GenThumbnail

Exploring the actor model, BEAM, OTP and Supervision tree.

gen_thumbnail is a set of two applications that create thumbnails (25%, 50% and 200% version) for a given image.

Architecture

The thumbnail_http project exposes a simple REST API and is based on the awesome Plug specification.

The thumbnail_server project has all the logic for thumbnails creation: a GenServer thumbnail_receptor:

1. Receives the query
2. Starts an Agent (i.e thumbnail_store) that stores all the paths to the differents thumbnails of the query
3. Spawn four Tasks (i.e thumbnail_worker) that create the different thumbnails. Each Task uses a Port to launch the linux command convert for the creation of the thumbnail.

Running

iex -S mix

Usage

The application listens on the 8080port for the requests.

Submit an image for thumbnails creation

curl -X POST \
  http://localhost:8080/thumbnails \
  -H 'Content-Type: application/x-www-form-urlencoded' \
  -H 'content-type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW' \
  -F image=@/home/salmane/Desktop/elixir.png

Upon success, gen_thumbnail responds with the following payloads:

{
    "thumbnail_job_id": "0432d218-7641-11e9-b5be-000c293aa689"
}

Retrieve details about a thumbnail creation job

curl -X GET \
  http://localhost:8080/thumbnails/0432d218-7641-11e9-b5be-000c293aa689 \

The following response is returned:

{
    "min_thumbnail_url": "/thumbnails/25_elixir.png",
    "mid_thumbnail_url": "/thumbnails/50_elixir.png",
    "max_thumbnail_url": "/thumbnails/200_elixir.png"
}

Access thumbnails

curl -X GET \
  http://localhost:8080/thumbnails/200_elixir.png \

Supervision tree