Client-server communication

Hardware unit index (clients, servers, communication interfaces, printers, etc.)... 

Client/server communications management It provides communications between clients and servers and between servers in various ways, including conversations, request-response, RPC, queueing, and batch. 

The first form led to client-server-styled systems, with the client combining user-interface and application logic and communicating via SQL requests with a database server that dealt with persistence, transactions, security, and so on. All communication involved database processing requests in SQL, and clients did not communicate with one another (except indirectly through shared data on the server). 

HTTP is designed beautifully for client-server and server-client communication and the design of HTML follows suit. They were not designed for server-server communications and some deficiencies in this area show up when implementing a distributed information system on top of HTT P/HTML. Fortunately, these are easy to work around. 

Biometrics can be used in granting the remote access to the network. The scenario employs a common client-server network model, thus incorporating standard security mechanisms with biometric enhancements. The client terminal (see Figure 9) is a biometric-based host, equipped with the capturing device and the processing unit that measures the biometric trait and calculates the features vector (biometric template). The client capabilities may be understood in a wider sense, thus enabling the client to be equipped with sensors related to more than one biometric modality. The proposed access scenario enables to include the aliveness detection capability and the biometric replay attack prevention. To insert the necessary elements into the communication flow, capture-dependent parameters will be retrieved by the client terminal prior to the biometric trait measurement. 

Legacy system data structures Manual process data Data transformation requirements Data cleansing Data archive and restoration Security requirements Access levels Security mechanism Communication interfaces Information transfers Transfer frequencies Legacy system protocols Client/server infrastructure Standards... 

Client-Server Architecture. A computer architecture in which a "server" computer (usually a larger and faster machine at a central location) runs programs that communicate over a network with numerous workstations or "client" machines that reside in offices and laboratories. The server computer performs heavy duty computing tasks such as database searching and molecular and data modeling, in response to commands from the users of the client comvuters. It then communicates the results back to the client machines. There, depending on whether the client is "thick" (a... 

In each example, a simple SQL statement is used to select rows that match a particular substructure. The rows are then simply fetched and printed. These examples should serve as a starting point to understand how client programs communicate with an RDBMS server using SQL. The examples can also server as a basis for other more complex client programs. 

Internet, 237-243. See also World Wide Web addressing/naming system for, 237, 241-243 architecture of, 238-239 business effects of, 705-706 caching of information on, 232, 233 and client-server mechanism, 240-241 connectivity, Internet, 254-255 data communication via, 2124 and design by customers, 701 and electronic commerce, see Electronic commerce... 

Fig. 2. ExPo architecture. The ExPo exchange is a Ruby on Rails web server application with RESTful architecture, using a MySQL database for storage. Clients (automated trader agents, or human traders using a web browser) connect and message the server using HTTP messaging. ExPo internal servers communicate via unix sockets.

A conventional DBMS generally involves a single server communicating with a number of user clients, as illustrated in Fig. 18. In such a model, the services provided by the database are principally supported by the central server, which includes a secondary storage manager, concurrency control facilities, etc., as described in Section I. 

In relational database systems, clients generally communicate with the database by sending SQL query or update statements to the server as strings. The server then compiles and optimizes the SQL, and returns any result or error reports to the client. 

THE EVENT-TRIGGERED (ET) model of computation is presented as a generalization of the time-triggered (TT) approach. It supports hard real-time and flexible soft real-time services. The ET model is built upon a number of key notions temporal firewalls, controlled objects, temporarily valid state data, and unidirectional communications between isolated subsystems. It uses the producer/consumer rather than client/server model of interaction. In addition to describing a systems model and computation model, this article considers issues of schedu-labiUty and fault tolerance. The ET model is not radically different from the TT approach (as in many systems most events will originate from clocks) but it does provide a more appropriate architecture for open adaptive applications. 

HTTP/1.1 is essentially a superset of HTTP/1.0. HTTP/1.1 servers must continue to support clients who communicate using HTTP/1.0. The most important additional features introduced in HTTP/1.1 are as follows ... 

Traditional ERP systems were client/server based and consisted of a database system, communication protocols and a user interface framework. With the advent of the Internet, vendors went to web-based interfaces. This made it possible to access the system though any web-enabled device (since no code rests... 

Security services are intended to protect a system from security attacks, to prevent attacks, or both by utilizing different security mechanisms. User authentication is the process of verifying the identity of a user. In the case of a user-to-user communication, both users have to be checked. Traditionally, in the client-server domain, the authentication is focused on the client side, since the system should be protected from users and not vice versa. However, for some applications such as e-commerce, server authentication is equally important to ensure that it is the correct server a customer is communicating with. Data authentication describes the verification of a particular data or message origin. 

In message passing, SEND and RECEIVE operations are used to synchronize, and to pass data via a specified communication channel. At one end of the message-passing spectrum, the SEND can refer to the specific process to which the information is sent, and the RECEIVE can refer to the specific process from which the information is received this option is referred to as direct naming. At the other end of the spectrum, the SEND and RECEIVE can refer to global mailboxes. Since the mailbox is not directly tied to a particular process, this method is more general, and provides better support for client / server interaction, where there are multiple clients or servers. 

The VFB enables the interconnection of these modules via ports independent of the actual hardware topology and system deployment, which is not known at the VFB level. Furthermore, ports can provide different communication paradigms, such as sender-receiver or client-server. 

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