# Lifespan Events { #lifespan-events }

You can define logic (code) that should be executed before the application **starts up**. This means that this code will be executed **once**, **before** the application **starts receiving requests**.

The same way, you can define logic (code) that should be executed when the application is **shutting down**. In this case, this code will be executed **once**, **after** having handled possibly **many requests**.

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package jcifs;

import java.util.List;
import java.util.concurrent.Callable;

/**
 * Handle for receiving change notifications from an SMB server
 *
 *
 * @author mbechler
 *
 */
public interface SmbWatchHandle extends AutoCloseable, Callable<List<FileNotifyInformation>> {

    /**

The contents are **encrypted**, even though they are being sent with the **HTTP protocol**.

It is a common practice to have **one program/HTTP server** running on the server (the machine, host, etc.) and **managing all the HTTPS parts**: receiving the **encrypted HTTPS requests**, sending the **decrypted HTTP requests** to the actual HTTP application running in the same server (the **FastAPI** application, in this case), take the **HTTP response** from the application, **encrypt it** using...

   * leaking resources callers must [close the response body][ResponseBody] or the response.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not
   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP
   * response code like 404 or 500.
   *

You can define background tasks to be run *after* returning a response.

This is useful for operations that need to happen after a request, but that the client doesn't really have to be waiting for the operation to complete before receiving the response.

This includes, for example:

* Email notifications sent after performing an action:

            region.close();
            totalReleased.incrementAndGet();
        }
    }

    /**
     * Get a receive region from the pool or allocate a new one
     *
     * @return memory region for receiving
     * @throws IOException if allocation fails
     */
    public RdmaMemoryRegion getReceiveRegion() throws IOException {
        RdmaMemoryRegion region = availableReceiveRegions.poll();
        if (region != null) {

   *
   * This method returns false unless it is overridden by a subclass.
   *
   * ### Duplex Transmission
   *
   * With regular HTTP calls the request always completes sending before the response may begin
   * receiving. With duplex the request and response may be interleaved! That is, request body bytes
   * may be sent after response headers or body bytes have been received.
   *

CAREFUL: When utilizing two-way communication, it is important to ensure that the remote handler is not blocked on a send.
If the remote handler is blocked on a send, and the client is trying to send without the remote receiving,
the operation would become deadlocked if the channels are full.

### Typed handlers

Typed handlers are handlers that have a specific type for the request and response payloads.

```go

                                 n_ask_attempts=_DEFAULT_PROMPT_ASK_ATTEMPTS):
  """Loop over user prompts for an ENV param until receiving a valid response.

  For the env param var_name, read from the environment or verify user input
  until receiving valid input. When done, set var_name in the environ_cp to its
  new value.

  Args:
    environ_cp: (Dict) copy of the os.environ.

   * This was misleading for tracing because it was too early.
   */
  open fun responseHeadersStart(call: Call) {
  }

  /**
   * Invoked immediately after receiving response headers.
   *
   * This method is always invoked after [responseHeadersStart].
   *
   * @param response the response received over the network. It is an error to access the body of
   *     this response.