ShowVoc System Administration Manual

This manual supports System Administrators in all task related to installation and maintenance of the tool, usually including tasks which cannot be performed by the ShowVoc Administrator through the UI

Installation Options

Semantic Turkey Installation Options

The Installation Options section of Semantic Turkey's site provides many details on how to customize the configuration of the system for various environments or according to specific requirements. Please refer to that page for ST-specific configuration options.

Separate HTTP Server

The standalone distribution contains everything needed to start playing with the system. Depending on the system administrator preference, organization policies, load balance optimization etc..., it might be desired to separate the RDF services managed by Semantic Turkey from ShowVoc. In particular, since the Web Application contains only static assets, any standard http server can be adopted.

ShowVoc is available as a web archive (.war file) in the /deploy directory of the distribution, with name: showvoc-<versionnumber>.war

In both cases, it might be necessary to have ShowVoc explicitly pointing to the Semantic Turkey server, as explained in the following section.

Further Configuration for reaching Semantic Turkey on a different host/port

Note that the custom settings below are not possible when running ShowVoc from inside the standalone distribution. You might want to have ShowVoc installed as a separate web application in a dedicated server, as explained in the previous section.

In svconfig.js (under src/ of the source package, or under the root folder of the built distribution) it is possible to configure the SemanticTurkey host resolution. By default ShowVoc resolves dynamically the IP address of the SemanticTurkey server (by using the same IP address of the ShowVoc host machine) and the port number (by using the same port of the ShowVoc container).

In case ShowVoc runs on a different container or on a dedicated server (that is, its port/host are different from those of SemanticTurkey) the port and host cannot be automatically inferred as they belong to a separate (and unknown to ShowVoc) server. It is thus mandatory to change the following configuration by specifying the values for the st_host (only if ST is on a different machine) and st_port variables.

    /**
    * IP address/logical host name of the machine hosting Semantic Turkey.
    * By default (variable left unspecified) the host is resolved dynamically
    * by using the same address of the machine hosting VocBench.
    * Thus if ShowVoc and Semantic Turkey are running on the same machine
    * this variable can be left commented, otherwise uncomment the line and
    * edit the value.
    */
    // var st_host = "127.0.0.1";

    /**
    * Port of the container hosting Semantic Turkey.
    * By default (variable left unspecified) the port is resolved dynamically
    * by using the same port of the container hosting ShowVoc.
    * Thus if ShowVoc and Semantic Turkey are running on the same container
    * this variable can be left commented, otherwise uncomment the line and
    * edit the value.
    */
    // var st_port = "1979";

It is also possible to change the path where the SemanticTurkey server is listening and the protocol to use. The latter, if unspecified, is dynamically resolved as well as st_host and st_port just described.

    /**
    * Path where SemanticTurkey server is listening. If omitted, the sole host
    * is considered.
    * Please note that the path of Semantic Turkey services is defined as in:
    * http://semanticturkey.uniroma2.it/doc/user/web_api.jsf#services_address_structure
    * This additional path information is considered to be the starting part
    * of the path described above, and is usually necessary in case Semantic
    * Turkey is installed behind a proxy redirecting the ST URL.
    */ 
    var st_path;

    /**
    * Protocol - either http or https
    * By default (variable left unspecified) the protocol is resolved 
    * dynamically by using the same one of the container hosting ShowVoc.
    */
    // var st_protocol = "http";

Running ShowVoc on HTTPS

The last part of the svconfig.js file concerns is related to the protocol for connecting to the Semantic Turkeyserver, either http or https.

/**   
  * Protocol - either http or https   
  */  

var st_protocol = "http";

Please note that the Spring Boot container for the ST server must be configured for HTTPS, as explained in the ST documentation.

Data Management

Separate Triple Store

ShowVoc (or better, its RDF Backend Semantic Turkey), comes with an embedded distribution of RDF4J, which includes a couple of storage solutions: in-memory store and native store. Creating local repositories with this embedded solution is very convenient for quickly playing with the platform without any additional installation.

However, to the purpose of having full control over your data, we recommed to adopt a separate triple store and connect to it remotely.

ShowVoc requires a triple store compliant with the RDF4J client API and, in order to support the more advanced features of the system such as history and validation, compliant with the RDF4J's Sail Stack mechanism.

Current available options are:

Configuring ShowVoc and GraphDB for large quantities of data

When large quantities of data (hundreds of megabytes if not gigabytes) are being loaded, Semantic Turkey (the RDF management platform behind VB) might require higher memory settings in order to work properly.

The following environment variables can be setup for improving performance with large quantities of data:

JAVA_MAX_MEM and JAVA_MIN_MEM: general Java settings, that will be used by Semantic Turkey

GDB_MAX_MEM and GDB_MIN_MEM: specific settings read by GraphDB

The following one is a recommended configuration for a PC with 16Gb of RAM. The values can be increased upon need.

GDB_MAX_MEM=6144M
GDB_MIN_MEM=2048M
JAVA_MAX_MEM=2048M
JAVA_MIN_MEM=256M

System Customization

Instance name customization

ShowVoc provides a basic way for slightly customize the portal home page. This customization meets the demands of those companies who prefer to show a custom name in place of the generic "ShowVoc".

Note: this procedure requires a system administrator to have access to the filesystem of the ShowVoc installation. Furthermore, since it is necessary to manipulate the content of ShowVoc .war, this procedure can be performed only if the web archive has been extracted and deployed on a separate HTTP server as described previously.

Through the same file met before, svconfig.js (under src/ of the source package, or under the root folder of the built distribution), it is possible to change the variable showvoc_instance_name (commented by default) and set a custom name. For instance, by setting "MyPortal" as value, the home page will change from this...

... to this...

and the Datasets page, from this...

... to this...

Home page customization

ShowVoc, by default, comes with a clean home page that consists of a top navigation bar, a bottom footer and a middle section containing the application logo flanked by a brief description of what ShowVoc is. Anyway, it provides a basic customization of the middle section, in particular it allows for adding custom content to the blank section between the application description and the footer.

Note: this procedure requires a system administrator to have access to the filesystem of the ShowVoc installation. Furthermore, since it is necessary to manipulate the content of ShowVoc .war, this procedure can be performed only if the web archive has been extracted and deployed on a separate HTTP server as described in the dedicated section above (Separate HTTP Server).
A further way to customize the web page from the ShowVoc UI is described here. The method described in this section is more thought for unchangeable custom content that should distinguish a certain SV installation (e.g. logo of the organization etc..) while the latter is thought more for dynamic content (e.g. communicatoions to all users) that might be changed by the SV administrator.

The <SHOWVOC_INST_ROOT>/assets/ext/home/ directory contains the file custom_content.html, containing a brief description of how to customize the home page. This description is already formatted as (commented) HTML code and might represent custom content itself. The administrator can directly edit this content. 

  
<!--
<h1>This is a custom content</h1>

<p>
This document can be edited in order to insert a custom content in the home page of ShowVoc.
The content will be inserted in the central section of the page, just between the brief description of ShowVoc (on the top)
and the footer that contains the organizations that contributed to ShowVoc.
In order to try this feature, you can uncomment the content of this document and see how the home page changes.
</p>

<p>
The container <code><div/></code> element has the <code>"overflow-y: auto"</code> style
applied in order to make the content responsive through a vertical scrollbar in case the available space is exceeded.
</p>

<p>
It is also possible to insert images simply by adding them to the assets/ext/home/ folder and to use them as follow:
</p>

<img src="./assets/ext/home/example.png">
-->

For example, uncommenting the above code, the home page will be shown as follow

Home page custom

Internationalization: providing localizations for new languages.

The internationalization page of this system admin manual describes how to prepare a new localization file and register it to VocBench.

SAML Authentication

ShowVoc, from version 2.0, supports the authentication with any SAML Identity Provider. This means that system administrator can configure ShowVoc/SemanticTurkey in order to let a user to authenticate through an external IDP that uses the SAML standard. Anyway, even if ShowVoc recognizes only users authenticated through the SAML IDP, they still have to be registered also in ShowVoc, it is then a SemanticTurkey's task to map the SAML authenticated user to a local one. The Identity Provider just needs to be configured properly as we will see at the end of this section.

ShowVoc configuration

Enabling SAML authentication

In order to enable the SAML authentication in the ShowVoc UI, login into the application with the administrator user and go to Administration Dashboard > Configuration. Under "Other settings" a selector allows administrator to choose between Default and SAML authnetication mode.

Logout from ShowVoc and refresh the page. Now, after clicking on the login button, user will be redirected to the Identity Provider authentication page while the Standard login form in ShowVoc will no longer be available.

Semantic Turkey configuration

Changing authentication service

An alternative way to enable the SAML authentication is to do it directly from SemanticTurkey. Edit the setting authService in SemanticTurkeyData\system\plugins\it.uniroma2.art.semanticturkey.settings.core.SemanticTurkeyCoreSettingsManager\settings.props. The allowed values are: Default and SAML. This procedure can be useful if the authService has been accidentally changed to SAML from ShowVoc UI and the administrator is not able to login again for restoring the Default one.

SAML configuration

In SemanticTurkey there are two files that need to be configured in order to instruct the system to communicate with the SAML IDP:

The first one contains properties that need to be provided manually. An important property is saml.defaultIDP which depends on the SAML Identity Provider. 

    # A value between https or http. It is related to the protocol used by the server (service provider) on which VocBench will be deployed.
    saml.scheme=https
    # The name of the service provider (without "http://" and without "/" at the end).
    saml.serverName=example.org
    # The entityID of the Identity Provider. Take this value from metadata file received from the team responsible for registering your instance.
    saml.defaultIDP=entityID
    # The base url of the server (service provider) --> scheme://serverName/contextPath
    saml.entityBaseURL=https://example.org/semanticturkey
    # The url of the client application
    saml.redirect=https://example.org/showvoc
The second one contains a “placeholder” xml code that must be replaced with the metadata generated from the Identity Provider. 
    <?xml version="1.0" encoding="UTF-8"?>
    <!-- Replace this EntityDescriptor with your metadata -->
    <EntityDescriptor xmlns="urn:oasis:names:tc:SAML:2.0:metadata">
    </EntityDescriptor>

Generation of metadata

In order to be recognized from an Identity Provider, SemanticTurkey needs to be registered as a Service Provider into the latter. In order to do that, the Identity Provider needs SemanticTurkey metadata. These metadata can be automatically produced simply by accessing the following URL (eventually replacing localhost:1979 with the proper ST host url) when SemanticTurkey is up and running.
http://localhost:1979/semanticturkey/it.uniroma2.art.semanticturkey/st-core-services/saml/metadata

Attributes mapping

SemanticTurkey supports any SAML Identity Provider but it requires a minimal configuration of the IDP. In fact, once a user tries to log into VocBench passing through a SAML Identity Provider, this one sends back to SemanticTurkey a response (assertion) which contains attributes of the authenticated user. SemanticTurkey, in order to recognize the SAML user and map this to an internal registered one, needs that the user's email address is mapped to an attribute that must be named emailAddress, so the Identity Provider must be configured accordingly. In addition, two further optional attributes are the user's given name and family name which need to be returned in the assertion in attributes named respectively firstName and lastName.