking

17. What are the major design issues in distributed file system

18. What are synchronization and concurrency issues in a distributed systems

19. Explain significance of a fault-tolerant service with fragmented and replicated data system

20. What are the various services provided by distributed file system

21. Explain the semantics and implementation of Andrew File System

22. Explain distributed dead lock prevention

UNIX QUESTION

2009-04-29T08:26:00.000-07:00

1. What are the major feature of the unix operating system

2. How can you use “cat” to create a file “f1” consisting of keyword input sandwiched between two files f1 and f2

3. What is a filter? What is its advantage

4. What is the difference between a process and a program

5. Explain shell function with an example

6. Explain Bourne shell variable

7. How can you, as a user of unix, modify the priority of your process

8. What is the relationship between the priorities of kernel process and user process

9. Explain the following unix tools a)grep b)tr c)awk

10. Define and describe the following terms with reference to the unix operating system a) kernel b) utilities c) shell d)editor

11. Explain how files are organized in unix giving an example with the help of a tree diagram

12. Give the syntax and compare grep, fgrep and egrep. Explain with examples

13. What is meant by standard input, standard output and standard error? Explain redirection and pipes with examples

14. Explain the following commands with examples a) ls b)mail c)sed

15. Where is a file stored in unix

16. Can the directory be also called a file? If not, why? If so, what are its contents?

17. What is a filter? What is its advantage?

18. A file has got a permission 756(octal). What protection does it really have?

19. Explain rm command with its options

20. What is the output of the commands ls- l /dev/

21. Explain the commands related to the file comparison

22. What is the difference between absolute and relative pathname of the unix file?

23. What is the output of “who” and “ps” commands?

24. Discuss the internal and external commands

25. Why unix OS is called platform independent and portable

26. What are the different types of unix os version? Explalin

27. Explain the working of commands interpreter in unix

28. What are the function of kernel in unix

29. What are the different shells built in with unix OS

30. Write the features of unix operating system

31. What is meant kernel

32. Explain how copy operation can be performed , in unix, from a directory to another directory

33. Explain how a mail messages is created and sent

34. Writes notes on emacs

35.

What are the major features of unix operating system
Present the overall structure of the unix operating system
Explain any one editor in the unix operating system
Explain the structure of unix OS with the help of neat diagram
Explain the file structure of unix OS. Give examples of each types of files and show the hierarchical structure
Write notes on the following commands a)ls with all its option/switches b)cal c)cp d) grep e)awk

Module 1

With the help of neat sketch explain the organization of unix OS
Explain the file structure of unix
Write notes on the following unix commands a)banner b)cancel c)stty d) tail e)wc

Module 2

Name the different editors built-in with unix operating system? Explain how the text file “Myfile” can be created using VI editor. Show how

a) One character can be shifted to right from left

b) One line can be deleted

c) One word can be substituted with another

Module 3

1. Explain the following as far as shell programming is concerned

a) What is meant by Meta Characters?

b) Arithmetic operation

c) Logical Operation

2. Write a shell program to find the factorial of n

Module 6 Internetworking Version 2 CSE IIT, Kharagpur Lesson 2 Internet Protocol (IP)

2009-04-29T08:22:00.000-07:00

Explain the relationship between TCP/IP and OSI model

•

Explain different classes of IP addresses

•

Explain the concept of subnetting and subnet masking

•

Explain the ARP/RARP protocol

•

Explain fragmentation and reassembly

•

Explain the ICMP protocols

•

State the key features of IPv6

6.2.1 Introduction

In the previous lesson we have discussed various devices required for internetworking. In addition to these devices, several protocols are required to provide necessary functionality for internetworking. The software that provide these protocols is known as Transmission Control Protocol/Internet Protocol (TCP/IP). TCP/IP acts as a glue to link different types of LAN and WAN to provide Internet, a single integrated network for seamless communication. The IP provides unreliable, connectionless best-effort datagram delivery service, whereas TCP provides reliable, efficient and cost-effective end-to-end delivery of data. The relationship between TCP/IP and the OSI model is shown in Fig. 6.2.1. This lesson introduces the IP protocol and various issues related to it.

6.2.2 Addressing

To send a packet from a source node to a destination node correctly through a network, the packet must contain enough information about the destination address. It is also common to include the source address, so that retransmission can be done, if necessary. The addressing scheme used for this purpose has considerable effect on routing.

There are two possible approaches used for addressing; flat and hierarchical. In flat addressing every possible node is assigned a unique number. When a new node is added to the network, it must be given an address within the allowed address range. Addressing used in Ethernet is an example of flat addressing, where addresses (48-bits long) are allocated centrally, blocks of addresses are apportioned to manufactures, so that no two devices in the world will have the same address. Flat addressing has the advantage that if a node is moved from one location to another, it can retain its unique address.

Version 2 CSE IIT, Kharagpur

Figure 6.2.1 Relationship between the TCP/IP and the OSI model

In hierarchical addressing, each address consists of a number of fields; as each field is inspected, the packet is taken nearer to the destination. This is very similar to the addressing used in postal system. A significant advantage of hierarchical addressing is that it is possible to relate a hierarchical address structure to the topology of the network, so that routing is simplified. This scheme has the disadvantage that if a host moves from one location to another, a new address needs to be allocated to it, in the same manner that an address change is required as we change house.

6.2.2 IP Addressing

Every host and router on the internet is provided with a unique standard form of network address, which encodes its network number and host number. The combination is unique; no two nodes have the same IP addresses. The IP addresses are 32-bit long having the formats shown in Fig 6.2.2. The three main address formats are assigned with network addresses (net id) and host address (host id) fields of different sizes. The class A format allows up to 126 networks with 16 million hosts each. Class B allows up to 16,382 networks with up to 64 K hosts each. Class C allows 2 million networks with up to 254 hosts each. The Class D is used for multicasting in which a datagram is directed to multiple hosts. Addresses beginning with 11110 are reserved for future use. Network addresses are usually written in dotted decimal notation, such as 126.12.15.220, where each byte is written in decimal number corresponding to the binary value. Figure 6.2.3 illustrates how the dotted decimal representation is obtained for a particular IP address in binary form. Range of IP addresses for different classes is given in Fig. 6.2.4. Some IP addresses, which are used in special situations such as the same host, a host the same network, broadcast on the same network, broadcast on a distant network, or loopback are given in Fig. 6.2.5. This approach of representing IP addresses in terms of classes is known as classful addressing. In mid 90’s another approach known as classlees Version 2 CSE IIT, Kharagpur

addressing has been proposed, which may supersede the existing classful addressing approach in future.

Figure 6.2.2 IP address formats

Figure 6.2.3 Dotted decimal representation

Version 2 CSE IIT, Kharagpur

Figure 6.2.4 Dotted decimal notation of the IP addresses

Figure 6.2.5 Special IP addresses

6.2.3 Subnetting

To filter packets for a particular network, a router uses a concept known as masking, which filters out the net id part (by ANDing with all 1’s) by removing the host id part (by ANDing with all 0’s). The net id part is then compared with the network address as shown in Fig. 6.2.6. All the hosts in a network must have the same network number. This property of IP addressing causes problem as the network grows. To overcome this problem, a concept known as subnets is used, which splits a network into several parts for internal use, but still acts like a single network to the outside world. To facilitate routing, a concept known as subnet mask is used. As shown in Fig. 6.2.7, a part of hostid is used as subnet address with a corresponding subnet mask. Subnetting reduces router table space by creating a three-level hierarchy; net id, subnet id followed by hosted.

Version 2 CSE IIT, Kharagpur

Figure 6.2.6 Masking with the help of router

Figure 6.2.7 Subnet masking with the help of router

6.2.4 Network Address Translation (NAT)

With the increasing number of internet users requiring an unique IP address for each host, there is an acute shortage of IP addresses (until everybody moves to IPV6). The Network Address Translation (NAT) approach is a quick interim solution to this problem. NAT allows a large set of IP addresses to be used in an internal (private) network and a handful of addresses to be used for the external internet. The internet authorities has set aside three sets of addresses to be used as private addresses as shown in Table 6.2.1. It may be

Version 2 CSE IIT, Kharagpur

noted that these addresses can be reused within different internal networks simultaneously, which in effect has helped to increase the lifespan of the IPV4. However, to make use of the concept, it is necessary to have a router to perform the operation of address translation between the private network and the internet. As shown in Fig. 6.2.8, the NAT router maintains a table with a pair of entries for private and internet address. The source address of all outgoing packets passing through the NAT router gets replaced by an internet address based on table look up. Similarly, the destination address of all incoming packets passing through the NAT router gets replaced by the corresponding private address, as shown in the figure. The NAT can use a pool of internet addresses to have internet access by a limited number of stations of the private network at a time.

Table 6.2.1 Addresses for Private Network

Range of addresses

Total number

10.0.0.0 to 10.255.255.255

224

172.16.0.0 to 172.31.255.255

220

192.168.0.0 to 192.168.255.255

216

Figure 6.2.8 NAT Address translation

6.2.5 Address Resolution Protocol (ARP)

It may be noted that the knowledge of hosts’ IP address is not sufficient for sending packets, because data link hardware does not understand internet addresses. For example, in an Ethernet network, the Ethernet controller card can send and receive using 48-bit Ethernet addresses. The 32-bit IP addresses are unknown to these cards. This requires a mapping of the IP addresses to the corresponding Ethernet addresses. This mapping is accomplished by using a technique known as Address Resolution Protocol (ARP).

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One possible approach is to have a configuration file somewhere in the system that maps IP addresses onto the Ethernet addresses. Although this approach is straightforward, maintaining an up-to0-date table has a high overhead on the system. Another elegant approach is to broadcast packet onto the Ethernet asking “who owns the destination IP address?”. The destination node responds with its Ethernet address after hearing the request. This protocol of asking the question and getting the reply is called ARP (Addressing Resolution Protocol), which is widely used. ARP is a dynamic mapping approach for finding a physical address for a known IP address. It involves following two basic steps as shown in Fig. 6.2.9.

•

An ARP request is broadcast to all stations in the network

• An ARP reply is an unicast to the host requesting the mapping

(a)

(b)

Figure 6.2.9 (a) ARP request with a broadcast to all the stations and

(b) ARP response is a unicast only to the requesting host

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Various optimizations are commonly used to improve the efficiency of the ARP protocol. One possible approach is to use cache memory to hold the recently acquired frame containing the physical address. As a consequence, no broadcasting is necessary in near future. Figure 6.2.10 shows how an ARP packet is encapsulated into the data field of a MAC frame.

Reverse ARP (RARP)

The TCP/IP protocols include another related protocol known as reverse ARP, which can be used by a computer such as a diskless host to find out its own IP address. It involves the following steps:

•

Diskless host A broadcasts a RARP request specifying itself as the target

•

RARP server responds with the reply directly to host A

• Host A preserves the IP address in its main memory for future use until it reboots

Figure 6.2.10 An ARP packet is encapsulated directly into the data field a MAC frame

6.2.6 IP Datagram

As we have mentioned earlier, IP is an unreliable and connectionless best-effort delivery service protocol. By best effort we mean that there is no error and flow control. However, IP performs error detection and discards a packet, if it is corrupted. To achieve reliability, it is necessary to combine it with a reliable protocol such as TCP. Packets in IP layer are called datagrams. The IP header provides information about various functions the IP performs. The IP header format is shown in Fig. 6.2.11. The 20 to 60 octets of header has a number of fields to provide:

•

Source and destination IP addresses

•

Non transparent fragmentation

•

Error checking

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•

Priority

•

Security

•

Source routing option

•

Route Recording option

•

Stream identification

•

Time stamping

Figure 6.2.11 IP packet format

A brief description of each of the fields are given below:

•

VER (4 bits): Version of the IP protocol in use (typically 4).

•

HLEN (4 bits): Length of the header, expressed as the number of 32-bit words. Minimum size is 5, and maximum 15.

•

Total Length (16 bits): Length in bytes of the datagram, including headers. Maximum datagram size is (216) 65536 bytes.

•

Service Type (8 bits): Allows packet to be assigned a priority. Router can use this field to route packets. Not universally used.

•

Time to Live (8 bits): Prevents a packet from traveling forever in a loop. Senders sets a value, that is decremented at each hop. If it reaches zero, packet is discarded.

•

Protocol: Defines the higher level protocol that uses the service of the IP layer

•

Source IP address (32 bits): Internet address of the sender.

•

Destination IP address (32 bits): Internet address of the destination.

•

Identification, Flags, Fragment Offset: Used for handling fragmentation.

•

Options (variable width): Can be used to provide more functionality to the IP datagram

•

Header Checksum (16 bits):

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Covers only the IP header.

Steps:

Header treated as a sequence of 16-bit integers

The integers are all added using ones complement arithmetic

o Ones complement of the final sum is taken as the checksum

Datagram is discarded in case of mismatch in checksum values

6.2.7 Multiplexing and Demultiplexing

IP datagram can encapsulate data from several higher-level protocols such as TCP, UDP, ICMP, etc. The Protocol field in the datagram specifies the final destination protocol to which IP datagram to be delivered. When the datagram arrives at the destination, the information in this field is used to perform demultiplex the operation. The multiplexing and demultiplexing operations are shown in Fig. 6.2.12.

Figure 6.2.12 Multiplexing and demultiplexing in the IP layer

6.2.8 Fragmentation and Reassembly

Each network imposes a limit on maximum size, known as maximum transfer unit (MTU) of a packet because of various reasons. One approach is to prevent the problem to occur in the first place, i.e. send packets smaller than the MTU. Second approach is to deal with the problem using fragmentation. When a gateway connects two networks that have different maximum and or minimum packet sizes, it is necessary to allow the gateway to break packets up into fragments, sending each one as an internet packet. The technique is known as fragmentation. The following fields of an IP datagram are related to fragmentation:

•

Identification: A16-bit field identifies a datagram originating from the source host.

• Flags: There are 3 bits, the first bit is reserved, the second bit is do not fragment bit, and the last bit is more fragment bit.

• Fragmentation offset: This 13-bit field shows the relative position of the segment with respect to the complete datagram measured in units of 8 bytes.

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Figure 6.2.13 shows a fragmentation example, where a packet is fragmented into packets of 1600 bytes. So, the offset of the second fragmented packet is 1600/8 = 200 and the offset of the third fragmented packet is 400 and so on.

The reverse process, known as reassembly, which puts the fragments together, is a more difficult task. There are two opposing strategies for performing the re-assembly. In the first case, the fragmentation in one network is made transparent to any subsequent networks. This requires that packets to be reassembled before sending it to subsequent networks as shown in Fig. 6.2.14(a). This strategy is used in ATM. As re-assembly requires sufficient buffer space for storage of all the fragments, this approach has large storage overhead. To overcome this problem in the second strategy, re-assembly is done only at the ultimate destination. This approach does not require large buffer but additional fields are to be added to each packet for independent addressing and to indicate the fragment number as shown in Fig. 6.2.14(b).

Figure 6.2.13 Fragmentation example

(a)

. (b)

igure 6.2.14 (a) Transparent Fragmentation (ATM),

(b) Nontransparent fragmentation (IP)

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6.2.9 ICMP

To make efficient use of the network resources, IP was designed to provide unreliable and connectionless best-effort datagram delivery service. As a consequence, IP has no error-control mechanism and also lacks mechanism for host and management queries. A companion protocol known as Internet Control Message Protocol (ICMP), has been designed to compensate these two deficiencies. ICMP messages can be broadly divided into two broad categories: error reporting messages and query messages as follows.

•

Error reporting Messages: Destination unreachable, Time exceeded, Source quench, Parameter problems, Redirect

• Query: Echo request and reply, Timestamp request and reply, Address mask request and reply

The frame formats of these query and messages are shown in Fig. 6.2.15.

Figure 8.2. .ICMP Query and Message Formats

Figure 6.2.15 ICMP message formats

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6.2.10 IPV6

The network layer that is present in use in commonly referred to as IPv4. Although IPv4 is well designed and has helped the internet to grow rapidly, it has some deficiencies, These deficiencies has made it unsuitable for the fast growing internet. To overcome these deficiencies, Internet Protocol, Version 6 protocol has been proposed and it has evolved into a standard. Important features of IPv6 are highlighted below:

•

IPv6 uses 128-bit address instead of 32-bit address to provide larger address space

• Uses more flexible header format, which simplifies and speeds up the routing process

• Basic header followed by extended header

• Resource Allocation options, which was not present in IPv4

• Provision of new/future protocol options

• Support for security with the help of encryption and authentication

•

Support for fragmentation at source

Review Questions

Q1.

Fill in the blanks :

(a)

Two possible addressing techniques are _______ addressing and _________ addressing.

(b)

Ethernet address is an example of ________ addressing while IP address is an example of __________ addressing.

(c)

The Class C address class can have _____ networks and about _____ hosts in each network.

(d)

The mapping of the IP address to the corresponding Ethernet Address is done by a protocol named as ______.

Ans:

Q1.

Fill in the blanks :

(a)

flat, hierarchical

(b)

Flat,hierarchical

(c)

254, 2 million

(d)

ARP

Q2.Why do you need ARP protocol?

Ans: Two machines on a network can communicate only if they know each other’s physical address. So, IP address is not enough to deliver a packet to the destination node. It is necessary to know its physical (LAN) address. The ARP protocol allows a host to find out the physical address of a destination host on the same physical network, given only the IP address of the destination host.

Q3.What is the purpose of dotted decimal representation? Give dotted decimal representation of the IP address 11011101 10001111 11111101 00001111.

Ans: To represent the 32-bit IP address in short and easy to read form, Internet addresses are represented in decimal form with decimal points separating the bytes. This is known

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as dotted decimal notation. For the given IP address the dotted decimal representation is 221.143.253.15.

Q4.How is masking is related to subnetting?

Ans: Masking is a process that extracts the physical network address part from the 32-bit IP address. When subnetting is done, the masking is performed to get the subnetwork address rather than the network address.

Q5. What is the function of NAT?

Ans: The Network Address Translation (NAT) approach is a quick interim solution to this problem of acute shortage of IP addresses for individual hosts in IPv4. NAT allows a large set of IP addresses to be used in an internal (private) network and a handful of addresses to be used for the global internet.

Q6. What is the function of the ICMP?

Ans: The ICMP has been designed as companion protocol to compensate two important deficiencies of the IP protocol, namely error-control mechanism and the lack of mechanism for host and management queries.

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AI QUESTION PAPER

2009-04-28T08:52:00.000-07:00

1. Characteristics of AI System

2. Situations where both simple & steepest assent hill climbing algorithm fails

3. Factors influence , whether to reason forward or backward

4. Components of production system

5. Desirable properties of good knowledge representation system

6. Comment on any AI language

7. Steps in natural language understanding

8. How resolution algorithm helps answer problems

9. Components of expert system,type

10. Steps in building expert system

11. What are production system

12. Use hill climbing to solve 8-puzzle problem

13. What are weak methods

14. Issues in knowledge representation

15. Explain non- monotonic reasoning ,eg

16. What male understanding hard

17. Explain learning by parameter adjustment

18. How expert system acquires specialized knowledge

19. Explain forward chaining ,eg

20. What are AI problems? How it diff from other

21. Explain state space representation

22. State and solve knight tour problem

23. Arithmetic problem, forty + ten+ ten=sixty

24. Natural deduction

25. Truth maintains system

26. Explain Semantic nets ,eg

27. How will you understand a single sentence

28. Characteristics of Expert System

29. How robot recognize an object

30. Explain constrains satisfaction while solving the crypt arithmetic problem

31. Rule based system ,eg

32. Explain reasoning , types

33. Explain speech recognizing in natural language

34. What is learning? How will u implement in machine learning?

35. How will u learn a expert system

Explain the physical symbol system hypothesis
Give DFS Algorithm , Advantage
Explain alpha-beta cutoff ,eg
Explain AO* algorithm ,eg
Different approach to knowledge representation
Explain natural deduction
Predicate calculus to clause form
Collection of sentence, prove a sentence using resolution
Solve water jug problem
Explain A* algorithm ,eg
Explain Min-Max procedure
How will you understand multiple sentences
Explain unification algorithm
What is reasoning? Explain TMS? What are the various RMS using reasoning?
Means-end analysis
Hill-climbing, problem with hill-climbing, eg
Diff b/w forward and backward reasoning
What is learning? What are the types of learning
Sentence to clause form
Explain understanding ? Explain how using focus is important in understanding
Solve the problem using forward chaining
What is conceptual dependency. Represent the problem in CD
What are the application of AI
What are search techniques
Genetic algorithms and neural network
Role of learning while making robot? How will recognize an object ?