Distributed systems

Introduction

For disribuito system means a computer system, or not based on Web technology, consisting of different components, and geographically separated from each other, requiring hardware and software Enlarged to ensure a certain level of performance. The purpose is to share data and resources between users of the system.

Architecture of a distributed system

There is no single model of a distributed system: a system is defined such that, for any reason, integrates several hardware and software platforms and is present in a wide swath of territory.

A system based on Web technology resources involved can be seen as main frames, personal computers and midi; not even say that the network communications occur through the same protocols and according to unified specifications. There may be broken up databases on different servers and software is not very flexible and magnified to run on any platform.

A distributed system based on Web technology, however, sees the involvement of types of networks such as Internet, intranet and mobile network. The same system based on Internet or intranet may require a Web server, mail server, FTP server, a server firewall for security, a proxy for multiple connections and so on. A mobile system, however, involves technologies such as GSM, WiFi, GPRS, Blue Tooth and other, working together to provide a unified service.

The end of monopolies

With the rise to fame of the philosophy of open-source giants like IBM and Microsoft have implemented hardware and software systems to make more Enlarged portable computer systems, untying a good percentage of the basic components of the parent.

For example, a system written in PHP does not have to run on Linux but it can run on servers from Microsoft. The more difficult the other way, as I've heard for years of support. NET on the part of the penguin and you can not see a way to realize.

Great credit must go to and from XML based components, or at least, written in Java. Exploiting these two myths of the programming distributed systems have become simpler life and interest of everyone, even the giants, being present on the whole market and not to isolate themselves in their share without letting anybody.

Problems and solutions

So far we've talked about technology and computer systems, but we must not forget that the computer is not null and useless without the presence of man, then the information system.

The man, in addition to being user is also the creator of the system, and of course it is facing a series of problems to solve, some of which are already addressed in a discursive.

We make a schematic.

• Heterogeneity - A distributed system is characterized, as already mentioned, the presence of systems, machines, languages ​​and different data structures, ie all elements are not easy to manage. If it is not possible to unify the system in the same environment, the solution is to adopt a middleware Enlarged handle requests and responses of different systems with each other. The technologies typically used only Java, XML and. NET.

• Safety - For safety, we will be excluded from the system by users is not recognized, potentially harmful, and the management of data integrity within the system itself and the availability of the service over time. At the end it is necessary to build a strong base system, based on hardware and software tested and reliable, it is necessary to have a staff able to cope 'system, in the shortest possible time, for any malfunctions, and (most difficult thing in some ways a) a group of users trained and capable.

• Scalability - The system must be operational in time and not suffer collapse, or at least groped to avoid them or repair them. The possible drawbacks that have to face the maximum limits of active users to manage, bottlenecks at an early stage hardware or software, device management, and hardware and software failures. The solution is similar to the other: a capable and competent staff. Much depends on the quality of the products, the skill of the programmers and analysts in carrying out work wise, and the ability of systems engineers with the versatility to manage the network, such as organizing for adding servers, add or duplicate DNS, and so on.

• Competitiveness - A database that is queried and updated by users of a distributed system is a database subject to the work of hundreds or even thousands of visitors a day, which is why it is possible that data integrity is at risk. The first solution depends on the initial choice of the DBMS, the analysis of the structure of the database application that interacts with the scalability and the ability of the Enlarged system administrators to configure everything according to certain safety criteria, levels of user access and manipulation of the database lock.

• Transparency - It 'necessary to allow users of a distributed system to access resources, which are local or remote, with simplicity. It 'necessary to make available resources without knowing the allocation and configure, if necessary, permits the read-only, reserving those in writing to the administrator and the bodies entitled to make available resources.