Subscription and Notification Pattern

Is used by Doing Business Abroad Pilot in Use Case "Doing Business in Another Member State" (DBA UC2)

After receiving evidence from a Data Owner (DO), it can be essential for a Data Evaluator (DE) to be informed on changes regarding the subject of this evidence to be able to take appropriate action. The goal of this interaction pattern is to allow the DE to subscribe to a service of the DO that provides autmatic and regual notifications. The cross-border message exchange for the subscriptions and notifications are put in the responsibility of the Data Requester (DR) and the Data Transferor (DT) respectively to allow an easier distribution of responsibility on national level, i.e. to intermediary platforms an national gateway providers.

Functional Variants of the Subscription and Notification Pattern

There are two distinct purposes, or business requirements for Subscription and Notification, which both are relevant for the DE4A Doing Business Abroad Pilot: Evidence update notification and Event notification.

Evidence Update Notification

The goal is to keep previously shared evidence data that is stored at the DE up to date.

Description: Data may change in the base register. In case the DE needs an exact copy of the evidence data on record, they need to be notified in case the data has changed in teh base registry.

Business or Life Event Notification

The goal is to assess the impact of company changes on the eServices provided by the data evaluator.

Description: Some eServices oblige the subject (i.e. company or citizen) to continue in a specifc situation or state to remain entitled to the benefits of an eService provided to the subjcet. E.g., an agricultural company may receive a subsidy for its permanent pasture. As a prerequisite, the company must preserve the pasture for five consecutive years. The data evaluator needs to be notified of the company ending its operations and hence not meeting the five-year requirement. “ending its operation” is an example of a business event. Others examples are: going bankrupt, merge, etc.

Alternative Solution Approaches

Essentially there are two ways to approach the dual requirements for Subscription and Notification, either specific solutions for each requirement or hybrid approaches that can serve both.

Looking at specific solutions would mean that two specialized systems would need to be developed and implemented:

1. Specific Evidence Update Solution: The subscription would be linked directly to the previously exchanged evidence, hence the subscription would need to register the evidence type the subject ID and the subscriber ID. For any data change in the evidence type data set at the DO, the DP would need to push a complete new evidence to the DC, irrespective of that specific change being relevant for the public service provided to the user by the DC. Apart from this being not optimal from a data minimization principle perspective, it can not cover changes of the subject that are not represented in the evidence type data set, giving rise to a second subscription system for event. In addition, the subscription system would be impacted by changes in the canonical evidence type definitions over time. This approach might, however, be easier to integrate in the legal framework of the SDGR (see Legal Considerations below).
2. Pure Event Notification: The subscription would not need to be directly related to a previously shared exchanges evidence, but the subscription would be registered for an agreed set of events relating to a given subject. The subscription system would consequently be based on a list of events, rather than a list of evidence types. Quite obviously, this requires an agreement on a set of DE4A events, or canonical cross-border events. We expect that resolving existing legal barriers especially in the citizen domain would be easier for pure event notifications, becaus the notification would only contain identifiers rather than the underlying (personal) data.

Technical approach and business requirement do not relate one two one, giving rise to several hybrid approaches, where one solution is used to cater for both requirements:

1. Extended Evidence Type: The Specific Evidence Update can be used to derive relevant Events at the DC, if the evidence type definition is scoped, or extended, so that all relevant events are represented by data changes in the evidence type data set. This would require the DC to run a event identification routine on each received update to react accordingly. This hybrid solution would also meet its limitations for events that are dealt with by procedural means at the DP-side, rather than by data mutations. The extension of evidence type definitions beyond what is actually required by the eProcedure is, again, not optimal from a data minimization principle perspective.
2. Extended Notification Message: The pure Event Notification could be extended to carry an updated evidence as part of the Notification message, essentially piggy-bagging the evidence on an event notification. This approach would need to extend the event-centric subscription system to maintain with underlying evidence type, or potentially multiple evidence types, are potentially relevant for each event type, so that evidence can be retrieved and packed as extension of the Notification Message. This solution would consequently end up to be rather complext and again not optimal from a from a data minimization principle perspective. [A BPMN Process Analysis of this approach is available on request]
3. Event Notification + Lookup: The pure Event Notification is used as described above, while it is made sure that the agreed event set of canonical DE4A events is complete in the sense that in covers also relevant update needs, for example a company that moved HQ means that the adres (part of the Company Registration evidence) changed as an effect. It is then left at the discretion of the DC, whether a particular event requires an update of the evidence on record. It could be that, i.e. the postal adres of a company is not relevant for the continuation of the public service provisioning, in which case a flag that the adres on record is not up to date, or a change to "unknown" would be sufficient as event response. This is fully in line with the data minimization principle perspective. If the DC considers that an an update of one evidence or potentially several evidences is required as part of the event response, then the DC would use the Lookup Pattern to request new copies of evidences.

The reference Architecture for the DE4A projects focusses on the third option, on Event Notification combined with the Lookup Pattern to cover both business requirements with one hybrid solution, rather then setting up two specific solutions next to each other. The combination of Event Notification and Lookup Pattern appears to be the most flexible approach is expected to have the following advantages:

• Data minimization: Evidences are only requested if they are actually needed for the public service provided by the DC
• Low complexity of message definitions: The required message definitions for the notifications and updates between DP and DC remains low in complexity: A simple event notification (consisting of event type, identifiers and timestamp) and and evidence response analogous to the event response message of the Intermediation Pattern and User-supported Intermediation Pattern.
• Multiplicity: Case that single events require multiple evidences to be updated, or several events require the update of the same evidence can be covered quiet easily without requiring overly complex message definitions.
• Flexibility in legal basis and authorizations: As the Event Notification does only contain identifiers and not the underlying (personal) data, the legal basis and corresponding authorizations might differ between Notification and Lookup, adding flexibility to the overall solution.
• Independence from a previously shared evidence: The solution approach is not directly linked to a previously shared evidence, which means that a subscription and subsequent lookup can also be applied in cases where the original procedure (leading to the public service being provided) was completed without any automated evidence exchange, i.e. evidence was provided by the user electronically or in person, provided that there is a legal basis (see below).

Working hypotheses and implementation principles

Table 5: Subscription and Notification Pattern working hypotheses and implementation principles

Interdisciplinary Topic	Hypothesis / Principle	Implications and Limitations
Orchestration / Choreography	Subscription: The DC is controls the overall flow for the subscription. This means that the process on DP side is a child process of the process on the DC side. Notification: The Notification is conceived as a "fire and forget" coinversation, meaning that the processes are not really orchestrated. The DP process triggers (if successful) the DC process.	If issues on the DC-side (subscriber) prevented receiving notifications, a resubmission would need to be requested explicitly. The DP required functionality for such (manual) resubmission of notifications.
Interrupted vs. Uninterrupted exchange	Once the OOP sequence is started by receipt of an explicit request, the whole OOP exchange is handled in an uninterrupted manner, while the user remains waiting for the evidence. This means that any exception during the OOP exchange leads to the termination of this OOP attempt, potentially to be repeated at a later time as a new attempt. Notwithstanding the possibility for the eProcedure portal of the DC to offer a “save and resume” functionality, the OOP request itself needs to be repeated in its entirety upon returning to the eProcedure. In this way we keep the save and resume entirely in the control of the single Procedure portal and “simulate” a disrupted procedure case, without the need to manage persistent process instances across a multitude of highly independent systems.	One example of a disrupted procedure is evidence that is not readily available in a digital format [..] said to be out of scope of the SDGR, however appears to be a frequent case for older evidence that resides still in paper archives. We might consider a subprocess at the DP that digitizes the requested evidence and informs the user (e.g. via a direct e-mail) about the evidence now being available in a digital format.
Explicit request and transitivity between actors	After 2023 (with SDGR as legal basis), the DP does not need to re-validate the explicit user request, they can rely on the DC to have done so. It is questionable whether this is presently possible in the Pilots, as the SDGR Article 14 enters into force after the Pilot timeline (Article 39). The assumption is, however, that piloting for the SDGR is part of the public authority tasks related to the SDGR (i.e. fall under the application of Article 14 (11)).	We need the MS participating in the pilots to sustain this interpretation, i.e. in a MoU and accept the limitation that the pilot solution cannot transition to full production on grounds of this legal basis, before the full Article 14 of the SDGR enters into force on 12.12. 2023.
Preview & Approval UI	The preview can be provided, and the user approval collected, by the DC, prior to the evidence being used in eProcedure. It is well understood that the data processing of the evidence on the part of the DC is restricted to providing the preview to the user. This entails the risk that operators of the receiving competent authority could gain, either by accident or (disingenuous) intent, access to the evidence data prior to user authorisation, i.e. for example by using administrator rights on the underlying ICT infrastructure.	There are legal, privacy and security concerns with this hypothesis and there are indications that not all MS are prepared to accept these. A preview provided by the DC would for instance break the privacy-by-design principle. It is also noteworthy that the DP does not know about the outcome of a DC-side preview or would need to be explicitly informed about it. The preview at the DC side must be able to show previews of evidences from multiple countries and must be implemented for every DC. The DC has in any case to implement a solution guaranteeing that “the data included in the preview should not be stored longer than is technically necessary” (recital 47 SDGR)[3] if the user decides not to reuse or to submit the data.
Identity and Record Matching	From experience on MS-level we see that a reasonably good match can result from the use of the (mandatory) eIDAS attributes. The working hypothesis is that this insight can be generalised to all pilot MSs. Two consequences of this hypothesis are that a) the user does not need to provide supplementary attributes and b) a second eIDAS authentication at the DP (potentially multiple DP) is not required.	As the matching based on eIDAS attributes is never 100% it is only considered sufficient from a piloting perspective, where an unsuccessful match could be dropped from the pilot population. Most MS consider current examples of implementation of record matching as insufficiently matured and scalable across all EU MS. A process has to be defined, for example, to manage the situations where this automatic matching doesn’t work. The Intermediation pattern has limitations for catching these exceptions especially in case of an unsuccessful match at the DP, as no direct interaction between U and DP is foreseen.
Transitivity of user identity	After 12.12.2023, the SDGR and the legal task of the DC provide the legal basis for the exchange of user or data subject data from DC to DP. We assume that the development in preparation of the SDGR (i.e. piloting) is part of the public authorities’ tasks covered by the SDGR (i.e. Article 14 (11)), hence that the SDGR provides the legal basis for the pilots. Adding a GDPR consent in the explicit request is not a valid legal basis for the case that the identification does include personal data of other data subjects than the requestor (e.g. change of address for families).	IF the intermediation pattern is used in in teh citizen domain, we need the MS participating in the pilots adopting the intermediation pattern to sustain this interpretation.
Hand-on of UI between actors	The DC handles all user interaction of the eProcedure, including the OOP transfer of evidence, thus foreclosing the need to hand-over user sessions across MSs.	This means that the pilot cases do not include additional information, other than included in the initial request and (mandatory) eIDAS attributes, to be used by the DP.
Mandate and Proxy	The mandate and proxy challenge can be resolved by an extension of the eIDAS node. A simple solution can be build on the "full powers"-assumption with current eIDAS functionality.	The results from SEMPER can be adopted for piloting. It is expected that solutions based in this approach cannot go production live within the timelines of DE4A, as it would require an adjustment of the eIDAS Regulation.
Encryption Gap	OOP in the public sector does not require true E2E encryption. The exchange between DR and DP must be encrypted and signed, as well as the transfers (if applicable on national level) between DR and DE on DC side and DT and DO on DP side (i.e. using the national OOP layer), but the encryption gap within the systems of the DR and DT is acceptable.	This might not hold for cases where the gateway would be outsourced to a private sector subcontractor, which is not foreseen for the DE4A pilots.
Structured data vs. unstructured data	Evidence is handled as structured data. This is not contradicting the addition of an unstructured or scanned document/certificate as part of the structured data transfer (hybrid approach) for reasons of legal validity.
Automated re-use of data	Evidence and its use in public service procedures has legal consequences. We assume that automated re-use without premediated harmonization of evidence data definitions is not applicable for the OOP transfer of evidence between MS.	To facilitate automated re-us of data requires establishing canonical evidence definitions.
Production system and real-life cases	With reference to SDGR Article 14(11), pilots based on the intermediation pattern can interface with productive systems and use real-life cases (if participants are made aware that they are participating in a DE4A pilot).	Pilots considering the intermediation pattern must align with their participating MS that they accept the interpretation of the Article 14(11) as legal basis of the pilot even before the full Article 14 of the SDGR enters into force on 12.12. 2023. The situation in the business domain is differnt as the company registration data is already publicly available.
Payment for evidence	In the context of the pilots we assume that no payments are required.	This can restrict transition of pilot solutions to production in cases that compenent authorities requie payment for issuing evidence.
BRIS integration	A technical re-use or bridge to BRIS is not possible because of differences in scope and accessibility by competent authorities other then business registers. The semantic definitions of BRIS can be largely reused.	The pilot system for the Doing Business Abroad Pilot need to be set-up separte from BRIS.
Matching evidences between Member States	The final system should support both harmonized and harmonized evidence type and the architecture is taking account of both bases. In the pilot context, focus will be put on establishing deep semantic interoperability through the definition of canonical evidences	Heterogenous, national evidence types do not need to be matched in run-time. For all evidence types in DE4A, a canonical form must be defined an agreed between the the pilot partners. Each partner needs to implement a transformation from national to canonical evidence.
Multi-evidence Cases	The system should support all four multi-evience cases, which means that an array of evidence types and evidences must be included in a single OOP request/response.	The second iteration should expand the MVP restriction to a single request to single evidence cases, which requires an update of the Exchange Information Model. It is likely that piloting would focus on simpler cases to show the inclusion of multiple evidences in a single evidence response. The multi-evidence cases are likely not relevant for the Doing Business Abroad Pilot. Theoretically, the 'Multi Evidence Types'-case could be applied in the second iteration to request e.g. company registration evidence and annual financial statement in a single request.

Legal Considerations

From a legal perspective, the central challenge is the need for a legal basis that allows impacted authorities to exchange Evidence Updates and/or Event Notifications. This is certainly critical for personal data (since the GDPR requires a legal basis), but even in the case of pure business data that contains no personal data, authorities will need to be able to demonstrate that they have a legal basis allowing them to send Evidence Updates and/or Event Notifications abroad.

The SDGR is in principle not an answer to this issue, since it focuses on user-driven exchanges (based on a user request, and with a preview option). While a user request could have been scoped in a way that allows a user to define a time period for exchanges ('I request authority A to send evidence X to authority B, including any updates, for a period of Y years'), this is not the implementation path that has been chosen in the Implementing Act. Moreover, such a request wouldn't enable a preview as the SDGR requires. Thus, referring to the SDGR is not a sufficiently encompassing option.

This does not imply that subscriptions or event notifications are impossible, but rather than an alternative legal basis must be chosen. A few options are available, which will be discussed briefly below. For the avoidance of doubt: these options should only be applied in relation to business data; subscriptions/event notifications relating to individual persons (citizens) do not have a clear legal basis under data protection law, and due to the public sector context, reliance on consent or legitimate interest of the public administrations is not legally feasible.

For business data subscriptions and event notifications, the following options would be available:

- there should be no legal challenge in principle if the relevant information is already made publicly accessible by the relevant authority. If the information can be freely accessed and lawfully used by the public, proactively communicating it to specific authorities (in the form of evidence or a notification) should not be problematic either. While typically some terms and conditions would apply even to publicly accessible databases (e.g. to forbid commercial exploitation), it would be possible to conclude comparable agreements in the context of DE4A as well.

- exchanges should similarly be possible for information that's not publicly available, but that can only be accessed and used by parties if they conclude a suitable agreement with the relevant business register. In some Member States, business register data is made available to commercial entities on the basis of (usually) paid contracts, e.g. allowing them to integrate that data into business intelligence services. Companies can subscribe to such services to check e.g. credit rating or bankruptcy status of their customers. In countries that support this model, it should be legally feasible to conclude similar agreements to support DE4A pilot exchanges, hopefully on a free of charge basis, if this is acceptable to the data source.

These scenarios are likely more relevant for Updates of evidences than for pure Event Notifications, since formal evidences (extracts, certificates, attestations etc) are normally not included in these models.

Specifically for Evidence Subscriptions, the principal legal solution would be to establish a legal basis for the subscription outside of the SDGR. This could be viable under national laws, in combination with the request of a representative of the affected legal entity. A pure appeal to national law (without any request for a subscription service from the user) likely will not work; this is only possible if there's already a specific legal basis for direct evidence exchanges between the authorities, and that does not seem to be the case. The BRIS Directive is the closest approximation, but doesn't provide a basis for evidence subscriptions. This is why the request is important, as a way to strengthen the legal mandate of the evidence provider, allowing them to build on any existing right of the company representative to obtain evidences in relation to their company.

Business Process of the Event Subscription and Notification

The subscription and notification pattern realizes the goal to inform the data evaluator of relevant changes in the subject (i.e. company or citizen). This is done in two steps:

1. In the subscription step the DE expresses the need to be informed on changes regarding a certain subject and this need is registered as a subscription.
2. In the notification step the DO monitors the subject and if a change occurs, all subscribers will be informed on this change

These two steps are independently triggered processes and are hence represented below in two separate BPMN Business Process Collaboration views. Please note that the Subscription is triggered by the DC (i.e. DC is the upper participant in the Subscription BPMN diagram), while the Notification is triggered by the DP (i.e. the DP is the upper participant in the Notification BPMN diagram).

Event Subscription and Notification Starting Points

Some high-level starting points for the process design of this pattern are:

• Harmonised DE4A events: a list of harmonised, canonical events needs to be agreed upon so DE knows how to interpret events notified by DO. For the DE4A-pilots, i.e. the Use Case "Doing Business in Another Member State" (DBA UC2), it is an option to start with a short list of harmonised business evens.
• Subscription registration: the subscription consists at least of the subject identifier and the subscriber identification (i.e. DE Id).
• Business or Life event based notification: the event-based approach informs the DC, i.e. the subscriber, of every business of life event of the subject (i.e. company or citizen) subscribed to. Examples of such events: address changed, new owner, bankruptcy, employed/unemployed, death.
• Notification message: the notification consists at least of the subject (i.e. company) identifier, the harmonised event type of the event that took place and the timestamp of the event.
• Data evaluator post-processing: the DE needs to interpret the event and decide on the actions needed: e.g., request updated data, discard notification, start a specific procedure.

Event Subscription

Business Process Collaboration

Event Subscription process

Activity Table

Activity / UC	Role	Activity Type*	Description
Trigger: Need for a subscription idenfitied	Public Service Procedure	Process	A procedure of a public service provider (e.g.: subsidy) leads to the registration of a subject. After this registration events can occur to the subject that could have impact on the service delivery to this subject. In order to be informed on these events, the public service provider can subscribe to the life-events or business-events of the subject. The  subscription process can also be triggered for technical reasons: for instance to resend failed subscription requests. E.g.: In the pilot Doing Business Abroad the subject is the represented company itself or a new branch of the represented company (the parent-company of the branch) and Data Evaluators subscribe to be notified on the business events of the represented company.
Trigger: Change subscription	eProcedure / Public service / Notification	Process	Potential triggers to change a subscription are: Public service: public service delivery can lead to the need to cancel the subscription (the public service has ended, e.g. a multi-year subsidy procedure, the country can decide to cancel the  branch-office registration). eProcedure: the user can also withdraw from service and thereby initiating cancellation of the subscription. Notification: after receiving a notification the assessment can be that the subscription is no longer needed (exception flow). Technical reasons: for instance an error at the DO-side could lead to the need to resend the request to cancel a subscription.
Initiate subscription	DE	Service	To initiate subscription data is collected and the subscription need is formulated: subject identifier data owner identifier subscriber identifier event catalogue action 'subscribe' subscription start and end date The subscription need is forwarded to the Data Requestor (if applicable).
Change subscription	DE	Service	To change a subscription data is collected and the changed subscription need is formulated: subject identifier data owner identifier subscriber identifier event catalogue action 'cancel subscription' new subscription end date The cancellation of a subscription is thus a a change of the end date the current date. The changed subscription need is forward to the Data Requestor (if applicable).
Lookup event provider routing information	DR	Service	The DR uses the data owner identifier to look up routing information of the competent authority that facilitates subscription service. It is possible that at the DP-side the service provider of the subscription is different from the service provider of the evidence.
REMOVE: Inform National Contact point that subscription or change was not successful	DR	User	In case of the cancellation of a subscription there is a slight chance the participant ID of DO has changed: a manual process deals with this (unhappy) flow.
Send subscription request	DR	Service	The request to subscribe or unsubscribe is send to the participant facilitating the subscription service using the previously retrieved routing information. The subscription / cancel subscription request contains: the participant id of the subscriber, the subject identifier, the event catalogue, the period of subscription and the requested action (subscribe / cancel subscription).
Exception: Forward subscription error	DR	Service	The subscription error message received from Data Transferor is forwarded to the Data Evaluator.
Exception: Investigate reason for subscription error	DE	User	The received error message is analysed and appropriate actions are taken. This exception flow is not further detailed in this design.
Forward confirmation	DR	Service	The confirmation of the subscription (received from the DT) is forwarded to the Data Evaluator.
Log subscription information	DE	Service	The confirmation is logged to complete the audit trail. Note: register in a way that it is easily readable (optional: include subscription id).
Validate subscription request	DT	Service	The request is validated on a technical level and check on DE authorisation. If the request validates it is forwarded to the Data Owner. [Technical exceptions are out of scope.]
Evaluate subscription request	DO	Service	The subscription request is evaluated to check if the request can be completed: Subscription functional checks: does subject exists, is event catalogue supported, is the subscription changing an existing subscription If the request does not pass the functional checks, the request is rejected and an error message will be send.
Exception: Prepare subscription error message	DO	Service	Collect the content of the error message and send it to the Data Transferor (if applicable). The (un)subscription error message contains: participant id of subscriber, subject identifier, requested action, reference to the request message, full request message and the errorcode.
Exception Send subscription error message	DT	Service	The error message is forwarded to the Data Requestor from whom the request was received.
Register subscription	DO	Service	The Data Owner creates or changes the subscription according the subscription request.
Confirm subscription	DO	Service	The confirmation of the subscription is created and send to the Data Transferor (if applicable). The confirmation message contains: subscription result (success), timestamp of subscription, subscription request reference, subscription id.
Send subscription confirmation	DT	Service	The subscription confirmation is sent to the Data Requestor from whom the request was received. The subscription confirmation message is added to the log.

*Activity Type and Task Type in accordance with BPMN 2.0

Design decisions

Explicit request and preview

The nature of the subscription and notification pattern leads to a different use of the explicit request and preview as stated in the SDG-regulation:

• Notification is performed without a user transaction, making real-time explicit request and preview impossible.
• Fraud prevention outweighs user centricity, making explicit request and preview less opportune.
• The public nature of company data relaxes the need of explicit request and preview.

Implementing an explicit request for future notifications introduces the burden of creating and maintaining an explicit request administration, with for instance options to retract a previously given explicit request

Design decision: for the Business event notification explicit request and preview as defined in the SDG-regulation is not applicable.

Positioning of subscription registration

For the location of the subscription registration certain options can be considered:

• Fully at the data providing MS: The subscription is registered at the data providing member state. The DE sends messages to the DO via DR and DT to manage the subscription (subscribe, cancel subscription).

• Split between data provider and data consuming MS: It is a possibility to split the register; the DO then only registers which MS subscribe to a certain company, and the DC MS registers which DE subscribe to the company. The process flow would be: (1) a central component at the DT registers which DE’s subscribe to which subjects of which data owners; (2) the DT registers as a MS for this company; (3) the DO registers which MS subscribes to which company and sends notifications to the DT (4) the DT distributes the notification to all DE.
• At a central component: The DE4A-architecture implements the four-corner model, a central subscription register would conflict with this principle. Moreover, a subscription is a direct relation between a DO and a DE regarding a subject, there will be no added value to place such a subscription in an external, central component.

Design decision: The registration of subscriptions is placed within the data providing member state. DP MS is free to choose in which environment this is (DT, DO or another environment). The assumption for the design of the S&N pattern is that the subscription registration is fully placed in the environment of the DO.

Subscription period

Including a subscription period with start and end date has several consequences... todo

Design decision: a subscription period with mandatory start and end dates is included in the subscription.

Catalogue of DE4A business events

TBD, see table below

Subscription register requirements

Evidence exchange and subscription request

The main flow of the DBA-pilot is that the intermediation pattern triggers the subscription and notification pattern. Part of the intermediation pattern is the exchange of evidence: DE requests a specific evidence type from a specific company from the DO. In the happy flow the DE subscribes to receive notifications regarding this company. This trigger can be implemented in different ways:

• As a part of the request for evidence. The evidence exchange request then consists at least of: company identifier, requested evidence type, DE identifier, subscribe y/n.

• In a separate subscription request message: after a user consent to the preview and a successful completion of the registration process a separate subscription message is sent.

Design decision: the subscription request is not combined with the evidence exchange request but is sent after successful registration of the company/branch.

Combining the subscription request with the evidence exchange would be too early in the process. It would lead to (possibly a relative high number of) requests to cancel the subscription if no consent was given or the registration was not successful. This would also introduce the risk of unauthorised subscriptions and notifications if the cancellation fails.

There are two main choices for the subscription criteria, subscribe to changes in:

• business events
• evidences

Design decision: not all business events are related to an evidence, subscriptions must therefore be made to business events to cover all notifications to be sent, see table below.

Business event - evidence mapping

Below example for Doing Business Abroad Pilot. Each pilot (domain) must define their common event list including a clear semantic explanation of each business or life event in order for the Data Evaluator to be able to interpret the event correctly and define an appropriate course of action, e.g. request an updated evidence or discontinue the public service.

DE4A Business event	Event includes changes in	Related evidence type	Comment
Company info event	EUID, Updated company name/updated address/updated head quarters/changed identifier (EUID)/changed legal form/changed representatives	Company registration	Split this event in: address change, name change, ...? And with a status change, notify the specific status?
Annual report event	Annual reports	Annual report	What is the event? New annual report available, annual report changed, ...? Split this event?
Directors disqualification event	Disqualifications updated for directors	Directors disqualification
National merger event	Merger initiated/completed/cancelled, transferring company identifier, aquring company identifier		Notifications are only relevant when the transferring company has subscribers.
Cross border merger event	Merger initiated/completed/cancelled, transferrring company identifier, aquaring company identifier		Notifications are relevant when the transferring company has subscribers. This event is also relevant without a subscription. The business register of a company involved in a merger wants notifications even if there is no prior subscription to the foreign company in the cross border merger.

Event Notification

Business Process Collaboration View

Activity Table

Activity / UC	Role	Type	Description
Identify cross-border event	DO	Service	The Data Owner evaluates all events identified in the register and identifies events that are potentially relevant for cross-border notifications. Note that the DO must have a mapping of it's own business events to the list of DE4A business events.
Check subscription	DO	Service	The subscription register is queried for subscribers to the subject related to the event: No active subscriptions: end of process Active subscriptions for the DE4A event catalogue found: continue notification process
Prepare notification message and subscriber list	DO	Service	Make a list of the subscribers to notify in terms of cross-border participant identifiers and create the payload of the notification, mainly the DE4A event name and subject identifer and the timestamp the event took place.
Resolve service metadata	DT	Service	Single notifications messages (one for each subscriber) are created from the list of subscribers and the notification payload. The routing information for each notification message is looked up. The messages contain: subject identifier, secondary subject identifier (in case the identifier changed), subscriber identification, event identification, event timestamp, subscription reference (optional).
Resolve subscriber participant ID and inform National Coordinator	DT	User	If address / DE participant id is not found in the metadata, manual action is needed: contact DE / MS of participant id to analyse the exception and take appropriate measures.
Request from DE to resend event notifications	DE	User	Exception flow for missed notifications (failed or non-failed): if a DE misses notifications a resend of notifications can be requested.
Resend past event notifications	DT	User	The resending of previously sent notifications requires a manual action at the DT, based on logs.
Send event notification	DT	Service	The event notification is send to the Data Requestor, a technical acknowledgement that the notification has been received by the DR is received. The audit log is updated with both the event notification and the acknowledgement.
Validate event notification	DR	Service	The Data Requestor performs a technical validation of the event notification and forwards it to the Data Evaluator. A technical exception flow is out of scope of this process description.
Determine event response	DE	Service	The notified event is analysed and the appropriate response is determined. Depenting on the event, different courses of action are possible (see details below): Event is not relevant Event requires a new (i.e. updated) evidence Business response required Exception: The notification does not match the record or the record is not active, hence the subscription needs to be changes (i.e. cancelled) The determination result is logged as a part of the audit trail: Subject identifier Notified event Request id Determined response Timestamp of determination
Request change of subscription	DE	Subprocess	When the company cannot be identified or the registered company or branch is no longer active a change (i.e. cancellation) of the subscription is requested. Afterwards this will be analysed to find the cause of this apparently wrong subscription and to take appropriate measures. This subprocess includes user tasks ad is not end-to-end automated.
Dismiss event	DE	Service	The notified event doesn't have impact on the procedures of the Data Evaluator and is dismissed. No further actions need to be taken.
Trigger evidence lookup	DE	Service	The lookup pattern is triggered to request a new, current, copy of the relevant evidence. The Doing Business Abroad Pilot will e.g.: request the Company Registration Evidence.
Identify business responses and notify responsible party	DE	Subprocess	The responsible organisational unit is identified and informed in order to take appropriate action. It depends on the specific process if this action can be performed automated or manually.

Design decisions

Response on event notification

Functional responses from Data Evaluator to Data Owner after receiving an event notification, for example to inform that appropriate actions have been taken, are out of scope of the Subscription and Notification pattern.

Notifications from Subscriber

Notifications from Data Evaluator to Data Owner, for example to inform Data Owner on changes in the branch registration, are out of scope of the Subscription and Notification pattern.

Process Realisation

As with the Business Process Collaboration Views above, the Subscription & Notification pattern has two sets of Process Realization Views that provide the details on functional Application Services required to realize the business process.

• Two Views concerning Event Subscription, starting with the view for the DC, as it is the DC that starts a Subscription
• Two Views concerning Event Notification, starting with the view of the DP, as it is the DP that starts a Notification

This pattern does not provide any Process Realization views as the user is not directly involved in the exchange. As can be see in the Business Process above, Subscription is triggered by a public service process that requires updates for as long as the public service is provided and the Notification is triggered by Events identified in the Base Registry.

Please see to the respective sections per Application Collaboration in the Reference Application Architecture for detailed descriptions of each Application Service.

Event Subscription

The figure below shows the Process Realisation of the Subscription process at the Data Consumer, triggered by the need for a subscription, i.e. for public service provided over an extended period of time, and resulting (if successful) in receiving and logging the subscrition.

Subscription Process Realization of the Data Consumer

The Process Realisation view above shows that both Initiation and Change subscription is provided by essentially the same service from the EProcedure Back-office. Changes, i.e. changes of the subscription end-date are handled in the process essentially identical as new subscriptions and are used to effect prolongations (new, later end-date) and cancellation (new end-data set to current date) of subscriptions. This provides maximum freedom to Cross-border Subscriptions systems of the DP to handle cancellations and prolongation in the context of their own application architecture. For update cases a reference to the original subscription could be included as optional attribute in the request message. Service from the Information Desk, the Trust Architecture and Data Logistics are used to adres and sent the subscription request to the right DP. Even if the DP identity might already be known, at least the technical rooting information is looked up, given the highly-disctributes nature of cross-border systems.

The right halve of the Process realization shows reaction to receiving either a subscription error or confirmation. Investigating the reasons for a subscription error is a subprocess that usually includes manual work, as reasons can reach from simple ID mismatches to fraud.

Application Collaborations used by this Process Realization diagram:

• EProcedure Back-office
• Information Desk
• Trust Architecture
• Data Logistics

The figure below shows the Process Realisation of the Subscription process at the Data Provider, triggered by receiving a subscription request from the DC and resulting, if successful, by sending a confirmation that the subscription was registered in the Cross-border Subscriptions system.

Subscription Process Realization of the Data Provider

The Process Realisation view above shows that the process requires, apart from simple a technical validation, some sort of authorization at the start, the Authority Check, realized by the Information Desk. This is considered more relevant for Subscriptions than for the Intermediation Pattern, let alone the User-supported Intermediation Pattern, because the user is not directly involved here. The main part of the process is supported by a Cross-border Subscriptions system. This application collaboration realizes all Application services required to evaluate, register and confirm the subscription. Please note that the Subscription Creation and Update Service must identify whether a subscription request relates to an already existing subscription, i.e. is an update. This should happen at least as fall-back option, based on the subject ID and subscriber ID and overlapping subscription times, rather than a mandatory subscription ID, which should remain optional. In addition, Trust Architecture and Data Logistics are involved to guarantee secure message exchange.

Application Collaborations used by this Process Realization diagram:

• Cross-border Subscriptions
• Information Desk
• Trust Architecture
• Data Logistics

Event Notification

The Figure below shows the Process Realisation of the Notification process at the Data Provider, triggered by changes in the base registry and resulting, if successful, in sending a Notification to the DC.

Notification Process Realization of the Data Provider

The Process Realisation view above shows that the event stream from the base registry is first filtered to identify Cross-border events, i.e. events that are mapped to DE4A canonical event definitions. These events are then used to lookup active subscriptions, which are then collected into a subscriber list per event, coupled to the Notification Message (i.e. event type and subject ID). All of these steps are realized by the Cross-border Subscriptions Application Collaboration. The Information Desk is again used to lookup at least the technical part of the routing. This gives rise to an exception flow if for a subscriber, registered in Cross-border Subscriptions, no service metadata (i.e. consumer) can be found in the Information Desk. Resolving such a situation is a subprocess, involving manual work and often resulting in corrective action required at he subscriber side (e.g: reorganisation in the DC country did not update subscriptions, service metadata not maintained). Finally, Trust Architecture and Data Logistics providing for secure messaging.

It is important to note that the DP Process ends with sending the actual Notification message. Even though the transport protocol should ensure that this Notification was received by the gateway of the DC, this still means that it is functionally a "fire and forget" exchange; The DP is not informed whether the Notification was successfully processed by the DC. This gives rise to a second starting point of the process for exception handling: The DT might be asked by a DC, who experiences problems receiving or processing notifications to have all notifications (both sucessful and unsuccessful) of a given time period to be resent from the logs.

Application Collaborations used by this Process Realization diagram:

• Cross-border Subscriptions
• Information Desk
• Trust Architecture
• Data Logistics

The Figure below shows the Process Realisation of the Notification process at the Data Consumer, triggered by receiving an Event Notification message and resulting in the correct event response being triggered and logged.

Notification Process Realization of the Data Consumer

The Process Realisation view above shows that Trust Architecture and Data Logistics play again their role in secure message exchange, while the EProcedure Back-office plays the central role in determining the event response and in triggering the associated actions.

• For the hybrid approach described above, a lookup of an evidence (i.e. company registration) could be triggered.
• Changing or cancelling the subscription
• Notifying the responsible organisation to take actions (e.g. termination of public service, suspicion of fraud)
• No immediate reaction is required

Application Collaborations used by this Process Realization diagram:

• Trust Architecture
• Data Logistics
• EProcedure Back-office

Used by the following use cases

DBA (UC2)