The Advantages And Disadvantages Of Data Replication

The Advantages And Disadvantages Of Data Replication By having a file system replicated, if 1 of the replica crashes, the system is still able to continue working by switching it to another replica. Having multiple copies helps in protecting against corrupted data Example: If there are three copies of a file data with each of them performed read and write operation. We can prevent failing of a single write operation having the value returned by the other two copies are correct. Improve the performance by replicating the server as well as dividing the work. This can be achieved by increasing number of processes needed to access data managed by the server Scaling in geographical area Client at all sites can experience the improved availability of replicated data. When the local copy of the replicated data is unavailable, the clients will still be able to access the remote copy of the data Disadvantage: Leading to inconsistency of files containing data When there are multiple copies and that one copy is being modified, the copy will be different from the other replicas. If the copy is being modified and is not propagated to other copies. It will make the other copies out-dated. Example: replication to making improvement the access time of web pages. However, the users might not get the most updated webpages because the webpages that are returned might be a cached version of the pages previously fetched from the web server Cost of increased bandwidth for maintaining replication Replication of data in the files needs to be kept up to date, a network often has large number of message flowing through when the users interact with the file data having to modify or delete data. Thus, data replication will get expensive Give at least two examples of a distributed system, and explain how scalability is addressed in those systems. An online transaction processing system is scalable due to it can be upgraded by adding new processors, storage and devices to process more transactions. This can be upgraded easily and transparently without shutting the system down. The distributed nature of DNS (Domain Name System) allows working efficiently even when every host in the worldwide Internet are served. Thus, it is said to scale well. DNS has the hierarchical design around administratively delegated namespaces and also the use of caching. This seek to reduce load on the root servers at the top of the namespace hierarchy as well as the successful caching limit client-perceived delays with the wide area network bandwidth usage. Question 2 We mentioned in the lectures three different techniques for redirecting clients to servers: TCP handoff, DNS-based redirection, and HTTP-based redirection. What are the main advantages and disadvantages of each technique? TCP handoff Advantage: The TCP handoff achieved total transparency from the clientà ¢Ã¢â€š ¬Ã¢â€ž ¢s point of view as it operates on transport level streams. Therefore, the client will not be aware of them being redirected. When they send the requests to the service machine, they will not be able to know the intermediate gateway switch them between replicas. Disadvantage: The disadvantage of TCP handoff is that the client will not be offer more than one replica to choose from and the redirection mechanism remains in charge of what happen to the client requests. TCP handoff is being treated as a redirection mechanism as it distinguishes service based on the combination of the target machine port number and address. Thus, if we want to replicate service, it is needed to make full copy on the each replica where in this way will lose the flexibility of partial replication. DNS-based Redirection Advantage: DNS-based Redirection achieves transparency without the loss of scalability. It achieved transparency due to the clients are obliged to use the provided addresses by the DNS server. It cannot establish whether the addresses are from the home machine of the server or its replicas. DNS is very efficient as a distributed name resolution service. DNS allows multiple replicas addresses to be returned and to enable the client to choose one of them. Another advantage of DNS is its good maintainability. Disadvantage: DNS queries carry no information on the client triggering the name resolution. For the service-side DNS server, it knows the network address of the DNS server only that ask about the service location. DNS cannot distinguish between the different services that are located on the same machine. When a recursive query occurs, DNS server needs to create chain of queries that end at the server domain DNS server. This will only let the latter knows the address of the DNS server that is a step before the chain and not the origin of the created chain of queries. Thus, the service domain DNS server does not have information about the location of the client. HTTP-based Redirection Advantage: HTTP-based redirection is easy to deploy. What is needed is the possibility of serving dynamic generated web pages. In addition to create the actual content, the generator can determine an optimal replica which rewrite internal references that point to the replica. It is proven to be efficient even though it is always required to retrieve initial document from the main server. All the further works proceeded between client and selected replica; this is likely to give optimal performance to the client. Disadvantage: The disadvantage is that it lacked of transparency. Receiving a URL explicitly points to certain replica and that the browser will become aware of the switching between the different machines. And for scalability, the necessity of making contact with is always the same, the single service machine can make it bottleneck as the number of clients increase which makes situation worse. What is multicast communication? Explain an approach for achieving multicasting. Multicast communication refers to the delivery of a data source transmitted from a source node to an arbitrary number of destination nodes. Application-level multicast is an approach to achieving multicasting, the nodes are organise into overlay network and is use to disseminate information to the members. The nodes are organising into either a tree or a mesh where there will be a unique path between pair of nodes or every node will be having multiple neighbours which can mean that there are multiple paths between each pair. Having nodes organise into a mesh will be more robust due to having the opportunity to disseminate information without immediate reorganise the whole overlay network. Example: Multicast tree in chord This is because when a multicast message is send by a node towards the root of the tree, it looks up the data that is along the tree it wants. In the case of reliable FIFO-ordered multicasts, the communication layer is forced to deliver incoming messages from the same process in the same order as they have been sent. What are the permissible delivery orderings for the combination of FIFO and total-ordered multicasting in Figure. 8-15 (shown on the last page of this assignment)? Question 3 Why is receiver-based message logging considered to be better than sender-based logging? Explain the reasons behind your answer. The reason for this is that recovery is entirely local. In the sender-based logging, a recovering process has to contact the senders to retransmit their message. Example: When a receiving process crashes, most checkpoint state will be restored and replay the message that is been sent again. It combines checkpoint with message logging make it easier to have a state restore that lies beyond the recent checkpoint. As for sender-based logging, it is difficult to find recovery line as the checkpoint will cause a domino effect meaning that there will be inconsistency checkpoint and cost of taking a checkpoint is high. In conclusion, receiver-based message logging is better than sender-based logging Does the Triple Modular Redundancy Model (TMR) capable of masking any type of failure? Explain your answer. Triple Modular Redundancy Model is not capable of masking any type of failure. This is because TMR assumption on the voting circuit determines which replication it is in error having a 2 to 1 vote is observed. The voting circuit will output the result that is correct and discard the erroneous one. The TMR is able to mask the erroneous version successfully if it is assumed to be a failure presenting itself to the system. Also, if there is 1 fault or more appearing at the same time in the particular system, TMR will not be able to mask. In addition, TMR is not able to mask successfully if the above assumptions are invalid. Thus, it is sometimes extended to QMR (Quad Modular Redundancy). Example: if X1, X2 and X3 were to fail all at the same time, the voter will have a undefined output. Compare the two-phase commit protocol with the three-phase commit protocol (chapter 8 in the book). Would it be possible to eliminate blocking in a two-phase commit when the participants were to elect a new coordinator? Explain your answer. The blocking can never be completely eliminated. This is because after the election, the new coordinator might crash. Thus, the remaining participants will not reach a final decision because the election requires vote from the newly elected coordinator. Question 4 Why do persistent connections generally improve performance compared to non-persistent connections? Explain reasons to why persistent connections are disabled on some Web servers (why would anyone want to disable persistent connections)? The client is able to issue several requests without the need of waiting for the response to the 1st request. The server is also able to issue several requests without having to create spate connection for the communicate pair. It is so because when using non-persistent connections. A separate TCP connection is establish to load every component of a Web document and when the web documents contains embedded content such as images or multi-media content, it will become inefficient. Also it is because some of the web serversà ¢Ã¢â€š ¬Ã¢â€ž ¢ middleware layer is weak and unable to manage clients that are sending several requests. These requests will only stack up in the middleware layer that will cause response to be slow due to only 1 connection for all the requests. Explain the difference between static web content and dynamic content created by server-side CGI programs. The difference between static web content and dynamic content is that: Dynamic content is able to customize response and providing transparency to users. Users are unable to know if HTML document is generated on demand or it is physically stored in a location. The value can be store in database and will be retrieved and generated on demand when user requested for the values using the CGI program. Flexibility is provided in CGI program as it can run executable file from the server which allowed interactivity on the site. However, static web content is not able to do it. Static web content, the users are aware that the data is stored as information presented would be the same. If multiple webpages were needed to be updated it will be quite tedious. A lot of time is consume due to each update requires retrieving of HTML documents to update. When create a new webpage, time is consume. For static web content, overhead will not be generated as much as dynamic content as CGI program will take up time and memory to generate and produce output. Whereas for the static web content, it is displayed as how it is being retrieved.

Antigone †The First Feminist Essay -- Antigone Essays

Antigone – The First Feminist How old is feminism, and who was the first feminist? Although no one can say for sure the exact date on which the feminist movement started, most of it is attributed to the past two centuries. However, women who are feminists have been around much longer. In Sophocles’s Antigone, the main character (Antigone) acts as a protofeminist by defying the authority of a patriarchal society and taking action according to what she believes is right in her heart. She even shows some characteristics of a modern feminist. Feminists today are viewed as raging, man-hating bitches, but feminism in its true sense simply advocates women’s rights. While there are extremes on either side of the scale, most feminists fight for equality among the sexes rather than dominance of one over the other. Antigone can be considered a feminist because she challenges the â€Å"men-make-the-rules-and-women-follow-them-unquestioningly† mentality of the society she lives in. Antigone’s character is indeed among the first to stand up for women in a society that has remained patriarcha...

Marketing Syllabus Spring

The student will then have ten (10) days to respond in one of the following ways: Sign the form and request a meeting with the Academic Dean to discuss the allegations and or proposed sanctions; Sign and return the form to the Academic Dean accepting responsibility for the violation and agreeing to the recommended sanction(s); If the student fails to respond within thirty (30) days, a hold will be placed on the students account and the right to participate in the resolution of the allegation will be forfeited.Formal Resolutions: If the alleged violation could result in the suspension or dismissal from the university, or if the student or faculty member requests a formal resolution, the Academic Dean will notify the faculty member and the student(s) that a formal hearing of the Academic Dishonesty Committee will be convened. The committee will be comprised of seven (7) full time faculty members to be appointed by the Vice-President for Academic Affairs on an annual basis. The Academic Dean will serve as chair and will not have voting privileges. The Vice-President for Student Development will serve as an ex officio member of the committee.The Academic Dean will schedule a hearing in a timely manner and all parties will be notified often and location. If the accused student requests, the Academic Dean will assist the student in securing a member of the university community to advise and assist the student in preparing for the hearing. All parties will have the opportunity to present his/her evidence to the committee. The documents, testimony and record of the hearings will be confidential. Upon completion of the testimony, the Committee will meet in closed chambers and vote on the disposition of the student's status at the university.Penalties: Depending upon the intent and severity of the violation, a student found responsible for any act of academic dishonesty will be subject to one or more of the following penalties: The student is placed on academic honor pro bation until graduation. For any student on academic honor probation, a second violation will result in a minimum sanction of one semester of suspension from the university. In addition to academic honor probation, a student might also receive a grade of â€Å"F† on the assignment or test; students might also receive an â€Å"P' in the course; or be suspended or dismissed from the university.No provision will be made for the student to receive a â€Å"W† regardless of whether the professor or student initiate said request. If the student receives a grade of â€Å"F† for the course or is suspended or dismissed from the university, the transcript will indicate the grade with â€Å"HP† and/or the notation â€Å"Academic Honor Suspension (Dismissal). † All students found guilty of academic honor violations shall have a written letter detailing the violation and sanction placed in their permanent record. Copies of this letter will also be sent to the f aculty member of the course, appropriate College Dean, and to the Vice-President for StudentDevelopment. Appeals: A student may submit a written appeal of a guilty finding to the Vicissitude for Academic Affairs within ten days of receipt of the original decision. Appeals must be based on new evidence, additional information, or procedural errors or misconduct. The Vice-President's decision is final. 4) Exam Policy: The administration of a final examination prior to the date designated is considered a violation of University policy; therefore, no final exams for this course will be given other than on the specified day and time without the express approval of the Dean of the College of Business and Management.Such exceptions may be given for only the most extreme and sensitive cases. Other than such exceptions, no â€Å"make-up† examinations shall be administered. It is essential that each student plan accordingly, especially regarding post-term travel plans. 5) Accommodation Statement: â€Å"Lynn University makes reasonable accommodations for qualified students with documented disabilities under the Americans with Disabilities Act (DAD) and Section 504 of the Rehabilitation Act. If special accommodations are needed, please contact the DAD compliance Officer at 561-237-7069 or [email  protected] Du to assist in commenting and defining those needs.Accommodations are not retroactive therefore, for any accommodation the instructor must be presented with the form specifying the needs. The Academic DAD Specialist is located in the Green Center. 6) Incomplete Grade: A. For a student to be eligible to receive an incomplete for a course: 1) The student must provide to the dean of students documentation of the extenuating circumstance(s) that prevent him/her from satisfying the course requirements and learning outcomes of that particular course. 2) The student, at the time of applying for an incomplete, must have employed 2/3 of the term and have a passing gr ade.B. The application process: 1) The student will have the option of applying for an incomplete in one or more courses. 2) The student will obtain and complete the incomplete application form and bring it to the dean of students with appropriate documentation. The dean of students will verify that the student's application satisfies the eligibility criteria. If the application satisfies the eligibility criteria then the dean of students will return the approved form to the student who will then take the form to the professor of the course.The professor and student will draw out contract, which includes but is not limited to: all coursework to be completed and the deadline for this material to be submitted. After the student agrees to the terms of the contract and signs the form, the professor will take the contract to the dean of his/her college. The dean will then review the contract and sign the form upon approval. The â€Å"l† is now official and the contract is binding. The dean of the college will distribute copies of the contract to the professor, the student, the dean of students and the Registrar.Each recipient will place the copied contract in the appropriate file. The roofless will keep one copy and the original will be placed in the student's file in the college of his/her major. C. The form: 1) Will be available online. 2) Will contain current grade, what specific assignments are to be completed due date for all material (not to exceed One year beyond the original term final grade due date), and state that the final course grade will be a ‘W† if the student does not complete the requirements. 7) Withdrawals: Students are limited to eight undergraduate and three graduate course withdrawals. ) Assignments: Papers must be submitted ONLY through the Assignment link n Blackboard. For assistance with Blackboard, contact the IT Help Desk at 561-2377979. Late papers will not be accepted without penalty without the prior consent of the professor. Extensions may be granted on an individual basis and will only be granted for particularly sensitive cases. The granting of makeup papers shall be at the sole discretion of the professor and will not be given except for particularly sensitive cases that are discussed at length with the professor.In any group project, the student is expected to become an integral team member, with active input, interaction, and contributions. Once mea members have been selected, it is the responsibility of the team to agree upon the work assignment and allocation of team resources. A student who does not completely follow through with that student's commitments to the team will not receive a passing grade for the project. 9) Dress code: For all activities in the classroom that involve a guest presenter, as well as for field study visitations, the student shall be required to dress in business casual attire.If the instructor determines that the student's appearance is inappropriate for a sc heduled activity, the student will not be permitted to participate. 0) Questions and concerns: Students who have concerns or questions regarding academic matters relating to this course are urged to consult with the instructor. Students should be familiar with information found in the current Lynn University Academic Catalog. Required Texts Articles, Videos, and e-mails throughout the term as provided by the professor, including postings on this course's Blackboard companion site.Suggested Reading and Sources (1) Street & Smith's Sports Business Journal, subscription available at www. Superciliousness's. Com Course Requirements Each student will complete all assignments and is responsible for Discussion Board postings on Blackboard. Details about each of these projects are attached to this syllabus. You may complete any assignment in any order you please. Try to complete one project every two weeks, and to complete your Discussion board posts on a Weekly basis. All work is due by Fr iday Feb. 27 at 1 1 :pm properly posted in Blackboard.Grading Grading is based on the following system: Deal Maker USB LOC Discussion Board USB Advertising USB Launch Party Total 20 points 100 points Grades for each of the factors listed above will be posted progressively throughout the semester, and will be accessible to the student through the university online Blackboard system. Student final grades shall be rounded by tenths to the nearest whole number. A grade of exactly one-half point shall be rounded to the next highest whole number. Student grades shall not be rounded by hundredths to the nearest tenth.

Free sample - Alexamara Marine Group Case database management. translation missing

Alexamara Marine Group Case database management. Alexamara Marine Group Case database managementNormalization Normalization defines simple rules that ensure that a database is structured in the best way possible. it ensures that no data is unnecessarily duplicated .This means that no data is held in no more than one table. This is called duplication anomalies. It also ensures that the database has consistency (Date, 2006). The most important thing about normalization is that it allows the user to perform all types of queries which out errors. 1st Normal Formal Form (CategoryNum , Category Description ServiceID , SlipID, Description, CategoryNum, Status, EstHours ,SpentHours ,NextServiceDate). This is table in the first normal form. It has already been normalized from the 0nf because it has a primary key(Date, 2006). The table is in the first normal form (NF1) because it contains no repeating attributes or group of attributes. 2nd Normal Formal Form (CategoryNum , CategoryDescription ServiceID , SlipID, CategoryNum, Status, EstHours ,SpentHours ,NextServiceDate). This table is in second normal form because it is in first normal form and has no partial key dependency. It also means that there is no column that is not part of a primary key is dependent on only portion of the primary key. Â  Functional dependencies in Marina (Marina Num, Name, (Slip Num, Length, Rental Fee, Boat Name)) The functional dependencies are one is to many because marina can have many slips Marina Slip (Slip ID, Marina Num, Slip Num, Length, Rental Fee, Boat Name, Boat Type, Owner Num, Last Name, First Name) To convert this to third normal form one need to test non key dependency . A table in 3NF optimizes the way of holding data with no attributes being duplicated anywhere. Work cited Date, C. (2006) What First Normal Form Really Means in Date on Database: Writings 2000- 2006: New York, Springer-Verlag, pp. 127-128.

Illocutionary Acts in Speech-Act Theory

Illocutionary Acts in Speech-Act Theory In speech-act theory, the term illocutionary act refers to the use of a sentence  to express an attitude with a certain function or force, called an  illocutionary force, which differs from locutionary acts in that they carry a certain urgency and appeal to the meaning and direction of the speaker.   Although illocutionary acts are commonly made explicit by the use of performative verbs  like promise or request, they can often be vague as in someone saying Ill be there, wherein the audience cannot ascertain whether the speaker has made a promise or not. In addition, as Daniel R. Boisvert observes in Expressivism, Nondeclarative, and Success-Conditional Semantics that we can use sentences to warn, congratulate, complain, predict, command, apologize, inquire, explain, describe, request, bet, marry, and adjourn, to list just a few specific kinds of illocutionary act. The terms  illocutionary act  and  illocutionary force  were introduced by British linguistic philosopher John  Austin in 1962s How to Do Things With Words, and for some scholars, the term illocutionary act  is virtually synonymous with speech act. Locutionary, Illocutionary, and Perlocutionary Acts Acts of speech can be broken down into three categories: locutionary, illocutionary, and perlocutionary acts. In each of these, too, the acts can either be direct or indirect, which quantify how effective they are at conveying the speakers message to its intended audience. According to Susana Nuccetelli and Gary Seays Philosophy of Language: The Central Topics, locutionary acts are the mere act of producing some linguistic sounds or marks with a certain meaning and reference, but these are the least effective means of describing the acts, merely an umbrella term for the other two which can occur simultaneously. Speech acts can therefore further be broken down into illocutionary and perlocutionary wherein the illocutionary act carries a directive for the audience, such as promising, ordering, apologizing and thanking. Perlocutionary acts, on the other hand, bring about consequences to the audiences such as saying I will not be your friend. In this instance, the impending loss of friendship is an illocutionary act while the effect of frightening the friend into compliance is a perlocutionary act. Relationship Between Speaker and Listener Because perlocutionary and illocutionary acts depend on the audiences reaction to a given speech, the relationship between speaker and listener is important to understand in the context of such acts of speech. Etsuko Oishi wrote in Apologies, that the importance of the speakers intention in performing an illocutionary act is unquestionable, but, in communication, the utterance becomes an illocutionary act only when the hearer takes the utterance as such. By this, Oishi means that although the speakers act may always be an illocutionary one, the listener can choose to not interpret that way, therefore redefining the cognitive configuration of their shared outer world. Given this observation, the old adage know your audience becomes especially relevant in understanding discourse theory, and indeed in composing a good speech or speaking well in general. In order for the illocutionary act to be effective, the speaker must use language which his or her audience will understand as intended.

Auditing Essay Example | Topics and Well Written Essays - 500 words - 1

Auditing - Essay Example An auditor who works for a mid size firm takes on the assignment of auditing Telechubbies for the first time based on information that is provided to the auditor by Rachel Jones, the financial controller of Telechubbies. The basic information given to the auditor is that there is a requirement to maintain a 2:1 debt to equity ratio based on a loan contract. The provision for inventory obsolesces is 10% which is was cut 100 per cent from the previous year’s levels and the company wants another 100 per cent reduction this year to bring it down to 5%. A third piece of data given is that the long term receivables in the books belong to an R&D company owned by one of the directors. The auditor would start this audit by inspecting the balance sheet, income statement, annual report, code of ethics, and physical warehouse of Telechubbies. The balance sheet requires special attention. This financial statements has the data to calculate the debt to equity ratio. The auditor needs to inspect that the company is complying with the 2:1 requirement. After verifying the metric the auditor should go back a few years and compare the current debt to equity ratio level to the last three years results to find any tendency in the metric that might place the contract at risk in the near future. The company recently changed its inventory obsolescence provision to 10%. The auditor has to immediately verify if this changed was notified to the shareholders in the financial statements in the form of a note to the financial statements. This change represent a new discrepancy in the way the accounting methods thus it must be notified for purposes of following the accounting principle of consistency. The desired to cut the provision down to 5% requires certain numerical and physical auditing procedures. The long term receivable information is a worrisome sign since lending money to a company that is owned by a company director

Sexual Harassment Essay Example | Topics and Well Written Essays - 500 words - 3

Sexual Harassment - Essay Example Asking for sexual favors is a direct form of sexual harassment but in some cases indirect favors are also an important element of sexual harassment. The individual involved is either asked for the favor for a reward or he/she is put in such an environment that it becomes hostile for him (Lewis 2001). Many link sexual harassment to be a gender specific situation as most of the cases are seen to be following the women who are subordinating certain individuals. These sexual harassment situations not only lead to deleterious effects on health but they also affect the state of mind of the individual concerned. Sexual harassment is not only related to workplace environments but is also related to the people who are working in military and the service sector (Street et al 2008). Sexual harassment not only refers to the sexual favors but it also relates to the body language of the individuals. Behaviors that are unwelcome by individuals and can be clearly anticipated for making someone offen ded are said to be incorporating the broad definition of sexual harassment (Australian Human Rights Commission, 2013). Actions that are pervasive and considered hostile are also associated with the sexual harassment situations. It is also seen that sexual harassment can lead to post traumatic stress disorder in many people as the person undergoes anxiety and depression after undergoing these situations (Street et al 2008). More studies help to find out the correlation of race with sexual harassment as it can be seen that the African Americans are likely to come under the situations of sexual harassment more often than their counterparts. Adolescence is also a factor for the increase in the cases of sexual harassment as found by a study conducted by Goldstein (Goldstein et al 2007). The elements of sexual harassment that have not been reviewed properly are related to the sex