Below are documentation on Polyglot and Softwareserver, including how they work together. Intended for developers or interested users. Started with what Rui learned as part of work of BD-460 "Software Server not setting correct public IP on checkins".
User Interface
A user interacts with Polyglot. Polyglot works internally with software servers. By default Polyglot runs on port 8184, Softwareserver on port 8182. A user can use "http://<polyglot_ip>:8184/" to see the available endpoints / URLs, such as "http://<polyglot_ip>:8184/servers" to see the server IP list, or "http://<polyglot_ip>:8184/form" to use a form to submit a conversion request.
Internal Working
A Polyglot process goes to RabbitMQ, gets the consumer IPs, connects to these IP's softwareserver at the URL "<softewareserver_ip>:8182/applications". If the URL is accessible and contains valid content, Polyglot adds the IP to its server list.
A Softwareserver connects to RabbitMQ, picks up jobs (aka msgs) in the queues, processes them, and sends the results back by accessing Polyglot's endpoint at "<polyglot_ip>:8184/checkin/<jobid>/<result_url>".
SoftwareServer uses SoftwareServer.conf + scripts/*/.aliases.txt to configure which applications it will process. For example, SS on dap-dev is configured to convert only demclip and streamclip:
Implementation Details
Polyglot and SS are implemented in Java, currently using Restlet. Current configuration files are:
- Polyglot – PolyglotRestlet.conf (Polyglot port #, Softwareserver port #, etc.), PolyglotStewardAMQ.conf (RabbitMQ URI)
- Softwareserver – SoftwareServerRestlet.conf (port #, RabbitMQ URI).
Softwareserver job checkin is in SoftwareServerRESTUtilities.java, Polyglot accessing RabbitMQ part is in polyglot/PolyglotStewardAMQ.java.
- When Polyglot starts, it does:
- read the configuration file;
- start the PolyglotStewardAMQ thread;
- start a thread to update Mongo; call PolyglotRESTUtilities.updateMongo(). By default updates every 2 sec.
- start the restlet service.
- When PolyglotStewardAMQ thread starts, it starts 3 threads:
- discoveryAMQ(), every 30 s.
- process_jobs(), every 3 s,
- heartbeat(), to remove unresponsive SSs. every Heartbeat secs, default to 10 s.
- Two queryEndpoint() methods.
In SoftwareServerRESTUtilities.java: returns pure text; in PolyglotStewardAMQ.java, returns json.
Installation of Required Software Packages on Ubuntu Trusty (14.04)
Need to install the programs used in Softwareserver scripts:
convert, unoconv, daffodil, ffmpeg, 7z and 7za, libreoffice, avconv, xvfb-run, eog, flac, ps2pdf, gthumb, htmldoc, kabeja, rar (requires "multiverse"), unzip, unrar, cabextract, ncdump, pdf2djvu, prince, soundconverter, TeighaFileConverter, txt2html, unrtf, cvlc, ebook-convert
which are in the following Ubuntu packages:
imagemagick, unoconv, (daffodil/), ffmpeg, p7zip-full, libreoffice*, libav-tools, xvfb, eog, flac, gthumb, htmldoc, (kabeja?), rar, unrar, cabextract, netcdf-bin, pdf2djvu, (prince?), soundconverter, (TeighaFileConverter?), txt2html, unrtf, vlc-nox, calibre
unzip was already installed. ps2pdf is in ghostscript, already installed.
To install those that are available on Ubuntu 14.04, Daffodil and Kabeja, do: