Day: 11 August 2015

I recently published an article about how to bind non-transactional resources like web services / microservices into global distributed transactions so that recovery is handled automatically. Over the years I have often had to integrate "non-transactional" systems into Java EE application servers and data consistency was often a topic of discussion or even a non-functional requirement. I've put "non-transactional" into quotes because often the systems contain ways of ensuring data consistency, for example using calls to compensate, but the systems aren't what you might traditionally call transactional. There is certainly no way of configuring a Java EE application server to automatically handle recovery for such resources. The following is a list of patterns that we compiled, showing different ways to maintain consistency when faced with the task of integrating a non-transactional system. Write job to database - The common scenario whereby you want to send say an email confirmation after a sale is made. You cannot send the email and then attempt to commit the sales transaction to your database, because if the commit fails, the customer receives an email stating that they have bought something and you have no record of it. You cannot send the email after the sales transaction is committed to your database, because if the sending of the email fails (e.g. the mail server is temporarily down), the customer won't get their confirmation, perhaps with a link to the tickets that they bought. One solution is to write the fact that an email needs to…

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