Question definitions - Amazon Mechanical Turk
HTMLQuestionExternalQuestionQuestionForm

Question definitions

Mechanical Turk provides three XML schemas that you can use to define your questions:

Use the following topics to learn more about these schemas.

HTMLQuestion

Most developers use the HTMLQuestion schema to create HITs. HTMLQuestion wraps an HTML form that is displayed to workers. This typically takes the following form: 


<HTMLQuestion xmlns="http://mechanicalturk.amazonaws.com/AWSMechanicalTurkDataSchemas/2011-11-11/HTMLQuestion.xsd">
  <HTMLContent><![CDATA[
    <!DOCTYPE html>
    <script src="https://assets.crowd.aws/crowd-html-elements.js"></script>
    <crowd-form>
      <p>Describe the current weather where you live</p>
      <p><textarea name="weather" cols="80" rows="3"></textarea></p>
    </crowd-form>
  ]]></HTMLContent>
  <FrameHeight>0</FrameHeight>
</HTMLQuestion>

​As you can see in the preceding XML, the HTML content is enclosed in a CDATA element within the XML and includes the elements that define how your question appears to workers. More information on defining your HTML can be found in Use HTML to define questions.

ExternalQuestion

When you create a task using the HTMLQuestion format, your HTML is hosted by Mechanical Turk. Using Mechanical Turk to host your task helps ensure that it is in a highly available location. If, however, you want to host the task interface on your own servers or cloud resources, you can use the ExternalQuestion format.

To use ExternalQuestion, your URL must meet the following criteria:

  • The location specified by the URL must support HTTPS.

  • The location must be highly available and able to respond quickly when workers accept or preview your task.

  • The URL cannot include any of the reserved query parameters (assignmentId, hitId, turkSubmitTo, and workerId) that is appended by Mechanical Turk, as described in How Mechanical Turk tasks are rendered .

  • The location specified by the URL must perform a form POST operation with the assignmentId when the task is completed, as described in Use HTML to define questions.

Amazon S3 is a great option for hosting your task HTML. When you use an S3-hosted layout, you need to add a ContentType header and set the ACL to public read, as shown in the following Python SDK PutObject call: 


s3_client.put_object(
   ACL='public-read',
   Body=HTML layout,
   Bucket=S3 bucket name,
   Key=Object name,
   ContentType="text/html"
)
 

When using this schema, you simply need to indicate the URL you want to use. 


<?xml version="1.0" encoding="UTF-8"?>
<ExternalQuestion xmlns=" http://mechanicalturk.amazonaws.com/AWSMechanicalTurkDataSchemas/2006-07-14/ExternalQuestion.xsd">
  <ExternalURL>https://tictactoe.amazon.com/gamesurvey.cgi?gameid=01523</ExternalURL>
  <FrameHeight>0</FrameHeight>
</ExternalQuestion>
 

When you use ExternalQuestion, you can make the served HTML as complex or simple as necessary for your particular task.  However, you must use of a form element to submit a POST to Mechanical Turk when the task is complete. This directs the browser to advance and notify Mechanical Turk that the task is complete.

QuestionForm

QuestionForm is a legacy XML format that can be used to define Mechanical Turk tasks using an XML schema. While it is still supported, we recommend building your task using HTMLQuestion or ExternalQuestion.