External Triggers

LISTSERV Maestro offers several actions that can be triggered remotely from an external source by simply accessing a special external trigger URL, via the HTTP protocol. This trigger URL can be accessed without the need to first login to Maestro.

With this, several scenarios are possible:

• If there are actions that need to be triggered manually by a user who does not want to login to Maestro first; then, the user could create bookmarks in his browser, where each bookmark contains a trigger URL and stands for an action that can be triggered. Or, perhaps a custom-made HTML page could be created with links that point to the trigger URLs.

• In a different scenario, these actions could be triggered by another process, such as a script or program. To trigger an action, all this other process has to do is to open a HTTP communication to the action's trigger URL. This type of external process could, for example, trigger an action according to a certain time schedule or each time a certain outside event happens.

To secure the external trigger URLs against unauthorized access, a security token needs to be included in each URL. Each action that can be triggered externally has a unique security token. Therefore, the security token in the URL serves two purposes: It identifies the action that is to be triggered, and it validates that the user or process that makes this request is indeed authorized to do so.

The security token for the action in question can be obtained from inside of the Maestro user interface. The exact location where the token can be obtained depends on the action that it stands for. Please see the description of the action in question for this information.

Important: You should make sure that this security token is not given out to unauthorized persons because anyone who knows the security token of a certain action is able to trigger this action, as long as he also has HTTP access to the Maestro server. If you suspect that an unauthorized person has gained access to the token, then you can create a new token (and invalidate the existing token) by clicking the appropriate link at the location where you obtained the token.

A trigger URL always has the following form:

http://SERVER_NAME/lui/externalAction.do?token=SECURITY_TOKEN

• where SERVER_NAME is replaced with the name of your Maestro server. (If a non-standard HTTP port is used, also include the port, separated with a colon ":". If access to your Maestro is protected with HTTPS, you need to specify "https://" instead of "http://".)

• where SECURITY_TOKEN is replaced with the security token for the action that the URL shall trigger.

External triggers come in two variants:

• Simple URL Access: The action is triggered by accessing the external trigger URL with a HTTP GET request.

  By accessing this URL, a HTTP GET request is made to Maestro. The server then first verifies the given security token and, if it is valid, triggers the corresponding action. The result of the action is returned in the form of a HTTP response.

  If everything went well, a response with the status code "200 - OK" is returned. In this case, the response body contains the result of the action. Most actions return a simple "OK" text in the result, but some actions may also return more data in the result; for example, if the purpose of the action was to download certain data from Maestro.

  If there was a problem executing the action, a response with a different status code is returned, such as "404 - Not Found" if an invalid security token was specified.

• URL Access with Additional Data: The action is triggered by accessing the external trigger URL with a HTTP POST request.

  In contrast to the "simple URL access" of above, the trigger URL must be accessed with a HTTP POST request, and the additional data that is necessary for the action must be included as part of the request body. The data that is required depends on the action in question. Please see the description of the action for this information.

  The result of the action is returned in form of a HTTP response, just like for the "simple URL access". Please see above for details.