Major Internet Applications

Major Internet Applications It is traditionally the most significant and remains the most commonly employed. This illustrates the simple structure in which client processes cooperate with individual server process in separate host computers in order to access the shared resources those they mange. Servers may in twist be clients of other servers, as the figure indicates. For example, a web server is frequently a client of a local file server that manages the files in which the web pages are store. For the applications discussed in Exercise 2.1 state how the servers cooperate in providing a service. Web servers and most other Internet services are clients of the DNS service, which translate Internet Domain Names to network addresses. Also, search engines, which enable users to look up summary of information obtainable on web pages at site all over the Internet. A search engine is a web server that responds to client requests to search in its stored indexes and (concurrently) runs several web crawler tasks to build and update the indexes. What are the requirements for synchronization between these concurrent activities? What happen are the server tasks (respond to user queries) and the crawler tasks (making request to other web servers) are completely independent because there is small need to synchronize them and they may run concurrently. In reality, atypical search engine would normally include many concurrent threads of execution some serving its clients and others running web crawlers. The host computers used in peer-to-peer systems is often simply desktop computers in users offices of homes. What are the implications of this for the availability and security of any shared data objects tat they hold and to what extent can any weaknesses be overcome through the use of replication? List the types of local resource that are vulnerable to an attack by an untrusted program that is downloaded from a remote site and run in a local computer. Network communication the program might attempt to create sockets, connect to them, and send messages .Access to printers. It may also impersonate the user in various ways for example: sending receiving email Objects in the file system for example files, directories can be read/written/created/deleted using the rights of the local user who runs the program. Mobile agent is a running program (including both code and data) that movements from one computer to another in a network transport out a task on someones behalf, such as collect information, finally returning with the results. A mobile agent can make many invocations to local resources at each site it visits for example, access individual database entries. Give some examples of applications where the use of mobile code is beneficial. Applets one example of mobile code which means: the user running a browser selects a link to an applet whose code is stored on a web server so the code is downloaded to the browser and runs there Accessing services which mean: running code that can invoke their operations. What factors affect the responsiveness of an application that accesses shared data managed by a server? Describe remedies that are available and discuss their usefulness. When the client accesses a server, it makes an invocation of a process in a server running in a remote computer. These things that affect the responsiveness: Server overloaded, Latency in exchanging request and replies, Load on network. The use of reserve helps with all of the above problems. In fact client reserve reduces all of them. Proxy server reserve helps with duplication of the service also helps with the use of lightweight communication protocols helps with. Distinguish between buffering and caching. Buffering: a method for store data transmit from a sending process to a receiving process in local memory or disk storage until the receiving process is prepared to use it. For example, when reading data from a file or transmitting messages during a network, it is useful to handle it in huge blocks. The blocks are held in buffer storage in the receiving process memory space. The buffer is free when the data has been used by the process. Caching: a technique for optimizing access to isolated data objects by hold a copy of them in local memory or disk storage. Accesses to parts of the remote object are translated into accesses to the related parts of the local copy. Unlike buffering, the local copy may be retained as long as there is local memory obtainable to hold it. A cache management algorithm and a release policy are wanted to run the use of the memory allocated to the cache. Give some examples of faults in hardware and software that can/cannot be tolerated by the use of redundancy in a distributed system. To what extent does the use of redundancy in the appropriate cases make a system fault-tolerant? Hardware faults processors, disks, and network connections can use redundancy for example: run process on multiple computers, write to two disks, have two separate routes in the network available. Software bugs, crashes. Redundancy is not high-quality with bugs because they will be replicated. Replicated processes help with crashes which may be due to bugs in unrelated parts of the system. Retransmitted messages help with lost messages. Redundancy makes faults less likely to occur Consider a pair of processes X and Y that use the communication service B from Exercise 2.14 to communicate with one another. Suppose that X is a client and Y a server and that an invocation consists of a request message from X to Y (that carries out the request) followed by a reply message from Y to X. Describe the classes of failure that may be exhibited by an invocation. An invocation may suffer from the following failures: Crash failures: X or Y may crash. Therefore an invocation may suffer from crash failures. Omission failures: as SB suffers from omission failures the request or reply message may be lost. Describe possible occurrences of each of the main types of security threat (threats to processes, threats to communication channels, denial of service) that might occur in the Internet. Threats to processes: not including authentication of main and servers, a lot of threats exist. An enemy could access other users files or mailboxes. Threats to communication channels: IP spoofing sending requests to servers with a false source address.

Use of Proper Judgment in Othello :: Othello essays

  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   A central tenet of Othello is the concept of proper judgment, and to always use it when making decisions. The renaissance definition of proper judgment can be illustrated by the "hierarchy of proper judgment." Governing all is reason, which includes understanding and will. Below reason are common sense, memory, and imagination. Finally, at the bottom are the 5 senses, emotions, and passions. In order to judge properly, it was believed that reason had to govern all else. Proper judgment could never occur if only one item was relied upon to make the decision. In Othello, Shakespeare uses this concept to demonstrate how proper judgment occurs, and the consequences when it does not.      Ã‚  Ã‚  Ã‚  Ã‚   The first scene in which proper judgment is used is when the Duke makes a decision as to what should be done about the expected Turkish invasion. He does not immediately act on the information he receives, instead, he thinks out the steps logically. When he states, "I do not so secure me in the error, but the main article I do approve in the fearful sense (I 3 12-14)," he is showing that he will not rely solely on the information he is receiving, but also use common sense, memory, and understanding, and therefore judge properly. Only after Proper judgment was used did he take action, and therefore avoid disaster. The Duke is a model of Proper judgment who can be compared to other characters in the play to show their weaknesses and shortcomings.      Ã‚  Ã‚  Ã‚  Ã‚   In the same scene, proper judgment is demonstrated again by the Duke, when he is faced with the mater of Othello marrying Desdemona. Initially, the Duke rejects wise judgment by promising to allow Brabantio to sentence whoever had done this to whatever punishment he saw fit, without analyzing the situation further, and without even knowing who that man was. However, upon assessing the situation more, he realizes the consequences of not using Proper judgment, and, after hearing all sides of the story, tell Brabantio to "Take up this mangled matter at best. Men do their broken weapons rather use than their bare hands (I 3 199-201)." Later on, he gives Brabantio wise advice when he tells him that "to mourn a mischief that is past and gone is the next way to draw new mischief in (I 3

Conflict is an inherent part of life Essay

Conflict can erupt when parties differ significantly in power, status, or culture. Power. If dependence is not mutual, but one way, the potential for conflict increases. If party A needs the collaboration of party B to accomplish its goals, but B does not need A’s assistance, antagonism may develop. B has power over A, and A has nothing with which to bargain. A good example is the quality control system in many factories. Production workers might be highly dependent upon INSPECTORS to approve their work, but this dependence is not reciprocated. The inspectors might have a separate boss, their own office, and their own circle of friends (other inspectors). In this case, production workers might begin to treat inspectors with hostility, one of the symptoms of conflict. Status. Status differences provide little impetus for conflict when people of lower status are dependent upon those of higher status. This is the way organizations often work, and most members are socialized to expect it. However because of the design of the work, there are occasions when employees with technically lower status find themselves giving orders to, or controlling the tasks of, higher-status people . The restaurant business provides a good  example. In many restaurants, lower-status waiters and waitresses give orders and initiate queries to higher-status cooks or chefs. The latter might come to resent this reversal of usual lines of influence.10 The advent of the â€Å"electronic office† led to similar kinds of conflict. As secretaries mastered the complexities of electronic mail, they found themselves having to educate senior executives about the capabilities and limitations of such systems. Some executives are defensive about this reversal of roles. Culture. When two or more very different cultures develop in an organization, the clash in beliefs and values can result in overt conflict. Hospital administrators who develop a strong culture centered on efficiency and cost  effectiveness might find themselves in conflict with physicians who share a strong culture based on providing excellent PATIENT CARE at any cost. A telling case of cultural conflict occurred when Apple Computer expanded and hired professionals away from several companies with their own strong cultures. During the first couple of years Apple recruited heavily from HEWLETT PACKARD, National Semiconductor and Intel, and the habits and differences in style among these companies were reflected in Cupertino. There was a general friction between the rough and tough ways of the semiconductor men (there were few women) and the people who made computers, calculators, and instruments at Hewlett-Packard some of the Hewlett-Packard men began to see themselves as civilizing influences and were horrified at the uncouth rough-and-tumble practices of the brutes from the semiconductor industry. Many of the men from National Semiconductor and other stern backgrounds harbored a similar contempt for the Hewlett Packard recruits. They came to look on them as prissy fusspots.

Education Disparity Essays

Education Disparity Essays Education Disparity Essay Education Disparity Essay I consider the education the most important thing. This is the inducement of everything. It is the basis, the key of everything what then you can rely on. The inequality in the education was always an issue everywhere in the world, where a minority is exist. Not just in the developing countries, for instance Africa, but in the developed countries too. The lack of good education is I think the first issue facing various societies all over the world.A good education, which is not reached of everyone, provides the children for have good chances in the life, to be successful, to be able to compete in the labor market and to get a good job. Those who do not have the opportunity to learn in the same circumstances, because of the discrimination based on race or financial status, without education they will not be able to cope with the others, so it’s a vicious circle.The state, which not support the social mobility and the government which not make enough effort for the integration can’t be succeed, because I think, the state’s aim is to have well educated, occupied citizens to be able to develop. The state should not grudge the money for these integration programs and for the education, because these educational differences cause mostly the problem between the minority and majority. It’s something which is completely solvable; we just should deal with it. I would like to introduce an example from Hungary. Here, there is a very big gipsy minority which causes a big problem in the country.People just can not keep saying that they do not work, they do not study, they do not pay the taxes. But why they do not work? Why they do not study? May because they do not have the same opportunity to do it, because there are segregated schools and they not treated the same like the others. I was volunteering in one of these segregated schools in Budapest, where just gipsy kids were studying. After school on Fridays I went there and I tutored some of these kids, I helped them to learn reading, counting, I prepared them to a performance. I saw the circumstances where they were learning, their teachers, their parents, their possibilities.If you live in a poor neighborhood, or you are a member of the minority, it’s expected that the school you attend are lacking many necessities. This issue is also in connection with the racism, and I would like to come up with Jane Elliott’s „blue-eyed/brown-eyed experience. If there is an prejudice from the minority, that for instance they do not study and work, after a time they will act according to the prejudice. So if people say that the minority do not want to work and study, and people do not do anything against this (they do not give the opportunity), the minority will accept that situation and they will act like the prejudice.The break-out is very hard, because the parental education and behaviors really affect the children’s future. The disparity is also manifest itself in financial differences. The poverty in many cases also do not have the same opportunities like the others, however they are the same or even more talented. It’s more true about the higher-education, because I think it does not promote social equality as effectively as it should. In many cases there are very talented, enthusiastic students who can not attend in the higher education because of the lack of money.I would pay much more attention to these problems. First of all I would create equality in the education to give the possibilities to everyone. I would invest more money to the education, because in long- term this is the key why a nation can be successful. It’s something which is very profitable, because the education and the economy are strongly connected. Secondly, there should be more programs which promote the social mobility and the talented people. I would expand the economic foundation for the grants and scholarship.