Author: phunt
Date: Fri Nov 20 19:47:03 2009
New Revision: 882696
URL: http://svn.apache.org/viewvc?rev=882696&view=rev
Log:
ZOOKEEPER-576. docs need to be updated for session moved exception and how to
handle it
Modified:
hadoop/zookeeper/trunk/CHANGES.txt
hadoop/zookeeper/trunk/docs/zookeeperProgrammers.html
hadoop/zookeeper/trunk/docs/zookeeperProgrammers.pdf
hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/zookeeperProgrammers.xml
Modified: hadoop/zookeeper/trunk/CHANGES.txt
URL:
http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/CHANGES.txt?rev=882696&r1=882695&r2=882696&view=diff
==============================================================================
--- hadoop/zookeeper/trunk/CHANGES.txt (original)
+++ hadoop/zookeeper/trunk/CHANGES.txt Fri Nov 20 19:47:03 2009
@@ -127,6 +127,9 @@
ZOOKEEPER-3. syncLimit has slightly different comments in the class header,
and > inline with the variable. (mahadev via breed)
+ ZOOKEEPER-576. docs need to be updated for session moved exception and how
+ to handle it (breed via phunt)
+
IMPROVEMENTS:
ZOOKEEPER-473. cleanup junit tests to eliminate false positives due to
"socket reuse" and failure to close client (phunt via mahadev)
Modified: hadoop/zookeeper/trunk/docs/zookeeperProgrammers.html
URL:
http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/docs/zookeeperProgrammers.html?rev=882696&r1=882695&r2=882696&view=diff
==============================================================================
--- hadoop/zookeeper/trunk/docs/zookeeperProgrammers.html (original)
+++ hadoop/zookeeper/trunk/docs/zookeeperProgrammers.html Fri Nov 20 19:47:03
2009
@@ -867,10 +867,23 @@
</li>
</ol>
+<p>
+<strong>Added in 3.2.0 -- SessionMovedException</strong>. There is an internal
+ exception that is generally not seen by clients called the
SessionMovedException.
+ This exception occurs because a request was received on a connection for
a session
+ which has be reestablished on a different server. The normal cause of
this error is
+ a client that sends a request to a server, but the network packet gets
delayed, so
+ the client times out and connects to a new server. When the delayed
packet arrives at
+ the first server, the old server detects that the session has moved and
sends back
+ the SESSION_MOVED error. Clients normally do not see this error since
they do not read
+ from those old connections. (Old connections are usually closed.) One
situation in which this
+ error can be seen is when two clients try to reestablish the same
connection using
+ a saved session id and password. One of the clients will reestablish the
connection
+ and the second client will get the SessionMovedException.</p>
</div>
-<a name="N101D9"></a><a name="ch_zkWatches"></a>
+<a name="N101DF"></a><a name="ch_zkWatches"></a>
<h2 class="h3">ZooKeeper Watches</h2>
<div class="section">
<p>All of the read operations in ZooKeeper - <strong>getData()</strong>,
<strong>getChildren()</strong>, and <strong>exists()</strong> - have the option
of setting a watch as a
@@ -953,7 +966,7 @@
general this all occurs transparently. There is one case where a watch
may be missed: a watch for the existance of a znode not yet created will
be missed if the znode is created and deleted while disconnected.</p>
-<a name="N1020F"></a><a name="sc_WatchGuarantees"></a>
+<a name="N10215"></a><a name="sc_WatchGuarantees"></a>
<h3 class="h4">What ZooKeeper Guarantees about Watches</h3>
<p>With regard to watches, ZooKeeper maintains these
guarantees:</p>
@@ -988,7 +1001,7 @@
</li>
</ul>
-<a name="N10234"></a><a name="sc_WatchRememberThese"></a>
+<a name="N1023A"></a><a name="sc_WatchRememberThese"></a>
<h3 class="h4">Things to Remember about Watches</h3>
<ul>
@@ -1047,7 +1060,7 @@
</div>
-<a name="N10260"></a><a name="sc_ZooKeeperAccessControl"></a>
+<a name="N10266"></a><a name="sc_ZooKeeperAccessControl"></a>
<h2 class="h3">ZooKeeper access control using ACLs</h2>
<div class="section">
<p>ZooKeeper uses ACLs to control access to its znodes (the
@@ -1082,7 +1095,7 @@
example, the pair <em>(ip:19.22.0.0/16, READ)</em>
gives the <em>READ</em> permission to any clients with
an IP address that starts with 19.22.</p>
-<a name="N10293"></a><a name="sc_ACLPermissions"></a>
+<a name="N10299"></a><a name="sc_ACLPermissions"></a>
<h3 class="h4">ACL Permissions</h3>
<p>ZooKeeper supports the following permissions:</p>
<ul>
@@ -1138,7 +1151,7 @@
node, but nothing more. (The problem is, if you want to call
zoo_exists() on a node that doesn't exist, there is no
permission to check.)</p>
-<a name="N102E9"></a><a name="sc_BuiltinACLSchemes"></a>
+<a name="N102EF"></a><a name="sc_BuiltinACLSchemes"></a>
<h4>Builtin ACL Schemes</h4>
<p>ZooKeeeper has the following built in schemes:</p>
<ul>
@@ -1187,7 +1200,7 @@
</ul>
-<a name="N1032D"></a><a name="ZooKeeper+C+client+API"></a>
+<a name="N10333"></a><a name="ZooKeeper+C+client+API"></a>
<h4>ZooKeeper C client API</h4>
<p>The following constants are provided by the ZooKeeper C
library:</p>
@@ -1409,7 +1422,7 @@
</div>
-<a name="N10444"></a><a name="sc_ZooKeeperPluggableAuthentication"></a>
+<a name="N1044A"></a><a name="sc_ZooKeeperPluggableAuthentication"></a>
<h2 class="h3">Pluggable ZooKeeper authentication</h2>
<div class="section">
<p>ZooKeeper runs in a variety of different environments with
@@ -1495,7 +1508,7 @@
</div>
-<a name="N104B0"></a><a name="ch_zkGuarantees"></a>
+<a name="N104B6"></a><a name="ch_zkGuarantees"></a>
<h2 class="h3">Consistency Guarantees</h2>
<div class="section">
<p>ZooKeeper is a high performance, scalable service. Both reads and
@@ -1621,12 +1634,12 @@
</div>
-<a name="N10517"></a><a name="ch_bindings"></a>
+<a name="N1051D"></a><a name="ch_bindings"></a>
<h2 class="h3">Bindings</h2>
<div class="section">
<p>The ZooKeeper client libraries come in two languages: Java and C.
The following sections describe these.</p>
-<a name="N10520"></a><a name="Java+Binding"></a>
+<a name="N10526"></a><a name="Java+Binding"></a>
<h3 class="h4">Java Binding</h3>
<p>There are two packages that make up the ZooKeeper Java binding:
<strong>org.apache.zookeeper</strong> and
<strong>org.apache.zookeeper.data</strong>. The rest of the
@@ -1693,7 +1706,7 @@
(SESSION_EXPIRED and AUTH_FAILED), the ZooKeeper object becomes invalid.
On a close, the two threads shut down and any further access on zookeeper
handle is undefined behavior and should be avoided. </p>
-<a name="N10569"></a><a name="C+Binding"></a>
+<a name="N1056F"></a><a name="C+Binding"></a>
<h3 class="h4">C Binding</h3>
<p>The C binding has a single-threaded and multi-threaded library.
The multi-threaded library is easiest to use and is most similar to the
@@ -1710,7 +1723,7 @@
(i.e. FreeBSD 4.x). In all other cases, application developers should
link with zookeeper_mt, as it includes support for both Sync and Async
API.</p>
-<a name="N10578"></a><a name="Installation"></a>
+<a name="N1057E"></a><a name="Installation"></a>
<h4>Installation</h4>
<p>If you're building the client from a check-out from the Apache
repository, follow the steps outlined below. If you're building from a
@@ -1841,7 +1854,7 @@
</li>
</ol>
-<a name="N10621"></a><a name="Using+the+C+Client"></a>
+<a name="N10627"></a><a name="Using+the+C+Client"></a>
<h4>Using the C Client</h4>
<p>You can test your client by running a ZooKeeper server (see
instructions on the project wiki page on how to run it) and connecting
@@ -1899,7 +1912,7 @@
</div>
-<a name="N10667"></a><a name="ch_guideToZkOperations"></a>
+<a name="N1066D"></a><a name="ch_guideToZkOperations"></a>
<h2 class="h3">Building Blocks: A Guide to ZooKeeper Operations</h2>
<div class="section">
<p>This section surveys all the operations a developer can perform
@@ -1917,28 +1930,28 @@
</li>
</ul>
-<a name="N1067B"></a><a name="sc_errorsZk"></a>
+<a name="N10681"></a><a name="sc_errorsZk"></a>
<h3 class="h4">Handling Errors</h3>
<p>Both the Java and C client bindings may report errors. The Java client
binding does so by throwing KeeperException, calling code() on the exception
will return the specific error code. The C client binding returns an error code
as defined in the enum ZOO_ERRORS. API callbacks indicate result code for both
language bindings. See the API documentation (javadoc for Java, doxygen for C)
for full details on the possible errors and their meaning.</p>
-<a name="N10685"></a><a name="sc_connectingToZk"></a>
+<a name="N1068B"></a><a name="sc_connectingToZk"></a>
<h3 class="h4">Connecting to ZooKeeper</h3>
<p></p>
-<a name="N1068E"></a><a name="sc_readOps"></a>
+<a name="N10694"></a><a name="sc_readOps"></a>
<h3 class="h4">Read Operations</h3>
<p></p>
-<a name="N10697"></a><a name="sc_writeOps"></a>
+<a name="N1069D"></a><a name="sc_writeOps"></a>
<h3 class="h4">Write Operations</h3>
<p></p>
-<a name="N106A0"></a><a name="sc_handlingWatches"></a>
+<a name="N106A6"></a><a name="sc_handlingWatches"></a>
<h3 class="h4">Handling Watches</h3>
<p></p>
-<a name="N106A9"></a><a name="sc_miscOps"></a>
+<a name="N106AF"></a><a name="sc_miscOps"></a>
<h3 class="h4">Miscelleaneous ZooKeeper Operations</h3>
<p></p>
</div>
-<a name="N106B3"></a><a name="ch_programStructureWithExample"></a>
+<a name="N106B9"></a><a name="ch_programStructureWithExample"></a>
<h2 class="h3">Program Structure, with Simple Example</h2>
<div class="section">
<p>
@@ -1947,7 +1960,7 @@
</div>
-<a name="N106BE"></a><a name="ch_gotchas"></a>
+<a name="N106C4"></a><a name="ch_gotchas"></a>
<h2 class="h3">Gotchas: Common Problems and Troubleshooting</h2>
<div class="section">
<p>So now you know ZooKeeper. It's fast, simple, your application
Modified: hadoop/zookeeper/trunk/docs/zookeeperProgrammers.pdf
URL:
http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/docs/zookeeperProgrammers.pdf?rev=882696&r1=882695&r2=882696&view=diff
==============================================================================
Binary files - no diff available.
Modified:
hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/zookeeperProgrammers.xml
URL:
http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/zookeeperProgrammers.xml?rev=882696&r1=882695&r2=882696&view=diff
==============================================================================
---
hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/zookeeperProgrammers.xml
(original)
+++
hadoop/zookeeper/trunk/src/docs/src/documentation/content/xdocs/zookeeperProgrammers.xml
Fri Nov 20 19:47:03 2009
@@ -473,6 +473,19 @@
</para></listitem>
</orderedlist>
+ <para> <emphasis role="bold">Added in 3.2.0 --
SessionMovedException</emphasis>. There is an internal
+ exception that is generally not seen by clients called the
SessionMovedException.
+ This exception occurs because a request was received on a connection for
a session
+ which has be reestablished on a different server. The normal cause of
this error is
+ a client that sends a request to a server, but the network packet gets
delayed, so
+ the client times out and connects to a new server. When the delayed
packet arrives at
+ the first server, the old server detects that the session has moved and
sends back
+ the SESSION_MOVED error. Clients normally do not see this error since
they do not read
+ from those old connections. (Old connections are usually closed.) One
situation in which this
+ error can be seen is when two clients try to reestablish the same
connection using
+ a saved session id and password. One of the clients will reestablish the
connection
+ and the second client will get the SessionMovedException.</para>
+
</section>
<section id="ch_zkWatches">
