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1 Introduction
This chapter includes abstract, brief introduction to the project and project background.
1.1 Abstract
This is Client-Server based, administration utility. The administrator can view and control the remote machine connected in network as if he has sit in front of that remote machine. This is the GUI utility to control remote machine. Server Application checks on particular port for incoming connection continuously. Client Application requests to connect to the remote machine on which server application is running. Server application accepts the requests if client is authorized. After connection established, server application sends its desktop screen to client application. Client application displays that screen on its machine. Client application tracks mouse and key events on its machine and sends to server application in predefined form. Server application reflects those events that are received from client on its machine. Server application again sends its desktop screen to client, reflecting changes due to received events from client. Client application displays newly received screen on its window. This sequence of operations continues till either server or client closes connection.
1.2 Brief Introduction
Remote System Administration is a simple utility for remote access to graphical user interfaces. Because it works at the screen level it is applicable to all windowing systems and applications such as Windows Linux.
Figure 1.1
The endpoint where the user sits (i.e. the display plus keyboard and/or pointer) is called the client or viewer. The remote endpoint where changes to the screen originate (i.e. the windowing system and applications) is known as the server.
At the endpoint, the user will see exactly the same graphical user interface as at the original endpoint. In effect, the interface to the user’s applications becomes completely mobile. Wherever suitable network connectivity exists, the user can access their applications. This provides the user with a familiar, uniform view of the computing infrastructure wherever they go.
Security
Security is given by password. Client application requests password from user and if password is correct than the server will accepts the connection.
Display at Client
The display side of the client is based around a single graphics primitive: “put a rectangle of pixel data at a given x, y position”. At first glance this might seem an inefficient way of drawing many user interface components. However, allowing various different encodings for the pixel data gives us a large degree of flexibility in how to trade off various parameters such as network bandwidth, client drawing speed and server processing speed.
The update is responsive by server. That is, an update is only sent from the server to the client in response to events such as mouse and keyboard from the client. This gives the protocol an adaptive quality.
The slower the client and the network are, the lower the rate of updates becomes. Transient states of the screen can be ignored, resulting in less network traffic and less drawing for the client.
Input at Client
The input side of the client is based on a standard workstation model of a keyboard and multi-button pointing device. Input events are simply sent to the server by the client whenever the user presses a key or pointer button, or whenever the pointing device is moved.
Representation of pixel data
The Pixel data are sent to client in particular format and encoding to client.
Pixel format refers to the representation of individual colours by pixel values. The most common pixel formats are 24-bit or 16-bit true colour, where bit-fields within the pixel value translate directly to red, green and blue intensities, and 8-bit colour map, where an arbitrary mapping can be used to translate from pixel values to the RGB intensities.
Encoding refers to how a rectangle of pixel data will be sent on the wire. Every rectangle of pixel data is prefixed by a header giving the X, Y position of the rectangle on the screen, the width and height of the rectangle. In our Application we have used RLE (RUN LENGTH ENCODING).