Online API

In order to receive access to the PenReader Online API, please contact our managers at penreader_sdk@penreader.com to receive login and password information for the online version of the SDK once it is available. You will receive a set of http commands to send strokes and receive recognition results, which will allow you to evaluate the quality of PenReader’s handwriting recognition.

1. Request format

HTTP POST request is sent to http://engine.penreader.com/api, its body should be a JSON of the following format:

 
							
							
							
{"language":"english", "mode":"letter", "points":[[[0,0], [100,100]],[[0,0]]], "auth_token":"your_hex_token"}
							
							
							

language* - language name, case insensitive

mode - recognition mode, may have one of the following values:

letter - letter-by-letter recognition

separated - separate characters recognition

solid** - joint-up recognition

points* - an array of strokes. Each stroke is an array of points. A point is represented by a two-element array of coordinates [x, y].

auth_token* -a key containing 32-character hex-sequence

* - is mandatory for each request

** - used as a default value

2. Response format

In case a request has been successfully processed, the service sends status 200 OK along with a recognized phrase in JSON format:

 
							
							
							
{"data":"recognized phrase"}
							
							
							

In the case of an error response is of the following format:

 
							
							
							
{"error":"error message"}
							
							
							

3. api usage example

 
							
							
							
#!/bin/ruby
							
require 'json'
require 'net/http'
							
language = 'english'
token = '0123456789abcdef0123456789abcdef' # this is like login/password pair
host = 'engine.penreader.com'
port = 80
							
# parsing the file with data. it contains points coordinates and initial phrase, separated by \t
line = File.read('./data.txt')
points, char_codes = line.split("\t").map {|json| JSON.parse(json)}
should_be = char_codes.map{|code| code.chr(Encoding::UTF_8)}.join
							
# making http post request
start_time = Time.now
http = Net::HTTP.new(host, port)
request = Net::HTTP::Post.new('/api')
request.body =  {:language => language, :points => points, :auth_token => token}.to_json
raw_response = http.start {|h| h.request(request)}
response = JSON.parse raw_response.body # response body is also in json format
recognition_time = (Time.now.to_f - start_time.to_f).round(2)
							
text = response['data']
puts "should be: #{should_be}"
puts "response : #{text}"
# sometimes case may differ
if text.downcase == should_be.downcase
  puts "Success!!"
else
  puts "Test failed!!"
end
puts "Recognition time: #{recognition_time}"
							
							
							

The following archive contains a file with input data to be used in the example: penreader_sdk.zip