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POConnect to an Oracle cluster in Java
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copied!<p>We have a pair of Oracle servers which are set up as nodes in a cluster (apologies if my terminology is way off). In my <code>tnsnames.ora</code> file, we have an entry that looks like</p> <pre><code>EXAMPLE.GOV = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 1.2.3.4)(PORT = 1521)) (ADDRESS = (PROTOCOL = TCP)(HOST = 1.2.3.5)(PORT = 1521)) (LOAD_BALANCE = yes) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = example.gov) ) ) </code></pre> <p>and this works when I connect with programs which use the <code>tnsnames.ora</code> file. However, I also have a Java program which uses the <a href="http://www.princeton.edu/~storacle/jdbc8_doc/oracle.jdbc.pool.OracleDataSource.html" rel="nofollow noreferrer">oracle.jdbc.pool.OracleDataSource</a> class to establish a connection</p> <pre><code>public static Connection connect() throws Exception { OracleDataSource ods = new OracleDataSource(); ods.setDriverType("thin"); ods.setServerName("1.2.3.4"); ods.setDatabaseName("example"); ods.setPortNumber(1521); ods.setUser("scott"); ods.setPassword("tiger"); return ods.getConnection(); } </code></pre> <p>which just connects to one of the nodes directly. I'd like to instead use the load-balancing <code>tnsnames.ora</code> approach, where it uses load balancing or whatever to connect to either one of the nodes, so that if one of them is down then it'll automatically connect to the other.</p> <p>Since I only have two nodes, I could easily just try opening a connection to the first node, then if that doesn't work open a connection to the second one. However, I'm wondering if there's a more correct way to do this.</p> <p>I see that there's a <code>setTNSEntryName</code> parameter, but since my <code>tnsnames.ora</code> is in a nonstandard place, I'd need to set the <code>TNS_ADMIN</code> environment variable, which I'm not sure that I can even do from within Java. Nor am I certain that this would work in any case.</p> <p>Does anyone know how to connect to a cluster of Oracle nodes from a Java program?</p>

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