Progate - A Remote Desktop Sharing System to
support Multiparty Conference
Prof. Rupali Bagate, Sumeet Singh, Rajni Joshi, Gaurav Pandey, Ritu Bhargarh
Pursuing Fourth year degree course in
Information Technology, University of Pune
Army Institute of Technology, Pune, Maharashtra India
www.aitpune.com
rupali.bagate@gmail.com, sumeet.s.krishna@gmail.com, rajni.joshi0103@gmail.com,
gauravpandey19914u@gmail.com, rtbhargarh203@gmail.com
Abstract - PRO-GATE is a simple, fast and secure application for
PC remote control which can support multiparty conference to
share desktop for online presentations or collaboration. The basic
purpose of PRO-GATE is to provide an application which will help
the users in accessing and controlling any desktop from
anywhere in the world. The idea is to create a virtual space for
interaction of more than two users, i.e. a conference supportive
system and not only peer-to-peer system. This allows creating,
modifying and sharing documents and information jointly. Most
of the available systems have bad scalability and slow down with
increase in number of users, PRO-GATE uses existing technologies
and advanced functions to provide a better real-time
collaboration system. The user access in PRO-GATE is kept as
simple as possible with minimal human intervention while setting
up. This is an open source tool, and thus could be customized
according to individual preferences. The application can be used
in industries, organizations and educational institutes for
collaborative studies, project demonstrations and distance
learning. It can be used to maintain cyber security by monitoring
any suspicious activities on desktop.
Keywords – Collaboration, VNC – Virtual Network Computing;
RFB – Remote Frame Buffer Protocol; Socket Programming;
Multi-threading; GUI – Graphical User Interface
I. INTRODUCTION
PC remote control means ability to access and control a
shared desktop from anywhere in the world. The user can
log-in via a web application and directly view his/her
desktop without tedious procedure. Collaboration means
working together, a computer supported collaboration
system would help to provide a remote support to create a
notion of virtual space where online presentations and
meetings could be held. And multiparty conference would
support not only peer-to-peer interaction, but an ability to
get more than two users to be able to collaborate and work
together. Here multiple clients could use this real-time
collaboration system to join a meeting hosted by a user,
such that each one of them would be able to view and
control the desktop of the host. These characteristics make
it very useful in professional, educational and personal
context – they enable exchange of information and
documents, to create, share and modify projects and ideas
jointly. The ability of this tool to be installed in a private
network gives maximum security while sharing a desktop.
Also it has functions to send chat messages, transfer files
and folders, helping in exchange of information amongst
individuals.
There are already many Desktop Sharing Softwares
available in markets which work on computer-supported
real-time collaboration systems [6], but with certain
limitations.
1)
2)
3)
4)
Many systems are slow, i.e. have bad scalability as their
performances decreases with the increase in number of
users.
Do not have a good Graphical user Interface, which
could be easily used and understood by the users.
Many of them are required to be installed at the user
site and thus involve a tedious procedure while setting
up for use.
They charge for their commercial use, which makes it
difficult for the start-up companies to provide remote
support for the clients.
In this paper, we propose an ALL IN ONE solution which
overcomes above limitations. This is achieved by using
existing technologies – VNC – Virtual Network Computing,
which is having Remote Frame Buffer Protocol, RFB as its
underlying technology [1][5].
VNC is a platformindependent system, which supports graphical desktop
sharing. Optimization of VNC is done to support real time
collaboration. Ruby on Rails – Rails is a web application
development framework written in the Ruby language used
to develop the Graphical User Interface. The GUI is such
that it makes user access in PRO-GATE very simple with
minimal human intervention while setting up. This is an
open source tool so organizations can customize it
according to their own needs.
This paper is organized as: Section 2 specifies literature
survey of the topic, Section 3 defines the Progate Design,
Section 4 defines the algorithm and handling of clients and
Section 5 depicts the conclusion and future work.
II. RELATED WORK
During detailed study of the existing technologies it was
found that the following technologies would be required to
develop the application.
A. VNC
B. Sockets
VNC – Virtual Network Computing – is remote control
software, which allows interacting with one computer using
a simple program on another computer [1]. It is a protocol
for accessing graphical user interfaces. It works at the
framebuffer level, which makes it platform-independent,
and thus it is potentially applicable to all operating systems.
It thus allows a user to control a remote machine, i.e. server
on a local machine, i.e. client. The basic operations:
Sockets are used for inter-process communication. They are
a way to speak to the other programs using standard UNIX
file descriptors. Socket API is especially provided by the
operating system allowing application programs to control
and use network sockets [2][3]. File descriptor for network
communication is got through a call to the socket () system
routine,
which
returns the
socket
descriptor.
Communication is done through it using the specialized
send () and recv () socket calls. The file descriptor returned
by socket () is sockfd, listen () is used to wait for the
incoming connections, accept () returns a new socket file
descriptor for each connection established. Socket-tosocket virtual connection is known as session and send ()
and recv () are used for communicating over datagram
sockets or stream sockets, refer Figure 1.
1)
VNC Server
It is a program which runs on a machine that shares its
screen. It allows to view a desktop not only on the machine
on which it runs, but from anywhere on the Internet, The
server sends framebuffer as small rectangles to the client
and passively allows the client to take control of it [1].
2)
VNC Client
It is a program installed on the client’s machine and
connects to the server component [1]. Also known as VNC
viewer, it watches, controls, and interacts with the remote
machine, i.e. server by sending to it the inputs and
accepting the outputs
3)
RFB Protocol
A Communication Protocol on which VNC is based. It is used
to remotely access the graphical user interfaces. This
protocol all server to update framebuffer which is displayed
on viewer’s side. The events – keyboard press and mouse
movements – messages from client are sent to server.
Desktop is represented as small rectangles of pixel data at
the specified x, y position and transmission is done by
relaying the updated graphical screen portions in the other
direction, over a network [1]. The RFB relies on sending
encoded pixels to the client that contains the information of
the Desktop of Server. The client then decodes the pixels
and draws them on a graphical application running on its
machine. Events occurring at the client side like keyboard
press and mouse pointer movements are trapped and sent
to the Server. Server then reflects back these changes. For
this purpose the RFB protocol suggests the use of a Frame
Buffer. The Frame Buffer actually contains the desktop
information which is updated when the client generates any
kind of event. This updated buffer must be sent to the
Server which updates its own desktop accordingly. Similarly
when the Server generates events that affect the desktop,
the updated buffer is redrawn at the Client. This exchange
of framebuffers provides synchronized desktop sharing. The
basic emphasis is that there should be very few
requirements at the client’s side. As RFB works at the level
of framebuffer, it is independent of the platform, i.e. it is
applicable to all windowing systems. So, clients can run on
widest range of hardware, this makes implementation of
client as simple as possible.
Sockets deliver the incoming data packets to specific
process or thread of an application. Server is the computer
application that provides application services. It creates
sockets on start up in listening mode [2] [7]. Once listener is
run, all it does is to sit there and listen whether a packet
arrives or not. Similarly many functions are there which are
said to block, i.e. if there is no data, they sleep there until
some data arrives. Such functions are accept (), recv (), even
when the first socket descriptor is created using socket (),
the kernel sets it to block. But to put a program on busy
wait looking for data is not a good practice as it’ll suck up
CPU time and thus reduces the overall efficiency.
Figure 1. Server Client Communication
C. Advanced Techniques
To solve the above problem select () function can be used
to perform synchronous handling of input and output at
multiple sockets.
Select (): This function is used as synchronous I/O
multiplexing and thus can monitor multiple sockets, Figure
2, at the same time. It will tell which sockets are ready to
read, which are ready to write and which ones have got an
exception. And rather than always being in busy-wait
condition while blocking to perform read and write
operations, a time structure could be used to specify a
timeout period. Thus select () function is used to determine
the status of the sockets, that it handles [3] [7]. It has to
monitor sets of file descriptors, FD_SET in a synchronous
manner.
web application [4].The user access in Progate is kept as
simple as possible with minimal human intervention while
setting up. As it provides one click access to the remote
desktop this increases the ease of use of the product. This is
facilitated by automatic downloading of the exe at the
client’s side. It is an open source tool, free to use and could
be customized according to individual preferences.
B. Working
Desktop sharing [8] such that one could access it from a
distant place is kept simple. As soon as user registers using
our web page an executable file is downloaded at user’s
machine and irrespective of whether it is host machine or
guest machine. This executable file is downloaded at user’s
machine without any prompt to the user and since the size
of file is too less, that is 52 kb, it is downloaded quickly. This
downloaded file is stored in a temporary file (for
example %temp% folder in windows) and hence it is
executed. Now, the problem which may arise here is that
the browser doesn’t have the rights to execute the
executable file, but the java applet could execute it. As the
browser can run the java applet. So now we were able to
download and execute the executable file at user’s end
without even bringing it in notice of user. Now, once this
executable file is downloaded and executed it will start
communicating with our Progate Server. And now the
Server will just act as a bridge between the host client and
the guest client and the executable file will run at both the
clients.
C. Role of Server
Figure 2. File descriptors
D. Ruby on rails
Web development technology, wherein Rails is a web
application development framework written in the Ruby
language – a fully featured object-oriented language. In rails
changes made are reflected immediately in run-time
environment that makes it easier for developers to use [4].
Ruby on the other hand is also easily testable. Integration of
Ruby with Rails is simply, clean and seamless due to
dynamic nature of Ruby. So, ruby on rails provide a
consistent approach to support development of web
services.
The server acts as a reflector, Figure 3, present in the public
domain and maintains Control Connection table and Data
connection Table. Control Connections are made first at the
time of user log-in and registration in the Progate. Once the
entries in control tables have been made, the user is free to
either host a new session or to join an existing session by
providing the id of the host to which it wishes to connect to.
Data Connections are made in addition to handle the data
transfer between the stream sockets for a particular
session. The session ends as the client logs out or the
meeting is no longer continued by the host.
III. PROGATE DESIGN
The requirements to design a real-time collaboration
system to support interaction of more than two users were
identified and above mentioned technologies were kept in
mind while developing Progate.The design is focussed to
provide an easy to access collaboration system that
supports multiple users and not only peer-to-peer.
A. GUI
The Graphical user interface has been developed using
Ruby on Rails, which provides a consistent way to develop a
Figure 3. Server as a Reflector
Here in the socket programming the server has to listen for
incoming connections as well as keep reading and writing
from and to the connections it already has. For this accept ()
and recv()s could be used as blocking functions but this
sucks up CPU time and efficiency. As there are multiple
users which are requesting server for connection and data
transfer requests, so multiple threads are required to
handle these connections. To share resources amongst
multiple threads a function is required to assure thread
safety, so that these threads can work simultaneously
within the same process. So as discussed above an
advanced function – select () – is thus used for synchronous
I/O multiplexing to handle multiple sockets created by
connection handling threads. The select () API [2] [3] creates
a common point where multiple threads are put on to wait.
This function monitors “sets” of file descriptors; in
particular readfds, writefds, and exceptfds, thus
multithreading can be handled efficiently.
IV. METHODOLOGY
For the tool to be developed, a very simple methodology is
used in which the server will be running in listening mode
[8]. As soon as the client logins, an executable will run on
the client side which will contain the VNC server and the
VNC client, these are responsible for desktop sharing as well
as desktop accessing. This executable is responsible for
connecting to the server and doing further work. The
shared desktop and the sharing desktop are connected to
the server via a control connection. This will create an entry
in the control connection table which is present at the
server location. Some of the columns in data connection
table will be filled when the sharing desktop is connected
and the entry will be full if the accessing desktop completes
all the credentials and asks for the permission to access the
desktop.
The Client interacts with the Server through the following
functions: Get Support Connection Setup method is called
when a client asks to connect to Server and makes a Control
Connection, Figure 4.1. Give Support Connection Setup
provides Control Connection to the client, Figure 4.2.To
request for data transmission Remote Support Request is
done, Figure 4.3. Accept Support Acknowledgement,
accepts the data connection request and a Data Connection
gets established, Figure 4.4. After Data Connection
establishment Data Exchange, Figure 4.5, occurs
synchronously among the clients joined during a session.
This way the server interacts with the clients who are
connecting to it, and the data connections and data transfer
are facilitated by the connection handler method which
manages the file descriptors.
This interaction between the Server and Client stops once a
client either logs out or the host dissolves the session,
causing the data connections with its clients to get cleaned
up. This could be done using Get Logout Request and Give
Logout Request methods.
Figure 4. Sequence Diagrams
A. SERVER CONFIGURATION
V. CONCLUSION
The server maintains the record of clients which wants to
share the desktop. It bridges the data connection of
interested clients. Control connection of client with server is
always active.
Better is the connectivity between two machines better will
be the Performance. Connection Schema identifying clients
on Server is stored in the following manner, Figure 5:
TABLE I
CONTROL CONNECTION TABLE
USER ID
PASSWORD
SYSTEM ID
SOCKET ID
TABLE II
DATA CONNECTION TABLE
REQ
SYS
ID
TARGET
SYS ID
REQ
USER
ID
TARGET
USER
ID
REQ
CONTROL
SOCK ID
TARGET
CONTROL
SOCK ID
Figure 5. Control and Data Connection Tables
The data connection table is partially created when the
meeting is created and fully filled when somebody else joins
the meeting. Unique ID will be generated for each meeting
which will help the users to make their meeting private and
secure. So until or unless you don’t make your team ID
public you are safe.
B. APPROACH TO IMPLEMENTATION
The project is divided in many phases as given below:1.
2.
3.
It includes making PROGATE as an online service
and as a software that can be installed in a
network.
It focuses on providing registration facility and
multiparty conferences.
It is the final phase and includes providing security
to the system using SSL encryption.
The code for the server and the client can be written using
socket programming in any language like C++/java.
The existing technologies and additional advanced functions
along with a user friendly GUI could create a much faster
and simpler remote desktop sharing system to support
multiparty conference where in addition to peer-to-peer,
more than two users can interact. The project is free and
open source, the source code and documentation would be
available at the project web site.
The multiple clients are handled by providing a time slice to
the sockets requesting for data transmission and thus the
multiple threads governing the sockets are handled
accordingly. The increase in number of users, i.e. the
scalability can be taken care of by extending VNC to support
multicast data transmission. Whether you want quick
access to your home computer from anywhere in the world,
remote desktop applications can make your life easier. With
the right remote desktop tool, you can access your home
computer as though you're sitting right in front of it— no
matter where you are, no matter what you're doing.
VI. FUTURE WORK
Future enhancements could be done to extend the audio
and video abilities of remote desktop sharing. As the tool
goes by the open source terms anyone in the world can
access the source code and make the changes for the
betterment of the System. It will be released as a free
service for the use of common man. To ensure the better
scalability and performance of the service it will be hosted
on Cloud. Mobile based application which will be having the
potential to support the service can be developed.
ACKNOWLEDGMENT
Propalms pvt ltd sponsored the project Progate. Mr.
Vijender Yadav, the external guide and Prof. Rupali Bagate,
project guide at Army Institute of Technology wishes to
acknowledge Sumeet Singh, Gaurav Pandey, Rajni Joshi and
Ritu Bhargarh for developing Progate to support remote
desktop sharing for multiparty conference. This research is
totally attributed to the guidance of above mentioned.
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