=Paper= {{Paper |id=Vol-3618/forum_paper_12 |storemode=property |title=A general domain model of distributed ledger technologies |pdfUrl=https://ceur-ws.org/Vol-3618/forum_paper_12.pdf |volume=Vol-3618 |authors=Simon Curty,Hans-Georg Fill |dblpUrl=https://dblp.org/rec/conf/er/CurtyF23 }} ==A general domain model of distributed ledger technologies== https://ceur-ws.org/Vol-3618/forum_paper_12.pdf
                                A general domain model of distributed ledger
                                technologies
                                Simon Curty1,∗ , Hans-Georg Fill1
                                1
                                    Digitalization and Information Systems Group, University of Fribourg, Bd de Pérolles 90, 1700 Fribourg, Switzerland


                                                                         Abstract
                                                                         Distributed ledger technologies (DLT) comprise a versatile set of concepts whose combination is poten-
                                                                         tially highly disruptive from a business and technical perspective. However, the underlying technological
                                                                         variety and complexity hinder a more widespread adoption. In particular, it is a major challenge to
                                                                         understand the interplay of business and technical aspects in DLT-based systems. In the paper at hand, we
                                                                         address this challenge by proposing a generally applicable domain model for distributed ledger technolo-
                                                                         gies. Whereas previous approaches predominantly focused on specific aspects of DLT or technological
                                                                         variations, we put a focus on the relations between governance, economic, and technical perspectives in
                                                                         a holistic manner. For illustrating the value of the domain model, we apply it for describing a conceptual
                                                                         representation of the widely used Ethereum blockchain environment.

                                                                         Keywords
                                                                         Distributed ledger technology, Blockchain, Domain model, Conceptual modeling




                                1. Introduction
                                The family of distributed ledger technologies (DLT) — often equated with blockchain — has seen
                                a growing number of members, offering rich feature sets for various use cases. Thereby, the core
                                properties of DLT, such as tamper-proof distributed storage or authorization mechanisms [1, 2],
                                are often approached in a conceptually similar manner. For example, blockchains share the
                                fundamental data structure of the distributed ledger which enables tamper-proof records. As no
                                single solution can meet the requirements to fit every use case, numerous new concepts, technical
                                approaches, and operation practices have emerged over the years. This conceptual variety,
                                the technological complexity, and the disrupting nature of DLT from a business perspective
                                pose difficulties for the successful adoption of DLT. For facilitating the understanding of these
                                complex systems, we thus propose in the following a general domain model for conceptualizing
                                systems built on distributed ledger technologies. In line with the definition by Guizzardi and
                                Proper, we regard a domain model as a social artifact for representing an abstraction of a domain
                                for a particular purpose [3]. Our aim is to increase the shared understanding of the domain of
                                DLT with a particular focus on the interplay between their governance, economic mechanisms,
                                and technical realization.

                                ER2023: Companion Proceedings of the 42nd International Conference on Conceptual Modeling: ER Forum, 7th SCME,
                                Project Exhibitions, Posters and Demos, and Doctoral Consortium, November 06-09, 2023, Lisbon, Portugal
                                ∗
                                    Corresponding author.
                                Envelope-Open simon.curty@unifr.ch (S. Curty); hans-georg.fill@unifr.ch (H. Fill)
                                Orcid 0000-0002-2868-9001 (S. Curty); 0000-0001-5076-5341 (H. Fill)
                                                                       © 2023 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
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   Previously, a number of conceptualizations of this field have been proposed, e.g., in form of on-
tologies. Thereby, past approaches focused primarily on selected aspects, such as governance [4],
or on specific technologies, e.g., the technologies underlying the Ethereum blockchain [5]. How-
ever, for understanding the relations between isolated aspects, such as the impact of a consensus
mechanism on a business case, more over-arching, holistic models are required. The challenge in
designing such a model lies in capturing the significant concepts on an appropriate abstraction
level, such that also relations between seemingly separate perspectives can be expressed. Thus,
the main research objective of this work is to provide a technology-agnostic conceptualization of
distributed ledger technologies, including the relations between technical concerns, governance
models and economic structures.
   The remainder of this paper is structured as follows. In Section 2 we will introduce foundations
on DLT and blockchain-based systems, as well as existing approaches for the conceptualization
of DLT. In Section 3 we will present the general domain model of DLT, split into models for
representing governance, economic, and technical structures. An application of the domain
model will then be illustrated with a conceptualization of the Ethereum ecosystem in Section
4. The paper will conclude with a discussion of the approach in Section 5 and an outlook to
further research in Section 6.


2. Foundations and related work
In the following we present brief foundations on distributed ledger technologies and the core
concepts that are relevant for our approach. Furthermore, we will outline prior work on
conceptualizations of the DLT domain.

2.1. Distributed ledger technologies
Distributed ledger technologies are characterized by a collection of various technical and socio-
technical concepts, which work together to enable properties such as the decentralized immutable
storage of transaction records in the form of a distributed ledger shared between authorized
parties [6]. Thereby, a consensus mechanism defines a protocol to ensure the consistency and
validity of the ledger. This protocol is enforced by nodes that form a peer-to-peer network.
Participation in a network may be restricted such that only permissioned parties can access
the ledger. Most predominately, the data structure of the ledger is a chain of cryptographically
linked data blocks, forming a so-called blockchain. Further, so-called smart contracts may be
added to transactions in some DLT systems for the decentralized execution of algorithms [1].
Decentralized applications (also known as DApps) then rely on distributed algorithms to achieve
parts of their function [6].
   The computational resources necessary for network operations are provided by the participat-
ing nodes. The required infrastructure and operating costs are incurred either by the involved
parties themselves or by a crypto-economic approach. In the former case, the parties have
some interest in providing resources, e.g., because they are part of a business consortium along
with collaborators. In the latter, the node operators are typically rewarded for their efforts in
securing the DLT system with payments in the form of cryptocurrencies.
  The evolution of a DLT-based system requires decision making on emerging technical de-
velopments, adjustments to the consensus mechanism, and changes to the economic structure.
The processes and parties involved in making these decisions are subsumed under the term
governance. This may for example involve community-based voting, or simply a centralized
organization with exclusive decision power.

2.2. Previous conceptual representations of DLT
A number of conceptual modeling methods for various aspects of DLT have been elaborated
in the past. Their goals span, e.g., from providing support for the development of DLT-based
applications, the design of business models, over the integration of DLT systems in enterprises,
strategic decision making, and to semantic reasoning and technology taxonomies. In the fol-
lowing, we briefly summarize selected works on taxonomies, reference models, and ontological
approaches that we deem most closely related to our approach. For a comprehensive overview
on modeling methods in the context of DLT, we refer readers to a recent literature survey [7].
   For dealing with the technological complexity and variety, guidelines, and decision models
for choosing appropriate DLT systems have been published. Such models may be derived from
taxonomies and subsequent classifications of systems. This includes for example architectural
characteristics of DLT systems [8], consensus protocols [9], and cryptoeconomic design [10].
   Other approaches revert to schematic reference models or ontologies to present aspects of
DLT. Thereby, some regard specific systems: EthOn [11] is a detailed ontology formalizing the
technical concepts of the Ethereum blockchain. Olivé [5] presented another conceptualization of
Ethereum, focusing on system architecture and the data model of the ledger. Of further interest
is the ERC-721 standard for the implementation of non-fungible tokens on Ethereum [12],
where Ethereum and token contracts are modeled with the OASIS ontology [13] which has been
extended with smart contract concepts [14]. In addition, ontological approaches may apply
inference mechanisms to derive new insights on modeled systems. This has been leveraged, for
example, by Besançon et al. [15] who presented an OWL ontology based on the aforementioned
EthON approach for the formalization and development of decentralized applications. In a
similar vein, other authors focus on smart contracts and reverted to ontologies in combination
with semantic rules for the verification of contracts [16] or the generation thereof [17].
   Multiple blockchain-based systems were considered by Ellervee, Matulevicius, and Mayer [18]
to derive a reference model using ArchiMate, BPMN and UML of the general architecture and
technical processes of blockchains. ArchiMate was also used by another approach to draw a
comparison of the architectural differences of Ethereum and Hyperledger Fabric [19]. Non-
technical perspectives on DLT may profit especially from considering multiple systems or the
domain as a whole. Such system-agnostic conceptualizations were presented, for example, by de-
tailing smart contracts as formalization of legal contracts [20, 21], or for designing decentralized
governance [4].
   Ontologies stemming from the field of enterprise modeling were also considered for support-
ing the development of DLT-based systems. For example, Kim et al. [22] extended the Toronto
virtual enterprise ontology [23] with traceability concepts for blockchain-based supply chain
provenance. The business ontology of the resource-event-agent accounting framework [24]
was used in combination with DEMO [25] for the ontological modeling of blockchain trans-
actions and how these relate to economic commitments [26]. Another approach applies the
resource-event-agent ontology as part of a development method for smart contracts for multiple
blockchains [27].
   In summary, existing conceptualizations predominantly regard specific aspects of the DLT
domain, e.g., smart contracts on various level of abstraction, or investigate specific systems,
most commonly involving Ethereum [7]. Such a focus allows to derive conceptualizations that
capture the universe of discourse in detail. Considering isolated concerns in a larger context
is still a necessity to understand how these relate to each other. This could be supported by
general domain models. Such models for the DLT domain have been sparsely researched so far.


3. Domain model of distributed ledger technologies
For the development of the domain model, we pursued an exploratory research approach by
searching for generalizations leading to a detailed understanding of the object under study [28].
Thereby, we aim to lay a foundation for subsequent, confirmatory research approaches. Thus,
at first, existing conceptualizations, as outlined in Section 2.2 were considered, as well as our
own experience of the domain from various projects and as derived from discussions with
industry experts. The development was guided by three design objectives: First, the domain
model should be technology-agnostic, that is, it should represent distributed ledger technologies
in general, rather than a specific technical platform. Second, it should capture the domain
from a holistic perspective, rather than focus on specific concerns such as only technical or
only economics aspects. Third, to account for future developments, the model should be easily
extensible. For ensuring this latter objective, we revert to UML class diagrams that have been
extended with reference points to link multiple diagrams together to increase comprehensibility.
   The model is split into three parts that each represents a perspective of the DLT domain,
focusing on governance, economic, and technical concerns. For clarity, some concepts and rela-
tions have been purposely omitted from individual figures. Concepts that appear in more than
one perspective are color-coded and tagged with acronyms for each perspective (gov,eco,tech).

3.1. Governance perspective
DLT systems require a governance concept that describes the decision structure for managing
the initial development as well as future evolution of the system. While this is also true for
traditional IT systems, the decision structure might be decentralized, using the distributed ledger
itself and community-driven. Technology projects, such as Ethereum, individual networks, as
well as decentralized applications always define a governance concept, may it be implicitly or
explicitly. In Figure 1, a general model of a concept related to governance in DLT is shown,
which will be summarized in the following.

Types of governance structures: We distinguish between three types of specializations of
     governance. In the case of decentralized governance, the decision makers are participants
     in the DLT system. This includes, for example, community-driven governance. When
     reverting to consortial governance, the decisions are made by organizations taking part in
     the system. And when using centralized governance, a single party makes the decisions.
                                                                               *                                                                                                            voters
        [gov/eco/tech]                                 [gov/eco/tech]
                                  * driven by                                     *                       has
           Interest                        *             Identity              1..*
                                                                                                                                                         *   has
                                                                                                                                   Role                                          Responsibility
                                                   *                *                                                    *                                              *


                                                                                                  participants



                                                Consensus-managed                                                adheres to
          Self-managed Identity
                                                     Identity

                                                                        1
    associates                                                                                *              1      1                   1            1                             1
                                                                        appoints                    1

                                                                                          *             [gov/eco/tech]                      [gov/tech]                      [gov/eco]
                                                                                                                                                                                                  1
                             Centralized                                                                 Consensus              Technical Specification                Economic Structure
                 1           Governance
                                                                                   1..*
                                                                                                              1                                  1                 1

                                                                            Decentralized
                         Consortial Governance
                                                                             Governance
                                                                                                                              defines


                                   1..*                                               *
                                                                                                                                                                                          influences           *
                                                                                                                                  1
                                   *                                                                                     1                                                                             *   *
                                                   *
                     *                                                                                                                  1                proposes
                             Organization                                                                          Governance                                                               Voting
                                                                                                                                                                             *
                 *



Figure 1: Governance perspective on the DLT domain.


             This is, for example, the case for private blockchains or government operated networks
             such as the European Blockchain Services Infrastructure (EBSI1 ). In accordance with
             governance decision specifications, economic structures and consensus processes are
             defined. To decide on changes to the system, voting sessions may be proposed by the
             governance structure. The outcome of such voting may then impact the governance itself.

Identity and decision drivers: An identity in a DLT system is held by some entity, partaking
     in the system. Within the boundaries of the system, an identity is unique and represents
     what interests and roles the holder has. Identities may participate in the consensus process
     or in voting sessions and can be associated to organizations. The model introduces two
     specialized identities: a self-managed identity, which is created and managed by the holder
     entity. An example for self-managed identities are accounts in Ethereum [1]. In contrast,
     a consensus managed identity is issued to an entity upon some consensus. For example,
     in Hyperledger Fabric networks, identities can be issued by certificate authorities that
     have the required authorization. Identities can have roles with associated responsibilities
     and are driven by some interest. This can be anything from monetary compensation to
     the fulfillment of a mission.

Establishing consensus: The consensus concept is a representation of all processes in the
     system that have been established for reaching consensus on some matter relevant for
     the system’s correct operation. This includes, for example, a consensus protocol, which
     will be added through the economic and technical perspectives. These processes adhere
     to the specification of the system and its economic structure. Identities may partake in
     such a consensus process in a manner that is dictated by their interests and roles.
1
    https://ec.europa.eu/digital-building-blocks/wikis/display/EBSI/Home
3.2. Economic perspective
An important part of a DLT system is its economic structure. This may include operational costs,
as well as incentives for the participants for correct behaviors. In particular, public blockchains
require monetary incentives, so that node operators provide the necessary computational
resources for securing the ledger. For this service, node operators are typically rewarded in
some cryptocurrency, which is an integral part of the system. In private and consortium DLT
systems, the effort of operating the infrastructure is provided by the authorized participants,
usually without any involvement of cryptocurrency. The fundamental concepts of the economics
of a DLT system are illustrated in Figure 2.
                                                                 [eco/tech]                  incurs                                                          [gov/eco/tech]              *
                                                                                 1
                                                                                                               Operating Cost
                                             0..1                    Node                              1                                                          Interest
                                                        *

                                                                                                           *
                     enforces
                                                                                                                    [eco/tech]
                                                                 Reward                                                                                        Incentive
                                                    *                                                      Monetary Incentive
               1
                                                                                                                                                              *         *
        [eco/tech]
                                1 yields
                                                                     Fee
   Consensus Protocol                               *                                *

                   1..*                                                                                                                              involvment

                                                               [gov/eco/tech]    *                                                                                           driven by

                                                        1        Identity
                                                        1                                                                   incurs
                                                              1..*               2
                                                                                             from/to                                  transferring
               1          *                                                                                                                              *          *
                                                                                                                *         *       1
                                                                                         1
      [gov/eco/tech]                adherence                    [gov/eco]                                             [eco/tech]                              [eco/tech]
                                1
                                                                                         1
       Consensus                                1           Economic Structure                                         Transfer                                    Asset
                                                                                                                                                     *
                                     holds                                                                                                                    *




Figure 2: Economic perspective on the DLT domain.


Incentives: An integral part of the economic structure of a DLT-based system is the provision
     of incentives. This includes monetary incentives in the form of rewards and fees that result
     from the execution of the consensus protocol. That is, the consensus protocol may allot
     rewards for correct behavior — for example, nodes that contribute to securing the ledger
     by adhering to the consensus protocol. Participants that do act maliciously towards the
     network may be punished.
Operating costs: Running a node that participates in the consensus protocol incurs operating
    costs paid by the node’s operator. These include, for example, hardware provisioning,
    maintenance, energy consumption, and facilities. In systems, where there are no rewards
    directly tied to the execution of the consensus protocol, providing computing resources is
    motivated by some other intent. In the model, this is expressed as an interest that serves
    as motivation for the identity held by a node.
Assets and transfers: Assets represent something of value that is held by an identity and can
     be transferred to another. Both fungible tokens, e.g., cryptocurrencies, and non-fungible
          tokens are represented by the asset concept. Assets may be awarded for participating
          in the consensus protocol. In the model, this is expressed as an incentive, namely the
          payment of some assets.

3.3. Technology perspective
From a computer science perspective, DLT-based systems are inherently state machines, where
the current and previous states are recorded in a ledger that is distributed among interconnected
nodes. Thereby, a state change is caused, for example, by transferring tokens between partici-
pants. To preserve the integrity of the ledger, nodes must reach consensus on the contained
data. Figure 3 represents these ideas from a technical perspective.

Specification: DLT systems are developed according to a technical specification. This may be
     in form of a document, or a reference implementation. The specification may define the
     consensus and networking protocols, how assets are represented, execution environments
     for distributed algorithms, and languages.

Consensus protocols: The consensus protocols are part of the general consensus concept,
    encompassing all processes for reaching some consensus. These protocols are enforced
    by nodes to ensure that a state-changing result produced by a node is a valid next state.
    Further, consensus can be reached on software artifacts, for example, a smart contract.
    An artifact is written in some language, e.g., in a smart contract language such as Solidity,
    with a defined syntax and expresses a meaning, i.e., semantics. The artifact concept is not
    commonly present in popular blockchains, e.g., Ethereum. However, in academia this has
    been demonstrated, e.g., for reaching consensus on collaboratively constructed process
    models and their execution [29].

Architecture of nodes: Nodes are the fundamental infrastructure building blocks of DLT
     systems and the peer-to-peer network. Here, we do not conceptually distinguish between
     the node as software and the device that runs it. Nodes may however have a number of
     components, each contributing to the overall function of the node. Not all nodes may have
     the same function or purpose. For example, in Ethereum several types of nodes exist that
     store the entire ledger or only parts of it. The purpose of a node is given by the identity
     holding the node, attached roles and its responsibilities (see Figure 1).

Networking: Usually DLT systems employ a peer-to-peer networking model. While peer
    connections are not directly represented in the domain model, interconnected nodes form
    network boundaries. Within a boundary, nodes access the same distributed ledger. It is
    possible for a DLT system to have multiple networks or sub-networks, represented by
    hierarchical network boundaries. This is similar to the channel concept of Hyperledger
    Fabric, where the network may be divided into so-called channels that have their own
    ledger and access policies2 . Authorization to networks is represented by giving access to
    identities.

2
    https://hyperledger-fabric.readthedocs.io/en/release-2.5/glossary.html#channel
                                                                                    1 replicates
                                                                                                                             [eco/tech]
                              1..*                                                  1 validates                                                  1..*                      contains
       World State                                             Ledger                                                                                                                                Network Boundary
                                1         1                                         1 queries                1..*               Node             *                                      1..*

                                                                                                                       *                                                                                *   0..*                 *
             «read                                                                                                                  0..1        1                     enforces          structures                     0..*
                                      replaces
             access»                                                                                                    provides            *                                                    1


                                                                                                                       1                        Component                                              Networking
                                      1..*

                                                                                                                                                                                                                *
       View Result                        New State Result                               Execution Environment                  *

                                                                                                             1
                       1              1       1            *                                                                                    validates

                                                                 results in                                  runs
                                                                                                         *                                                                  1
                                                                                           1                                                                      1
                                                                                                                                                                                                       *
                                                                                                                                                                         [eco/tech]
                                                                                           Execution Instance
                                                                                     *                                                                            Consensus Protocol               1            consensus on

                                                                                                                                                                1..*                        *
             results in                                    conforms to                                       1
                                                                                                             creates
                                                                                                         1                          has a

                                                                                                 Interaction

                                                                                                                                                                                 yields           specifies         has access

                                                          1..*                                                              1..*
             1
        [eco/tech]
                                                                        1
                                      Behavior Specification                             Smart Contract
        Transfer                                                            1

       1
              *                                       *
                                                      set of                                         0..1
                                                                                                                                                                                        *
                                                  *
                   triggers                                                                          has a                                                                           [eco/tech]
                                       Instruction/Operation
                              *                                                                                                                                           Monetary Incentive

                                                      *
       transferring
                                                                                                     1                      1..*    1
                                                                                                             [gov/eco/tech]                         driven by                    [gov/eco/tech]
                                                                                                                                        *
   *                                                                                                             Identity                                         *                  Interest

        [eco/tech]                                                                                                     * 1..*
                                  *                                                                                                                         1
           Asset                                                                                                                                                                                            1
                                                                                                                                                    [gov/eco/tech]                                     [gov/tech]
                                                                                                                                                                                 1
                                                                                                                                        *            Consensus                          1 Technical Specification

                                                                                                                                                                                                                1




                                                  *                     *

                                                                              *   expressed in
                                                      Artifact                                                      Language                                      Syntax                                    Semantics
                                                                                                 1




Figure 3: Technical perspective on the DLT domain.


State results: Two types of actions may result in a new state, leading to changes to the ledger.
      First, a transfer of assets from one identity to another (see Figure 2). Second, an interaction
      that triggers a state changing execution of a smart contract. The latter case is represented
      as an interaction with a contract identity, creating an execution instance that is run
      by an execution environment provided by a node. The execution instance conforms to
      the behavior specifications of invovled smart contracts. Not every interaction is state
      changing. For example, read-only access to data of smart contracts requires querying the
      current world state. This is represented as view results in the model. If a state transition is
            necessary, the new state needs to be valid in accordance with the consensus protocol. If
            that is the case, the new state replaces the current and is included in the ledger.


4. Illustrative application of the domain model
As an illustrative application example, we present a conceptualization of various parts of
Ethereum by reverting to the domain model. In the individual models, some elements and
relations have been omitted for brevity or due to redundancy. In particular, we regard the public
Ethereum mainnet in its current stage of development.

       Consensus client :                                                                                                                       P2P-network Protocol :
                                Execution client : Component                                               Mainnet : Network Boundary
         Component                                                                                                                                   Networking




      A Light Node : Node            A Full Node : Node              An Archival Node : Node              Mainnet Ledger : Ledger
                                                                                                                                                            specifies



                                                                                             replicates                    has access



                                                                enforces


                                  Full Node Account : Self-                ArchivalNode : Self-                                                 Ethereum Specification :
Light Node Account : Identity                                                                                       Archivist : Role
                                      managed Identity                      managed Identity                                                    Technical Specification



                                                                                                                                                            defines

      Partial Replication :                                                                 Full Replication :                  Ethereum Community :
                                      Validator : Role
         Responsibility                                                                      Responsibility                    Decentralized Governance



                                                                                                                                                                specifies

       Block Validation :                         Proof-of-stake :                                                              defines
                                                                                       ETH Consensus : Consensus
         Responsibility                          ConsensusProtocol




Figure 4: Basic network structure of the mainnet and the three node types with their roles and
responsibilities.


   Figure 4 shows an overview of the network and infrastructure of the Ethereum mainnet. In
Ethereum, there are three types of nodes that differ mainly by the synchronization mechanisms
for the ledger, specifying to what extent the ledger is replicated. For example, archival nodes
hold a full copy of the ledger back to the very first transaction, but full nodes prune the ledger
data to preserve storage space3 . In contrast, light nodes only store a summary of the ledger in
form of block headers and rely on full or archival nodes to access further information. These
nodes cannot participate in consensus. All identities are self-managed, that is, users and node
operators must create and manage their identities themselves. However, an identity is in
principle transferable. The capabilities of the node types are expressed by their assigned roles
and responsibilities. For, example, an archival node has the responsibility to fully replicate the
ledger and to validate new blocks to be appended to the chain. Further, the model expresses
that a node must operate, or have access to, two pieces of software, namely a consensus client

3
    https://ethereum.org/en/developers/docs/nodes-and-clients/#node-types
    Ethereum Reward Structure :               Ethereum Incentive Structure
                                                                                        Ethereum Fee Structure : Fee
             Reward                                   : Incentive




                                                                                                                       incurrs    Ethereum Transfer Structure
    Attestation Reward : Reward                      Penalty : Fee                                  Gas : Fee
                                                                                                                                          : Transfer



                                                            results in                involvement                                               transferring


                                  specifies                                                                                                [eco/tech]
      Ethereum Specification :                     Proof-of-stake :                                                                Ethereum Asset Structure :
                                                                                             Ether Token : Asset
      Technical Specification                     ConsensusProtocol                                                                          Asset



                                                                                                                                 Specialized token types

                                                                                           ETH Mainnet Economy :
                                              ETH Consensus : Consensus                                                               ERC-20 Token : Asset
                                                                                            Economic Structure




                                                                                                                                     ERC-721 Token : Asset
                                                            defines



      Another Organization :                    Ethereum Community :
                                                                                        Mainnet : Network Boundary                   ERC-1155 Token : Asset
          Organization                         Decentralized Governance



                                                                         has access                                                has access                  driven by




      Ethereum Foundation :
           Organization                                                                                                               Full Node Account :
                                               Community Member : Self-                      A Full Node : Node
                                                 Self-managed Identity                                                                SelfManagedIdentity
                                                   managed Identity




Figure 5: Governance and economic structure of the Ethereum mainnet, including some popular tokens.


and an execution client4 . The Ethereum mainnet utilizes a proof-of-stake consensus protocol5
enforced by validator nodes.
   In Figure 5, another perspective of the Ethereum ecosystem is shown, focusing on governance
and economic aspects. Ethereum applies a decentralized governance concept, driven by its
community. In addition, various organizations are invested in Ethereum, for example the
non-profit Ethereum Foundation 6 . Private or consortial networks based on Ethereum might
deviate from official developments and governance decisions and instead implement their own
governance concept. The mainnet is public, that is, everyone can access the network and the
ledger. This is simply expressed by an association between the network boundary and the
identities of the community members — here we assume that everyone who interacts with
the network is considered a community member. Ethereum defines several token standards7 .
Some popular tokens are depicted as assets, namely Ether (ETH) the main cryptocurrency of
Ethereum, other fungible tokens (e.g., ERC-20), and non-fungible tokens (e.g., ERC-721). These

4
  https://ethereum.org/en/developers/docs/nodes-and-clients/#what-are-nodes-and-clients
5
  https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/
6
  https://ethereum.org/en/foundation/
7
  https://ethereum.org/en/developers/docs/standards/tokens/
tokens are a fundamental part of the crypto-economic system of the mainnet, condensed in
the economic structure concept. The token assets can be transferred for a so-called gas fee
paid in Ether. Depicted is another fee that is paid by misbehaving nodes as penalty — slashing,
i.e., removing a node entirely from the network, is omitted here. Validating nodes that behave
correctly get paid for their effort with an attestation reward. These rewards and fees are the
motivational drivers for proper conduct and participation in the network.


5. Discussion
The technical complexity and variety of DLT leads to a domain that is challenging to grasp,
even for experts. This hinders the adoption of DLT and its integration in existing enterprise
architectures and the design of viable business cases. Conceptual models of DLT help to address
this by representing knowledge on various aspects of this technology, its economic ecosystem,
and strategic implications. However, these aspects should not be regarded as separately, but
instead relations and dependencies need to be investigated. In this regard, the proposed domain
model offers an overview of DLT by giving perspectives on governance, economic, and technical
characteristics. A successful adoption of DLT real-world scenarios requires to consider all
layers from strategic and business considerations down to the technical infrastructure. This
is due to multiple factors, including the low maturity of the technology and its surrounding
ecosystem [30], but organizational barriers may also inhibit adoption in practice [31]. In
alignment with the model types and goal taxonomy proposed by Guizzardi and Proper [3], our
domain model can be best described as a descriptive model. Its main goals are to facilitate a
better understanding of the domain and to support communication. Our holistic approach for
representing the DLT domain allows to make the relationships between the different concepts
and layers explicit. Consequently, it permits to trace dependencies between different layers.
Further, the use of UML notation allows to instantiate and easily extend the concepts, as
illustrated with the example of Ethereum, and facilitates the exploration of varied situations
concerning DLT systems, e.g., specific decentralized applications.
   The domain model is of considerable complexity, despite a number of purposely omitted or
abstractly represented concepts. However, DLT constitute a very complex domain per se. As
such, the model reflects the domain’s complexity. Some omitted concepts commonly appear
in other conceptualizations of DLT. This includes for example, wallets that hold tokens and
cryptocurrencies and are associated with an identity. This has been condensed in our model
into the identity concept. Since token ownership can still be expressed, we consider this an
acceptable simplification. For similar reasons, we did not include an actor concept. The relation
between an actor and identities seems quite intuitive — an actor may have multiple identities
at the same time. Further, concepts for representing the data structure of the ledger are not
available. A concrete data structure is rather project-specific and we were so far not able to
derive a coherent, general conceptual representation in line with the level of abstraction that we
aimed for. This may however change in future: next steps will include to validate the domain
model with further instances — thereby refining the model in an iterative fashion.
6. Conclusion and future research
This work presents a general domain model of distributed ledger technologies, including
system governance concerns, as well as the economic and technological structures. Further, we
demonstrated the application of the domain model through a conceptual representation of the
public Ethereum blockchain mainnet. The main benefits of such a general model as a holistic
conceptualization of the DLT domain are on one hand the capability to represent multiple DLT
scenarios and environments and on the other hand to express relations between concepts across
perspectives. Thereby, an inherent downside is a loss in specificity of the contained concepts.
   In the future we plan to further refine the domain model. Additionally, a dedicated graphical
notation for the domain model could ease interaction and use. This could be done, for example,
along previous work [32], where a combination of established modeling languages was used to
facilitate the holistic development of decentralized applications, from the business case to the
technical realization. Alternatively, future work may investigate domain-specific notations.


Acknowledgments
This work was supported by the Swiss National Science Foundation project Domain-Specific
Conceptual Modeling for Distributed Ledger Technologies [196889].


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