Remote Events Providers (EPiServer 7.5)
A long time ago I wrote an article that among other things used a trick to change how Remote Events works (the system used in load balancing). The implementation switched out Windows Communication Foundation (WCF) in favor of a custom database implementation to get events flowing in synch with data (when using SQL replication).
But now we have official support for Event Providers in 7.5 – and it’s used by both Commerce and CMS. It’s a pretty easy API to implement if you want to make your own provider:
The built-in provider, based on WCF, is the same implementation used in previous versions so it should be a smooth upgrade if you have a complex setup with TCP endpoints for example.
But we are also releasing more providers on the NuGet feed, one for Azure Service Bus and one for Amazon SQS/SNS to take advantage of the elastic scaling of cloud environments. How to configure them are available in the CMS SDK.
Anyhow, I picked up the old code from my custom implementation and rewrote it into the new event provider system. Basically its just serializes and deserializes message to and from a table in SQL Server, more a proof of concept than anything I would put into production. It’s available on GitHub if you want to play with it.
Cool!
Awesome stuff, how are the bus providers (Azure / Amazon) in terms of reliability?
The previous UDP based multicast system was a fire and forget system and If a server missed an event the server would be out of sync.
Is a message only removed once all servers have "received/acknowledged" a message it or is it still a fire and forget system in Azure as well?
They are implemented using a publish/subscribe pattern so senders hand off the message to a topic and receivers poll their subscriptions (which are individual queues per server). So basically if UDP is as synchronous you can get the cloud providers are as asynchronous you can get with guaranteed message delivery.