HTTP Poll

HTTP Poll task is used to invoke HTTP API endpoints until the specified condition matches.

Definitions

   {
     "name": "http_poll",
     "taskReferenceName": "http_poll_ref",
     "type": "HTTP_POLL",
     "inputParameters": {
       "http_request": {
         "uri": "https://orkes-api-tester.orkesconductor.com/api",
         "method": "GET",
         "accept": "application/json",
         "contentType": "application/json",
         "terminationCondition": "(function(){ return $.output.response.body.randomInt > 10;})();",
         "pollingInterval": "60",
         "pollingStrategy": "FIXED",
         "encode": true,
         "headers": {
           "Cache-Control": "${workflow.input.cache.control}"
         },
         "body": {
           "key": "value"
         }
       }
     },
     "cacheConfig": {
       "ttlInSecond": 2000,
       "key": "cache-key"
     },
     "optional": false
   }

Input Parameters

Attribute	Description
uri	Provide the URI for the service. It can be a partial value when using vipAddress or it can be the server address.
method	Choose the HTTP method. Conductor supports the methods: GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, and TRACE.
accept	Provide the accept header as required by the server. The supported types are: application/java-archive application/EDI-X12 application/EDIFACT application/javascript application/octet-stream application/ogg application/pdf application/xhtml+xml application/x-shockwave-flash application/json application/ld+json application/xml application/zip application/x-www-form-urlencoded audio/mpeg audio/x-ms-wma audio/vnd.rn-realaudio audio/x-wav image/gif image/jpeg image/png image/tiff image/vnd.microsoft.icon image/x-icon image/vnd.djvu image/svg+xml By default, it is set to application/json. You can also pass any other headers as variables.
contentType	Provide the content type for the server. The supported types are: application/java-archive application/EDI-X12 application/EDIFACT application/javascript application/octet-stream application/ogg application/pdf application/xhtml+xml application/x-shockwave-flash application/json application/ld+json application/xml application/zip application/x-www-form-urlencoded audio/mpeg audio/x-ms-wma audio/vnd.rn-realaudio audio/x-wav image/gif image/jpeg image/png image/tiff image/vnd.microsoft.icon image/x-icon image/vnd.djvu image/svg+xml By default, it is set to application/json. You can also pass this parameter as a variable.
terminationCondition	Specifies the condition to be evaluated after every HTTP API invocation. If the condition is evaluated as true, the task will be marked as completed. On the other hand, if the condition is evaluated as false, Conductor will schedule the next poll according to the configurations (pollingInterval & pollingStrategy). While writing the termination condition, It can be passed as parameters. To use the current http poll as input to the condition, a $ needs to be prefixed. For example, $.output.status. Similarly, previous tasks' output can be referred to using $.task_ref_name.output. An example termination condition is as follows:(function(){ return $.output.response.body.randomInt > 10;})();
pollingInterval	Specify the time duration in seconds between each HTTP invocation. By default, the value is set to 60.
pollingStrategy	Choose the required polling strategy. It can take any of the following values: FIXED - The duration between each HTTP API invocation will be fixed. LINEAR_BACKOFF - The duration between each HTTP API invocation will be calculated by multiplying the poll count with pollingInterval. Note that the poll count is the incremental value based on each invocation. EXPONENTIAL_BACKOFF - The duration between each HTTP API invocation will be calculated by multiplying the poll count by 2 base exponentials of the polling interval. By default, the value is set to FIXED.
headers	A map of additional HTTP headers to be sent along with the request. The supported types are: Accept-Language Authorization Cache Control Content-MD5 From If-Match If-Modified-Since If-None-Match Max-Forwards Pragma If-Range If-Unmodified-Since Proxy-Authorization Range Warning x-api-key Accept-Charset Accept-Encoding Accept-Control-Request-Headers Accept-Control-Request-Method Content-Transfer-Encoding Expect Transfer-Encoding Trailer
body	Request body when using POST, PUT, or PATCH. It can be added as text ("body": "text") or parameters such as string, number, boolean, null, or object/array.
encode	Determines whether the URI needs encoding. When set to true (the default), the Conductor will automatically encode the query parameters before sending the HTTP request. Set this to false if the URI is already encoded. In this case, the Conductor will assume the query parameters are properly encoded and pass them to the HTTP endpoint as specified in the URI.
cacheConfig	Enabling this option allows saving the cache output of the task. On enabling, you can provide the following parameters: ttlInSecond - Provide the time to live in seconds. You can also pass this parameter as a variable. key - Provide the cache key, which is a string with parameter substitution based on the task input. You can also pass this parameter as a variable.
optional	Enabling this option renders the task optional. The workflow continues unaffected by the task's outcome, whether it fails or remains incomplete.

Output Parameters

Attribute	Description
response	A JSON object representing the response, if present.
headers	An object containing the metadata about the response.
statusCode	Returns the HTTP status code indicating the success or failure of the request.
reasonPhrase	Returns the reason phrase associated with the HTTP status code.
body	Returns the body of the response containing the actual data returned by the API.

Examples

UI

1. Add task type HTTP Poll.
2. Configure polling endpoint, interval, strategy, and termination condition.

JSON

 {
     "name": "http_poll",
     "taskReferenceName": "http_poll_ref",
     "type": "HTTP_POLL",
     "inputParameters": {
       "http_request": {
         "uri": "https://orkes-api-tester.orkesconductor.com/api",
         "method": "GET",
         "accept": "application/json",
         "contentType": "application/json",
         "terminationCondition": "(function(){ return $.output.response.body.randomInt > 10;})();",
         "pollingInterval": "60",
         "pollingStrategy": "FIXED",
         "encode": true,
         "headers": {
           "Cache-Control": "${workflow.input.cache.control}"
         },
         "body": {
           "key": "value"
         }
       }
     },
     "cacheConfig": {
       "ttlInSecond": 2000,
       "key": "cache-key"
     },
     "optional": false
   }

Sample Workflow

Let’s see a sample workflow:

    {
      "name": "your_workflow_name",
      "description": "Sample workflow to get started with HTTP POLL task.",
      "tasks": [
        {
          "name": "example",
          "taskReferenceName": "example",
          "inputParameters": {
            "http_request": {
              "uri": "https://jsonplaceholder.typicode.com/posts/1",
              "method": "GET",
              "terminationCondition": "$.output.body.length > 10 ? true : false;",
              "pollingInterval": "60",
              "pollingStrategy": "FIXED"
            }
          },
          "type": "HTTP_POLL"
        }
      ]
    }

So, here, the input parameters for the HTTP Poll task are defined as follows:

      "terminationCondition": "$.output.body.length > 10 ? true : false;",
      "pollingInterval": "60",
      "pollingStrategy": "FIXED"

Conductor will invoke the HTTP API every 60 seconds until the invoked URI gives the output that is longer than 10 characters.