A chat system with knock-on-the-door sound and

shadow

Keishi Suzumura

, Natsuko Hikage , and Yuko Murayama

Iwate Prefectural University, Graduate School of Software and Information Science, Postfach

020-0193, 152-52 Sugo, Takizawa, Iwate, Japan

Iwate Prefectural University, Faculty of Software and Information Science, Postfach

020-0193, 152-52 Sugo, Takizawa, Iwate, Japan

Abstract. In this research we try and implement communication system us-

ing the metaphor of a door on the World Wide Web (WWW) as a media for

novel types of informal communications. We call those informal communica-

tions through a door ”on-door communications.” As an on-door communication

system, we have designed and implemented a system for a chat at a net door. One

has a door page on WWW and a chat system is presented there so that the others

pay a visit to have a chat at the door with two features for awareness, viz. knock

and shadow. A knock on the door is used to let the others to notice of the arrival

of a visitor at the door with an auditory signal. A shadow indicates the existence

of visitors as well as that of the door owner. This paper reports on our design and

implementation of our prototype system as well as its operations.

1 Introduction

In this research, we call the informal communication which uses the metaphor of a

door “on-door communication.” We have brought some systems on the World-Wide

Web (WWW), such as the on-door message board[4], the chat system with knock and

shadow, and the under-the-door communication system. This paper presents the chat

system.

In the real world, one uses knock-on-the-door sounds and a bell to indicate the

arrival of a visitor. Our chat system on WWW makes use of such sounds as a trigger for

conversation. Moreover, shadows and lights on a door window tell a visitor tacitly the

existence of a resident in the room. We look into such a role of a door as well as actions

performed through a door. It is quite difﬁcult to know of the existence of the others on

networks compared to the real world. This paper presents our work on some awareness

tools on the network such as a knock on the door and a shadow on a door window. We

report on our experimental operation of our chat system with those awareness tools as

well.

The next section presents the model of the on-door knock communications, and

section 3 givessome related work. Section 4 describes the system design with awareness

functions using auditory sound and shadow. Section 5 presents the implementation of

Suzumura K., Hikage N. and Murayama Y. (2004).

A chat system with knock-on-the-door sound and shadow.

In Proceedings of the 1st International Workshop on Computer Supported Activity Coordination, pages 81-90

DOI: 10.5220/0002659700810090

 SciTePress

our prototype system. Section 6 reports the results from the experimental use. Section 7

present the difference from an ordinary chat systems. Section 8 reports the future work.

Finally, Section 9 gives some conclusions.

2 The model of the on-door knock communications

In this section we describe the model of a knock-on-the-door communications. In the

real world, one visits the door of someone’s room and knows whether the resident is in

or not presumably by looking at a door window if any as well as by hearing some noise

from the inside of the room. Moreover, the visitor knocks on the door, alternatively she

rings a bell to notify the resident of herarrival. In case of no answer, one would conclude

that the resident is not available in the room. If the resident is in, he would reply to the

visitor’s request for communication. Figure 1 shows the model of the knock-on-the-

door system.

Fig.1. the model of the knock-on-the-door communication

A knock-on-the-door system is composed of a door, the resident of the room, and

the visitor. The door is a portal for an informal communication space with the resident.

The portal has the user interface easy to guess for a user due to the door metaphor.

3 Related work

A protocol for User Awareness on WWW[1] provides with a discussion on awareness

system with CGI and JAVA. This paper proposed an open awareness protocol to notify

the presence of user to the other. Our KCP is designed for the same purpose but for

auditory awareness. Sound has been used effectively for awareness[2].

The shadow view system[7] provides the user the function using the metaphor of the

shadow. The shadow function is used in order to protect a usre’s privacy. Nichols and

others[9] have focused on the role of the door like the mediator between the resident

of the room and visitors. Ubique[3] is a system that aims to create virtual places on the

WWW. This system has such functions as ”who is on-line”, chat and instant message.

The system also dose not use auditory signal in chat.

CyberWindow[6] implemented the metaphor of a window on WWW, and intercon-

nects the real world and the WWW environment with sound awareness. In this system,

users in the real world carry hand held computers with a wireless connection to the net-

work. The visitor uses one of the three types of message volume: ”whispered”, ”said”

and ”shouted”. The received messages are transformed into voice messages by means

of a text-speech engine. A visitor can also show his/her emotions to the others by using

various types of sound; laugh, applause and knock. In our system, not only awareness

of sound but also visual awareness is given to a visitor.

4 The system Design of the knock-on-the-door communications

We presume the use of our system as the following scenario. The resident installs our

system for a portal to his informal communication space. The others visit the door

site. When a resident is in the room, his shadow appears on the door window. Visitors’

shadow would be projected in front of the door-image.

In the following subsections, we describe the awareness functions, system conﬁgu-

ration, and the knock-on-the-door protocol.

4.1 Awareness functions

The following awareness functions need to be implemented in our system.

1. to produce an auditory signal for a knock

2. to present the shadows of a resident and visitors

3. to provide users easy interfaces related to a door

An auditory signal should be provided for a knock sound. We may need some other

types such as the ones for laughing voice and beep sound. Shadows are expressed as

black images. In order to knock, one needs to give a click on a door image and a knock

sound is produced.

Our system provides users with a simple tool for knocking with a click using a

standard input device such as a mouse. A click produces a sound of a knock on the

door, so that anyone who has been opening that door page can hear. The shadow of the

resident of the room is displayed on the window frame portion of a door, and a visitor’s

shadow is displayed before the door.

After a visitor connects with a system, the a shadow image is displayed in front of

the door image just as an avator. A visitor is aware of the existence of the others by their

shadows. Similarly the shadow of a resident is displayed on the door window.

4.2 The system conﬁguration

In this subsection we describe the system conﬁguration. Our system provides users with

the two services, viz. Awareness services include notifying the others of one’s existence

and intention to talk by a knock sound and letting user know of the others’ existence by

shadow, and a communication service. Our system has the client and server architecture.

– The client functions provide interface for users.

to knock on the door

to generate the knock sound

to display the user’s shadow

– The server functions provide the user with other user’s information.

to exchange of knock, chat, and shadow message information

to obtain the user information

The server manages the information from the clients. The information includes chat

messages, auditory requests and user IDs. It needs to maintain such information. It

provides clients with those information so as to provideclients with a message exchange

service as well.

A client interfaces the user such as a resident and visitors to the server. It presents

information from the server to the user such as chat messages, the other users’ shadows

and auditory sounds such as knock sounds. Accordingly it requires to have the functions

for the user to give a knock on the door as well as to present a knock sound to the user.

Moreover, it needs to display shadows. It sends information such as chat messages and

request for a knock from its local user to the server as well. Fig. 2 shows this. The client

system is installed on WWW. HTTP protocol is used for a client in order to connect

with the server.

4.3 Knock-on-the-door Communication Protocol

After connection with the server, the client and the server communicate with each

other using our original protocol called the Knock-on-the-door Communication Pro-

tocol (KCP).

KCP is a connection oriented protocol. The Protocol Data Unit (PDU) Table of a

KCP protocol is shown in Table 1. PDU is composed of the ID of a door knock system,

a command, and some data. KCP has three message types, viz. a knock message, a chat

message, and a management message. See Table 2 for the detail. The knock and chat

messages are sent to the server from a client. The server sends them to all the other

clients which connect to the same door. The management message is used to eliminate

a message, as well as to control visitor´s access.

A user inputs a handle name after system starting. The handle name is used as a

user ID in the chat system.

WWW Server

Knock Server

Web browser

[Client][Server]

Legend:

through a local interface

through the internet

*KCP:the Knock-on-the-door Communicaion Protocol

[Resident]

[Visitor]

HTTP/TCP

KCP/TCP

Fig.2. the protocol of knock-on-the-door

Table 1. the protocol data unit

ID command data

5 Implementation of a prototype system

This section describes the implementation of a prototype system. The system was im-

plemented using the JAVA language. The language is ﬂexible so that it is easy to add

new functions and services.

The server was implemented with JAVA application and the client was the JAVA

applet. The JAVA virtual machine of server side is JDK 1.2. The interface by the side

of a client was implemented using Abstract Window Toolkit (AWT). Using the web

browser which can perform JAVA applet, a user accesses the page in which the knock

system was installed.

Browser environment recommends Netscape Communicator 4.5 or more and Inter-

net Explorer 5.0 or more.

Figure 3 shows an example screen image of the prototype system. In the ﬁgure

the resident and two other visitors are shown. The maximum of three shadows can be

displayed in front of the door image — i.e. even when we have more than three users,

up to three shadows could be presented. When the resident comes to his door page, his

Table 2. The contents of each entity

Entity Format Content

ID a string an on-door ID number

Command a string a knock message, a chat message,

a management message

Data a string a chat message

Fig.3. A prototype system

shadow is displayed on the door window. A knock on the door can be done by clicking

on the door-image with a mouse. The knock sound is reproduced using AU (AUdio ﬁle)

format.

The prototype system deals with multiple doors. In order to enable this, the server

publishes a door ID to the resident. The door ID is used in all the messages exchanged

by clients and the server. The ID is used to indicate the chat group associated with the

door with that ID.

With the chat system, we have added more function to express a user´s feeling such

as laughing voice. If a “LAUGH” button is pushed, laughing voice will be presented

to the others just as a knock sound. Accordingly, the smile mark in text, “ :-)” would

appear on a chat text line. Similarly, if a “BOOING” button is selected, it gives beep

sound as well as the face mark, “:-

” would appear.

Each chat message is maintained in the server with a time stamp. This way the chat

system can be used to leave a message as well, so that when one visits a door and leave

a message.

6 An experimental use

6.1 An experimental environment

We operated our prototype system to study whether knock sound was used as a trigger

for conversation or not. The experimental use started from May, last year. The server

environment of the experiment is shown in Table 3.

Table 3. The server environment

a sever system

OS / Kernel Vine Linux / 2.6

CPU Intel Celeron 1.7GHz

Memory 512M

Network 10/100BASE-T

JAVA J2SE1.4 j

HTTP Server Apache 1.3.27

The OS and browser environment is shown in Table 4.

Table 4. The client environment

OS Browser environment

Windows Me Netscape Communicator 6.1

Microsoft Internet Explorer 5.5

Windows 98 Opera6.0 J

SunOS 5.6 Netscape Communicator 4.7

Netscape Communicator 4.5

The knock-on-the-door system was installed into ﬁve places in total. Those of two

clients are located in the campus intranet. The others are connected to the Internet(Table

5). Each door were assigned an unique door IDs. We assumed that all of visitors would

be connected through the campus network and the Internet.

Table 5. The number of clients, and installed locations

ID the administrator Network the number of clients

DoorA, DoorB the student’s web page the campus intranet 2

DoorC, DoorD the student’s web page the Internet 2

DoorE the laboratory web page the Internet 1

6.2 Logﬁles analysis

We studied the conversation log to know in what way knock sounds and shadows had

been used. In the following example, User yuki knocked the door to start conversation

with User tomimoto.

yuki> Knock!, 15:26 5/8

tomimoto> hello, 15:27 5/8

tomimoto> I’am tomimoto with Iwate prefec-

tural Univ. 15:27 5/8

yuki> hi, 15:27 5/8

In the following log, although the knock is not performed, yuki has noticed the

shadow displayed on his browser , and she was aware of takahashi’s existence.

yuki> Hello, 16:16 5/8

yuki> Who are you?, 16:16 5/8

yuki> Your name, please? 16:17 5/8

takahashi> I’m Takahashi, 16:17 5/8

Figure 4 shows the expressions used in a chat during the experiment. “Chat” indicates

the text-only chat without sound, “Knock” is the knock sound, “:-)” indicate the face

mark with laughing voice and “:-

” is those with beep sound.

32% of the conversation used text-only chat, and 68% used sounds such as knock

sound, laughing voice and beep sound. Sounds are used frequently. Interestingly for

the urgent conversation, at the time of the conversation, an user want to communicate

with others quickly. Used of the text-only chat was 57% and used of the knock sound

was 42%. In this case, very few used face mark. Presumably the knock sound has less

semantics than laughing voice and beep sound. We conclude that the knock sound is

applicable for various scenes. A state of conversation and an user’s emotion could be

deduced by analyzing how often each type of sound is used. We will study this in the

future work.

We examined the usefulness of the awareness functions such as knock sound and

the shadow. Our purpose is evaluating whether knock sound is used as a trigger for a

conversation as well as whether one can notice of the existence of the others by display-

ing shadows. We analyzed the conversation log to evaluate them to surveyed the usage

by questionnaire to the users.

The conversation logs show the followings.

– Sounds are used frequently in the begining of the conversation and the during the

conversaion.

– One notices of the existence of the others by the knock sound.

– By shadow, a user notices of the existence of the others and invites them to join her

in conversation.

We found some problems as well. Although we have implemented a function with

which a user writes and leaves a message when the resident is absent, few users made

use of it.

According to the user comments, few uses knew of the function. The left message

is displayed on the same place as chat area. Moreover, among three weeks, there are 72

accesses to our system and 5 conversations were held. Most of the users could not make

Fig.4. the expression used in a chat

use of our system because the number of conversation held was small. The reasons are

as follows;

1. Few users accessed to web pages.

2. The resident forgot to logon, alternatively duration of her logging on was too short.

3. Some users disabled the JAVA function of their browser.

The followings are required in order to investigate the above reasons.

1. The number of accesses of each web page.

2. The duration of a resident logging into our system.

3. The setting of a browser whether JAVA function is enabled or not.

4. How a user will make use of our system when she will be given no explanation

about the system.

7 The difference from an ordinary chat system

The goal of the knock-on-the-door system is to enable users to be aware of the others’

existence using knock sound and shadow. What is most different from the ordinary chat

systems is our awareness function. In the experimental use, the knock sound are used

as that a user tells the others about his existence and used as a trigger for conversation.

Moreover, the knock sound was used in various scenes, such as for a response to a

question, for a reminder of a response, and for a change of the subject of conversation,

for a invitation to the conversation. The sound without the speciﬁc semantics such as

the knock provides the user with the various applications.

In an urgent conversation, the speaker notiﬁes of the renewal of the chat using the

knock sounds to the other who is looking at another computer screen. Moreover, the

expressions used conversation is different from the situations.

8 Future work

In the future work, we look into a web browser, and add the awareness functions such

as a knock-on-the-door sound and shadow. We call such a system “On-door browser.”

We will implement this system on WWW.

9 Conclusion

In this paper, we proposed the communiation system using the metaphor of a door.

We looked into such a role of a door as well as actions performed thorough a door,

and proposed the knock-on-the-door system. The knock-on-the-door system provides a

user with an awareness function. The awareness function is implemented by the knock

action and expression of user’s shadow. The next section, we proposed the model of the

knock-on-the-door system.

In the section of “The system Design of the knock-on-the-door communiations”, we

showed functions of the knock-on-the-door system and designed it. We experimented

using the prototype system. In the experiment, the knock sound was used as a trigger

for conversation. The knock sound was used when a user changed the conversation of a

chat and went out of a chat room. By expressing a user with a shadow, the user notices

of the existence of others and invites them to join her in conversation. From the above,

we saw the usefulness of the awareness with knock sound and shadow, then described

the future work.

In the future work, we will implement the on-door browser system and evaluate it.

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