2．3 Persistence
2．3．1 AMQ Message Store
??? AMQ Message Store是ActiveMQ5.0缺
省的持久化存儲。Message commands被保存到transactional journal（由rolling data
logs組成）。Messages被保存到data logs中，同時被reference store進行索引以提高存取速度。Date
logs由一些單獨的data log文件組成，缺省的文件大小是32M，如果某個消息的大小超過了data
log文件的大小，那么可以修改配置以增加data log文件的大小。如果某個data log文件中所有的消息都被成功消費了，那么這個data
log文件將會被標記，以便在下一輪的清理中被刪除或者歸檔。以下是其配置的一個例子：
-
<
broker
?
brokerName
=
"broker"
?
persistent
=
"true"
?
useShutdownHook
=
"false"
>
??
-
??<persistenceAdapter>??
-
?????<amqPersistenceAdapter?directory="${activemq.base}/data"?maxFileLength="32mb"/>??
-
??</persistenceAdapter>??
-
</
broker
>
??
|
Property name
|
Default value
|
Comments
|
| directory |
activemq-data |
the path to the directory to use to store the message store data and log files |
| useNIO |
true |
use NIO to write messages to the data logs |
| syncOnWrite |
false |
sync every write to disk |
| maxFileLength |
32mb |
a hint to set the maximum size of the message data logs |
| persistentIndex |
true |
use a persistent index for the message logs. If this is false, an in-memory structure is maintained |
| maxCheckpointMessageAddSize |
4kb |
the maximum number of messages to keep in a transaction before automatically committing |
| cleanupInterval |
30000 |
time (ms) before checking for a discarding/moving message data logs that are no longer used |
| indexBinSize |
1024 |
default number of bins used by the index. The bigger the bin size - the better the relative performance of the index |
| indexKeySize |
96 |
the size of the index key - the key is the message id |
| indexPageSize |
16kb |
the size of the index page - the bigger the page - the better the write performance of the index |
| directoryArchive |
archive |
the path to the directory to use to store discarded data logs |
| archiveDataLogs |
false |
if true data logs are moved to the archive directory instead of being deleted |
?
2．3．2 Kaha Persistence
??? Kaha Persistence 是一個專門針對消息持久化的解決方案。它對典型的消息使用模式進行了優化。在Kaha中，數據被追加到data logs中。當不再需要log文件中的數據的時候，log文件會被丟棄。以下是其配置的一個例子：
-
<
broker
?
brokerName
=
"broker"
?
persistent
=
"true"
?
useShutdownHook
=
"false"
>
??
-
??????<persistenceAdapter>??
-
????????<kahaPersistenceAdapter?directory="activemq-data"?maxDataFileLength="33554432"/>??
-
??????</persistenceAdapter>??
-
</
broker
>
??
?
2．3．3 JDBC Persistence
??? 目前支持的數據庫有Apache Derby, Axion, DB2, HSQL, Informix, MaxDB, MySQL, Oracle, Postgresql, SQLServer, Sybase。
??? 如果你使用的數據庫不被支持，那么可以調整StatementProvider 來保證使用正確的SQL方言（flavour of SQL）。通常絕大多數數據庫支持以下adaptor：
- org.activemq.store.jdbc.adapter.BlobJDBCAdapter
- org.activemq.store.jdbc.adapter.BytesJDBCAdapter
- org.activemq.store.jdbc.adapter.DefaultJDBCAdapter
- org.activemq.store.jdbc.adapter.ImageJDBCAdapter
?? 也可以在配置文件中直接指定JDBC adaptor，例如：
-
<
jdbcPersistenceAdapter
??
adapterClass
=
"org.apache.activemq.store.jdbc.adapter.ImageBasedJDBCAdaptor"
/>
??
??? 以下是其配置的一個例子：
?
- <persistence>??
- ??????<jdbcPersistence?dataSourceRef="?mysql-ds"/>??
- </persistence>??
- ??
- <bean?id="mysql-ds"?class="org.apache.commons.dbcp.BasicDataSource"?destroy-method="close">??
- ??????<property?name="driverClassName"?value="com.mysql.jdbc.Driver"/>??
- ??????<property?name="url"?value="jdbc:mysql://localhost/activemq?relaxAutoCommit=true"/>??
- ??????<property?name="username"?value="activemq"/>??
- ??????<property?name="password"?value="activemq"/>??
- ??????<property?name="poolPreparedStatements"?value="true"/>??
- </bean>??
??? 需要注意的是，如果使用MySQL，那么需要設置relaxAutoCommit 標志為true。
?
2．3．4 Disable Persistence
??? 以下是其配置的一個例子：
- <broker?persistent="false">??
- </broker>