Retry Policies

In some situations, Tapis may be unable to publish a specific notification. When this happens, Tapis will immediately retry the notification 5 times in an attempt to deliver it successfully. When delivery fails for a 5th time, the notification is abandoned. If your application requires a more tenacious or methodical approach to retry delivery, you may provide a notification policy.

Example notification subscription object with custom retry policy:

{
  "url" : "$REQUEST_BIN?path=${PATH}&system=${SYSTEM}&event=${EVENT}",
  "event" : "*",
  "persistent": true,
  "policy": {
      "retryStrategy": "IMMEDIATE",
      "retryLimit": 20,
      "retryRate": 5,
      "retryDelay": 0,
      "saveOnFailure": true
    }
}

Name	Type	Description
retryStrategy	NONE, IMMEDIATE, DELAYED, EXPONENTIAL	The retry strategy to employ. Default is IMMEDIATE
retryRate	int; 0:86400	The frequency with which attempts should be made to deliver the message.
retryLimit	int; 0:1440	The maximum attempts that should be made to delivery the message.
retryDelay	int; 0:86400	The initial delay between the initial delivery attempt and the first retry.
saveOnFailure	boolean	Whether the failed message should be persisted if unable to be delivered within the retryLimit

Notification retry policies describe the strategy, frequency, delay, limit, and persistence to be applied when publishing an individual event for a given notification. The example above is our previous example with a notification policy included.

Failed deliveries

By providing a retry policy where saveOnFailure is true, failed messages will be persisted and made available for querying at a later time. This is a great way to handled missed work due to a server failure, maintenance downtime, etc.

To query failed attempts for a specific notification, enter the following CLI command:

Show curl

curl -sk -H "Authorization: Bearer $ACCESS_TOKEN" \
https://$API_BASE_URL/notifications/$API_VERSION/229681451607921126-8e1831906a8e-0001-042"/attempts

A list of notification attempts will be returned.

Show json response

[
{
  "id" : "229681451607921126-8e1831906a8e-0001-042",
  "url" : "https://httpbin.org/status/500",
  "event" : "SENT",
  "associatedUuid" : "5833036796741676570-b0b0b0bb0b-0001-011",
  "startTime" : "2016-06-19T22:21:02.266-05:00",
  "endTime" : "2016-06-19T22:21:03.268-05:00",
  "response" : {
    "code" : 500,
    "message" : ""
  },
  "_links" : {
    "self" : {
      "href" : "https://$API_BASE_URL/notifications/$API_VERSION/229123105859441126-8e1831906a8e-0001-011/attempts/229681451607921126-8e1831906a8e-0001-042"
    },
    "notification" : {
      "href" : "https://$API_BASE_URL/notifications/$API_VERSION/5833036796741676570-b0b0b0bb0b-0001-011"
    },
    "profile" : {
      "href" : "https://$API_BASE_URL/profiles/$API_VERSION/ipcservices"
    }
  }
}
]

Note: There is no way to save successful notification deliveries.