官术网_书友最值得收藏!

Design considerations for distributed systems

Following are some of the characteristics of distributed systems that should be considered in designing a project in a distributed environment:

No global clock: Being distributed across the world, distributed systems cannot be expected to have a common clock, and this gives a chance for the intrinsic asynchrony between the processors performing the computing. Distributed system coordination usually depends on a shared idea of the time at which the programs or business state occurs. However, with distributed systems, having no global clock, it is a challenge to attain the accuracy with which the computers in the network can synchronize their clocks to reflect the time at which the expected program execution happened. This limitation expects the systems in the network to communicate through messages instead of time-based events.

Geographical distribution: The individual systems taking a part in distributed system are expected to be connected through a network, previously through a Wide-Area Network (WAN), and now with a Network Of Workstations/Cluster Of Workstations (NOW/COW). An in-house distributed system is expected to be configured within a LAN connectivity. NOW is becoming widespread in the market with its low-cost, high-speed, off-the-shelf processing capability. Most popular NOW architectures include the Google search engine, Amazon.

No shared memory: An important and key feature of distributed computing and the message-passing model of communication is having no shared memory, which also infers the nonexistence of a common physical clock.

Independence and heterogeneity: The distributed system processors are loosely coupled so that they have their own individual capabilities in terms of speed and method of execution with versatile operating systems. They are not expected to be part of a dedicated system; however, they cooperate with one another by exposing the services and/or executing the tasks together as subtasks.

Fail-over mechanism: We often see computer systems failing, and it is the design responsibility of setting the expected behavior with the consequence of possible failures. Distributed systems are observed to be failed in integration as well as the individual sub systems. A fault in the network can result in the isolation of an individual or a group of computers in the distributed system; however, they might still be executing the programs they are expected to execute. In reality, the individual programs may not be able to detect such network failures or timeouts. Similarly, the failure of a particular computer, a system being terminated abruptly with an abrupt program or system failure, may not immediately be known by the other systems/components in the network with which the failed computer usually communicates with. The consequences of this characteristic of distributed systems has to be captured in the system design.

Security concerns: Distributed systems being set up on a shared Internet are prone to more unauthorized attacks and vulnerabilities.

Distributed systems are becoming increasingly popular with their ability to allow the polling of resources, including CPU cycles, data storage, devices and services becoming increasingly economical. Distributed systems are more reliable as they allow replication of resources and services, which reduces service outages due to individual system failures. Cost, speed, and availability of Internet are making it a decent platform on which to maintain distributed systems.

主站蜘蛛池模板: 桐梓县| 贵州省| 紫金县| 镶黄旗| 商河县| 黎平县| 西城区| 五常市| 祁门县| 蓝田县| 河北省| 绍兴市| 镇平县| 民县| 广饶县| 滦南县| 噶尔县| 山东省| 邳州市| 富川| 江陵县| 定日县| 开原市| 桑日县| 延庆县| 祁连县| 山东省| 宁乡县| 双柏县| 冀州市| 保靖县| 马关县| 大同县| 辽阳县| 商河县| 怀宁县| 巢湖市| 庐江县| 积石山| 江城| 湄潭县|