@Sse() not compatible with compression() middleware

[bchoii]

Bug Report

Current behavior

Current SSE not compatible with compression() middleware (https://github.com/expressjs/compression).

If compression middleware is present, SSE events do not seem to reach the browser.

Expected behavior

Expecting SSE to work with compression() middleware

Possible Solutions

Option 1:
Filter sse from compression()

  app.use(
    compression({
      filter: (req, res) =>
        !res.getHeaders()['content-type']?.includes('text/event-stream'),
    }),
  );

Option 2:
Add "no-transform" to "Cache-Control" headers for SSE responses. Compression middleware will detect this header and skip compression on this particular response. See expressjs/compression#51

 response.set({
    'Cache-Control': 'no-transform',
  });

[kamilmysliwiec]

This will be fixed in the next patch/minor release 41d46c0