Use "\0" instead of "|" as a push message delimiter (#11692)

Used with TrackMessageSizeInterceptor and with client-to-server Websocket message splitting (see #11648)

The original issue that the delimiter can not appear in the message (unescaped) is apparently fixed in Atmosphere 1.0.13

Also ensure the max size of a websocket fragment in bytes does not exceed the buffer size (#11842)

Change-Id: I768524bb54a5b8b9479dc7bda821256bd843dc52

2 files changed, 46 insertions, 4 deletions

diff --git a/shared/src/com/vaadin/shared/ApplicationConstants.java b/shared/src/com/vaadin/shared/ApplicationConstants.java
index fc4abd1988..04cba79c0c 100644
--- a/shared/src/com/vaadin/shared/ApplicationConstants.java
+++ b/shared/src/com/vaadin/shared/ApplicationConstants.java
@@ -83,8 +83,4 @@ public class ApplicationConstants implements Serializable {
      * Name of the parameter used to transmit the CSRF token.
      */
     public static final String CSRF_TOKEN_PARAMETER = "v-csrfToken";
-
-    public static final int WEBSOCKET_BUFFER_SIZE = 65536;
-
-    public static final char WEBSOCKET_MESSAGE_DELIMITER = '|';
 }
diff --git a/shared/src/com/vaadin/shared/communication/PushConstants.java b/shared/src/com/vaadin/shared/communication/PushConstants.java
new file mode 100644
index 0000000000..2d63621c12
--- /dev/null
+++ b/shared/src/com/vaadin/shared/communication/PushConstants.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2000-2013 Vaadin Ltd.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.shared.communication;
+
+import java.io.Serializable;
+
+/**
+ * Shared constants used by push.
+ * 
+ * @since 7.1
+ * @author Vaadin Ltd
+ */
+public class PushConstants implements Serializable {
+
+    /**
+     * The size, in <b>bytes</b>, of the receiving buffer used by some servers.
+     */
+    public static final int WEBSOCKET_BUFFER_SIZE = 65536;
+
+    /**
+     * The maximum size, in <b>characters</b>, of a websocket message fragment.
+     * This is a conservative maximum chosen so that the size in bytes will not
+     * exceed {@link PushConstants#WEBSOCKET_BUFFER_SIZE} given a UTF-8 encoded
+     * message.
+     */
+    public static final int WEBSOCKET_FRAGMENT_SIZE = WEBSOCKET_BUFFER_SIZE / 4 - 1;
+
+    /**
+     * The character used to mark message boundaries when messages may be split
+     * into multiple fragments.
+     */
+    public static final char MESSAGE_DELIMITER = '\0';
+}