JDBC connection string for failover

In its HA manual, Deepnet suggests a few HA scenarios, but it doesn’t cover the following usage.

You may have a mirrored SQL database, and it can be automatic failover, but it has no VIP (virtual IP). Also you want to run a DualShield instance only. How can DualShield benefit from the existing SQL failover feature?

Well, DualShield Authentication Sever utilizes JDBC driver to connect its SQL database, you can achieve it by adding the second server into the JDBC connection string.

Let us look at an example in MySQL. The original one in the file server.xml

<Resource driverClassName="com.mysql.jdbc.Driver" maxActive="1000" maxIdle="2" maxWait="5000" name="jdbc/DasDS" password="changeit" type="javax.sql.DataSource" url="jdbc:mysql://localhost:3306/dualshield?useUnicode=true& characterEncoding=UTF-8" username="root" validationQuery="Select 1"/>

The new string which supports HA,

<Resource driverClassName="com.mysql.jdbc.Driver" maxActive="1000" maxIdle="2" maxWait="5000" name="jdbc/DasDS" password="changeit" type="javax.sql.DataSource" url="jdbc:mysql://localhost,192.168.124.201:3306/dualshield?useUnicode=true&failOverReadOnly=false&characterEncoding=UTF-8" username="root" validationQuery="Select 1"/>

As you can see, we appended the second server after the original one “localhost”, separated with comma.
Don’t forget to set the HA property “failOverReadOnly=false”(its default value = true), otherwise you will get an error “Connection is read-only. Queries leading to data modification are not allowed”.

MS SQL and ORACE have the similar failover settings in their JDBC connection strings. In MS SQL, it is called “failoverPartner”.

The PDF version is available from here

Reference

Driver/Datasource Class Names, URL Syntax and Configuration Properties for Connector/J

Using Database Mirroring (JDBC)

Java – JDBC – Microsoft Drivers