Distributed Systems Definitions

Distributed Systems Definitions Distributed Systems: There is always compromise when we use distributed systems. Being a distributed systems expertise means knowing the best compromise to make. There is no global clock. Distributed systems definition: A distributed systems is defined as a collection of independent computers that appears to its users as single coherent system. Software systems that operate on more than one computer Internet, Intranet. Mobile computing, Wireless and other modern technologies. Distributed Systems areas: Parallel computing Grid computing Cluster computing Distributed computing Motivation for distributed systems: Resources sharing Geographical and legacy reasons Flexibility Scalability Robustness Security System Design Distributed pervasive Systems Requirements for pervasive systems Wireless, small, battery powered Discover environment. Embrace contextual changes. Encourage ad hoc composition Recognize sharing as the default Personal space vs. shared space No central admin 1.Distributed Systems: A distributed systems is defined by collection of autonomous independent systems that shown to users as a single system via through network. The characteristics of distributed system are multiple autonomous components which are not all shared by the users. Resources cannot be shared to all the users. Software running on the system is concurrent on different processors. In which happened to be multiple point of control and multiple points of failure. Some common characteristics can be achieved using distributed systems resource sharing, openness, concurrency, scalability, fault tolerance, transparency. Types of distributed systems include distributed computing systems, distributed informative systems, distributed pervasive systems. 2.Transmission Control Protocol: Transmission Control Protocol totally depends on network connection to transfer data, TCP requires connection between client and server, It does like a three way handshake.   Host A sends a SYN to B, B sends a SYN and ACK and Host A sends a ACK to B then TCP connection is established. I used this as reference http://www.inetdaemon.com/tutorials/internet/tcp/3-way_handshake.shtml. 3.User Datagram Protocol: User Datagram protocol is connectionless. It does not check if the packets are received are not and there is no guaranteed connection. There is chance in packet loss during transmission,   more unreliable way to send data.   The advantage is speed and cost free. UDP mostly used in online gaming which uses more interaction and respond quickly from player, video streaming like YouTube, twitch 4.Lamport Bakery Algorithm: Lesile Lamports bakery algorithm is designed for the safety purpose of using shared resources between multiple threads by mutual exclusion.   There will be a global counter that displays the number threads being served. The remaining threads have to wait in the line. When the thread completes its process the next thread being served. There are some limitations in the analogy. Its is possible that more than one thread have same number and when they request it. Request cannot be provided So to clear this limitation each thread is provided with a priority. The priority is based on the lower value or higher value then thread will enter the critical section. Critical section: The critical section requires immediate attention access to resources and only be executed one thread at a time.   When a thread enters a critical section, Its has to have its turn and must have smallest number because in case the other threads have the same number the smallest will be executed first. 5.Remote Procedure Call(RPC): Remote procedure call is based on the client and server model. The client machine sends the data to the server machine based on request from user its is a synchronous operation that requires suspend the current program until the RPC is returned. Its a light weight process so multiple RPC can be performed concurrently. RPC Is like a function call, the calling arguments are passed through to the remote procedure and the caller waits for the response from the remote procedure. The RPC is made between two networked systems. A thread can be blocked until either a request or reply is arrived or it will time out. When the request is received the server will send a dispatch routine that performs the requested services and sends the client a reply. 6. Internet Protocols: Internet protocols are used for computer communication and also used to identify a computers address. An IP address as a 32 bit number and this called as IPV4 the development of IPV6 is predicted that depletion of available addresses. So IPV6 uses 128 bits for a address. IPV4 example 172.16.254.1 (IPV4) and 2001:db8:0:1234:0:567:8:1 (IPv6). 7. Synchronization: Synchronization policy is not to go into deadlock condition. Consider multiple process tries to access resources which is in the distributed environment. The synchronization process is to handle all the requests from the process and assign them the resources based on the priority requested client and with pre-defined conditions synchronizing the clients with their request without going into deadlock condition. 8. Server: A server is a computer programs that runs in a computer or other computer and it provides other computer to connect through via network. A computer that usually runs server program are usually the server. If it run every time then it usually called the dedicated server. In client/server program the server program always waits and fulfills the client request. The few types of servers from other number of possibilities: Application Server: Its in the distributed networks that provide the business logic for an application program. Proxy Server: A proxy server is software that acts as a mediator between endpoint devices such as computer and a client and another server from which a user or client requesting a service. Virtual Server A virtual server is a program that usually runs on the shared server. The way it seems to each user that they have the complete control over the server. Policy Server: Policy server is a security component which has a policy based network that provides authorization services and facilitates tracking and control of files. 9. Client: A client is a computer that retrieves information from or users resources provided by the server or main computer. Web browsers are clients that connect to the web servers and retrieve web pages for display same as email clients and multiplayer video games. A client is a part of client-server architecture and client and servers are computer programs that may be run in the same computer and get connected to each other through Inter process communication (i[i) techniques through Internet sockets. There are different types of clients Fat client, Thin Client and Hybrid Client. Fat Client: A fat client is also said to be rich client which stores bulk number of data and does not rely on data processing operations itself. Thin Client: A thin client is a minimal sort of client. It requires resources from the host computer. It process data only provided by an application server. Hybrid Client: A hybrid client is combination of both fat and thin client. But relies on the server for storing the persistent data. Fat client supports (multimedia support, high performance) and thin client supports (high manageability, flexibility). 10. Bandwidth: Bandwidth is referred in bits, how many bits of data are transferred per second in a connection. Higher bandwidth often translates into high performance, although overall performance also depends on the other factors. Bandwidth can measured in units of bits per second(bps). 11. Synchronous and Asynchronous calls: A synchronous call can be defined by call opens a socket and waits for a response before closing the socket. Using synchronous calls server can waste resources, and can timeout. Such as running a server upgrade or downloading a big file. When using Asynchronous calls can be defined by, the client sends the request and then immediately a   response is sent to the specified callback server. A http 202 response is immediately returned from the HTTP connection that invoked the service. Asynchronous calls do not wait for a response to the close the socket. Once the service is complete, the response is sent to the specified callback server. 12. Gossip Protocol: A gossip protocol   is a method of communication now used in the modern days to spread message. This is epidemic protocol sometimes pronounced as gossip protocol where the gossips spread the information in a manner similar to virus spread. Most often distributed systems use gossip protocol to solve the mighty difficulty problems because the network might be huge, because gossip solutions are the easiest ones to spread the solutions. There are three prevailing types of Gossip protocols Dissemination Protocols: They basically work as a   flooding agents in the network. It produces the worst case loads: Event dissemination protocols: It uses high latency to report events. Gossips occurs periodically and the events dont trigger any gossip. Background data dissemination Protocols: Constantly gossip about the information associated with the participating nodes. Latency isnt a concern Anti-entropy protocols: Anti-entropy protocols are used to repair the replicate the data. By comparing the replicas and reconciling differences. Protocols that computes aggregates: These compute the network-wide aggregates by sampling the information at the nodes in the network and combing the values to arrive at a system-wide value- The largest value for some measurement nodes are making, the smallest etc. The key requirement is that the aggregate must be computable by fixed-size pair wise information exchanges; these typically terminate the after a number rounds of information exchange logarithmic in the system size. 13. Network Address Translation Network address Translation (NAT) is the virtualization of internet protocol addresses. NAT is a process of remapping the IP address space into one another by modifying the network information in internet protocol. The technique was originally used to improve security and decrease the number of IP addresses an organization needs. The more advanced implementations used in NAT are the Ip masquerading. Ip masquerading is also form of NAT which allows the internal computers with no known address outside their networks, to communicate to the outside. 14. Middleware: Middleware is defined as the software layer that is between the operating system and system applications and it can be found in both client and server machines.   When two computers are getting communicated the middle ware hides the information of both computers to one another. The middleware also acts as a bridge between the client and server.   The middleware allows the client and server to communicate with each other so that there arent any issues such as incompatible OS, programs. 15. DHCP: DHCP (Dynamic host configuration protocol) is a client/server protocol. There is a DHCP server that will dynamically distribute network configuration parameters. It assigns the IP address to the network dynamically. When a client connects to a network, the DHCP clients sends a broadcast request a information. DHCP manages a pool of IP addresses and information about the client such as default gateway, domain name, name servers. A DHCP server can assign a new address whenever it wants based on administrator assignment policies. DHCP server have three methods of allocating IP address: 1) Dynamic allocation 2) Automatic allocation 3) Manual Allocation 16.Inter-process communication: Inter process communication is interfaces that allow programmer to coordinate activates among different program processes that can run concurrently in a an operating system. This allows program to handle many user requests at the same time. The single request may lead to multiple process running on this situation process needs to communicate each other. So IPC interfaces will take care. 17.Bluetooth: Bluetooth is a wireless technology was designed in 1994 by Ericsson. Bluetooth uses UHF radio waves which covers a short distances of ISM band from 2.4 Ghz to 2.485 Ghz. It was the wireless alternative to RS-232 data cables. It uses a radio technology called frequency-hopping spread spectrum. Data is getting divided into packets and transmits each packets to designated Bluetooth channels. The channels bandwidth is of 1MHz. A Bluetooth device can connect up to maximum of 7 devices. It switches rapidly from one to another using a round robin scheduling algorithm. 18.One time pad: One time pad is an encryption technique. In this technique the actual message is converted into binary form and data is padded with extra new random binary bits the logic is implemented along with it. When the process is done we should be having a new binary bits which is no longer similar to the original message or the padded bits. These bits are padded using XOR binary operator. The padding bits has to lengthy so decrypting will take a time. If its too short the padding can be easily decrypted. 19.Authorization:

First Date

A first date can tell you a lot about a person. Even though i was just in seventh grade my first date was pretty great. Now I know in seventh grade and dating really back then was oh I will see you at school and that is about it. For me my first date was with Ray Hoover. I felt like the coolest girl in school, I had a â€Å"boyfriend†, we wrote notes everyday, got in trouble for hugging in the hallway. It was great I was a cheerleader he was one of the best football players. I thought we were going to be together for ever.When boys and girls traveled together we where always around each other and it is great. He asked me if I wanted to go to the movies with a bunch of people on friday night. Of course I said yes but then I had to ask my mom. After I asked my mom and she had said yes I could go, but first I had to tell her everyone who is going and bring my best friend at the time Mallorie Mclaughin with me. I asked my mom if she would do my hair and I wanted to get a new outfi t and everything. I was so ready for friday to get her I couldn't wait.Ray and I would talk about it everyday till then. The big day was finally her and school couldn't go by any slower. I was going on my first date and that is all I could think about. As soon as I got back from school mom curled my hair and I put on my outfit and was ready to go. I felt like it was ready for forever. Then mom told me it was time to go and I was so nervous I felt like i was going to be sick. We went and picked up Mallorie and then we were off. We arrive at the movies and mom gives me money, I tell her I love her, then got out of the car.I show up and Ray isn't there yet but is on his way. Holly Bradley, Kyle Orick, John Caswell. Kyle told me that Ray was on his way. While we were waiting all us girls went to the bathroom. When we came out of the bathroom Ray was there. He had on khakis, and a polo. Holly wispers in my hear and says he looks really nice. I just smiled. Us girl all decided we wanted t o watch Spanglish and the boys wanted to watch some other movie. Ray was a good guy and besides to go with me to the other movie.Mallorie sat my me and Ray on the other side. It was the dumbest movie I ever saw in my life. To this day It is still the dumbest movie. We held hands during the whole movie and It it was the best first date. The movie was over and lights went on and then Ray lend in and gave me a kiss on the ceeck. I was so happy I couldn't stop from smiling. We walk out of the theater and my moms car is outside. Mallorie says goodbye to everyone, while me and Ray hug goodbye and say we will see each other monday at school and I will call you tomorrow.After that Mallorie and I left to take her home and then head home ourself. As soon as I got home Mallorie called and we talked for an hour about the date. Even though I thought that my first date with Ray would be my last first date. As everyone know you will usually break up with your 7th grade boyfriend and we did break u p. I still think that it was the best first date the any girl could have went on. The only thing that I would change about that date is the movie. Other than that I wouldn't change a thing. It was just perfect.

Difference Between Monopoly Pricing and Competitive Pricing Essay

Congress is discussing the possibility of removing patent protection for life saving drugs in order to reduce the cost of the Medicare and Medicaid systems. Discuss both the short-run and long-run implications for the economic situation of the drug industry. Include in your answer the impact on prices, new development, etc. of drugs. Include appropriate graphs showing the difference between monopoly pricing and competitive pricing. The drug industry currently takes on both monopolistic and competitive market structures. When a drug company develops a new drug, there are patent laws that allow the company to have a monopoly on selling the drug. In the short-run, the company is able to charge the monopoly price (above marginal cost) and maximize profit by producing the quantity where marginal revenue equals marginal cost. Once the patent runs out, other drug companies have an incentive to enter the market causing it to become more competitive. These new companies produce generic versions of the drug and charge a price below the monopolist’s price. As more and more competitors enter the price is driven down to marginal cost. If congress were to remove patent protection on life-savings drugs, drug company’s profits for life saving drugs would decrease. More companies would be able to begin producing the drugs without waiting for the patent period to end therefore, the original drug maker would not be able to charge the monopoly price for very long because competitors could quickly engineer generic versions. The original producer would no longer be a price maker and instead need to follow profit maximization rules of a competitive market by producing the quantity where marginal revenue equals marginal cost and charge a price equal to marginal marginal revenue. Since the original drug maker will not be able to benefit from monopoly pricing during the patent period, there will be less incentive for them to create lifesaving drugs. A part of the benefit of higher profits during the monopoly period is the ability to recoup some of the research, develop, and testing costs of producing these drugs that the generic makers do not incur. Consumers on the other hand would benefit from competition in the market which prevents a single drug maker from dictating the market price of these newly developed lifesaving drugs.

What Products Use Carbon Fiber Today

Every day, a new application is found for carbon fiber. What started out forty years ago as a highly exotic material is now a part of our everyday lives. These thin filaments, a tenth of the thickness of a human hair, are now available in a wide range of useful forms. The fibers are bundled, woven and shaped into tubes and sheets (up to 1/2-inch thick) for construction purposes, supplied as cloth for molding, or just regular thread for filament winding. Carbon Fiber In Flight Carbon fiber has gone to the moon on spacecraft, but it is also used widely in aircraft components and structures, where its superior strength to weight ratio far exceeds that of any metal. 30 percent of all carbon fiber is used in the aerospace industry. From helicopters to gliders, fighter jets to microlights, carbon fiber is playing its part, increasing range and simplifying maintenance. Sporting Goods Its application in sports goods ranges from the stiffening of running shoes to ice hockey stick, tennis racquets, and golf clubs. ‘Shells’ (hulls for rowing) are built from it, and many lives have been saved on motor racing circuits by its strength and damage tolerance in body structures. It is used in crash helmets too, for rock climbers, horse riders, and motorcyclists – in fact in any sport where there is a danger of head injury. Military The applications in the military are very wide ranging – from planes and missiles to protective helmets, providing strengthening and weight reduction across all military equipment. It takes energy to move weight – whether it is a soldier’s personal gear or a field hospital, and weight saved means more weight moved per gallon of gas. A new military application is announced almost every day. Perhaps the latest and most exotic military application is for small flapping wings on miniaturized flying drones, used for surveillance missions. Of course, we don’t know about all military applications – some carbon fiber uses will always remain part of ‘black ops’ - in more ways than one. Carbon Fiber at Home The uses of carbon fiber in the home are as broad as your imagination, whether it is style or practical application. For those who are style-conscious, it is often tagged as ‘the new black’. If you want a shiny black bathtub built from carbon fiber or a coffee table then you can have just that, off the shelf. iPhone cases, pens, and even bow ties – the look of carbon fiber is unique and sexy. Medical Applications Carbon fiber offers several advantages over other materials in the medical field, including the fact that it is ‘radiolucent’ – transparent to X-rays and shows as black on X-ray images. It is used widely in imaging equipment structures to support limbs being X-rayed or treated with radiation. The use of carbon fiber to strengthen of damaged cruciate ligaments in the knee is being researched, but probably the most well known medical use is that of prosthetics – artificial limbs. South African athlete Oscar Pistorius brought carbon fiber limbs to prominence when the International Association of Athletics Federations failed to ban him from competing in the Beijing Olympics. His controversial carbon fiber right leg was said to give him an unfair advantage, and there is still considerable debate about this. Automobile Industry As costs come down, carbon fiber is being more widely adopted in automobiles. Supercar bodies are built now, but its wider use is likely to be on internal components such as instrument housings and seat frames. Environmental Applications As a chemical purifier, carbon is a powerful absorbent. When it comes to absorption of noxious or unpleasant chemicals, then surface area is important. For a given weight of carbon, thin filaments have far more surface area than granules. Although we see activated carbon granules used as pet litter and for water purification, the potential for wider environmental use is clear. DIY Despite its hi-tech image, easy to use kits are available enabling carbon fiber to be employed in a wide range of home and hobby projects where not only its strength but its visual appeal is a benefit. Whether in cloth, solid sheet, tube or thread, the space age material is now widely available for everyday projects.