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Tag Archives: glue conference

Last month I talked about webhooks at Glue, a new conference on the “glue” of the web. One of the other speakers was Josh Elman of the Facebook Platform team. I ended up on the flight back with him, so we talked about webhooks. He seemed excited about them as a fan of the callback/hooking pattern in classical programming. In fact, he mentioned how they were experimenting with them already for notifications within the Facebook Platform, but he brought up the issue of batching. Something I hadn’t thought of before, but is important for large-scale implementations that are likely to be posting a lot of events to a target endpoint.

Later, when I read about Google Wave, and how they use webhooks in their API for creating bots, they mentioned that they may batch events. I’ve yet to crack open my Google Wave developer account and play with their implementation, but I’ve since realized a very simple convention for batching: JSON lists as the outer structure.

This works because an event object is ALWAYS going to be a key/pair object. So receiving code just has to check if the payload JSON is an array or an object. If it’s an array, handle each object inside as separate events. If it’s an object, handle as you would.

This doesn’t work for POST variables, since it’s very difficult to do arrays in general, but particularly as the outer data structure. It’s just not made to be able to do that. So this would require you to use at least JSON. It works in XML as well, but because there’s more variety in XML payloads, it’s probably harder to settle on such a simple convention as this.

Let me know what you think. Or if any of you already know how Google Wave batches events in their Robot API.