This topic explains how to use API to listen to configurations in ACM.


Capture configuration changes in real time by listening to configurations on ACM. In case of any configuration changes, you can use the Get configurations to obtain the latest value of the configuration and dynamically refresh the local cache.

Registered listening adopts asynchronous Servlet technique. Registered listening is essentially to compare the MD5 with configurations and configuration values to that in the backend. If the MD5 values don’t match, then it immediately returns the different configuration. If they match, it holds for 30 seconds. And it returns an empty string.

Request type


Request URL


Request parameters

Parameter Type Required Description
Probe-Modify-Request String Yes Listen to data messages. The format is dataId^2group^2contentMD5^2tenant^1.
  • dataId: Configuration ID
  • group: Configuration group
  • contentMD5: MD5 of the configuration content
  • tenant: The tenant, corresponding to the namespace field of ACM

Header parameters

Parameter Type Required Description
longPullingTimeout String Yes If the long pulling timeout is 30 seconds, then enter 30000 here.
Spas-AccessKey String Yes The accessKey can be found in the ACM console.
timeStamp String Yes The request time in milliseconds
Spas-Signature String Yes SpasSigner.sign(Tenant+ group+ timeStamp, secretKey). Sign "tenant + group + timestamp" with secret key. The signature algorithm is HmacSHA1. The timestamp signature prevents replay attacks. The signature is valid for 60 seconds.

Parameter description

  • A delimiter to separate fields within a configuration: ^2 = Character.toString((char) 2)
  • A delimiter to separate configurations: ^1 = Character.toString((char) 1)
  • contentMD5: MD5(content). This is an empty string because the first local cache is empty.

Response parameters

Parameter type Description
String Configuration value

Error code

Error code Error message Explanation
400 Bad Request Syntax error in client request
403 Forbidden No permission
404 Not Found Client error, not found
500 Internal Server Error Internal errors of the server
200 OK Normal


  • Request example

    POST request body data:
  • Response example

    In case of any configuration changes
    If no configuration changes: an empty string is returned