Some tips for writing JavaScript adapters for IBM MobileFirst

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I've been doing a lot of playing lately with MobileFirst, and one of the cooler features it has is the ability to write adapters in JavaScript. I blogged about this last week and today I thought I'd share a few tips/notes for folks who may be new to this feature.

First and foremost, it is important to remember that you are not using a full Node.js-style stack. You are working with a subset of the Rhino container developed by Mozilla. This is a JavaScript engine that runs within the context of a Java server. However, this is not a full Rhino implementation as some features, like load(), are not implemented. Unfortunately we don't document these differences (yet - I'm filing an enhancement request for this today).

Second, you cannot debug via console.log. Instead, simply use the WL.Logger API as shown below:

function getDetail(id) {"getDetail, requesting id "+id);
	return WL.Server.invokeSQLStatement({
		preparedStatement : getDetailStmt,

And where do those logs show up? Type mfp logs at the command line to be shown where your logs exist:


Then you can simply go to that directory and look at messages.log. I'd simply tail -f it while you work to see incoming messages. The log is a bit verbose, but you could use other tools to filter it out.

The third point to consider is that adapters are session-based. That means you can persist data by simply using a global JavaScript variable, but it will not be global to the server.

Finally, and I've mentioned these before, but don't forget that you need to "build/deploy" when you edit your adapter files. You can use the bd shortcut for adapters just like you do for your web assets: mfp bd. You can also test your adapters directly from the command line using mfp invoke.

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About Raymond Camden

Raymond is a developer advocate for HERE Technologies. He focuses on JavaScript, serverless and enterprise cat demos. If you like this article, please consider visiting my Amazon Wishlist or donating via PayPal to show your support. You can even buy me a coffee!

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