Data feeds

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Introduction

Data feed is a mechanism to deliver structured data from one system to another, like from a server to a client. Data feeds make it possible to automatically have new content or updates delivered to the player as soon as it is available.

Data feeds are often described in terms of their methods of delivery. The data feed can be in the form of a file (product information, corporate communication, information about current or upcoming events etc.), a web server response (live news, Facebook news feed, Twitter timeline, weather forecast, stock quotes from the Internet etc.), or the result of an interactive action (a push instant messages from the reception desks).

The file types can vary - formats like CSV and RSS / XML are common for structured data, plain text files can be used because of their simplicity, thus allowing non-technical people to easily create their own data feeds.

The HMP is able to integrate dynamic / static data feeds and present the desired information with a certain style on the screen. This can be resumed in three steps:

  1. The HMP retrieves the raw data from the data source. Any text-based data format can be used, such as: RSS, plain-text, CSV, ICS, XML, JSON etc.
  2. The HMP processes the raw data in order to retain only the meaningful data.
  3. The HMP displays the final data on the screen using the predefined content layout.

Data source

The HMP can retrieve data from a variety of local or remote data sources, like:

  • RSS feeds
    RSS (Rich Site Summary; often called Really Simple Syndication) feeds are commonly used to share frequently updated information: news headlines, blog entries, audio, video etc.) and can be easily found on the Internet. RSS feeds enable publishers to syndicate data automatically.
    The RSS widgets can be used to display content syndicated through RSS feeds provided by different publishers.
  • Text files
    Because of their simplicity, plain text files are commonly used for storage of information, like service / product descriptions, details of a procedure / process, notifications, rules, warnings etc. There are many software tools that allows writing / modifying text files, like Notepad, WordPad, Microsoft Word, Google Docs, OpenOffice Writer, LibreOffice Writer etc.
    Text file widgets can be used to display the content of such text files, allowing to add styling information to the text and using animations whenever the entire text doesn't fit into the widget area.
  • CSV spreadsheet files
    Spreadsheets are commonly used to store data in tabular form (i.e data cells arranged into rows and columns), like sport scores, employee birthdays, production results, price lists, poll results, restaurant menus, etc. A CSV file is a delimited text file that uses a comma (though other separators can be used as well) to separate values. Almost all spreadsheets and database management systems can natively export data as CSV file - some examples include: Microsoft Excel, Google Sheets, OpenOffice Calc, LibreOffice Calc, Numbers (spreadsheet) etc.
    The spreadsheet widgets can be used to display the content of such files within digital signage projects.
  • Media folders / locations
    A media folder is commonly used to store media files (usually images and / or videos). The source directory is usually included into the project itself (total autonomy) and the files are imported into it using Elementi (simple), or they are periodically retrieved from a content server (advanced).
    It can also be located on a web server (which must have the WebDAV extension enabled) like NAS devices, Box.com, Dropbox.com, myDrive.ch etc.
    The media files widgets can be used to automatically display the media content from a given folder, with or without a filter based on the file name / extension.
  • Weather forecast
    The weather information can be retrieved from Open Weather Map, Weather Undeground, World Weather Online, or Yahoo! Weather, and displayed with the weather widgets.


"Technical note"
Other data formats, like JSON and XML, are also available for advanced users; in fact, any text-based format can be used as a data source, including web services and HTML, and be processed through custom JavaScript parsers.
The advanced data feed widgets can be used to display content extracted from data sources based on any type of text-based format.

Data processing

The information retrieved from the data source is parsed and arranged in a table-like format, with columns and rows, using the built-in data parsers:

Elementi X users can further transform the resulted information, so that only the meaningful data can be displayed on the screen, as following:

  • Each data field (column) can be further parsed using the parsers listed above, plus Date/Time and Query String parsers.
  • Each data field (column) can be filtered using Numeric, Date and / or String filters.
  • The resulted data set can be sorted by one of the data fields (columns).

Finally, the resulted data set can be limited to a certain number of rows of data.


"Technical note"
Programmers could also use jSignage data feed functions. Or getURL() function along with low-level parsing functions.

Data-driven content

Data-driven widgets

See Data-driven widgets page for more details.

The data-driven widgets included into Elementi Library have been designed to ease up the creation of data-driven content from common types of data feeds (e.g., RSS, Text, Spreadsheets, Calendars etc.). They can be used to automatically display data extracted from local or external data sources.

Data mapping

The mapping between the data retrieved from the data source and the layers composing the layout of the widget is done using data placeholders. A data placeholder is a special notation having, in its simplest form, a double-pair of square brackets around the name of the field from where the data is taken - for instance [[title]], [[description]] etc.

See the full article on Data placeholders.

Sample projects

Data caching

The raw data retrieved from an external data source through data-driven widgets is cached locally (in localStorage) up to 24 hours, to protect from cases when the network is down or the player reboots.

  • Any of the data-driven widgets included in Elementi can be configured to automatically refresh the cashed data after a certain amount of time.
  • The raw data is cached per widget - the same data source URI can be used in different widgets, in case the data processing is done differently per widget.
  • The player built-in HTTP caching mechanism for external resources is not employed by default because with data feeds it is important to get the latest version of the data, not some potentially outdated copy. If needed, that can also be activated - see this tutorial for more details.

Troubleshooting

URI encoding

  • URIs must contain only valid URI characters (as defined by RFC 3986). Other characters must be escaped. For example, the URI "http://www.acme.corp/rss/monday|01041^^3F" should be correctly written as "http://www.acme.corp/rss/monday%7C01041%5E%5E3F".
  • Note that Elementi data feed dialog does the URI encoding automatically.

Text source encoding

  • Ensure that your text file is encoded using UTF-8. Otherwise the output may be garbled or missing characters.
  • When using Notepad, the encoding can be set when the file is saved from the "Save as" window, "Encoding:" drop-down box (next to the "Save" button).

MIME types

  • In Elementi, the MIME type of a file is determined by the extension. If the image ('enclosure') content of your feed contains a link to an ASX or PHP file, or another file which generates the image on the fly, then Elementi will not be able to auto-determine the MIME type. Open the layer properties and select the correct MIME type from the drop-down.

Data feed not displayed on Elementi

  • Elementi can open data sources that require authentication, only if the correct credentials have been added within the "Network Credentials" dialog, which can be opened from "Menu" > "Settings". In addition, the HMP must have the appropriate credentials specified in HMP Control Center.

Data feed not displayed on HMP

When the data feed is displayed on Elementi, but not on HMP, you should do the following:

  • Check the path used for the data source:
    • SMB/CIFS file sharing (i.e. UNC path like "\\server\share\file_path") is not supported by the HMP - this is working on Elementi only (though it is strongly discouraged).
    • Check that you are not using data from your local computer (e.g. "C:\file_path").
  • Check that the HMP has full access to the Internet (for Proxy and Gateway settings, see Network Settings page).
  • Also see the generic remarks when using Web servers.
This page was last modified on 6 October 2017, at 14:00.