Hardware and server environment¶
Please note that it is difficult to provide an authoritative baseline or recommended system specification for running AtoM because what is considered an “acceptable” performance level is subjective, and the performance of the application depends greatly on factors such as the how much data is in the database, and how many users are accessing the site simultaneously.
Furthermore, AtoM makes use of different components and services that could be deployed in a distributed manner (across multiple machines in a network) in order to accept an escalating number of users. The main goal of this documentation is to describe the configuration of AtoM and its dependencies on a single machine, but some aspects of a multi-node installation will also be described.
Software dependencies (required)¶
These are the minimum requirements, but please remember that in most of the cases you’ll experience better results working with the latest stable releases of each component.
- A webserver like Apache or Nginx; Artefactual prefers the latter in development
- Elasticsearch 1.3.0 or newer (we use ES 1.7.6 in development). Elasticsearch 2.0 or newer is still not supported as they have deprecated a number of APIs still used in AtoM
- Oracle Java 7 or newer (required for Elasticsearch)
- MySQL 5.1 or newer
- PHP 5.5 or 5.6 (with Ubuntu 14.04) or 7.0 (with Ubuntu 16.04)
- Gearman job server
Additionally, the following PHP extensions are mandatory:
- APC (apcu in PHP 5.5+, apcu-bc also required in PHP 7.0+)
- PDO and PDO-MySQL
- Readline (not available in Windows).
ImageMagick® is a software suite to create, edit, compose, or convert bitmap images. It can read and write images in a variety of formats (over 100) including DPX, EXR, GIF, JPEG, JPEG-2000, PDF, PhotoCD, PNG, Postscript, SVG, and TIFF. Use ImageMagick to resize, flip, mirror, rotate, distort, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and Bézier curves.
ImageMagick is used in AtoM to create image derivatives (reference and thumbnail) from the master digital object, including the creation of derivatives from uploaded multi-page TIFFs. ImageMagick and Ghostscript are required for creating single page and mulit-page PDF derivative images as well.
Ghostscript is a suite of software based on an interpreter for Adobe Systems’ PostScript and Portable Document Format (PDF) page description languages. Its main purposes are the rasterization or rendering of such page description language files, for the display or printing of document pages, and the conversion between PostScript and PDF files. (Wikipedia)
Ghostscript is used in AtoM with ImageMagick for creating single-page and multi-page PDF derivative images
FFmpeg is a complete, cross-platform solution to record, convert and stream audio and video. It includes libavcodec - the leading audio/video codec library.
FFmpeg is used in AtoM to create video derivatives, including creating a flash reference video derivative for in-browser viewing.
pdftotext (part of poppler-utils)
pdftotext is an open source command-line utility for converting PDF files to plain text files —i.e. extracting text data from PDF-encapsulated files. It is freely available and included by default with many Linux distributions, and is also available for Windows as part of the Xpdf Windows port. (Wikipedia)
pdftotext is used in AtoM to extract PDF text to make it searchable via AtoM’s user interface.
Apache™ FOP (Formatting Objects Processor) is a print formatter driven by XSL formatting objects (XSL-FO) and an output independent formatter. It is a Java application that reads a formatting object (FO) tree and renders the resulting pages to a specified output.
Apache FOP is used in AtoM to create PDF finding aids.