<NME> README.reservations
<BEF> ADDFILE
<MSG> ACCUMULO-1613 added documentation for conditional writer

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+Title: Apache Accumulo Isolation Example
+Notice:    Licensed to the Apache Software Foundation (ASF) under one
+           or more contributor license agreements.  See the NOTICE file
+           distributed with this work for additional information
+           regarding copyright ownership.  The ASF licenses this file
+           to you 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.
+
+This example shows running a simple reservation system implemented using
+conditional mutations.  This system garuntees that only one concurrent user can
+reserve a resource.  The example's reserve command allows multiple users to be
+specified.  When this is done it creates a separate reservation thread for each
+user.  In the example below threads are spun up for alice, bob, eve, mallory,
+and trent to reserve room06 on 20140101.  Bob ends up getting the reservation
+and everyone else is put on a wait list.  The example code will take any string
+for what, when and who.
+
+    $ ./bin/accumulo org.apache.accumulo.examples.simple.reservations.ARS
+    >connect test16 localhost root secret ars
+      connected
+    >
+      Commands : 
+        reserve <what> <when> <who> {who}
+        cancel <what> <when> <who>
+        list <what> <when>
+    >reserve room06 20140101 alice bob eve mallory trent
+                       bob : RESERVED
+                   mallory : WAIT_LISTED
+                     alice : WAIT_LISTED
+                     trent : WAIT_LISTED
+                       eve : WAIT_LISTED
+    >list room06 20140101
+      Reservation holder : bob
+      Wait list : [mallory, alice, trent, eve]
+    >cancel room06 20140101 alice
+    >cancel room06 20140101 bob
+    >list room06 20140101
+      Reservation holder : mallory
+      Wait list : [trent, eve]
+    >quit
+
+Scanning the table in the Accumulo shell after running the example shows the
+following:
+
+    root@test16> table ars
+    root@test16 ars> scan
+    room06:20140101 res:0001 []    mallory
+    room06:20140101 res:0003 []    trent
+    room06:20140101 res:0004 []    eve
+    room06:20140101 tx:seq []    6
+
+The tx:seq column is incremented for each update to the row allowing for
+detection of concurrent changes.  For an update to go through the sequence
+number must not have changed since the data was read.  If it does change then
+the conditional mutation will fail and the example code will retry.
+

{'addition_count': 66, 'commit_subject': 'ACCUMULO-1613 added documentation for conditional writer', 'deletion_count': 0, 'file_extension': '.reservations', 'lang': 'reservations', 'license': 'apache-2.0', 'repo_name': 'apache/accumulo'}