Access

Marks a member of an aggregate's state as one of the aggregate's access attributes: a fact of the state that decides who may read and change the aggregate, which the service's access policies compare with the caller's claims.

class DocumentState {
    @Access val department: String = ""
    @Access val sharedWith: Set<String> = emptySet()
    @Access("org") val orgPath: String = "" // A materialized path, such as "/acme/sales/east".
    var title: String = ""
}

• What it marks: a property of the state class (stored or computed), or a function of it without parameters, inherited ones included, neither private nor an extension, since the generated model reads it.

• A pure, cheap function of the state: the runtime derives every attribute on each commit, so the member reads the state alone and does little work. It does no I/O, reads no clock and draws no random number; the compiler refuses one that suspends or is @Blocking.

• Its value: a String, an Int, a Long, a Boolean or an enum, nullable for none, or a value class that wraps one of them (@JvmInline value class DepartmentId(val value: String)), published as the value it wraps; or a List, Set or Collection of them, neither the collection nor its elements nullable, for an attribute of several values. An enum is published as the name Jackson writes for its constant.

• Its name: name, else the member's name (a function's name as written). It is how the Manifest, the generated attribute references and the stored records name the attribute: lower camel case, a lower-case letter then letters and digits, at most 40 characters (me.ahoo.wow.manifest.AccessAttributeName), unique within the aggregate ignoring case, and neither owner nor space, the built-in attributes every aggregate has.

The compiler writes each attribute into the Manifest (its name, type, and whether it holds several values) and generates <State>Access, an object with a typed reference to each, beside the state. An attribute changes only as the state does: to grant access, write a domain command and its event (ShareDocument, DocumentShared), which the domain checks and the log records.