Times Square Integration

Times Square is a notebook execution system integrated into the squareone app for displaying computational notebooks.

Core Concepts

• Pages: Notebooks that can be executed and displayed
• Parameters: URL-based parameters for notebook execution
• SSE (Server-Sent Events): Real-time updates during execution
• GitHub PR Previews: Preview notebooks from pull requests

Context Providers

TimesSquareUrlParametersContext

Manages URL-based state for Times Square pages.

import { TimesSquareUrlParametersContext } from '../contexts/TimesSquareUrlParametersContext';

// Provider setup (usually in page)
<TimesSquareUrlParametersContext.Provider value={urlParams}>
  <TimesSquarePage />
</TimesSquareUrlParametersContext.Provider>

// Usage in components
const { getParameter, setParameter } = useContext(TimesSquareUrlParametersContext);

const value = getParameter('myParam');
setParameter('myParam', 'newValue');

TimesSquareHtmlEventsContext

Manages real-time SSE (Server-Sent Events) updates.

import { TimesSquareHtmlEventsContext } from '../contexts/TimesSquareHtmlEventsContext';

// Provider setup
<TimesSquareHtmlEventsContext.Provider value={eventSource}>
  <TimesSquarePage />
</TimesSquareHtmlEventsContext.Provider>

// Usage
const events = useContext(TimesSquareHtmlEventsContext);
// events provides real-time updates from notebook execution

Data Fetching Hooks

useTimesSquarePage

Custom hook for fetching Times Square page data.

import { useTimesSquarePage } from '../hooks/useTimesSquarePage';

function MyComponent({ pageSlug }) {
  const { data, error, isLoading } = useTimesSquarePage(pageSlug);

  if (isLoading) return <div>Loading...</div>;
  if (error) return <div>Error: {error.message}</div>;

  return <div>{data.displayName}</div>;
}

Pattern uses SWR for caching and revalidation.

Routing Patterns

Regular Pages

/times-square/{page-slug}

GitHub PR Previews

/times-square/github-pr/{owner}/{repo}/{commit}

Example:

/times-square/github-pr/lsst-sqre/times-square-demo/abc123

API Routes

Mock API endpoints in development (/pages/api/dev/times-square/):

• GET /times-square/api/v1/pages - List pages
• GET /times-square/api/v1/pages/:page - Page metadata
• GET /times-square/api/v1/pages/:page/html - Rendered HTML
• GET /times-square/api/v1/pages/:page/htmlstatus - Execution status
• GET /times-square/api/v1/pages/:page/htmlevents - SSE endpoint

Mock API Endpoints

For local development without Times Square backend:

// pages/api/dev/times-square/v1/pages/[page]/html.ts
import type { NextApiRequest, NextApiResponse } from 'next';

export default async function handler(
  req: NextApiRequest,
  res: NextApiResponse
) {
  const { page } = req.query;

  // Return mock HTML
  res.status(200).json({
    html: '<div>Mock Times Square page</div>',
    parameters: {},
  });
}

Page Component Pattern

import { GetServerSideProps } from 'next';
import { useTimesSquarePage } from '../hooks/useTimesSquarePage';
import { TimesSquareUrlParametersContext } from '../contexts/TimesSquareUrlParametersContext';
import { loadAppConfig } from '../lib/config/loader';

type Props = {
  pageSlug: string;
};

export default function TimesSquarePage({ pageSlug }: Props) {
  const { data, error, isLoading } = useTimesSquarePage(pageSlug);

  if (isLoading) return <div>Loading notebook...</div>;
  if (error) return <div>Error loading notebook</div>;

  return (
    <div>
      <h1>{data.displayName}</h1>
      <div dangerouslySetInnerHTML={{ __html: data.html }} />
    </div>
  );
}

export const getServerSideProps: GetServerSideProps<Props> = async (context) => {
  const appConfig = await loadAppConfig();
  const pageSlug = context.params?.page as string;

  return {
    props: {
      appConfig,
      pageSlug,
    },
  };
};

SSE Integration

function TimesSquareLivePage({ pageSlug }) {
  const [eventSource, setEventSource] = useState(null);

  useEffect(() => {
    const es = new EventSource(
      `/times-square/api/v1/pages/${pageSlug}/htmlevents`
    );

    es.onmessage = (event) => {
      const data = JSON.parse(event.data);
      // Handle real-time updates
      console.log('New data:', data);
    };

    setEventSource(es);

    return () => es.close();
  }, [pageSlug]);

  return (
    <TimesSquareHtmlEventsContext.Provider value={eventSource}>
      {/* Page content */}
    </TimesSquareHtmlEventsContext.Provider>
  );
}

Configuration

Times Square URL configured in AppConfig:

# squareone.config.yaml
timesSquareUrl: 'http://localhost:3000/times-square/api'  # Dev
# timesSquareUrl: 'https://data.lsst.cloud/times-square/api'  # Prod

Access in components:

import { useAppConfig } from '../contexts/AppConfigContext';

const config = useAppConfig();
const timesSquareUrl = config.timesSquareUrl;

Best Practices

1. Use context providers for shared state
2. Cache with SWR for performance
3. Mock APIs for development
4. Handle loading states gracefully
5. Clean up SSE connections on unmount
6. Validate parameters before execution
7. Show execution progress with SSE
8. Handle errors appropriately