After this, the client and the server have an **encrypted TCP connection**, this is what TLS provides. And then they can use that connection to start the actual **HTTP communication**.

And that's what **HTTPS** is, it's just plain **HTTP** inside a **secure TLS connection** instead of a pure (unencrypted) TCP connection.

/// tip

const updateInterval = 250 * time.Millisecond

// DeadlineConn - is a generic stream-oriented network connection supporting buffered reader and read/write timeout.
type DeadlineConn struct {
	net.Conn
	readDeadline  time.Duration // sets the read deadline on a connection.
	readSetAt     time.Time
	writeDeadline time.Duration // sets the write deadline on a connection.
	writeSetAt    time.Time
}

// Sets read deadline

   * - Both request discover no existing connection. They both make a connection.
   * - The first request "wins the race".
   * - The second request discovers it "lost the race" and closes the connection it just opened.
   * - The second request uses the coalesced connection from request1.
   * - The coalesced connection is violently closed after servicing the first request.

 */
package okhttp3.internal.connection

/** Reuse a connection from the pool. */
internal class ReusePlan(
  val connection: RealConnection,
) : RoutePlanner.Plan {
  override val isReady = true

  override fun connectTcp() = error("already connected")

  override fun connectTlsEtc() = error("already connected")

  override fun handleSuccess() = connection

      object : EventListener() {
        var socket: SSLSocket? = null
        var closed = false

        override fun connectionAcquired(
          call: Call,
          connection: Connection,
        ) {
          socket = connection.socket() as SSLSocket
        }

        override fun requestHeadersStart(call: Call) {
          if (closed) {
            throw IOException("fake socket failure")
          }

A **Manager** is used to manage all incoming and outgoing connections to a server.

On startup all remote servers must be specified. 
From that individual connections will be spawned to each remote server, 
or incoming requests will be hooked up to the appropriate connection.

To get a connection to a specific server, use `Manager.Connection(host)` to get a connection to the specified host.
From this connection individual requests can be made.

    clientListener.assertTextMessage("Hello, WebSockets!")
    closeWebSockets(webSocket, server)
  }

  /**
   * We had a bug where web socket connections were leaked if the HTTP connection upgrade was not
   * successful. This test confirms that connections are released back to the connection pool!
   * https://github.com/square/okhttp/issues/4258
   */
  @Test
  @Throws(Exception::class)
  fun webSocketConnectionIsReleased() {

  <version>11-SNAPSHOT</version>
  <name>Model urls inheritance test child</name>

  <scm child.scm.connection.inherit.append.path="false"
       child.scm.developerConnection.inherit.append.path="false"
       child.scm.url.inherit.append.path="false">
    <connection>scm:my-scm:http://domain.org/base</connection>
    <developerConnection>scm:my-scm:https://domain.org/base/</developerConnection>
    <url>https://domain.org/override</url>

  <scm child.scm.connection.inherit.append.path="false"
       child.scm.developerConnection.inherit.append.path="false"
       child.scm.url.inherit.append.path="false">
    <connection>scm:my-scm:http://domain.org/base</connection>
    <developerConnection>scm:my-scm:https://domain.org/base/</developerConnection>
    <url>https://domain.org/base</url>

  override fun connectionConnectEnd(
    connection: Connection,
    route: Route,
  ) {
    poolConnectionListener.connectEnd(connection, route, call)
  }

  override fun connectionAcquired(connection: Connection) {
    eventListener.connectionAcquired(call, connection)
  }

  override fun acquireConnectionNoEvents(connection: RealConnection) {
    call.acquireConnectionNoEvents(connection)
  }