Collaboration Store, Part XXXVIII

“You don’t have to be good to start … you just have to start to be good!”
— Joe Sabah

Last time out we really did not accomplish anything of any consequence, but today let’s see if we can actually make some progress on something of real value. We need to create a process that will run every so often and check to make sure that all of the instances in the community have all of the latest content. We can use the Flow Designer to create and schedule a flow that will run daily on the Host instance and compare the artifacts present on each Client instance with the artifacts present on the Host, and then send over any missing items that never made it over originally for whatever reason. Doing it this way will eliminate the need to track and record errors when they happen, since we will just compare the Client inventory with that of the Host and correct any discrepancies. We don’t really need to know what failed or why.

We could make all of the REST API calls to the Client instances using the Integration Hub, but since that is a collection of optional products, not every instance will have all of those components installed and we would not want to make that a prerequisite for the product. To make this work on any ServiceNow configuration, we will want to roll our own calls via Javascript, and we will just use the Flow Designer to schedule a simple flow that loops through all of the Client instance records and then calls a Script Action that will do all of the heavy lifting. Before we build the Action though, we will want to build a Script Include function that can be called in the Action. Since this will be a significant script, we should probably create a new Script Include specific to this purpose rather than adding a number of new functions to any of our existing Script Includes. We can call our new Script Include InstanceSyncUtils and create a simple function called syncInstance with a single argument of the sys_id of the record for the instance to be synced. For now, we can just stub out the function with a simple logging statement and then circle back later to fill in the details. Right now, we just want to have something to call in our Flow Designer Action.

With that out of the way, we can now fire up the Flow Designer and navigate to New -> Action. We will call our new Action Sync Instance and configure a single Input called Instance ID.

For the Script step, we will just pass the Input to our new Script Include function:

(function execute(inputs, outputs) {
	var isu = new InstanceSyncUtils();
	isu.syncInstance(inputs.instance_id);
})(inputs, outputs);

There is currently nothing returned by the function, so there is no need to define any Outputs. At this point, all we need to do is to Save and Publish the Action before turning our attentions to the actual Flow itself.

To build a Flow, go back to the Home Page of the Flow Designer and select New -> Flow. On the resulting pop-up Flow Properties panel, enter all of the details for the Flow and set the Run As value to System User.

Since we want this Flow to run on its own every day, we can set the Trigger to Daily, and the Time to 12:30, which should run it in the middle of the lunch hour in the Host time zone, when most instances should be available.

Since we only want this Flow to run on the Host instance, the first thing that we need to do is to create a Flow Variable that indicates whether or not this instance is the Host. To set the value of the variable, we add a Set Flow Variables step that uses the following script to determine if this instance is the Host based on System Properties.

return gs.getProperty('instance_name') == gs.getProperty('x_11556_col_store.host_instance');

The next step then will be a conditional that checks the value of the new Flow Variable.

Failing this test will terminate the Flow, but if this is the Host instance, then the next thing that we need to do is gather up all of the Client instance records and then loop through them and call our new Action for each one in turn.

Inside the following For Each Item loop, we can then invoke our new Action, passing in the sys_id of the current record.

That completes the work on the Flow, and all we need to do now is to Save and Activate the Flow. At this point, the Flow will kick off every day at 12:30 local time, but it won’t really do much except put a few entries in the System Log. The real work will be done in the Script Include, and since that’s a major effort in and of itself, we’ll leave that for our next exciting episode.