AN EVALUATION OF A VISUAL QUERY LANGUAGE FOR

INFORMATION SYSTEMS

Haifa Elsidani Elariss, Souheil Khaddaj

Faculty of Computing, Information Systems and Mathematics, Kingston University London, Kingston upon Thames,UK

Ramzi Haraty

Division of ComputerScience and Mathematics, Lebanese American University, Mme Curie Street, Beirut, Lebanon

Keywords: International visual user interface, Spatio-temporal databases and Mobile phone applications.

Abstract: In recent years, many non-expert user applications have been developed to query Geographic Information

Systems. GIS are used to browse and view data about space and time thus naming them spatio-temporal

databases. The Location Based Services which are considered as part of the spatio-temporal field, concern

the user who asks questions related to his current position by using a mobile phone. Our research aims at

designing and developing an International Visual Query Language (IVQL) that allows users to query

databases based on their location. The databases are installed on a GIS server computer. The queries are sent

to the server from a mobile phone through the Short Messages System (SMS). With the emerging

Globalization of user interfaces, IVQL is meant to have a global and international user interface that could

be understood by all users worldwide. We propose a user interface consisting of smiley icons that are used

to build an international query language. Smiley icons enable the users to access data and build queries

easily and in a user-friendly way. IVQL, its user interface, model and evaluation are explained. The query

formulation is illustrated using a sample GIS system for tourists, to perform network and proximity analysis.

1 INTRODUCTION

During the last decades, computer applications have

been deployed to manage spatial data with

Geographic Information Systems. GIS are able to

store, analyze and visualize a large volume of

geographic information. They play a major role in

many domains such as urban and environmental

planning, transportation and tourism. They can be

applied in different fields such as location based

services, fire and emergency departments, problem

solving and many others (Clementini, 1993). They

deal with spatial data objects and relations that are

often represented by a visual approach. The spatial

objects are stored in the form of maps. To execute

operations that analyze spatial data, structured query

languages (SQL) are used to integrate the analysis

with the GIS. One problem is that SQL query

languages possess complex textual syntax. Another

problem is the need to know the structure of the

database schema before writing a query (Djordjevic-

Kajan, 1996). Most of GIS users are expected to be

non experts in the geographic domain. Since it is

difficult for casual users to learn query languages,

the need emerges to design and develop visual, user-

friendly and ease-of-use query interfaces. A major

challenge nowadays is the visualization of query

languages. The purpose of visual query languages is

to enhance the GIS effectiveness and usability. They

facilitate the process of query formulation.

Moreover, there is an urgent need to deal with the

globalization of visual query languages in order to

meet global and diversified demands. Globalization

refers to the production of products that are used

internationally. The need to develop international

user interfaces becomes a crucial issue in visual

query languages. Marcus, in his paper (Marcus,

1999), defines globalization and demonstrates why

globalization is vital to the success of software.

Thus, with the emerging globalization of user

interfaces, in this work the use of smiley icons is

proposed in order to build an international query

language. A smiley is a graphical representation that

displays a smiley face to express emotions and

convey facial expressions such as, happy, sad or

bored. They can be easily understood by all peoples

worldwide. Smiley icons have a high level of

Elsidani Elariss H., Khaddaj S. and Haraty R. (2006).

AN EVALUATION OF A VISUAL QUERY LANGUAGE FOR INFORMATION SYSTEMS.

In Proceedings of the Eighth International Conference on Enterprise Information Systems - HCI, pages 51-58

DOI: 10.5220/0002465400510058

 SciTePress

expressiveness. Pang, in his thesis (Pang, 2002) uses

smiley icons to express the operator’s feelings in a

nonverbal interface for the McDrive system

developed for the McDonald chain. The smiley faces

are displayed on the screen to show the right facial

expression. In our research, smiley icons are used to

represent themes, objects and operators. They are

used to formulate queries in a global language. We

start by a brief overview of a number of visual

languages. Then, a framework for an International

Visual Query Language (IVQL) is proposed. The

approach addresses the visual query formulation

through the use of smiley icons that represent

geographic features, relations and functions such as,

themes, objects and operators. IVQL can be

extended as much as the user needs. It can include as

many icons as needed whether they represent themes

or objects. It is expected to manage dynamic query

processing. The query formulation is hereby

illustrated using a sample GIS system for tourists

who need to query the database based on their

current location from a mobile phone. The databases

are installed on a GIS server computer. The queries

are sent to the server for example using the Short

Messages System (SMS) from mobile devices.

2 VISUAL QUERY LANGUAGES

In this section we briefly describe some of the state

of the art visual query languages showing some of

their advantages as well as limitations.

2.1 The LVIS Language

LVIS (Bonhomme, 1999) is a visual query language

for spatio-temporal databases. Metaphors are used

for Querying Visually Spatio-Temporal Databases

(Bonhomme, 2000). Geographic pictures represent

spatial objects (object types) and Geometric shapes

represent relations among them (operators).

Balloons and Anchors are placed on a temporal axis

to describe spatio-temporal criteria. The user builds

a visual query by selecting a combination of the

icons that represent the pictures, shapes, and

temporal axis (Bonhomme, 2002). The temporal

queries are built inside balloons that may be

minimized in form of anchors for better visualization

of the query under development. The interface

contains a working area to build, validate and

execute the query which is then translated to a pivot

language that is independent from the host query

language of the target GIS platform. The pivot

language is compatible with the standardized

Spatial-SQL (ISO/IEC, 1996) for spatial operators

and with TSQL (Snodgrass, 1995) for temporal

operators and uses the Allen temporal intervals

(Allen, 1983). Then, the visual query is translated

into the GIS target language and the result of the

query is visualized on a map. LVIS is an extension

of the CIGALES (Aufaure, 1995) and (Lbath, 1997)

which is a visual query language for spatial

databases where temporal aspects are not

considered. Psycho-cognitive tests have been

developed to measure the interpretability and

comprehension of the metaphors. The major aim of

the tests is to show that the metaphors of the

language are well recognized by end-users. Two

subject groups were chosen: persons working with

GIS and persons who are non-experts. The results of

the experimentation have shown that the recognition

of metaphors is effective to users especially the ones

without prior experience with GIS systems. The

results showed also that the subjects were able to

recognize the relationship between spatial objects

very easily and that the metaphors are well accepted

by the two populations.

2.2 The PHENOMENA Language

PHENOMENA, described in (Laurini, 2003) and

(Paolino, 2004), is a visual query language for

Continuous Fields developed for GIS. It manages

both continuous fields and discrete objects in a

uniform manner. Continuous fields represent real-

world events such as temperature and pressure.

Discrete objects represent points, lines or areas. The

user is provided with the capability to capture some

features of a scenario by selecting an area of interest

and handling the events involved. Continuous fields

and spatial conditions are visualized using

metaphors called geometaphors. To build a query,

the user chooses a continuous field that is

represented as geographic data then a function that

describes its behavior. Combining continuous fields

with spatial conditions provides the user with the

capability of querying those phenomena that vary in

space, such as the temperature on a region or the

density of population in a city. Thus, it is intended to

be used by domain experts such as geologists and

meteorologist. The user interface is made up of two

areas. The area on the left contains the icons that

represent continuous fields such as temperature and

the icons that represent spatial objects such as river.

The area on the right contains the icons that

represent the aggregate functions such as minimum.

The user drags and drops the icons into the central

tabbed panel in order to formulate the SQL-like

query that can be either executed or saved.

ICEIS 2006 - HUMAN-COMPUTER INTERACTION

2.3 The GeoQA Language

GeoQA (Stojanovic, 2000) is a visual query and

analysis tool that has been proposed as an integral

component of the GinisNT which is an Object-

Oriented GIS framework used for GIS applications

development. GeoQA has an interactive visual

interface used for formulating and processing

spatial, non-spatial and combined queries. GeoQA

may be applied in GIS applications that are used for

urban planning and prevention of pollution, etc. It

has been applied on the GIS application GeoTT

which is developed for managing the Telegraph-

Telephone cable network in the Republic of Serbia,

Yugoslavia as described in (Djordjevic, 1996) and

(Stojanovic, 1998). The visual graphical user

interface of GeoQA is a WYSIWYG interface made

up of icons, toolbars and a panel in which maps are

displayed each in a separate window. The GUI has

dialog boxes and pop-up menus. Two sets of Icons

are displayed in toolbars based on their function and

representation. The first set contains icons

representing all spatial entities. The second set

contains icons representing spatial relations

(topological, geometric and direction) and spatial

operators (point, region, window). The user uses the

mouse and the icons to manipulate directly and

interactively the maps. Dialog boxes and text input

are used in formulating queries including spatial

relations. Queries can be saved for later loading. The

output result of a query is displayed in a window in

the panel with or without the background map based

on the user’s choice. GeoQA uses the Mediator

(Stoimenov, 1999) which is for an OO front-end to

RDBMSs. No evaluation of the language was made.

2.4 Other Visual Languages

There are also a number of other approaches to

Visual Query Languages that are hereby described.

Kaleidoquery (Murrey, 1998) is a visual query

language for object databases that depicts the query

as a filter flow. A comparative evaluation was

undertaken to compare the design of Kaleidoquery

to another textual query language, Object Query

Language (OQL). A paper and pencil test

experiment was conducted to obtain quantitative

data on user performance and questionnaires to

obtain qualitative data on ease of use, user

satisfaction and resolution of query language

problems. Two subject groups were selected from

students who hold university degrees and were

classified as programmers and non-programmers.

Programmers correctly defined significantly more

relationship queries in Kaleidoquery. They showed

higher preference for attribute comparison in OQL

and for data flows over and and or in OQL. Non-

programmers answered significantly more correct

queries in Kaleidoquery than OQL. They defined

more correct queries with results selection and

showed a higher performance for the structuring

aspects of Kaleidoquery. In general, programmers

performed better than non-programmers.

The Filter-flow (Morris, 2004) and (Morris,

2002) is a visual query language and interface for

large spatial databases. The various types of queries

are expressed by Basic Filters that are represented

by icons in order to construct query diagrams

between data input and data output elements. The

comparison between the Filter-flow visual language

and the ArcView GIS was used to evaluate the query

building process. Evaluation tests for both the

language and the interface have been designed. Two

subject groups of users were selected and classified

as users with some experience of using GIS systems

and users with no prior knowledge of GIS. The

results of the evaluation showed that the Filter-flow

visual query language simplified the learning

process of the user, made the query expression

process easier and proved to make the query

expression more readable.

The Exploratory Database View Constructor

(EDVC) (Smith, 2004) and (Smith, 2005) is a visual

query interface especially experimented to support

Link Analysis (LA) that is used to understand data

collected in criminal or terrorist threat analysis. It

uses rectangular icons to visualize objects such as

people and locations. It uses directional lines to

represent the connections and links between the

objects. To evaluate the query language, subjects

were chosen at random from different educational

background. All the subjects had experience with

graphical user interface but had no previous

knowledge on using a query language. The aspects

evaluated are: query writing, reading, interpretation,

comprehension, memory and problem solving.

These methods measure the ease of use of the query

language. The results of the user evaluation

indicated that the user interface is well suited to

supporting users with no experience. The subjects

were able to form a useful class of queries and this

was facilitated by the intuitive style of the

interaction provided in the explorer. The results also

indicated that the user interface for constructing path

filters needs to be improved.

Special Interactive Visual Tools have been

developed, as described by (Andrienko, 2004), to

explore the analysis of spatial-Temporal data. The

interface provides the user with time-control icons to

AN EVALUATION OF A VISUAL QUERY LANGUAGE FOR INFORMATION SYSTEMS

specify the beginning and end of a period of time

during which the changes have occurred on a spatial

location. No evaluation of the language was made.

2.5 Summary

The above described state-of-the-art visual query

languages have demonstrated a considerable

improvement in the field of visual query languages.

However, each one of them has some limitations.

We hereby discuss their advantages and limitations.

The LVIS visual query language described by

(Bonhomme, 2002) has a major advantage which is

using iconic Metaphors to represent and visualize

objects locations and operators. The PHENOMENA

visual query language described by (Laurini, 2003)

and (Paolino, 2004) has a major advantage which is

the use of a uniform visual environment, iconic

metaphors that represent operators to be applied

simultaneously to spatial and continuous fields. The

user can manage continuous fields as actual spatial

data. GeoQA described by (Stojanovic, 2000) has a

major advantage which is the flexibility in the

options in building queries. The user can text input a

query, build a query by using a combination of text

input and icons, and the possibility of building

complex queries by using only icons (iconic query

building). However, none of the above visual query

languages is able to provide the user with the ability

to formulate dynamic queries and none takes into

account mobile computing users. They do not

provide users from different culture and background

with an international visual query language that

depicts queries using icons. The IVQL visual query

language aims to present an integrated approach that

combines some of the advantages of the various

languages as well as remedy some of their

limitations. The use of iconic metaphors to depict

object, locations and operators has been used from

the LVIS visual query language by using the smiley

icons that have a more expressiveness power. The

idea of applying the same operators to continuous

fields as well as spatial fields in the PHENOMENA

visual query language has been used in the IVQL

visual query language. The operator < less than can

be applied to spatial and temporal fields such as,

find locations that fall within a certain distance and

to find events that fall within a certain time interval.

GeoQA provides the user with the possibility to

either text input a query or to build a query by using

only icons. IVQL provides the user with the

possibility to either text input his location with the

destination location or select them from list boxes.

As mentioned above some of visual query languages

have been evaluated while others have not which

means that their effectiveness and expressiveness

have not been tested. However, the IVQL will be

tested in future work using some of the strategies

discussed earlier as well as other possible strategies.

3 PROPOSED FRAMEWORK

3.1 IVQL Architecture

The IVQL user interface is installed on the target

device where the user can formulate a query

visually. The query is converted into a pivot

language and might be sent for example using an

SMS message to the GIS server where it is saved in

a sequential file. IVQL is implemented as a

middleware between the text-queries (pivot

language) and any Object-Relational database

management system (ORDBMS). An ORDBMS has

an object-oriented (OO) environment, is based on an

OO data model as well as on an OO application

development methodology. Its underlying spatial

database is stored and organized by a RDBMS. The

architecture of IVQL is shown in Figure 1.

Figure 1: The architecture of IVQL.

Objects Components is a framework that allows

the creation of new domain-specific components

from previously developed ones. It forms a common

library of those software components called Objects

used to build, manage and query the database. They

allow users to develop new extensions and embed

maps functionality in applications, thus making the

database scaleable. SDE is used to handle, access,

manage, index and display spatial data stored in a

RDBMS. It enhances data management performance

and enables schema portability between RDBMSs.

Pivot language plays the role of a middleware

between the user interface and the query processor.

The user interface translates and converts the visual

queries into text queries by replacing each icon with

its textual name before the query is sent to the GIS

server for execution. Pilot language Text-queries is

ICEIS 2006 - HUMAN-COMPUTER INTERACTION

a sequential file that contains the received text

queries. IVQL query processor reads sequentially the

text queries that are stored in the Pilot language

Text-queries, converts them to GIS SQL statements

and executes them. It can process dynamic complex

queries and includes intelligent query mechanisms.

3.2 IVQL Query Representation

IVQL has a global query representation that is based

on smiley icons and intended for users from

different countries with different cultures, thus

enabling them to access data and build queries easily

and in a user-friendly way. Smiley icons are text-

free.

3.2.1 Themes, Objects and Instances

A theme represents a category of objects such as,

entertainment, transportation and tourist. Each object

represents a group of locations such as restaurant. A

location is an instance of an object such as XX

restaurant. Figure 2 shows the basic visual elements.

Figure 2: Basic elements of the IVQL user interface.

3.2.2 Visual Representations of Operators

The queries are formulated using the smiley icons

that represent and depict instructions to find the

shortest path between two locations, nearest object

or to find all locations of a certain type within a

certain distance as shown in Figure 3.

Find

Shortest path

Nearest and display shortest

path

All locations within a certain

distance

AND

Figure 3: The operators smiley icons and their meaning.

3.2.3 Visual User Interface

IVQL user interface may accommodate 6-7 rows

and 6-7 columns in order to fit the small screen of a

mobile phone. It provides the user with two major

toolbars, one horizontal and one vertical. It has a

middle area where objects are displayed and a query

formulation area at the bottom of the interface. The

horizontal toolbar contains the smiley icons that

represent proximity relations to be applied on icons

that are displayed in the vertical toolbar. The vertical

toolbar displays icons that represent themes. The

middle area displays the theme objects on which the

spatial operation is to be applied. The query

formulation is done first by selecting an icon from

AN EVALUATION OF A VISUAL QUERY LANGUAGE FOR INFORMATION SYSTEMS

the horizontal toolbar. The icon is moved to the

query formulation area at the bottom of the interface.

Second, the user selects a theme from the vertical

toolbar. All objects that belong to the selected theme

are displayed in the middle area. The user selects the

object needed that is moved to the query formulation

area. The user interface is shown in figure 4.

Figure 4: The IVQL user interface.

The first two rows of the IVQL user interface are

used to allow the user to text input the source and

destination addresses. He can input his current

location and input the address of the destination then

query the shortest path between them. In the first

row, the location of the user could be automatically

determined by a GPS, LBS (Location Based

Services), RADAR, etc. So, there will be no need to

include the Text Input of the user’s location. The

same applies to the second row. With the possibility

of having an open-line connection, the user can

query a list of hospitals and get back an output

showing their locations on the map as well as a list

box that includes the name and address of each

hospital. In such a case, the user can select the

hospital from the list box and use it as an input to the

destination and then ask for the shortest path. Figure

5 shows the query ‘find within 500m all restaurants’.

Figure 5: A formulated visual query.

The icon “more” appears as the last icon to inform

the user that there are more icons to display.

3.3 Query Processing Architecture

After building a query, the user clicks the FIND icon

to process it. IVQL converts the query into normal

text by assigning a TEXT name to each icon, such as

nearest within restaurant.

The Text query is displayed as an SMS message.

The user chooses the ‘send’ option and inputs the

phone number that is assigned to the GIS server. The

SMS message is received by the GIS server. The

query interpreter processes the SMS messages

sequentially. Each message processed is first

translated into a Select-From-Where SQL query and

then executed on the GIS database. The resulting

map of the query is sent to the user as an MMS

message. Figure 6 shows the query processing.

Figure 6: The architecture of the query processing.

The user interface is implemented for mobile

phones by using the J2ME platform installed on the

Symbian operating system. The query interpreter is

implemented on the server computer. Some of the

queries that can be formulated are presented below.

Query 1:

Find nearest golf club and the shortest path

Query 2:

Find all restaurants within 500m

500m

Query 3: Find universities & schools within 500m

500m 500m

Query 4:

Find shortest path to destination address

ICEIS 2006 - HUMAN-COMPUTER INTERACTION

Destination address

Query 5: Find all bus stations within 500m and all

train stations within 700m

500m 700m

The resulting map uses symbols to represent the

locations found by a query. Figure 7 shows some of

the international symbols used for tourists.

Figure 7: Some symbols of Garmin GPS 12 MAP.

3.4 IVQL Model

The suggested model has been developed based on

the fact that its elements are spatial geographic

features and taking into consideration the relations

that exist between them. Accordingly, a spatial data

model and a relations model have been designed.

3.4.1 Data Model

The data model of IVQL is based on the object-

oriented approach. Its major components are feature

objects, feature classes, attributes, inheritance and

aggregation. Figure 8 shows the hierarchy of spatial

classes that represent geographic spatial features.

Figure 8: The hierarchy of geographic feature class.

The Geographic Feature contains attributes and

methods that are common to all other classes below

it. The lowest-level classes such as Circular Arc,

Elliptic Arc, Line, Polyline and Polygon are used to

construct the Path class. Each of the lowest-level

classes possesses an internal identifier, a spatial

location and a thematic identifier. The spatial

location class contains the x and y coordinates of the

object whereas the thematic class contains its

attributes such as name. The Path class is used for

network analysis. The Class hierarchy is extensible.

3.4.2 Network Relations

Our model consists of geometric relations that define

metric properties of spatial objects such as length &

distance. The network relations can be derived from

them such as the length of a path, minimum distance

and within a distance. These relations play a major

role in proximity and network analysis such as

querying objects within a certain range, finding the

nearest neighbor of a certain feature class and

finding the shortest path between two defined

objects. Figure 9 shows the relations.

Figure 9: The models of the network relations.

The network relations are declared in the Path

class. The skeleton of their definition is explained.

The IPointToEID object finds the nearest element to

a given point. It returns the element EID nearest to

the input point. Its method is: GetNearest(in Point,

outnearestEID, outLocation). The ITraceFlowSolver

object the FindPath which determines the optimal

path between two locations. Its method is: FindPath

(in FlowMethod, out junctionEIDs, out edgeEIDs,

out segmentCosts). The NetSolver object finds all

features of a certain type within a distance. Its

method is: SetFilterRanges(in Element Type, in

fromValues, in toValues, out Locations).

4 CONCLUSION

In this paper a visual approach to querying databases

was proposed. The approach aims at designing and

implementing IVQL, a visual query language that

has an international user interface. A critical

evaluation of the different methods proposed in the

literature for querying spatio-temporal databases has

been carried out in order to build the presented

approach upon the current generation of spatio-

temporal query languages. Smiley icons are used in

the user interface to facilitate the query formulation.

In order to evaluate their use in IVQL, a

comparative evaluation of the methods used to

AN EVALUATION OF A VISUAL QUERY LANGUAGE FOR INFORMATION SYSTEMS

evaluate visual query languages has been carried

out. The proposed framework, architecture, model,

user interface and query processing have been

described using a tourist information system for

network and proximity analysis. We also suggest the

implementation of a prototype, the evaluation of the

framework as well as its user interface and

conducting usability testing and user testing to verify

the quality of the icons as well as the expressive

power of the iconic visual query language.

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