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Cratis

Author announcements without Direct

Direct is one application that authors announcements. Nothing in Marquee requires it: authoring is the package Cratis.Showrunner.Marquee.Authoring, and any Arc application with a Chronicle event store can host it. Use this when the people running your product write announcements in a tool of your own.

Host the authoring backend

Section titled “Host the authoring backend”
  1. Reference Cratis.Showrunner.Marquee.Authoring from the Arc application that will own announcements. Arc discovers its commands and query, and Chronicle its events, read model and outbox reactor.
  2. Register the policy that admits who may author. Every command and the query require MarqueeAuthoring.Policy, and a host that does not register it can not use them:
builder.Services.AddArcAuthorizationPolicy<OperatorsOnly>(MarqueeAuthoring.Policy);
  1. Tell each product which event store the announcements are published from. The name of the store the authoring application runs in goes in the product’s AuthoringStores, which defaults to Direct; see Receiving.

The commands, the outbox and what it guarantees are in Authoring.

Write the screen

Section titled “Write the screen”

Install the proxies, with no UI framework dependency:

Terminal window
yarn add @cratis/showrunner.marquee.authoring @cratis/arc @cratis/arc.react @cratis/fundamentals

Author an announcement with the command. An audience is a plain object whose kind decides which of the other values apply; leave the rest empty. The caller chooses the id, so a retried command is refused as already authored instead of authoring a second announcement:

import { Guid } from '@cratis/fundamentals';
import { AuthorAnnouncement, Audience, AudienceKind, Display, Importance } from '@cratis/showrunner.marquee.authoring';


export const authorMaintenanceNotice = async () => {
    const audience = new Audience();
    audience.kind = AudienceKind.everyone;
    audience.tenantIds = [];
    audience.module = '';
    audience.plan = '';


    const author = new AuthorAnnouncement();
    author.announcementId = Guid.create();
    author.product = 'ledger';
    author.audience = audience;
    author.title = 'Planned maintenance';
    author.body = 'Ledger is read-only on **Saturday** from 22:00 to 23:00 UTC.';
    author.display = Display.banner;
    author.importance = Importance.warning;
    author.activeFrom = new Date('2026-11-06T00:00:00Z');
    author.activeUntil = new Date('2026-11-08T00:00:00Z');


    const result = await author.execute();
    return result.isSuccess;
};

List what has been written for a product, withdrawn announcements included and the newest window first. The list is sent again each time one changes:

import { ForProduct } from '@cratis/showrunner.marquee.authoring';


export const AnnouncementList = () => {
    const [announcements] = ForProduct.use({ product: 'ledger' });


    return (
        <ul>
            {announcements.data.map(announcement => (
                <li key={announcement.id.toString()}>{announcement.title}</li>
            ))}
        </ul>
    );
};

AmendAnnouncement, RetargetAnnouncement and WithdrawAnnouncement change what was authored. How an announcement is displayed can not be changed: withdraw it and author another. A title holds up to 100 characters, a body up to 2,000, and leaving the window at its default date means from now and with no end.

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