10 mar 2014 kl. 21:39 skrev Rob Nikander <[email protected]>:

> On Monday, March 10, 2014 5:21:48 AM UTC-4, Björn Antonsson wrote:
> 
> The reason that Akka is moving away from transactions and doesn’t provide out 
> of the box support for distributed transactions is that they perform poorly 
> in real life and promote a thinking that leads to a non scaling design.
> 
> To build systems without distributed transactions you need to apply a 
> different way of thinking about your systems. A good read on the subject is 
> this Position Paper by Pat Helland: Life beyond Distributed Transactions.
> 
> 
> Is there an example somewhere of how to do a bank account transfer, using 
> this different way of thinking?  Or should I just stay away from Akka if I 
> need transactions of this sort?

Bank account transfers are not implemented using (distributed) transactions by 
real banks, that is just an academic ivory tower example ;-) In reality the 
bank will create a transfer command which is passed from system to system, 
using safe hand-off techniques (i.e. the money really is “in flight” for a 
while). If things go wrong, compensating commands are injected which put the 
money back into the original account.

In the end there is no way to stay away from the principles which make Akka 
seem different to you: distributed transactions do not really exist, they are 
always a slightly leaky illusion; that lies in the nature of distributed 
systems. You might want to check the CAP theorem (don’t trust the wikipedia 
page) and Eric Brewer’s follow-on article (he discusses ATMs as well).

Regards,

Roland

> 
> Rob
> 
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Dr. Roland Kuhn
Akka Tech Lead
Typesafe – Reactive apps on the JVM.
twitter: @rolandkuhn


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