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Connection closed exception when using Oracle Weblogic's JNDI datasource

I'm making use of Oracle Weblogic's (12.1.3) JNDI datasource for connection pooling. The max idle time for a connection is set to 30 seconds in the admin console. But, there is this method that takes more than a minute to complete, which results in the connection getting automatically closed.
My problem is that I have set autoCommit as false, and I'm unable to rollback the transaction in case of an Exception. I'm making use of pure JDBC. I tried using Spring's JdbcTemplate, surprisingly there is no Connection related issue when I'm making use of the #Transactional annotation.
Is there a technique using which I can keep the connections that I get from the Weblogic's JNDI datasource alive for more than 30 seconds, without modifying the configurations in the admin console?

Dynamic datasource config in wildfly

I have a wildfly 10 (Java + Spring) project. I have a requirement to dynamically inject the datasource (mysql) config details to wildfly. But since wildfly depends on the standalone xml file at startup, and needs it before even the java beans are created, the only way I've found so far is to inject is by setting env vars (by running some other program/script to fetch the configs before wildfly starts). Is there any other better option?
Is it possible to do this through the same java application itself, ignoring the xml and set the right config? If yes, how?

DataSource object via JNDI
Externalize your JDBC connection details by using JNDI to access a naming/directory server to obtain an object implementing the DataSource interface.
With a DataSource object in hand, call getConnection to obtain a Connection.
See tutorial by Oracle, Connecting with DataSource Objects.

How to handle re-connects to the DB with ActiveJDBC

I've a Spring Boot Java application in production that uses ActiveJDBC to access a MariaDB database.
If at launch the application boots before the db server, of if the db server crashes and restarts, the apps doesn't re-estabilish the connection with the db.
ActiveJDBC is on version 1.4.13 and if possible I'd prefer not upgrading it, to avoid possible breakages. The db parameters are configured using the database.properties file and typically the usage pattern is:
try {
Base.open();
...
} finally {
Base.close();
}
Is there a way to circumvent this problem, without monitoring and relaunching the application? Maybe using connection pools? If this is the case, are there any docs or examples?

If you are using a direct JDBC connection in your database.properties file, a new connection will be open every time you execute Base.open(). This means that any old connection that is broken is not relevant anymore. If you use a JDNI pool such as:
production.jndi=java:comp/env/jdbc/acme
then you want to configure your containers' pool to ensure that every connection served from the pool is valid just before the pool serves the connection to your app. It is up to the implementation and documentation of your container/pool how to do that.
In any case, I do not think you are going to have issues.

Execute custom query when a connection is fetched from dataSource

My web application runs on Tomcat 7.0 and uses Spring 3.2, Hibernate 4.3 and Oracle Database.
The entityManagerFactory is configured as org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean and the transactionManager is org.springframework.orm.jpa.JpaTransactionManager. The dataSource is defined as org.springframework.jndi.JndiObjectFactoryBean and internally refers to a connection pool of type org.apache.tomcat.jdbc.pool.DataSourceFactory.
Each time when a connection is fetched from the pool by the entityManager, I'd like to execute a custom sql statement in that connection. It will only change a property in the Oracle session context, like so:
dbms_session.set_context(context, propName, propValue);
So no dml is done.
Each time when a connection is released back to the pool, a similar statement should be executed to clear the property value.
The property value should be fetched dynamically from the spring-security context, so I can't hardcode this into a connection test statement.
I've also looked into Hibernate interceptors, but I've found no way to execute any sql in the same session from within an interceptor.
Any ideas?

SQL Azure and Connection Pooling

I have been searching high and low and gathered bits and pieces, apologies if this has already been answered elsewhere but I am unable to find it.
I am writing a web application in Java with Tomcat, and SQL Azure in the backend.
There are multiple servlets accessing the SQL Azure DB. I would like to use Connection Pools as managed by Tomcat 8.5
My application context.xml in META-INF is as follows:
<Context>
<Resource name="jdbc/sqlazure"
auth="Container"
driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver"
type="javax.sql.DataSource"
maxIdle="30"
username="[username]"
password="[password]"
url="jdbc:sqlserver://[database]:1433;database=BackInfo;encrypt=true;trustServerCertificate=false;hostNameInCertificate=*.database.windows.net;loginTimeout=30"
removeAbandonedTimeout="30"
logAbandoned="true" />
</Context>
In the Java Code, I access the typical way:
InitialContext ic = new InitialContext();ds = (DataSource)ic.lookup("java:comp/env/jdbc/sqlazure");
try(Connection con = ds.getConnection())....
Everything seems to work, so let me confirm my understanding here:
I do not need to specify a separate web.xml since I'm using Tomcat 8.5. Correct ?
Azure will automatically create a pool when I connect in this manner. The number of connections in the pool etc cannot (do not need to?) be configured.
Before I realized I would have other servlets that need to access the database, I had one servlet directly creating a Datasource via SQLServerConnectionPoolDataSource and getting a connection from there. The documentation states:
SQLServerConnectionPoolDataSource is typically used in Java Application Server environments that support built-in connection pooling and require a ConnectionPoolDataSource to provide physical connections, such as Java Platform, Enterprise Edition (Java EE) application servers that provide JDBC 3.0 API spec connection pooling.
Does this mean that when I use SQLServerConnectionPoolDataSource directly to ask for a connection, it will check if Tomcat supports pooling and then is basically using JDBC mechanisms to create a pool of SQL Azure connections managed by Tomcat ?
When getting the DataSource via Tomcat JNDI lookup, using SQLServerDriver as specified in context.xml. When the web app starts up, it will check context.xml and use SQLServerDriver to connect to SQL Azure, check if pooling is supported, if yes then Tomcat is using the driver to automatically creating a connection pool DataSource that it returns ?
I also just thought of one other question. Would it make sense to have a Singleton DataSource class that returns a reference to the pooled connection DataSource, or would it be better to have each servlet lookup the datasource in its init() and store in a private variable ?
Thanks

Based on my understanding, the jdbc connection pool for SQL Server is created by Java Application, not Azure does. My suggestion is that you need to refer to the Tomcat offical documents below to understand the JNDI Resources & JDBC DataSource.
JNDI Resources: http://tomcat.apache.org/tomcat-8.5-doc/jndi-resources-howto.html
JDBC DataSource: http://tomcat.apache.org/tomcat-8.5-doc/jndi-datasource-examples-howto.html