Main Roles of Actors

Main Roles of Actors

In order to describe how a Digital Library Organisation is expected to work, it is fundamental to identify the main roles actors can play when interacting with digital library systems and how they are bound to the core concepts of Content, User, Functionality, Quality, Policy and Architecture. With regard to the overall operation of the Digital Library Organisation and the way it is expected to deliver the service it is intended for, three different yet complementary roles come into play: Digital Library End-users, Managers and Software Developers.
Each role is primarily associated with one of the three ‘systems’ in the three-tier framework: Digital Library, Digital Library System, and Digital Library Management System. The ‘system’ that a role is associated with represents the entity that is expected to provide the actor playing such a role with the facilities needed to accomplish the mandate assigned to the role. Additionally, every actor, irrespective of the role he/she is playing, is expected to deal with all the foundational concepts characterising the Digital Library universe.

Digital Library End-users
End-users use the overall Digital Library service in order to provide, consume, and manage the Digital Library. They are the target clients of the service defined by the Digital Library Organisation in terms of the Content to be managed, the User(s) to be served, the Functionality to be supported, the Policy or Policies to be put in place and the Quality to be rendered. End-users perceive the Digital Library as a stateful entity serving their needs. This state of the Digital Library is a complex condition resulting from and impacting on Content, User, Functionality, Policy and Quality aspects of the Digital Library Organisation and it is expected to evolve during the lifetime of the Digital Library as a consequence of a series of actions and activities performed in the context of the Digital Library Organisation, as well as of external factors influencing the Digital Library Organisation.
DL End-users can be further divided into: Content Creators, Content Consumers and Digital Librarians.

• Content Creators are the “producers” of the Digital Library Content, i.e., they deal with producing new items contributing to the Digital Library Content. Their activity is performed through the Functionality that the Digital Library makes available; in compliance with the Policies defined in the Digital Library, and with the guarantee of Quality that the Digital Library declares.
• Content Consumers are the “clients” of the Digital Library Content, in that they access and use the items in the Digital Library Content. Their activity is performed through the Functionality that the Digital Library makes available, in compliance with the Policies defined in the Digital Library, and with the guarantee of Quality that the Digital Library declares.
• Digital Librarians are the “curators” of the Digital Library Content, in that they select, organise and look after the items in the Digital Library Content. Their activity is performed through the Functionality that the Digital Library makes available; in compliance with the Policies defined in the Digital Library and with the guarantee of Quality that the Digital Library declares. Additionally, Digital Librarians might influence the behaviour of the overall Digital Library service by acting as mediators between Content Creators and Content Consumers and people defining and operating this service, such as Digital Library Managers by communicating and expanding feedback on the Digital Library.

Digital Library Managers
Managers are the actors driving the overall Digital Library service. They are expected to rely on the facilities offered by the Digital Library Management System to define and operate the Digital Library and the Digital Library System implementing it. Managers can be further divided into Digital Library Designers, who develop the overall service, and Digital Library System Administrators, who deploy and operate the Digital Library System implementing the service. Digital Library Designers use their knowledge of the application environment which a Digital Library is called to serve in order to define, customise, and maintain it so that it is aligned with the needs of its target End-users. In doing so, they interact with the Digital Library Management System to define the characteristics the Digital Library should have in terms of:

• Content, such as the set of repositories, ontologies, classification schemas, information object types, metadata formats, authority files, and gazetteers that form the DL Content.
• User, such as eligible actors and roles, the information characterising the actors.
• Functionality, such as the functional facilities to be offered and the behaviour these facilities should implement.
• Policy, such as the rules and principles governing the evolution of the Digital Library Content, the actions allowed by each actor or group of actors and resource exploitation.
• Quality, such as the minimal availability of a Digital Library Functionality, the minimal response time of a Functionality, the completeness and authoritativeness of the Digital Library Content and confidentiality of the User actions.

These aspects characterise the overall Digital Library service and the way it is perceived by End-users. These parameters need not necessarily be carved in stone for the entire lifetime of the Digital Library as they may be reconfigured to enable the Digital Library to respond to the evolving expectations of target users and changes in any aspects.

Digital Library System Administrators work in tandem with Designers to set up the Digital Library System that implements the Digital Library service planned. They select, deploy and manage a set of networked computers and software modules needed to meet the expectations of End-users and designers. System Administrators perform their work by interacting with the Digital Library Management System and relying on the facilities these systems offer for Digital Library System constituent identification, linking, allocation, deployment, configuration, tuning, monitoring, alerting, and any other management facility needed to manage potentially distributed software systems as Digital Library Systems are expected to be. Different Digital Library Management Systems are expected to offer diverse management facilities spanning manual installation and configuration of computers and software modules on the target computers, and fully autonomic solutions designed to reduce human intervention to core activities.

Digital Library Software Developers
DL Software Developers develop and/or customise the software components used as constituents of the Digital Library Systems. Software developers are requested to produce the software implementing every aspect of the Digital Library service ranging from Digital Library Content and User to Functionality, Policy and Quality. However, Software Developers do not need to start from scratch as their work is expected to be performed by relying on the Digital Library Management System offering. A Digital Library Management System is a software system that is equipped with diverse off-the-shelf software modules implementing, to some extent, a number of Digital Library facilities, such as content repositories, user management systems, co-operative working environments, information retrieval engines, and policy enforcement modules. Software Developers include Software Engineers and Programmers responsible for customising and complementing the set of software modules provided by the Digital Library Management System used in order to achieve the set of software constituents needed to implement the Digital Library planned.

The roles described above encompass the entire spectrum of actors working in the digital library universe. Their conceptual models of such a universe are linked hierarchically, stemming from the definitions provided here. Digital Library End-users act on the Digital Library, whereas Managers and Application Developers operate on the Digital Library System, through the mediation of a Digital Library Management System, and, consequently, on the Digital Library as well. These relationships ensure that co-operating actors share a common vocabulary and knowledge. For instance, the Digital Library End-user expresses requirements in terms of the Digital Library model and, subsequently, the Digital Library Designer understands these requirements and defines the Digital Library accordingly.

As the responsibilities of librarians are cross-cutting, they are not expected to play just one of the roles envisaged. Activities envisaged for Digital Library End-users include provision, consumption and management of the Digital Library content. Thus, librarians acting as cataloguers and curators in the library world and librarians interfacing with and supporting the users of a library perform these activities in the Digital Library domain. Since the Digital Library Designer uses her/his knowledge of the application semantic domain to define, customise and maintain the Digital Library, this role is usually covered by the Chief Librarian, also referred to as Manager or Director, who decides the overall service offered. The Digital Library System Administrator role is played by the Librarian with technical skills entitling her/him to manage the Digital Library System realising the Digital Library service. Some Librarians might also be engaged in the customisation of the software system delivering the service, whereby they act as Digital Library Software Developers. While the Reference Model does not explicitly use the term ‘Librarian’, it captures the various activities today’s librarians are requested to perform in the digital library space.