This service exposes a very simple REST api with 1 endpoint allowing Collabosphere to generate preview images for files and links.
Download and install Ghostscript. This dependency takes care of converting PDF pages into images.
Download and install LibreOffice. This dependency takes care of converting Microsoft Office files to PDFs.
Download and install PhantomJS. This dependency is a headless WebKit that takes care of rendering links and taking screenshots.
node app
Preview requests are submitted to the REST API which then queues a job on an Amazon SQS queue. Jobs are picked up off the queue sequentially (ie: only job gets processed at a time) and get processed. The results get stored in Amazon S3 and then finally the result get posted back to the caller.
The REST API exposes 1 endpoint (/process) which takes in three parameters:
id: The asset idurl: The URL where the file can be downloaded from (or simply the link to the webpage)postBackUrl: A URL where the results can be sent to through an HTTP POST request
This gets fed onto SQS so it can be processed asynchronously and the system can't get overloaded.
When a job gets processed, a temporary directory gets created where files can be stored during processing. Once processing is over, that directory will be removed. All processing happens in a child process. This makes it easier to handle timeouts and resource cleanup.
Once processing is finished, the results are stored in Amazon S3 and the caller is notified about all the URLS and metadata through an HTTP post request.
As this application makes use of Amazon SQS and S3 it can be beneficial to run these locally rather than use the actual services.
The development configuration at config/development.json already assumes you're running these services locally.
You can mimick an SQS queue by running elasticmq locally.
Run it using the elasticmq.conf file in the etc/sqs directory:
java -Dconfig.file=etc/sqs/elasticmq.conf -jar elasticmq-server-0.9.3.jar
Install the fakes3 gem:
gem install fakes3
Create a directory where files can be stored
mkdir s3-data
Run the S3 server:
fakes3 -r ~/projects/fronteer/berkeley/fakes3 -p 4567
If your bucket is called ets-collabosphere you will have to add an entry to your /etc/hosts like so:
127.0.0.1 ets-collabosphere.localhost