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Why do you get that impression? I do have a clear understanding of realtime in the sense you are implying. That kind of "realtime" system is actually closer to

by volaski 14y ago

Why do you get that impression? I do have a clear understanding of realtime in the sense you are implying. That kind of "realtime" system is actually closer to the point I'm trying to make. Generally centralized architecture is better for building robust and reliable systems than decentralized. In fact it would be great if you could share some counter examples.

mbell 14y ago
'Realtime' may have many definitions but those I'm familiar with relate to near instantaneous feedback based control systems. More generally it applies to systems with mandatory and very limited time constraints. A common high level software example would be algorithmic stock trading. A more historically proper 'realtime' system is code/hardware that put MSL rover on the ground on Mars. These are not things which twitter does. Their UI may give the impression of 'realtime', their systems however are not, nor do they even pretend to be realtime systems. In short, you've taken a term and misappropriated it based on marketing hype. That is a reasonable thing to do when pitching to a bunch of consumers/marketing folks, it doesn't usually set all that well with engineers.
- deleted 14y ago
  [deleted]
- volaski 14y ago
  Like you said, "realtime" has many definitions. And I disagree it's a misappropriated term based on marketing hype. Twitter IS realtime, just in a different context. If you stick to your strict definition, it would be incorrect to even call things like XMPP realtime.
  - mbell 14y ago
    I have no idea how your bringing XMPP into this but just as Node, AMQP, ActiveMQ, ZeroMQ, Jetty, or <insert messaging or async tool here> they have have no singular impact on a system being realtime or not, they are just tools. If you want to consider a system which involves these tools and has a realtime constraint e.g. X arrives before Y time or we're seriously screwed, then sure, I'll happily concede and call the system, not the tool, realtime.
smlacy 14y ago
Clearly, you've never worked in distributed systems, and your impression of Twitter (and other large "centralized" by your definition systems) are actually huge, loosely coupled decentralized systems. The real difference is whether than decentralized, loosely coupled system is run by and owned by a single corporation, or not. It's the design of the system itself that determines latency, not the centralized vs. decentralized argument. You're speaking as if twitter.com is a single giant machine on a single IP address. In fact, it's thousands of loosely coupled machines and services all working in tandem across nearly the entire globe. Sounds like a typical decentralized system to me.
- volaski 14y ago
  I have a feeling that everyone in this particular branch of the thread seems to criticize me based on their disagreement with the definition of terms I used. I understand it can be confusing because I used these terms interchangeably as well as in more loose context, and I apologize for being incoherent. I tried to elaborate my logic throughout the rest of this thread here and there, so if you have time, please read through them. Trust me. I do know a thing or two about the technologies I mentioned in the post.

by volaski 14y ago

mbell 14y ago

'Realtime' may have many definitions but those I'm familiar with relate to near instantaneous feedback based control systems. More generally it applies to systems with mandatory and very limited time constraints. A common high level software example would be algorithmic stock trading. A more historically proper 'realtime' system is code/hardware that put MSL rover on the ground on Mars. These are not things which twitter does. Their UI may give the impression of 'realtime', their systems however are not, nor do they even pretend to be realtime systems. In short, you've taken a term and misappropriated it based on marketing hype. That is a reasonable thing to do when pitching to a bunch of consumers/marketing folks, it doesn't usually set all that well with engineers.

deleted 14y ago
[deleted]
volaski 14y ago
Like you said, "realtime" has many definitions. And I disagree it's a misappropriated term based on marketing hype. Twitter IS realtime, just in a different context. If you stick to your strict definition, it would be incorrect to even call things like XMPP realtime.
- mbell 14y ago
  I have no idea how your bringing XMPP into this but just as Node, AMQP, ActiveMQ, ZeroMQ, Jetty, or <insert messaging or async tool here> they have have no singular impact on a system being realtime or not, they are just tools. If you want to consider a system which involves these tools and has a realtime constraint e.g. X arrives before Y time or we're seriously screwed, then sure, I'll happily concede and call the system, not the tool, realtime.

smlacy 14y ago

Clearly, you've never worked in distributed systems, and your impression of Twitter (and other large "centralized" by your definition systems) are actually huge, loosely coupled decentralized systems. The real difference is whether than decentralized, loosely coupled system is run by and owned by a single corporation, or not. It's the design of the system itself that determines latency, not the centralized vs. decentralized argument. You're speaking as if twitter.com is a single giant machine on a single IP address. In fact, it's thousands of loosely coupled machines and services all working in tandem across nearly the entire globe. Sounds like a typical decentralized system to me.

volaski 14y ago
I have a feeling that everyone in this particular branch of the thread seems to criticize me based on their disagreement with the definition of terms I used. I understand it can be confusing because I used these terms interchangeably as well as in more loose context, and I apologize for being incoherent. I tried to elaborate my logic throughout the rest of this thread here and there, so if you have time, please read through them. Trust me. I do know a thing or two about the technologies I mentioned in the post.