The JSR-356 Java WebSocket 1.1 implementation is only available when Tomcat
   is running on Java 7 or later.
Tomcat provides a number of Tomcat specific configuration options for
   WebSocket. It is anticipated that these will be absorbed into the WebSocket
   specification over time.
The write timeout used when sending WebSocket messages in blocking mode
   defaults to 20000 milliseconds (20 seconds). This may be changed by setting
   the property org.apache.tomcat.websocket.BLOCKING_SEND_TIMEOUT
   in the user properties collection attached to the WebSocket session. The
   value assigned to this property should be a Long and represents
   the timeout to use in milliseconds. For an infinite timeout, use
   -1.
If the application does not define a MessageHandler.Partial for
   incoming binary messages, any incoming binary messages must be buffered so
   the entire message can be delivered in a single call to the registered
   MessageHandler.Whole for binary messages. The default buffer
   size for binary messages is 8192 bytes. This may be changed for a web
   application by setting the servlet context initialization parameter
   org.apache.tomcat.websocket.binaryBufferSize to the desired
   value in bytes.
If the application does not define a MessageHandler.Partial for
   incoming text messages, any incoming text messages must be buffered so the
   entire message can be delivered in a single call to the registered
   MessageHandler.Whole for text messages. The default buffer size
   for text messages is 8192 bytes. This may be changed for a web application by
   setting the servlet context initialization parameter
   org.apache.tomcat.websocket.textBufferSize to the desired value
   in bytes.
The Java WebSocket specification 1.0 does not permit programmatic deployment
   after the first endpoint has started a WebSocket handshake. By default,
   Tomcat continues to permit additional programmatic deployment. This
   behavior is controlled by the
   org.apache.tomcat.websocket.noAddAfterHandshake servlet context
   initialization parameter. The default may be changed by setting the
   org.apache.tomcat.websocket.STRICT_SPEC_COMPLIANCE system
   property to true but any explicit setting on the servlet context
   will always take priority.
The Java WebSocket 1.0 specification requires that callbacks for
   asynchronous writes are performed on a different thread to the thread that
   initiated the write. Since the container thread pool is not exposed via the
   Servlet API, the WebSocket implementation has to provide its own thread pool.
   This thread pool is controlled by the following servlet context
   initialization parameters:
   
     - org.apache.tomcat.websocket.executorCoreSize: The core
         size of the executor thread pool. If not set, the default of 0 (zero)
         is used. Note that the maximum permitted size of the executor thread
         pool is hard coded to- Integer.MAX_VALUEwhich effectively
         means it is unlimited.
- org.apache.tomcat.websocket.executorKeepAliveTimeSeconds:
         The maximum time an idle thread will remain in the executor thread pool
         until it is terminated. If not specified, the default of 60 seconds is
         used.
When using the WebSocket client to connect to server endpoints, the timeout
   for IO operations while establishing the connection is controlled by the
   userProperties of the provided
   javax.websocket.ClientEndpointConfig. The property is
   org.apache.tomcat.websocket.IO_TIMEOUT_MS and is the
   timeout as a String in milliseconds. The default is 5000 (5
   seconds).
When using the WebSocket client to connect to secure server endpoints, the
   client SSL configuration is controlled by the userProperties
   of the provided javax.websocket.ClientEndpointConfig. The
   following user properties are supported:
   
     - org.apache.tomcat.websocket.SSL_CONTEXT
- org.apache.tomcat.websocket.SSL_PROTOCOLS
- org.apache.tomcat.websocket.SSL_TRUSTSTORE
- org.apache.tomcat.websocket.SSL_TRUSTSTORE_PWD
The default truststore password is changeit.
If the org.apache.tomcat.websocket.SSL_CONTEXT property is
   set then the org.apache.tomcat.websocket.SSL_TRUSTSTORE and
   org.apache.tomcat.websocket.SSL_TRUSTSTORE_PWD properties
   will be ignored.
For secure server end points, host name verification is enabled by default.
   To bypass this verification (not recommended), it is necessary to provide a
   custom SSLContext via the
   org.apache.tomcat.websocket.SSL_CONTEXT user property. The
   custom SSLContext must be configured with a custom
   TrustManager that extends
   javax.net.ssl.X509ExtendedTrustManager. The desired verification
   (or lack of verification) can then be controlled by appropriate
   implementations of the individual abstract methods.
When using the WebSocket client to connect to server endpoints, the number of
   HTTP redirects that the client will follow is controlled by the
   userProperties of the provided
   javax.websocket.ClientEndpointConfig. The property is
   org.apache.tomcat.websocket.MAX_REDIRECTIONS. The default value
   is 20. Redirection support can be disabled by configuring a value of zero.