HTTP Triggers

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HTTP Triggers

An HTTP trigger allows you monitor a URI (Uniform Resource Identifier) for changes. Specifically, you can poll for changes the Last-Modified and Content-MD5 HTTP header fields. You can flexibly configure the polling interval (for example, every 60 seconds), and you can optionally set the start and expiry date of the trigger.

 

The following screen shot illustrates a sample HTTP trigger.

ff_http_trigger

Sample HTTP trigger

HTTP triggers have the following structure.

 

Check

Specifies how the trigger should poll the URI. Valid options:

 

HTTP Header date

Instructs the system to check the Last-Modified HTTP header. If the Last-Modified HTTP header is missing, the Content-MD5 header is checked (see next option).

Content

Instructs the system to check the Content-MD5 optional HTTP header. This is a 128-bit "digest" used as a message integrity check. If the MD5 header has changed after the polling interval has passed, then the trigger fires. If the header is not provided by the server, the content is retrieved and hashed locally.

Polling interval

Specifies the frequency, in seconds, with which the URI will be polled.

Wait N seconds for settle

Defines the time in seconds that the server will wait before starting the next job.

Start

Defines the trigger's starting date and time. This is an optional field.

 

Clicking in the Date field opens a pop-up calendar from which you can select the start date.

Expires

Defines the date and time when the trigger expires.

Time zone

Defines the time zone applicable to the start and expiry date and time. The default time zone is defined in the server administration settings (see Setting the Default Time Zone).

Enabled

The enabled check box allows you to enable or disable the trigger. This option is useful when creating and testing new jobs.

 

The "triggerfile" parameter

Whenever you create a file system or HTTP trigger, FlowForce Server automatically adds a triggerfile input parameter to the job. When the job runs, FlowForce Server set this parameter to:

 

a) the file that triggered the job (in case of file system triggers)

b) the name of the temporary file that contains the downloaded content of the polled URI (in case of HTTP triggers).

 

ff-dir1ab

 

You can pass the value of the triggerfile parameter as input value in any subsequent steps of the job. This way, you can user or process the triggering file as required.

 

By default, the triggerfile parameter contains the absolute path of the triggering file. To extract portions of the path, use the file path expression functions.

 

For an example of a job that uses the triggerfile parameter, see Creating a Directory Polling Job.


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