Mastering the Thumbnail Generator with Liferay 7 CE and DXP

The Thumbnail Generator aims to improve and facilitate the generation of thumbnails provided by Liferay.

This plugin was created during a project requiring a large number of thumbnails with precise dimensions in order to minimize the loading time of the web pages. Currently, Liferay is only capable of generating two different sizes of thumbnails, when a new image is uploaded on an application (using the dl.file.entry.thumbnail.custom* settings of portal-ext.proprties). This new plugin, however, allows you to have full control over the number of thumbnails created as well as the way they are generated.

This article is structured as follows. After briefly describing the main components of this plugin, I will explain how to configure it in order to manage an unlimited number of thumbnails with Liferay.

I. Describing the Plugin Components

The Listeners
The Thumbnail Generator uses two Model Listeners to listen to ”persistence events” like the creation, modification and deletion of documents in Liferay application. A document can match any file’s type (text, image, video, pdf, …). Later, you will learn how to configure the plugins in order to process only relevant documents.

The first Listener listens for the creation and modification of a document, then it creates or updates the document’s thumbnails. The second listens for the deletion of a document, and deletes the thumbnails associated with this document in the aftermath.

The Servlet Filter
The Servlet Filter intercepts all requests calling for a document of the application and performs a series of validation before returning a thumbnail in response. It will first analyze the parameters of the query in order to know if a thumbnail is requested. Next, the filter is going to verify that the thumbnail does exist in order to finally return it to the author of the request. If one of these checks fails, the query will be ignored by the filter and it will follow its normal course – i.e. returning the original document requested.

The ThumbnailService
Lastly, the ThumbnailService handles the creation/deletion of the thumbnails and organizes them in the storage system of Liferay, using the plugin’s configuration.

II. Using the Plugins

The use of the Thumbnail Generator entails configuring the plugins and retrieving the thumbnails.

Configuration
The Thumbnail Generator’s configuration page (Menu => Control Panel => Configuration => System Settings => Thumbnail Configuration) allows you to define two options:

  • The format of the files that will be processed by the plugin.
    For example, to restrict the creation of thumbnails for JPG and PNG files, simply add these formats to the configuration and all the other files will not be taken into account by the plugin.
  • The command lines that will generate the thumbnails.
    In order to define a thumbnail and to generate it, you need to add a line in the configuration with the following syntax : ‘name:command‘. The name will later provide access to this thumbnail, the command corresponds to the command line that will generate the thumbnail (see ImageMagick’s documentation to explore all possible options). For example : ‘img_480:convert ${inputFile} -resize 480×270 ${outputFile}‘ will generate a thumbnail of dimension 480×270 and that will be retrievable through its name « img_480 ».

Thumbnail Generator configuration page

In the above screenshot, three different thumbnails will be created for each JPG and PNG files uploaded in the application.

The plugin’s configuration not only allows the user to control the number of thumbnails to be generated, but also the way in which they are created. In this scenario, the ‘convert command’ comes from the powerful image editing library ImageMagick. Instead of this command, we could have used any other commands executable on the machine hosting the Liferay application.

Thumbnails’ Retrieval
Once the plugin is deployed and configured, it is ready for use. Thumbnails will be automatically generated each time a document is uploaded into your application. In order to retrieve the thumbnail of the document, you just have to add the parameter “thumb={thumbnailName}” in the URL using this document.

An Example of Thumbnail Retrieval Process

  • The URL of a document (test.jpg) on a local instance of Liferay looks like this : http://localhost:8080/documents/20147/0/test.jpg/0d72d709-3e48-24b3-3fe6-e39a3c528725?version=1.0&t=1494431839298&imagePreview=1
  • The URL of a thumbnail associated to this document, named img_480, can be called this way : http://localhost:8080/documents/20147/0/test.jpg/0d72d709-3e48-24b3-3fe6-e39a3c528725?version=1.0&t=1494431839298&imagePreview=1&thumb=img_480

III. Administration

In order to give more control to the user in the management of this module, an administration page (your site > Configuration >  Thumbnails administration) has been created allowing you to perform some actions on the thumbnails:

  • Re-generate all the thumbnails
  • Delete all the thumbnails
  • Delete orphans thumbnails (Which are no longer linked to any documents but are still present due to a change in the configuration)

Thumbnail Generator administration

In conclusion, this brief tutorial introduces to you the Liferay’s utility app called Thumbnail Generator and describes how to use, configure, retrieve the thumbnails and administer the plugin. Should you have any further questions or comments please contact us.

Liferay DXP on Azure: A Practical Case Study

When it comes to deploying a common Java server on a common cloud infrastructure, a range of possibilities crosses one’s mind. This article presents some feedback on a particular, real-life, case of deploying Liferay Digital Experience (DXP, aka. Liferay 7 EE) on Microsoft’s Azure cloud platform.

Initial Shopping List

  • Liferay DXP, with Enterprise Subscription, fitting in the compatibility matrix
  • Process of deploying Liferay DXP on Azure
  • Reliance on SaaS solutions as much as possible
  • Use of infrastructure & platform provisioned by Ansible

The Happy Path : Azure SaaS Building Blocks

In this process, we consistently use Azure’s SaaS platform. We set up the following three (3) services:

Service I : Azure SQL database

Our team configures Tomcat JDBC using driver sqljdbc42.jar from https://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=11774 .

Instructions :

/etc/tomcat8/Catalina/localhost/ROOT.xml :

<Resource
    name="jdbc/LiferayPool"
    auth="Container"
    type="javax.sql.DataSource"
    driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver"
    url="jdbc:sqlserver://******.database.windows.net:1433;databaseName=*******"
    username="liferay-dev"
    password="*******"
    maxActive="100"
    maxIdle="30"
    maxWait="10000"
>

(note : there seems to be a new MS-SQL JDBC release going on github)

Service II : Azure files

We set up the Liferay document store library using the Advanced File System Store mounted locally on Liferay’s VM. For the mounting process we use CIFS from an Azure file share.

Instructions :

/etc/fstab :

//<storage account name>.file.core.windows.net/<file share name> /var/lib/liferay/data-remote cifs vers=3.0,username=<storage account name>,password=<storage account key>,uid=tomcat8,gid=tomcat8 0 0

/var/lib/liferay/osgi/modules/com.liferay.portal.store.file.system.configuration.AdvancedFileSystemStoreConfiguration.cfg :

rootDir=/var/lib/liferay/data-remote


Service III : Azure Application Gateway

We use an Application Gateway to handle a)SSL termination ; and b)load-balancing of the web traffic between two Liferay instances (round robin only).

In order to convert the SSL certificate + chain + key to Azure’s .pfx bundle, use :

$> openssl pkcs12 -export -out <new pfx filename>.pfx -inkey <key filename>.key -in <certificate with chain filename>.crt -passout pass:<new pfx password>

The Plain Old Virtual Machine Part

Liferay DXP itself is installed on an Ubuntu Virtual Machine. This matches the recommended installation scheme for a production instance, which is deploying Liferay in the system tomcat8 installation. Liferay Hot Fixes and Service Packs can also be installed in this context, using Liferay’s patching-tool utility.

The Unexpected : Boundaries of Liferay’s Compatibility Matrix

Liferay DXP uses Elastic Search by default as its indexing and search provider. To stay within the compatibility matrix on production, Elastic Search needs to be hosted on a separate, dedicated Java Virtual Machine (JVM) (as opposed to the default development scheme which embeds ES alongside Liferay in a single JVM). Azure does not propose any Elastic Search as a service (managing your ES cluster is up to you). Furthermore, in order to secure a connection from Liferay DXP to a remote Elastic instance (e.g. Elastic cloud), you will need the extra “Liferay Elastic Shield Integration” marketplace item, purchasable as part of the Enterprise Search Add-On Subscription. This extra item would allow you to use Elastic Shield, though you cannot stay in the compatibility matrix today using Elastic Cloud, as its ES version is more recent than the one officially supported by Liferay.

Following this approach, we can install a 2.2 Elastic Search instance on a VM accessible from Liferay without having any need for Elastic Shield (on the same machine or internal network). Figure 1 below presents the summary of the global scheme explained here.

Figure 1. The Summary of the Global Scheme

Based on Figure 1 above, and the detailed explanations we can map three alternatives which can be evaluated and tested in future. First, it seems that the pre-packaged Liferay appliance allows for a single-click deployment on Azure but only for CE edition only. This is one avenue for further discovery. Second, we need to explore and evaluate the feasibility of pushing various Docker Liferay images to Azure Container Service and identify which ones do not offer this possibility. Third, is it possible to deploy Liferay as a custom Azure Web App? This is yet another issue to pursue further. For more insights on deploying Liferay Digital Experience Platform (DXP) on Microsoft’s Azure cloud platform stay tuned…