Multi-User Vs Client Server Relevance
There is
no denying the fact that the server is a multi-user computer where there is no
unusual hardware prerequisite that turns a computer into a server and as such
the hardware platform needs to be preferred based on application demands and
financial stringency involved in it. Servers meant for administering
application work unsurpassed when they are configured with an operating system
that supports shared memory, application isolation, and preemptive multitasking
phenomena. An operating system with preemptive multitasking enables a higher
priority task to take control of the processor from a currently executing of lower
priority task. The server provides and controls shared access to server
resources and as such applications on a server must be isolated from one other
as has been installed for the definitive purpose so that an error in one server
cannot damage another as a tentative flow. Preemptive multitasking ensures that
no single task can take overall the resources of the server and thwart other
tasks from providing services as expected virtually. There must be required
resources of crucial relative priority of the tasks on the server. These
requirements are specific to the client/server accomplishment and not to the
file server implementation. Due to the fact that the file servers execute only
the single task of file service, they can activate in a more limited operating
background without the calling for application isolation and anticipatory
multitasking.
The
conventional minicomputer and mainframe hosts may be utilized as de facto
servers for the network of terminals as they support. Suffice it to say that the
only functions available to the terminal user is through the host, personal
productivity data as well as business systems information is stored on this
host server. Network services, application services, and database services are
provided centrally from the host server. Many organizations download data from
legacy enterprise servers for local manipulation at workstations. In the
client/server model, the definition of server will continue to include these
functions, perhaps still implemented on the same or similar platforms.
Moreover, the advent of open systems based servers is facilitating the
placement of services on many different platforms. Client/server computing is a
phenomenon that developed from the ground up.
Remote workgroups have needed to share
expensive resources and have connected their desktop workstations into local
area networks LANs have grown until they are pervasive in the organization.
However, recurrently, they are out-of-the-way one from the other. Many groups have
integrated the functionality of their dumb terminals into their desktop
workstations to support character mode, host-based applications from the single
workstation. The next wave of client/server computing is occurring now, as
organizations of the mid-1990s begin to use the cheaper and more available
processing power of the workstation as part of their enterprise systems. In
this context, it is noteworthy that the Novell Network Operating System,
NetWare, is the most widely installed LAN. It provides the premier file and
print server supports. However, a check of NetWare for the needs of reliable
client/server applications may have the prerequisite for separate processor
running as a database server as a tentative flow. The accessibility of database
server software—from various establishments such as Sybase and Oracle—to run on
the NetWare server, is an allocation of memory to disseminate this drawback. As
regards of the functions, Servers provide application, file, database, print,
fax, image, communications, security, systems, and network administration
services. These are each illustrated in some details in the following sections.
It is interesting to note that a server is an architectural concept, not a
physical implementation expansion. Client-server functions can be provided by
the same physical devices. With the movement toward peer computing, every
device will potentially maneuver as a client and server in response to requests
for service.
In light of the above discussion, it is
obvious that application servers provide business functionality to support the
operation of the client workstation. In the client/server model these services
can be provided for an entire or partial business function invoked through an
Inter Process Communication request for service. Either message-based request
can be used. A collection of application servers may work in concert to provide
an entire business function. For example, in a payroll system the employee
information may be managed by one application server, earnings calculated by
another application server, and deductions calculated by a third application
server. These servers may run different operating systems on various hardware
platforms and may use different database servers. The client application
invokes these services without consideration of the technology or geographic
location of the various servers. Object technology provides the technical basis
for the application server, and widespread acceptance of the CORBA standards Which
ensures viability of this trend. File servers provide record level data
services to no database applications. Required memory space for storage is
allocated, and free space is managed by the file server.