# WebSockets

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

/// tip

        when(fileHandle.acquire()).thenReturn(fileHandle);
        when(fileHandle.getTree()).thenReturn(tree);

        // Mock response and send behavior
        Smb2IoctlResponse resp = mock(Smb2IoctlResponse.class);
        when(resp.getOutputLength()).thenReturn(42);
        when(tree.send(any(Smb2IoctlRequest.class), any())).thenReturn(resp);

        byte[] out = new byte[10];

    on('build', function(req) { req.httpRequest.headers['X-Minio-Extract'] = 'true'; }).
    on('httpData', function(chunk) { file.write(chunk); }).
    on('httpDone', function() { file.end(); }).

import org.codelibs.fess.mylasta.mail.EsStatusPostcard;
import org.codelibs.fess.opensearch.client.SearchEngineClient;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.mail.send.hook.SMailCallbackContext;
import org.lastaflute.core.mail.Postbox;

/**
 * Job for pinging search engine.
 */
public class PingSearchEngineJob {

    /**
     * Default constructor.
     */

				}
				if err := send(meta); err != nil {
					return err
				}
			case osIsNotExist(err), isSysErrIsDir(err):
				if legacy {
					meta.metadata, err = xioutil.ReadFile(pathJoinBuf(sb, volumeDir, meta.name, xlStorageFormatFileV1))
					diskHealthCheckOK(ctx, err)
					if err == nil {
						// It was an object
						if err := send(meta); err != nil {
							return err
						}

							bucket, version.Name, err))
					}
				}

				if !send(result) {
					return
				}
			}

			// All versions resulted in 'ObjectNotFound/VersionNotFound'
			if versionNotFound == len(fivs.Versions) {
				return
			}

			send(healEntryDone(entry.name))

			// Wait and proceed if there are active requests
			waitForLowHTTPReq()
		}

    }

    <T extends CommonServerMessageBlockResponse> T send(CommonServerMessageBlockRequest request, T response) throws CIFSException {
        return send(request, response, Collections.<RequestParam> emptySet());
    }

    <T extends CommonServerMessageBlockResponse> T send(CommonServerMessageBlockRequest request, T response, Set<RequestParam> params)
            throws CIFSException {

        }

        do {
            try {
                send(request, response, config.getNetbiosRetryTimeout());
            } catch (final InterruptedIOException ioe) {
                // second query thread to finish gets interrupted so this is expected
                if (log.isTraceEnabled()) {
                    log.trace("Failed to send nameservice request for " + name.name, ioe);
                }

This is normally called a **webhook**.

## Webhooks steps { #webhooks-steps }

The process normally is that **you define** in your code what is the message that you will send, the **body of the request**.

You also define in some way at which **moments** your app will send those requests or events.

  private val maskCursor: Buffer.UnsafeCursor? = if (isClient) Buffer.UnsafeCursor() else null

  /** Send a ping with the supplied [payload]. */
  @Throws(IOException::class)
  fun writePing(payload: ByteString) {
    writeControlFrame(OPCODE_CONTROL_PING, payload)
  }

  /** Send a pong with the supplied [payload]. */
  @Throws(IOException::class)
  fun writePong(payload: ByteString) {