I had a query regarding the connectivity of KNIME to external sources
like any JAVA/Hadoop server. Do we have any tutorials for the same on
how we can leverage the ability of KNIME as an automated connector to
other external application?
thanks and regards,
with the open-source database nodes you can connect to SQL databases such as Postgres, MySQL and more. In the Node Guide  under "Data Access", subsection "Databases" you find usage examples for working with databases in KNIME.
KNIME Big Data Connectors  are a commercial extension which allows you to run SQL queries against Hive and Impala on Hadoop. The usage is similar to working with normal SQL databases. Usage examples are in the Node Guide under "Big Data", subsection "Big Data Connectors".
KNIME Spark Executor  is a commercial extension that allows you to do preprocessing and machine learning with Spark on Hadoop. Usage examples are in the Node Guide under "Big Data", subsection "Spark Executor". To work with Spark from KNIME you also need to setup Spark Jobserver on your cluster, which is described in the respective installation guide (under  unfold the installation steps for your KNIME version and then click on "Installation Guide".
Is there anything specific you want to connect to?