Validation of the Ontology using CQs

To validiate the ontology we define sets of Competency Questions (CQs) for the genral ontology and each ontology module. The CQs are formulated as queries and come forth out of the requirements as CQs play the role of a type of requirement specification against which the ontology can be evaluated (Asunción, Mariano and Oscar, 2003). As proposed by (Bezerra et al., 2013) these sets of CQs and the relevant ontology modules in OntoUML were given to an ontology experts with a profound knowledge and experience in ontologies, UFO and UFO-S, with one of the ontology experts as one of the authors of the original UFO-S paper, one expert with more than 10 published UFO papers and one expert with 11 ontology papers, 3 UFO papers and one UFO-S paper published After, we compared the answers of the expert to the intended requirements, and in case of differences, the relevant DROP was remodelled, and the validation was repeated again.

What is a digital platform?

Expert 1: A Digital Platform is a service offering relator (or relationship) of a specific type of that connects the platform provider (the platform management that plays the role of service provider) and its software platform to its target community.

Expert 2: It is a service offering that relates a software platform to a predefined user roles and focuses on a target customer community.

Expert 3: I would define a digital platform as a service offering, where multiple users can enter different agreements with each other.

Who is involved in a digital platform and how?

Expert 1: The target community of users, the platform management (as the provider), and the platform software.

Expert 2: Software platform, target customer community.

Expert 3: Different agents are involved, being either persons or organizations. They engage in different agreements with one another.

Who is involved in a user affiliation and how?

Expert 1: The (i) digital platform (offering), that precedes the user affiliation (i.e., the service agreement), (ii) a platform user (who must be a member of the user community targeted by the digital platform, and (iii) the platform management (now a “hired” service provider) that offered the digital platform.

Expert 2: Platform user (bounded by user affiliation), platform management (bounded by user affiliation), digital platform (to what user affiliation conforms to).

Expert 3: User affiliations are formed between platform users (persons or organizations). They are supported by platform software and managed by a platform manager (an organization).

What is the platform software and how is it related to the digital platform?

Expert 1: The platform software is the technology enabling the relationships to be established between the participants of a digital platform.

Expert 2: It is a software that enables the operation of a digital platform.

Expert 3: The platform software is a software tool supporting the different platform actions that can be performed by the users.

What is the platform management?

Expert 1: The platform management is a functional complex composed of people and organizations that acts as the service provider for some digital platform.

Expert 2: It is something offered by the digital platform. Why was platform management modeled as a “kind”? What is the idea behind this concept? Platform management sounds like a “continuum”…

Expert 3: Platform management manages the digital platform, and conists of either persons and/or organizations.

What is a platform supported action, what are its types and what are the differences between the types?

Expert 1: A platform-supported action is an action performed by participants of a user affiliation (agreement) with the intention of fulfilling some part of said agreement and supported by “enabling” software platform. The different types of actions are characterized by the participants of the user affiliation involved (the user, the platform management, or both).

Expert 2: The concept that represents the actions supported by the software platform and that fulfills the commitments established in the service agreement.

Expert 3: Platform supported action can be considered as a user action, a platform management action or a platform software action. The difference is the kind of support offered to a specific agent.

Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 1?

Expert 1: It is unclear to me why model Platform Management as a «kind» rather the a «roleMixin» specializing UFO-S’s Service Provider. Actually, the model does not really connect Platform Management to the concept of Service Provider, so I’m concluding by recognizing the analogous application.

Expert 1: In a naïve read of the domain, I would be afraid to pin down the term “Digital Platform” the service offering relator, as it may “hide” the polysemic use of the term. Take for instance the term UFO-S, it avoids this issues by clearly naming the distinct facets of the term Service Offering, Service Agreement, and Service Delivery. I would, personally, be inclined to refer to the class as “Digital Platform Offering” and even “User Affiliation Agreement”. Nonetheless, I recognize that experts in the digital platforms’ domain may consider the renaming unnecessary.

Expert 1: Currently, the ontology only accounts for platform-supported service deliveries. I wonder if the intention is to exclude other service delivery action that the software platform plays no role, or if there may be service deliveries beyond the ones acknowledge here. A constraint may clarify this issue (e.g., every service delivery action must be a platform supported action in order to fulfill the user affiliation agreement).

Expert 1: I would introduce the concept of Service Delivery to the model of Figure 1, just like Service Offering and Service Agreement were introduced.

Expert 1: It may be interesting to specialize the constraints of UFO-S in order to enhance the consistency of the association cycles (e.g., every user affiliation conforming to a digital platform must be bound to the same platform management offering the digital platform).

Expert 2: I did not find the service provider.

Expert 3: No additional feedback that comes in mind.

What is main digital content?

Expert 1: A digital content that can be a digital message, some personal information, an offering description, a digital file, or yet another kind of digital content that is created by a user action of main digital content creation. A main digital content can also be consumed by (a sort of participation) a user action of main digital content consumption.

Expert 2: Digital content created and consumed in the context of user actions.

Expert 3: Digital content that is created by a user and consumed by other users., consisting of messages, personal information, an offering description or a digital file.

Who participates with this main digital content and how?

Expert 1: The main digital content creation event has the participation of a platform user playing the role of content creator.

Expert 2: Platform user (Content creator and user consumer).

Expert 3: Users that create digital content, and those that consume it.

What are the types of main digital content?

Expert 1: Digital message, personal information, offering description, and digital file.

Expert 2: Digital message, personal information, offering description and digital file.

Expert 3: Digital messages, personal information, an offering description or a digital file.

What is platform supported communication?

Expert 1: A platform supported communication event is a part of a platform supported interaction composed of a sum of main digital content creation and content consumption events.

Expert 2: It is a complex event composed of consumption and creation events.

Expert 3: An event that is part of digital content.

What is platform supported interaction?

Expert 1: The platform-supported interaction is an event composed of platform-supported communication events.

Expert 2: It is a complex event composed of at least two other platform supported communication complex event.

Expert 3: An event that aggregates at least two supported communication events

Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 2?

Expert 1: I do not see in the diagram a connection between Platform-Supported Communication, Platform-Supported Interaction, and Platform-Supported Action. Their names, however, suggest that the first the are specializations of the third.

Expert 1: Another thing is that every action here seems to be a specialization of UFO-S’ Hired Provider-Customer Interaction as every service delivery action has the participation of the service provider by means of its software platform. This should be made clear in Figure 1.

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Expert 1: The minimum cardinality of two In the composition relation between Platform Supported Interaction and Platform Supported Communication is problematic. It is correct that you cannot have a whole composed of a singular part (as the two would be the same), but you prevent a single platform-supported communication event from being an interaction itself, even if it is composed of multiple creation and consumption events. Maybe Platform Supported Communication should be itself the interaction event.

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Expert 2: No.

Expert 3: No additional feedback.

How is a user role related to a platform?

Expert 1: User roles are related to platforms through their instances, which are platform users involved in some user affiliation relationship with a digital platform.

Expert 2: A digital platform defines a set of user roles (types). A platform user can instantiate one or more roles.

Expert 3: How is a user role related to a platform?

What is a user action type and how is it related to user role and user action?

Expert 1: User action types are types of user actions that can be performed by users playing certain roles.

Expert 2: User action type are types of actions allowed to be performed by an specific user role. A user action type is instantiated by user actions.

Expert 3: What is a user action type and how is it related to user role and user action?

How can a platform user change its role?

Expert 1: According to the model, a user affiliation action changes a user role. This means that the type Ebay Seller, as an instance of User Role, could be changed by a user affiliation, affecting all instances of Ebay Seller. The modelers may, however, be interested on capturing how a single user’s role may be affected by an affiliation event. In that case the “changed by” relation should be connected to Platform User instead (maybe under the name “changes role of” and stereotyped as participation). I can still imagine valid ontologies where events change instances of User Role, but it is more likely that these are events involving the platform provider (for instance by changing the terms and conditions it may change the user roles themselves).

????

Expert 2: When a user affiliation action is performed, it changes the user role.

Expert 3: By changing user affiliation

 Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 3?

Expert 1: The cardinality of “changed by” may be problematic as user roles can only change under user affiliation events. In that case, I could only be an Ebay Seller through a user affiliation action independent of the one I used to become an Ebay Customer. Nonetheless, this could be the intended model.

Expert 2: No.

Expert 3: No other feedback

This digital platform ontology validation by UFO and UFO-S experts includes the validation of 17 modules over 7 properties:

What is a one-sided platform?

Expert 1: A one-sided platform is a type of digital platform targeted towards one-sided platform communities.

Expert 2: It is a kind of digital platform.

How many communities does a one-sided platform target?

Expert 1: A single community.

Expert 2: A one-sided platform is made towards one target one-sided platform community, but it also has a relationship to another community: as a digital platform, it is designed for a target platform user community.

What kind of one-sided platform user affiliations are there?

Expert 1: One-sided platform user affiliations include, but are not limited to, registrations and subscriptions.

Expert 2: Registration and subscription

Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 4?

Expert 1: It is not possible to say, according to Figure 4, that one-sided platform user affiliations only involve digital platforms that are one-sided platforms. In order to achieve that, a mediation from One-Sided Platform User Affiliation towards One-Sided Platform must be included specializing the mediation from User Affiliation towards Digital Platform.

Expert 1: The cardinality of the «subCollectionOf» relation on the side of the part forces every target platform user community to be a composition of a single target one-sided platform user community.

Expert 2: No.

What is a Multi-Sided (MS) platform and how many user roles can it have?

Expert 1: A MS platform is a digital platform targeted towards some MS platform user sides.

Expert 1: I do not understand the «creation» relation between User Role and MS Platform. This relation can only hold between an event and an endurant. Still, I do not see how MS platform can created user roles or be themselves created by user roles. I believe you may require a more complex pattern here.

Expert 2: It is a kind of digital platform. It can have 2 or more user roles.

How many sides does a MS platform target?

Expert 1: At least two.

Expert 2: At least two.

Who is involved in a MS user affiliation and how?

expert 1: A platform management, some MS platform users, some platform users, and a digital platform. In order to say that every digital platform involved in a MS user affiliation is a MS platform, a specialization of the mediation relation from User Affiliation towards Digital Platform is required. The same applies to platform users and MS platform users.

expert 2: MS platform user(s).

What kind of MS user affiliations are there?

Expert 1: MS platform user affiliations include, but are not limited to, registrations, subscriptions, transactions, and investments.

Expert 2: registration, subcription, transaction and investment.

What is a MS platform supported interaction?

Expert 1: A platform supported interaction with participation of at least two MS platform user sides.

Expert 2: It is an event in which at least two MS Platform User Side participate.

Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 5?

Expert 1: What is the stereotype of the relation between MS Platform User Side and Target MS Platform User Side. My guess is «subCollectionOf».

Expert 1: The way it is currently modeled, registrations and subscription are one-sided platform user affiliations AND MS user affiliations, at the same time. This may be a undesired modeling choice.

Expert 2: No.

By which event can a user become a registered platform user

Expert 1: Through a registration action, which is both a user affiliation action and a digital content creation action.

Expert 2: Registration action.

What is a registration and how is it related to the registration action and registered platform user?

Expert 1: A registration is a user affiliation that involves a registered platform user and is created by a registration action.

Expert 1: I wonder whether there needs to be a differentiation between user and user account in this ontology.

Expert 2: Registration is a kind of User affiliation, is created by the registration action and, by result, bounds a registred platform user.

What is collected by the registration action?

Expert 1: At least one instance of personal information.

Expert 2: personal information.

Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 6?

Expert 1: Actually, about the “Extra Info” part, you could define “registration” when the user account is bound to some sort of authentication under creation. That way you can avoid fixing your definition to some particular authentication technique, e.g., authentication that requires the user’s e-mail address.

Expert 2: No.

What is a Subscription?

Expert 1: A subscription is a user affiliation relationship that involves a subscribed platform user. A subscription is created by a subscription action. Even though a subscribed platform user is a registered platform user, a subscription is not a registration.

Expert 2: It is a type of user affiliation.

Who is bound to a subscription and how?

Expert 1: A platform management, a subscribed platform user, and a digital platform. As the subscription is created by a subscription action which depends on a registration action, there must be a registration prior to the subscription. However, without a cycle constraint it is a valid model the scenario where “Joe’s subscription to Spotify” depends on “Bob’s registration to Spotify” rather than “Joe’s registration”.

Expert 2: a subscribed platform user (which is also a registered platform user).

What and who is involved in a subscription action?

Expert 1: A registration action, a subscribed platform user, and a subscription.

Expert 2: a subscribed platform user (which is also a registered platform user).

What is a user payment action and how is it related to a subscription action?

Expert 1: A user payment action is a user action and subscriptions actions are composed of at least one user payment action each.

Expert 2: it is a user action and it is part of a subscription action.

Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 7?

Expert 1: Why do you use «historicalRoleMixin» here instead of «roleMixin»? I was expecting the later.

Expert 2: No.

What is a platform offering?

Expert 1: A platform offering is a relationship involving an offering creator, a MS transaction platform management, a target MS platform customer community, and an offering description. A platform offering is NOT a service offering in terms of UFO-S as Platform Offering and Service Offering are disjoint relator kinds in the model.

Expert 2: It is an offering by an offering creator towards a target MS platform customer community.

How does a platform offering come onto existence?

Expert 1: A platform offering is created by an offering creation event alongside an offering description. This offering creation event is performed by (i.e., has the participation of) an offering creator, however, it is not possible to say without a constraint that this offering creation is the same one involved in the platform offering created.

Expert 2: an offering creation event performed by an offering creator / content creator.

Who is involved in a platform offering and how?

Expert 1: A platform offering involves an offering creator, a MS transaction platform management, a target MS platform customer community, and an offering description.

Expert 2: offering creator (who offers), target MS platform customer community (to who it is offered to).

What is a platform Transaction and how is it related to the platform offering?

Expert 1: A platform transaction is a relationship involving a MS transaction platform management and a hired platform provider, but no platform customer (according to the model). A platform customer has a historical dependence on a platform transaction which must precede it in order to fulfill the cardinalities constraints.

Expert 1: It not clear to me why «historicalDependence» was used here where in UFO-S, with its analogous pattern, «mediation» is employed. In fact, «historicalDependence» was not a feature of OntoUML during the development of UFO-S. I would like to know if the authors are suggesting that «historicalDependence» better represents the phenomena captured earlier as a «mediation» relation.

Expert 2: It is the element that bounds the MS transaction platform management and the hired platform provider. Also it conforms to a platform offering in a specific scenario. Obs.: can a platform transaction be seen as a kind of “contract” (agreed between some parties)?

Who is involved in a platform transaction and how?

Expert 1: A platform transaction involves a MS transaction platform management and a hired platform provider, but no platform customer (according to the model).

Expert 2: hired platform provider(s). Obs.: for me it is not clear what a MS transaction platform management is.

What is a delivery and how is it related to the platform transaction?

Expert 1: A delivery is an event that has the participation a Platform Customer and partially fulfils a platform transaction.

Expert 2: It is an event that when performed (partially) fulfills the platform transaction. Obs.: are there some relationships between

What kind of deliveries are there, and who is involved in them?

Expert 1: Pure-platform deliveries and outer-platform deliveries.

Expert 2: Pure Platform delivery and outer-platform delivery. For each delivery, platform customer is related to it. Obs.: can a delivery be composed of a number of pure platform delivery and outer-platform delivery (as a complex event)?

Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 8?

Expert 1: I do not know if the cardinality of a unique user on the participation relation of a delivery event over constrains the model. It seems to prevent event that include the participation of multiple platform customers.

Expert 2: No.

What is a platform investment, to who/what is it related and how?

Expert 1: A platform investment is a platform transaction that involves a capital-seeking agent, a capital-giving agent, and some resources, as well as all entities involved in a regular platform transaction. A platform investment is composed of at least one future reimbursement commitment from the capital-seeking agent towards the capital-giving agent.

Expert 1: In order to make it clear that a platform investment is always composed of more than a single part, you should introduce the concept of claim as a counterpart to the commitment. This will not be necessary if you decide to specialize UFO-S’ Service Agreement class, which already introduces this pattern.

Expert 2: It is a kind of platform transaction. It bounds an investee, an investor agent, and the involved resource, being also part of one or more future reimbursement commitment. Obs.: is there no relationship between platform transaction and platform customer (similar as was done between platform transaction and hired platform provider)?

What is a future reimbursement commitment, to who/what is it related and how?

Expert 1: A future reimbursement commitment is a hired provider commitment from the capital-seeking agent towards the capital-giving agent and that exists as part of a platform investment.

Expert 2: It is a hired provider commitment that inheres in a capital-seeking agent (as a hired platform provider), is part of the agreement between them and is externally dependent on the investor.

Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding figure 9?

Expert 1: Overall, I believe that some of my comments were already solved by the authors and are simply out of the diagrams presented. Other comments may not be already solved but could be already under the authors list of concerns. I hope that my comments help the authors towards at least improving the communication of their work such that possible misinterpretation that I may have occurred into could be avoided.

Expert 1: One possible way to improve the reader capacity to understand to whole model beyond the diagrams selected for presentation is to also share the model files or even the OWL version of it.

Expert 2: What about the claim (counter part of future reimbursement commitment)?

The following answers are from Expert 3:

• What is a listing?

A decentralized offering on the platform

• What is a listing search? Who performs it and what is used to perform it?

An event performed by a decentralized target platform customer.

• What is the relationship between the listing search and the decentralized transaction?

Both are performed by a customer of the platform. A search can result in a decentralized transaction.

• What is a decentralized transaction and who and what is involved in it?

A platform transaction between two platform customers.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

No Feedback.

• What is a centralized offering?

An offering on the platform, offered by the centralized target platform customer community.

• What is a centralized transaction creation and who is involved in it?

A platform transaction between the platform customer and the centralized target platform customer.

• What’s a ‘match target customer to offering’ event, and who/what is involved in it?

A type of platform software action event, that is part of a centralized transaction creation between two platform customers.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

No feedback.

• What is a B2C Hired Platform Provider?

An organization that is a platform customer on the B2C market.

• What is a B2C Platform Customer?

A Person that is a hired platform provider, on the B2C market.

• What is a C2C Hired Platform Provider?

A person that is a platform customer, on the C2C market.

• What is a C2C Platform Customer?

A person that is a platform provider, on the C2C market.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

• What is the difference between a Peer User and a Non-Peer User?

Peer users preform automated affiliation actions while non peer users perform manually checked affiliation actions.

• What are C2C Hired Platform Providers and Customers?

Two type of roles that consist of a peer user.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

These diagrams I find more difficult to understand, not really sure what a user affiliation action entails.

• When is a delivery ‘product-oriented’?

A type of delivery to a platform customer involving a product.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

No feedback.

1. When is a delivery ‘result-oriented’?

A type of service delivery performed by a hired platform provider.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

No feedback.

• When is a delivery ‘user-oriented’?

When it is both product- and result-oriented.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

No feeback.

• What is the difference between an ‘access-based platform transaction’ and a ‘platform transaction’?

An access-based platform transaction is a type of platform transaction, performed between access-based hired provider and access-based platform customer.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

No other feedback.

• When is a product under-utilized?

When a product is personally used by a hired platform provider.

• Do you have any other feedback concerning the use of UFO and UFO-S patterns regarding the figure below?

No other feedback.

Changes made to the model