Databases Reference
In-Depth Information
As shown in the preceding diagram, the Varnish server runs in front of web servers.
The Hardware load balancer will sent all the requests to the Varnish server. Based on
the configuration, the Varnish server will decide if the request should be served from
the cache or should be send to the web server. It provides a way to clear the cache
as well. Depending upon the hardware configuration of the web server, it is also
possible to run the Varnish server on the web server itself. This architectural option
can be used with many portals which serves kind of static contents. Some of the
examples include news portals and product catalogue portals.
For more information about Varnish please refer to the following URL:
https://www.varnish-cache.org/
The search architecture
Search is an inescapable feature in every portal application. Liferay Portal also
provides search functionality out of the box. Liferay Portal includes the search
framework which can be integrated with external search engines. In this section,
we will look at various search integration options available with Liferay Portal.
Apache Lucene
Liferay Portal, by default, uses the embedded Apache Lucene search engine. Apache
Lucene is the leading open source search engine available in the market. By default,
Liferay Portal's search API connects with the local embedded Lucene search engine.
It stores search indexes on the local filesystem. When we use Lucene in a clustered
environment, we need to make sure the indexes are replicated across the cluster.
There are different approaches to make sure the same search indexes are available
to all Liferay Portal nodes.
Index storage on SAN
One of the options is to configure Lucene to store indexes on a centralized network
location. Hence, all the Liferay Portal nodes will refer to the same version of indexes.
Liferay provides a way to configure indexes on a particular location. This approach
is recommended only if we have SAN installed, and the SAN provider handles
file locking issues. As indexes are accessed and changed too often, if SAN is not
able to handle file locking issues, we will end up having problems with the search
functionality. This option gives the best performance. To configure the location of the
index directory, we need to add the following property in
portal-ext.properties
:
lucene.dir=<SAN lucene index location>
