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Path: Home | Publications | Quality criteria  |  Table of contents  | Chapter 2


Handbook for quality in cultural Web sites
Improving quality for citizens

2 Quality in Web Applications: general principles and operative proposal

2.1 Introduction

2.2 Accessibility of contents

  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 Usability

  2.3.1 Definition and methodology
  2.3.2 Principles of Usability

2.4 Criteria of Usability for Cultural Web Applications (CWA)

  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 Functional layout Functional graphic elements Functional multimedia elements
  2.4.7 Site Navigation
  2.4.8 Searching

2.5 Patterns and the language of Patterns

  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.



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.



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:

  1. 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:
  2. 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.
  3. 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:

  1. it guarantees the level of realism, and gives also consensus and communication on the project,
  2. 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.


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. 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. 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. 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.


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


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:

  1. from the Context, Conditions and propositions of the problem, it can be ascertained whether the Pattern is suited to the case in hand;
  2. 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;
  3. 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);
  4. 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;
  5. 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;
  6. the end result is a list of patterns such as the following:
    • Newsletter
    • Form
    • Controlled Input
    • Registration
    • Login
    • Communicate the Result of the Action
  7. The list, complete with its definitions, constitutes a document that can be used to realise the functionality of a Newsletter.
  8. 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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