Event Storming: Metadata Management

Event storming is a collaborative technique used for domain discovery. It is typically conducted in a workshop setting and allows the stakeholders of a given domain to build a high-level model of its systems and related processes. While many concepts from Domain-Driven Design are used in event storming, it is not a strictly DDD focused technique.

Most of the online resources related to event storming will show examples that are business domain oriented. We have taken the basic concepts from event storming and modified them to model the systems and processes involved in ProtoDUNE metadata management.

Notation

There are many commonly adopted patterns for notation in event storming, but you will often see variation in the definitions, the color palette, and the flow of interactions that are used by different practitioners. As a general practice interactions, are time ordered; flowing from left to right, and from top to bottom. The following describes the basic notation used in the design of the ProtoDUNE metadata management process models.

Event Storming Notation

Notation Type	Description
`Bounded Context (Dashed Box)`	An area of domain language consistency. A way to group all related domain events, entities, and their processes.
`Actor (Light Yellow)`	The users that participate in any process; they can be human, or computational.
`Command (Blue)`	The execution of an action.
`Domain Event (Orange)`	The result of an executed action. Considered the facts of a domain.
`External System (Pink)`	External platforms, APIs, sites, etc.
`Policy (Purple)`	A process that is called when something happens.
`Aggregate (Yellow)`	A top-level entity that encapsulates all of the domain rules, including the child entities involved in command execution.
`Read Model (Green)`	Data that needs to fetched from a source; often used to make process decisions.
`Hotspot (Red)`	Possible issues or items that we do not yet know how to handle.
`Comment (Light Grey)`	A callout indicating something of note.