Handbook for quality in cultural Web sites
Improving quality for citizens
2 Quality in Web Applications:
general principles and operative proposal
2.2.1 Disability
2.2.2 How do disabled people use the Web?
2.2.3 The Web Accessibility Initiative (WAI)
2.2.4 Indications of the European Union
2.3.1 Definition and methodology
2.3.2 Principles of Usability
2.4.1 Make contents perceivable
2.4.2 Recognise that the site is a Cultural Web Application
2.4.3 Recognise the aims of the site
2.4.4 Gain a general impression of the site before
proceeding to a detailed visit.
2.4.5 Be able to exploit quality contents
2.4.6 Presentation of Contents
2.4.6.1 Functional layout
2.4.6.2 Functional graphic
elements
2.4.6.3 Functional multimedia
elements
2.4.7 Site Navigation
2.4.8 Searching
2.5.1 Definitions
2.5.2. The Catalogue of Patterns
2.5.3 How to consult Patterns
2.5.4 An example of the use of the Catalogue of Patterns
2.1 Introduction
Now, after more than ten year of existence,
the Web has reached the maturity of a product of mass consumption.
First conceived in the scientific community as an instrument
for gathering together public and scientific documents, it soon
became a ready tool for vast scale communication, up-to-date learning,
commerce, entertainment and culture.
Initially, the Web imitated the techniques and methods of communication
of existing media; foremost among these were the Press and Television.
Subsequently however, following its explosive growth, the Web
discovered its own new methods and techniques, more suited to
its specific characteristics.
The innovative and experimental phase is over, and planning
and implementation of good Web sites now seeks the characteristic
that is common to all successful ventures: quality.
Quality is a word with a very broad meaning and the quality
of a Web site (or a cultural Web site) can be viewed in a very
subjective way. Having this in mind, it is necessary to investigate
in the state of art related to Web application quality.
A milestone in the exploration of quality issues is represented
by the ISO 9126 standard for software quality measurement, (called
“Software Quality Product Evaluation: Quality Characteristics
and Guidelines for their use”), proposed in 1992. Here software
quality is defined to be “The totality of features and characteristics
of a software product that bear on its ability to satisfy stated
or implied needs”.
ISO 9126 quality is defined by the following factors:
- Functionality: the amount of “functions”
contained in a delivered product.
- Reliability: the capability of a product to maintain
its level of performance under stated conditions for a stated
period of time”.
- Usability: the extent to which a product is convenient,
ease, and practical to use
- Efficiency: the amount of operations (and more generally,
resources) to achieve a goal.
- Maintainability: the extent to which a product is easy
to test, to modify, or to extend.
- Portability: the ability to move the product from one
host environment to another; the level of compliance to standards.
ISO/IEC 9126-1 - Information Technology. Software product quality:
quality model, defines the Quality as “the capability of
the software product to enable specified users to achieve specified
goals with effectiveness, productivity, safety and satisfaction
in specified contexts of use.”
The abovementioned definition highlights the fact that the quality
of a software product lies not in the absence of faults, richness
of functions, or technical innovation, but that it should be usable
and accessible according the needs of the users in the context
of use.
The Web is much more widely diffused than other software products
and therefore the types of users and contexts of use are many
and differing. In order to meet the required standards it is therefore
important to examine the two following characteristics of quality:
- Accessibility of content, which takes into account the diverse
types of users and contexts of use;
- Usability: a set of attributes bearing on the needs for effectiveness,
efficiency, safety and satisfaction.
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2.2 Accessibility of contents
A Web site is considered to be accessible when the informational
content, navigational modes and all the interactive features present
are accessible to all users, regardless of disabilities and independently
of technology used to access the site and of the context in which
they are working whilst accessing the site.
To give an idea of the vastness of the definition, it is worth
while quoting the situations described in the introduction to
“Guide lines - Web Accessibility Initiative (WAI) World
Wide Web Consortium (W3C).”
“For those unfamiliar with accessibility issues pertaining
to Web page design, consider that many users may be operating
in contexts very different from your own:
- They may not be able to see, hear, move, or may not be able
to process some types of information easily or at all.
- They may have difficulty reading or comprehending text.
- They may not have or be able to use a keyboard or mouse.
- They may have a text-only screen, a small screen, or a slow
Internet connection.
- They may not speak or understand fluently the language in which
the document is written.
- They may be in a situation where their eyes, ears, or hands
are busy or interfered with (e.g., driving to work, working in
a loud environment, etc.).
- They may have an early version of a browser, a different browser
entirely, a voice browser, or a different operating system.
Content developers must consider these different situations during
page design.”
In the contexts described above, particular attention is paid
to disabled users or users with specific disabilities, both in
terms of reference to instruments which these users may employ
for computer use in general, and for navigation on the Web in
particular.
It would be opportune to define “disability”.
2.2.1 Disability
The WHO World Health Organisation, in the International Classification
of Impairments, Disabilities and Handicaps (ICIDH-1, 1980), gives
the following definitions:
Impairment: "any loss or abnormality
of a psychological, or anatomical structure or function".
Disability: "any restriction
or inability (resulting from an impairment) to perform an activity
in the manner or within the range considered normal for a human
being".
Handicap: "any disadvantage
for a given individual, resulting from an impairment or a disability,
that limits or prevents the fulfilment of a role that is normal
... for that individual". The classification of handicap
is a classification of circumstances that place individuals "at
a disadvantage relative to their peers when viewed from the norms
of society". The classification of handicap deals with the
relationship that evolves between society, culture and people
who have impairments or disabilities, as reflected in people's
life roles.
In 2001 the WHO presented a new document for the definition of
disability, the International Classification of Functioning, Disability
and Health (ICF [ICIDH-2], 2001) To sum up, this document
- refers to “human functions” in general and not simply
to disability. Functioning is related to the state of the individual
not only at the level of body functions, but also in terms of
the activities of the individual and of participation in society.
- Moves away from the consequences of a “dysfunction”
to components of “health”, grouping them together
under the heading of “health domain” (this includes
sight, hearing, movement, learning) and “health-related
domains” which includes mobility, education, participation
in social life, etc.)
The model is universal; i.e. it does not concern only people
with disabilities, but all people. This makes the need to plan
accessible Web sites even clearer.
2.2.2 How do disabled people use the Web?
Certain types of disability can be catered for with compensatory
or so called “enabling” technology. This can be hardware
or software which:
- effect “equivalent” conversion of the information
from one sense organ to another. Some examples are:
- from the computer monitor (sight) to touch (Braille bar for
visually-impaired users),
- from the computer monitor (sight) to sound (vocal synthesis
for visually-impaired users),
- from sound (audio documents) to sight (text documents) (vocal
recognition for motor-disabled and deaf users);
- permit different ways of using certain tools, for example:
- special mouse (for motor-disabled);
- special keyboard (for motor-disabled);
- compensate for disability of a sensory faculty, for example:
- enlarging the text on the computer monitor (for the visually
impaired)
Specific tools are available to compensate for other types of
disability: in these cases access can be effected through the
use of specific technical and editorial tools during the realisation
of the Web site.
Some examples are:
- for users with difficulty in distinguishing colours, for example,
it is important to avoid giving information solely through use
of colour and also to guarantee sufficient contrast between
the text and the background.
- for users affected by photosensitive epilepsy, it is necessary
to avoid moving images at those frequencies that could provoke
an epileptic fit;
- for users with learning difficulties or language difficulties
it would be necessary to develop clear navigational mechanisms
and to use clear and simple language in the documents.
2.2.3 The Web Accessibility Initiative (WAI)
The Web Content Accessibility Guidelines of the WAI
project are constantly referred to in the search for quality accessibility
in a Web site.
The WAI
project deals with Web accessibility in the lay sense; that is,
not only as far as regards contents, but also in terms of the
tools used to realise the Web pages, the browser and, more generically,
technologies for Web access. For example, for this purpose, all
the images in a site "must provide text equivalents for images
and other multimedia content", and "non-text equivalents
of text (e.g., icons, pre-recorded speech, or a video of a person
translating the text into sign language) can make documents accessible
to people who may have difficulty accessing written text, including
many individuals with cognitive disabilities, learning disabilities,
and deafness".
The Web
Content Accessibility Guidelines (WCAG) version 1.0, 5 May
1999, is particularly important for accessibility of content.
The document consists of 14 GuideLines. Each of these presents
typical situation that could present difficulties for disabled
users. In every Guide Line a certain number of checkpoints are
defined and explain the specific way the guide can be applied
to developing content. The Guidelines introduce the concept of
priority and thence the concept of conformity. These concepts
are thus defined by the WCAG:
“Each checkpoint has a priority level assigned by the
Working Group based on the checkpoint's impact on accessibility.
[Priority 1]
A Web content developer ‘must’ satisfy this checkpoint.
Otherwise, one or more groups will find it impossible to access
information in the document. Satisfying this checkpoint is a basic
requirement for some groups to be able to use Web documents.
[Priority 2]
A Web content developer ‘should’ satisfy this checkpoint.
Otherwise, one or more groups will find it difficult to access
information in the document. Satisfying this checkpoint will remove
significant barriers to accessing Web documents.
[Priority 3]
A Web content developer ‘may’ address this checkpoint.
Otherwise, one or more groups will find it somewhat difficult
to access information in the document. Satisfying this checkpoint
will improve access to Web documents.
Some checkpoints specify a priority level that may change under
certain (indicated) conditions.
Respect of the above points leads to the concept of conformity:
Conformance Level "A": all Priority 1 checkpoints are
satisfied;
Conformance Level "Double-A": all Priority 1 and 2 checkpoints
are satisfied; Conformance Level "Triple-A": all Priority
1, 2, and 3 checkpoints are satisfied.
The list of checkpoint of the WCAG 1.0 can be found in the appendix.
The checkpoints are grouped by priority and by type of elements
that may be present on a Web page.
The list is especially useful in the planning phase in that potential
barriers and obstacles to access that may result from various
functions of the application can be identified.
Furthermore, the list can be used to evaluate the degree of conformity
in the realisation of the page.
Besides this list, various tools for evaluation of the accessibility
of Web contents are commercially available. These automatic tools
are not alone sufficient to guarantee conformity to the degree
of accessibility required. Indeed, many guidelines require a degree
of subjective evaluation that no automatic tool can supply.
2.2.4 Indications of the European Union
The European Union places great importance on accessibility to
Web sites of Public Administrative offices:
The eEurope action plan 2002 (June 2000) specifically states;
“Public sector Web sites and their content in Member
States and in the European Institutions must be designed to be
accessible to ensure that citizens with disabilities can access
information and take full advantage of the potential for e-government.”
(objective 2 point c)
In later resolutions the Council of Europe invited the Member
States to implement specific measures to reach the objective of
accessibility of Web sites of public administrative institutions
and indicated the adoption of the WAI guidelines as one of these
measures.
While not all Member States have formally adopted the WCAG 1.0
for the realisation of Public Web Sites, it is universally accepted
that these must conform to at least Level A as defined in the
GuideLines.
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2.3 Usability
2.3.1 Definition and methodology
The definition is that of the standard ISO 9241-11 "Ergonomic
requirements for office work with visual display terminals - Guidance
on usability" in which usability is defined as: “the
extent to which a product can be used by specified users to achieve
specified goals with effectiveness, efficiency and satisfaction
in a specified context of use.” This definition is
very similar to that already quoted in quality of software product
[ISO/IEC 9126-1] and for the meaning of the terms therein, we
can say that:
Effectiveness in the use of the product
indicates the accuracy and completeness with which the user can
attain the specified results.
Efficiency in the use of the product indicates
use of resources in relation to accuracy and completeness with
which the users achieve specified results.
Satisfaction indicates freedom from unease
and obligations and a favourable tendency in the user towards
the product.
Context of Use is that of the context of
the user, the aim or task, the hardware resources and software
used, the physical and social environment in which the product
is used.
The ‘product’ is the Web site as it has previously
been defined.
The essence of the ISO regulations (ISO/DIS 13407 – Human
centred design process for interactive systems in addition to
the two mentioned above) is that planning of interfaces, interactive
modes and the organisation of Web contents, must be user-centred:
No-one knows the competencies, culture, needs, limits, attitudes
of users better than the users themselves. It is thus important
to provide for involvement of the users in all stages of the planning,
realisation and running of a Web site.
A planning methodology based on the centrality of the user contains
the following points:
- the creation of a representative group or panel. A panel
can be considered representative when its components are chosen
on the basis of various roles and goals for which a user may be
interested in a site. Among the members of the panel there must
be disabled users in order to verify the accessibility of the
contents:
- the construction of situations of use: define context, purpose
and modes of interaction with the site. The site will be created,
planned, evaluated and continuously updated and improved on the
basis of these use-situations.
- evolutionary planning: the site will undergo evaluation on
the part of the panel on the basis of various complex use-situations.
This evaluation aims at the definition of new requirements and
new goals. The definition of new goals should be undertaken repeatedly,
through creating approximate prototypes that are, nevertheless,
able to evaluate solutions, identify constraints and establish
feasibility. Continuous feedback and discussion with the panel
allows in-progress evaluation of solutions and anticipates the
final evaluation of the project. The panel finally becomes an
observer of the use of the site and aids continuous up dating
and improvement.
Constituting the panel is thus a central element in the methodology
for the following reasons:
- it guarantees the level of realism, and gives also consensus
and communication on the project,
- it produces data and ideas and allows empirically guided
decision-making. From this latter point of view, the panel is
a place for experimentation with appropriacy and also with technological
constraints to interaction and accessibility.
2.3.2 Principles of Usability
It is not always possible to plan and realise a Web site using
the methods described above directly. This is because the organisational,
financial and human resources (sample users, experts on usability
etc.), required are not always available.
From experience using this methodology, experts in usability
have proposed a series of Principles and Criteria that can guide
decision making in planning in order to reach effectiveness, efficiency
and satisfaction in the realisation of a Web site.
The principles of Usability tend to group problems in general
categories. The most common principles are the following:
- Visibility: give users visual clues to
understand how to use the site. for example: a word or phrase
underlined in blue indicate the presence of a link, underlining
in purple indicates that the link-site has already been visited.
- Affordance: ensure that objects behave
in a manner that their appearance suggests. In order to complete
the function assigned to them a button should require to be
pushed and not, for example, to be highlighted.
- Natural Mapping: establish conceptual
correspondence between command and function. For example, for
the layout of a form in a search function, the text should be
typed into the input field and the “Return” button
should be pressed.
- Constraints: reduce the number of ways
in which a certain action can be carried out and plan the commands
for functions in a way that renders their use easily understandable.
- Conceptual Models: the user has a notion
of how things work, based on his/her experience and knowledge.
A good conceptual model in a Web site is one where the proposed
functions correspond as far as possible with the user’s
notion of those functions.
- Feedback: indicate the users’ position
in the operation or task, his/her result, be it positive or
negative. For example, when the user downloads a file, indicate
time required and time remaining for the operation. When the
user sends a form, confirm receipt.
- Safety: as far as possible limit the
risk of error on the part of the user. In the case of error,
give information as to possible causes and remedies.
- Flexibility: give users the possibility
to execute an operation in various ways. For example through
various navigational routes to reach a document.
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2.4 Criteria of Usability for Cultural Web Applications (CWA)
For the definition of quality in CWA’s, applying these
principles to the planning and realisation of Web sites has led
to the selection of Criteria of Usability. These criteria further
address and define the problem.
The Criteria are divided into Categories that represent user
needs to be satisfied.
2.4.1 Make contents perceivable
The user must be able to recognise that the site visited is
a CWA rather than another type of site; the general content must
be immediately clear and thence users can proceed to details;
contents must be of good quality (For example, absence of spelling,
grammar and syntactic mistakes).
2.4.2 Recognise that the site is a CWA
Institution image. The application should
include all the information needed to give the user a view of
what the cultural subject is, its initiatives, and its organisation.
This information contributes to creating a sense of trust in the
institution, and supports the establishment of the right "image"
of the institution itself.
Institution responsibility. It should be
clear which cultural subject is behind the Web site, who has the
responsibility for the overall site and in particular for its
contents.
IPR policy. The application should include
all the information about the IPR strategy and technology adopted
by the cultural subject to protect the contents sources made available
in the application.
Advertising policy. The advertising, if
any, should not overshadow the contents and where advertising
is a source of funding this should be clearly stated. The site
should display a brief description of the advertising policy adopted.
Advertising and other promotional material should be presented
to viewers in a manner and context that facilitates differentiation
between it and the original material created by the institution
operating the site.
2.4.3 Recognise the aims of the site
Application mission evidence There should
be some statement of the mission of the application, its main
goals, its main target users.
Responsibility for the application. There
should be some description of who is responsible for which aspects
of the Web site (this is sometimes reported in a "Credits"
section). In particular - who is responsible for the overall editorial
aspects, who should be contacted for further information, complaints,
technical support and help in general.
Evidence of maintenance strategy.
There should be some description of the maintenance strategy of
the Web site, how frequently it has been updated, when the last
update occurred.
Evidence of technical strategy. There should
be some description of the technical aspects of the site which
improve the use of the application functionality. In addition,
it is essential to inform the user about the physical size of
the contents, if it is large. When a large file can be downloaded,
the user should be informed of its size before the file begins
downloading and should have the opportunity to cancel the download.
2.4.4 Gain a general impression of the site before proceeding
to a detailed visit.
Appropriateness of grouping. Content elements
of a cultural Web Application are typically grouped according
to different criteria (e.g., theme, time, author…). The
information should be well composed and arranged logically and
consistently, but the appropriateness of organization criteria
depends upon other factors: the characteristics of the cultural
subject and adherence to the end-user’s level of knowledge,
conceptual model, and goals.
Appropriateness of nesting. Groups of information
are typically organized hierarchically, resulting in a layered
structure where the actual contents are on the bottom. The levels
of nesting should be intuitive, logical, intrinsically coherent,
and easy to understand. Once again, they must be appropriate for
the conceptual model and the goals of end users, the nature of
the contents domain, and the characteristics of the delivery channel.
Nested structures must support efficiency: the identification
of the needed information within the hierarchical structure of
nested groups must be performed successfully and quickly. For
example, the most relevant subjects for the user should not be
hidden inside over-nested groupings, and should be more directly
accessible than less relevant information.
Appropriateness of splitting. Large amount
of information can be divided into a set of individual pages,
but each page should be self-sufficient, i.e., it should cover
a specific topic or aspect without the need to access a different
page to understand its core message. When complex contents are
stored on a single page, good headings and a short introductory
synopsis may help users to graph immediately the core information
of the page immediately.
Evidence of organisation. The grouping criteria
must be clear and the semantic relations among group elements
have to be evident to end users. They must be explained to them.
There should be some description of what a group of "contents
objects" is about (using a synopsis, a comment, as summary,
etc.), how the contents have been organized, what are the main
contents that the user can find (or cannot find - to avoid creating
wrong expectations), which languages are available, and so on.
Tables of contents and indexes, site-maps and similar elements
are useful for providing global views of the site organization
(and also for orientation and navigation purposes). Some obvious
visual cues can be adopted - for example, different page backgrounds
of nodes to distinguish among different types of contents, or
textual labels to indicate the groupings to which current contents
object belongs. These cues are also useful for context orientation.
Evidence of membership evidence. In a group
of elements, it should be clear for the user which are the elements
in the group, by means of proper descriptors (textual or visual)
that identify the group members.
2.4.5 Be able to exploit quality contents
Consistency. Consistency is a very general
meta-principle for quality, which also applies to all application
dimensions. For contents, it states that similar pieces of information
are "dealt with" in similar fashions.
Currency. The concept of currency relates
to the time scope of the contents validity. However, the idea
of currency of information is rather more complex than simply
"is it recent." To be current, information does not
have to be "new"- sometimes older information is still
widely accepted as valid and reliable. The site should therefore
present the most currently available data and the currency of
the information must be appropriate for the specific field or
topic. The site should avoid the presence of outdated information.
The links used by the site should be up-to-date (e.g., avoiding
the presence of links to empty or under-construction pages, or
"dead" or unavailable sites). In addition, currency
properties must be evident to the user. This implies that the
time scope of the contents validity is clearly stated, and that
the maintenance policy should be dated.
Completeness. The concept of completeness
is strongly related to user profiles and goals. It defines the
level of information coverage of the application with respect
to the characteristics of the cultural subject and of the intended
users. By definition, completeness strongly depends on the nature
of the cultural subject, on the profile of the intended end users,
on the goals of both, and on the potential scenarios of use. An
application should not omit "crucial" information (needed
by all possible users) but the amount of available resources should
be appropriate and well balanced for the specific user needs.
It should cover all relevant aspects of a topic and lead into
the appropriate level of details for the specific topic and field,
but the appropriateness of the depth of a specific topic is relative
to the user needs. (For example, a "simple" user may
need less information than the user that is expert in a particular
topic). Completeness applies both to pieces of contents as well
to links, in the latter case referring to the amount of links
that the application provide to pages of external sites.
Comprehensiveness. The information should
be clear and easy to understand. Again, this criterion is usually
strongly related to the user needs. The language complexity should
be appropriate for the cultural level, experience, and interests
of the end users. (According to Nielsen, "Speak the user
language" is one of the cornerstones of usability)."
Conciseness. This "rhetorical"
principle mainly apply to textual contents: texts should not be
too long and redundant (reading on a computer is much more tiring
than reading on paper) and should convey the key message using
the minimum amount of words.
Richness. In some cases, richness of interesting
information (many examples, data, links to other resources…)
and use of multiple media to convey it can be an added value per
se, even if it is not strictly needed for the intended users.
It may increase the "image" of the cultural subject,
stimulate interest and curiosity, and provide reasons for the
users to return. Still, the richness of multimedia must be "appropriate",
as discussed in the following criterion.
Soundness of dynamic media. The use of
multiple dynamic media (audio, animation, video, 3D graphics)
can enforce richness (see above). Still, the choice of media should
be "sound", in terms of the "format" (e.g.,
as resolution, indicative size or duration), appropriateness of
the medium per se and the rhetoric style adopted to convey the
contents message.
Multilingualism. In an intrinsically global
world, at least the crucial information should be given in more
than one language, to reach and appeal to the largest possible
audience. The success and the popularity of an application is
strongly impacted by its amount of multilingualism. The multilingualism
allows the review and use of the site from individuals of different
nationalities, promotes and elects the cultural heritage of each
country outside its borders, respects and promotes the European
Strategies for the Information Society.
Accuracy. Accuracy has to do with the evidence
of bias or mistakes at any level, both syntactical and semantic.
Textual contents should be correct in terms of grammar, spelling,
and composition. All types of contents should avoid incongruities,
non necessary duplications and repetitions. Obviously misleading
statements or outrageous must be absent.
Authority/Responsibility. This criterion
refers to the evidence of who (individual or group of individuals)
is the author of the domain contents and of its competence in
relation to the subject. Identification of the sources (e.g.,
by means of valid up-to-dated references and bibliography) should
be provided.
Objectivity. Information should be "objective"
and "politically correct". Unsupported claims made by
the authors, one-sided arguments about controversial issues, "messages"
by individuals or groups with vested interest in the topic, should
be avoided. The application should clearly specify what are author´s
personal opinions (if any) and distinguish them from more objective,
factual information.
Uniqueness. In the world-wide proliferation
of Web Application almost on any cultural subject, providing domain
contents which is unique, original, peculiar, is a source of attraction
and interest for the user, and a good reason to return to the
site.
2.4.6 Presentation of Contents
Presentation of graphics in a CWA must be functional with Contents;
it is the inter-face through which the user accesses all the information.
2.4.6.1 Functional layout
Consistency. Users should not
have to wonder whether different words, situations, or actions
mean the same thing. Once users see a link, they expect when they
see it again it will look the same, be in the same location, and
function the same. If it has changed, users may be forced to relearn
the button, which will delay their completion of tasks. Maintaining
consistency allows users to develop a set of skills. Concepts
can be learned once and then applied in a variety of situations.
Efficiency. The most efficient viewing
and use of information should be ensured on each page of the site.
Developers should evaluate the most common use of each page and
make design decisions that ensure the best possible performance.
Spatial organization.
Navigation and identity should be displayed in the top and left
areas of the screen Users are comfortable and familiar with this
design. The use of tables and images wider than the defined image-safe
area should be avoided, users often become annoyed if they have
to manipulate a horizontal scrolling bar to see contents.
2.4.6.2 Functional graphic elements
Minimalism. Pages should not contain elements
which are irrelevant or rarely needed. Every extra element in
the Web site competes with the relevant and diminishes their relative
visibility.
Use of colours. When background and text
colours are close to the same hue, they may provide insufficient
contrast on monochrome displays and for people with certain types
of colour deficits. The text and graphics should be understandable
when viewed without colour. Avoid using image as background colour,
this may obstruct readability.
2.4.6.3 Functional multimedial elements
User controls. The users should always
have the control for all playable files: Play, Pause/Resume, Stop,
Rewind, Fast Forward and Volume.
Use of animations. Animation is a wonderful
tool in Web design, but in some cases can be over-used. Animated
graphics can be too big and too busy, If there are too many animated
elements, your page can be difficult to read and information can
be difficult to find. Lots of animation makes your page take longer
to load.
Objects size. The size of media objects
should not make the site heavy to download. Instructions for downloading
media objects should include the file size, the media type, and
a description of the subject matter. This information will help
users determine whether they want to wait for the download.
2.4.7 Site Navigation
Tools for navigation within a site, if well planned, are essential
for fast and reliable finding of information.
Link evidence. The meaning of links
should be clear, i.e., it should be easy for the user to understand
both the relationship represented by the link and the link destination
- before traversing it (expressive link labels and link descriptors
are useful for this purpose). In particular, links to external
sites should not just identified by urls, but shortly described
by meaningful labels or comments. It is advisable that external
links should be opened in a new window.
Link soundness. Links should only bring
to relevant material (e.g., not to "inaccessible" or
expired pages). There should not be any "dangling link",
or link which brings to a missing page, or to a page "under
construction" (this misbehavior should be evident to the
user before the link activation, to avoid loading a useless or
empty page, or a page just containing an error message).
Link coverage. This criterion refers to
the amount of links available to improve efficiency of access.
From a given starting point, users should quickly locate and access
the items that are needed for their task, without navigating through
non-relevant material; alternatively, they should quickly discover
that those items are not in the application. Efficiency of access
is strongly related to the organizational schema adopted for the
content which is reflected by the links. But it is improved by
the presence in the pages of "non semantic" links to
the most relevant portions of the site (oftentimes called "navigation
bars", "landmarks" or "accelerators")
which speed up navigation by providing jumps to different portions
of the site.
Backtracking soundness. Whenever the user
reaches a given point in the Web site, it should be easy to access
previously visited points and to continue navigation without restarting
the session from scratch, or without scanning backward all the
previously traversed pages using the browser backtracking button.
In particular, in guided tours it should be clear what happens
at the end of the tour, and how to return to the starting point.
Context evidence. This criterion refers
to the need for the user of understanding his/her current navigation
context, to reduce the risk of "getting lost in the hyperspace"
(a typical syndrome of large hypertextual structures). Users should
be always aware of the actual status of their navigation session,
they should be able to understand their current position within
the current cluster of objects they exploring and the entire application.
For this purpose, many hypermedia use active maps and overview
diagrams, with indications of the user´s current location
(and of previous steps), or some perceivable visual cues - for
example, different page backgrounds of nodes to distinguish among
different types of contents, or textual labels to indicate the
groupings to which current content object belongs.
Media control soundness. This criterion
refers to what we can call "navigation in the small",
i.e., interaction with multimedia element and modification of
their dynamic state. Media control soundness is the possibility,
for the user, to control the state or the behavior of multistate
media objects such as images (which can be zoomed in-out), video
or sound (which can be played, stopped, suspended etc.). The commands
designed for the user to manipulate the state of a multimedia
elements depend on the nature of the element (e.g., a picture
can be zoomed in or out, but the same commands make no sense for
a sound) and on its physical properties such as resolution, size,
duration. Control commands such as "start", "stop",
"pause", "re-start", "forward",
"backward" are meaningful, in principle, for all dynamic
element slots, but a video or a sound comment might require no
interaction if they are very short. Ultimately, the degree of
control must be appropriate to both the nature of the medium and
the actual need of users, based on their experience with digital
multimedia and their goals in using the system.
Media control evidence. Whatever multimedia
control actions are offered, they should be evident to the user,
and their meaning and effects should be clear.
2.4.8 Searching
Navigation is oftentimes complemented by search mechanisms,
that allow users to specify some characteristics of the information
they are looking for and to retrieve a list of pages matching
these characteristics. We will not discuss here the aspects concerning
the technical quality of the adopted search engine (the soundness
of the search algorithm and of its implementation, which we consider
a purely technical problem). We will focus here on the features
that directly impact on the ease of use of the search, considering
the following sub-criteria.
Comprehensiveness of query forms. It should
be clear for the users which characteristics they can specify
for the searched objects, and how they can be specified. Different
types of search specifications should be available for different
skill levels and preferences.
Comprehensiveness of query results. It
should be clear for the users which objects have been retrieved,
by complementing page address with short descriptors that identify
their meaning (see also Link Evidence Criterion).
Navigability of query results. It should
be easy to navigate the set of retrieved objects. Most search
mechanism only support "forward index navigation", allowing
users to access each of the retrieved page from the list of search
results. In some cases, there is no direct link to return to the
list of retrieved objects, unless using the browser back option.
A search should support the possibility of returning to the last
search results at any time, and also of navigating directly across
the retrieved objects, forward and backward, like in a guided
tour.
TOP
2.5 Patterns and the language of patterns
The principles of Usability, in as much as they are generic, are
often difficult to apply and the Criteria that supply more detailed
instructions can be interpreted in different ways or are tied
to a specific technological area. These problems, though to a
lesser extent, are also found in the application of GuideLines
to Accessibility.
A different approach to the concrete problems of planning and
realisation of Quality Web Sites is that of using Patterns to
resolve recurring problems through noted and consolidated solutions.
By now, the Web product has reached a degree of maturity such
that the solutions to certain problems related to its use are
considered common to all planners.
Furthermore, Patterns can be a useful reference point for those
involved in Web site construction while not being experts. Indeed,
in this case, Patterns can constitute a common language for communication
between professionals to indicate what is required and why, regardless
of how the solution is reached from the technical point of view.
Patterns neither eliminate nor substitute the need for involving
users. On the contrary, by definition, they benefit from the concrete
experience of users.
2.5.1 Definitions
The paradigm of Patterns was developed at the end of the ‘70’s
by Christopher Alexander, professor of Architecture at the University
of Berkeley in order to meet the complex problems related to urban
planning and construction. According to Alexander, the poor quality
of architecture in the ‘60’s was partly due to the
lack of formal method in planning. He noted that urban planning
and construction did not take concrete experience into account
and the projects themselves were detached from the real needs
of the users. This led to the idea of Patterns that establish
relations between a context – a group of conditions or constraints
tied to that context – and a solution which would resolve
problems with those conditions and in that context.
From the mid ‘90’s, the idea of using the language
of Patterns to assist planners, gained new credibility thanks
to the enormous success of its application to the field of software
engineering and “object oriented” planning. The paradigm
of Patterns has recently been applied to the field of Human Computer
Interaction (HCI), with extension to the world of the Web.
Patterns aim to provide a rigid method for describing a planner’s
experience through formulating a solution to a common problem.
What characterises this approach is the choice to not give “pre-codified”
solutions to the problem, but rather to try to accurately describe
both the context and the solution, grouping the experience and
the solutions adopted (also by other planners in similar experiences)
together under the same title.
A Pattern is made up of three parts:
- Context: this is the whole of the
conditions and the surroundings, the environment of the action,
all of the forces in action that the pattern has to consider
and which constrain the choices of solution.
- Problem: is a recurring situation
in the context that creates imbalances between the forces at
play,
- Solution: is an algorithm, a piece
of technology, an organisational structure, a well-known method,
a model of reference which can resolve the recurring problem
in that context.
It should be noted that a Pattern is made up of three parts:
this implies that a problem alone is not a pattern, neither is
a solution.
In a sentence: a Pattern is a proven solution to a recurring
problem in a specific context.
Further elements are required to complete the definition of
a pattern.
- Name:a pattern must have a meaningful name. Naming something
is the first step towards being able to communicate about it.
- Conditions: descriptions of the conditions (or constraints)
present in the context.
- Notes: considerations (both positive and negative) on
the consequences of the use of the current pattern (if any).
- Related patterns: relations between the current pattern
and other patterns used in the referral system (if any).
- Known uses: detailed reference to practical applications
of the current pattern (if any).
The language of Patterns groups together Patterns which work
together to resolve problems in a given context.
The general context of reference to which we intend to apply
the language of patterns, is the planning and realisation of Cultural
Web Applications that must be Accessible and Usable – that
is to say; of good quality.
Having established the common reference conditions, it is necessary
to organise the Patterns in some way in order to use them.
Here it is proposed that a Catalogue of Patterns be
created, with the aim of identifying general categories of problems
to be faced. Within each of these categories, the patterns that
define and resolve a particular problem will be placed.
2.5.2 The Catalogue of Patterns
The same general categories grouped under Criteria and Usability
will be used to create the Catalogue of Patterns to apply to the
planning and realisation of an Accessible and Usable PCWA. To
these are added:
Interact with the User: When a PCWA is present on the Internet
with a Web site, it opens a window to the public. Interactivity,
seen as the possibility for direct communication between citizen
and Cultural Entity (CE), becomes an important and vital function.
The Catalogue of Patterns and their definitions can be found
in the Appendices.
Most of the Patterns presented in the Catalogue
were inspired by the work of Martijn Van Welie (http://www.welie.com/patterns/),
who wrote Patterns for the Web, paying particular attention to
the Principles of Usability, bearing in mind the needs of both
the user and the planner.
At http://iawiki.net/WebsitePatterns
can be found a bibliography of collections of patterns for the
Web.
2.5.3 How to consult Patterns
How are Patterns used?
In a chapter of the book "A Pattern Language”, Alexander
suggests a path to follow, at the end of which a list of patterns
necessary to the project at hand will have been compiled. The
steps of this path are as follows:
- Examine the whole sequence available, the catalogue of patterns.
- Identify by name the pattern that best defines the project/problem
to be faced.
- Read the description carefully: here, patterns related to the
current one are listed. In this way a list is produced; a list
where the lower level patterns (more specific) should be marked,
while in general, the higher level patterns (less specific) should
be ignored.
- Read the next pattern highlighted on the list and again note
the low-level patterns related to it.
- If in doubt as to the usefulness of a pattern, this should be
excluded. Otherwise, the list would inevitable become over-long
and this could lead to confusion. Including only the patterns
considered to be useful would produce a list of sufficient length.
- Continue in this way until all patterns useful for inclusion
in the project have been identified.
- At this point the list must be supplemented, if necessary, by
adding its own elements.
- Finally, consider carefully adaptation and change in patterns
according to the needs of the project on hand.
2.5.4 An example of the use of the Catalogue of Patterns
A site already present on the Web wants to offer a Newsletter
service to users.
In the Catalogue, under the category Interact with Users,
the Pattern Newsletter can be found.
This is the definition
NEWSLETTER
CONTEXT: The site deals with various
themes. These can be events, publications, news and links of interest
on the themes of the site but external to it.
CONDITIONS: The user trusts the site,
recognises its authority in the context of the subjects it deals
with, wants to be regularly informed of news, is not able to visit
the site daily. Problem: How can the user’s trust be rewarded?
SOLUTION: Make a regular Newsletter
available. The Newsletter should be in a form that makes its origin
easily recognisable, easy-reading and not too “voluminous”
Typical elements of a Newsletter should be the following:
HEADING: this should clearly indicate the identity
of the sender. It would be better if the Newsletter
used the same headings (Page Layout) as the site;
DETAILS OF PUBLICATION: Year of publication,
date and number of issue:
INDEX OF ARTICLES: titles of the articles, each
linked to the corresponding article.
ARTICLES: should be no more than 10. Each article
should have a Meaningful Name, a brief summary,
be written in plain, clear language and have links to related
documents;
INSTRUCTIONS FOR ENROLMENT: these should include
functions for change of e-mail address, cancellation of the Newsletter,
organisation of Registration data (where required),
sending comments;
MODES OF USE: authorship rights, privacy, policies
for security adopted. This may be an explicit declaration or a
link to a page of the site dedicated to Modes of Use.
The user can enrol for the Newsletter by filling in a Form
with details of the e-mail address for receipt. If opportune,
Registration could be required. In any case communicate
the Results of the operation.
The Newsletter service should be clearly visible on the HomePage
or as a function of Main Navigation. There should
be a page dedicated to describing the aims of the Newsletter,
its issue dates and users should be able to access the functions
necessary for enrolment, cancellation, change of address, access
to published back-numbers of the Newsletter, view the Newsletter
on-line. The page dedicated to the Newsletter must also figure
on the SiteMap.
Notes: Respect of dates of issue is an indispensable
factor for success of a Newsletter. The Newsletter
should not substitute the function of Site News:
the aim of which is to supply broader information on the themes
contained in the site.
Related Patterns: Form, Registration, Communicate the
Result of the action.
Examples: www.nytimes.com
, www.governo.it
This definition gives much useful information for facing the
problem:
- from the Context, Conditions and propositions of the problem,
it can be ascertained whether the Pattern is suited to the case
in hand;
- concrete indications for how to realise the Newsletter can
be found in the Solutions. For example; how to offer to service
to the user and what organisational problems may arise;
- in the Patterns, the descriptions of the Solutions are in bold
type: some are at a more general level (for example: Page Layout,
Main Navigation, Modes of Use) as they refer to problems related
to the site in its entirety; others relate to functionality which
are considered similar or relevant to the question in hand (for
example: Site Map, Site News);
- then, in the Solutions indicate the Patterns for Form, Registration,
Communicate the Result of the Action, which are considered Related
to the Pattern in question. These differ from the previous ones
in the sense that the Related Patterns are considered essential
for a correct solution to the problem at hand, while the Patterns
indicated here define the environment of the intervention;
- reading the definitions for the Related Patterns (which are
not listed here for reasons of space) gives further information
and further Related Patterns can be identified. Among these there
may be Patterns which have already been examined and which will
therefore be listed only once;
- the end result is a list of patterns such as the following:
- Newsletter
- Form
- Controlled Input
- Registration
- Login
- Communicate the Result of the Action
- The list, complete with its definitions, constitutes a document
that can be used to realise the functionality of a Newsletter.
- Checks can be made by visiting the sites listed in the Examples
(the examples refer to the realisation resulting from Patterns
or some of their aspects. They do not refer to the sites in their
entirety)
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