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Building a Real-time SMS Voting App Part 1: Node.js and CouchDB

44 points by crabasa 14y ago

benmmurphy 14y ago
does the vote counter get incremented atomically?
- crabasa 14y ago
  Good question. Incoming votes get added to an in-memory array, which is then periodically flushed to the DB. During the flush, incoming votes are queued-up and aren't processed until the flush to the DB is complete.
  - shreyansj 14y ago
    Does that mean that when you implement visualization of voting data (in Part 2), there will be a small delay between the votes that have been cast and the votes that are being visualized? I have no experience with socket.io, so I am just asking out of curiosity.
    - crabasa 14y ago
      <<I really wish I could edit my comments>> Scratch my comment above, the caching and flushing is introduced in a future blog post. In this iteration of the code base, an attempt is made to save a vote to the DB. If it fails, it fails, there is no attempt to retry. https://github.com/crabasa/votr-part1/blob/master/events.js#L53 https://github.com/crabasa/votr-part1/blob/master/events.js#... A comment was made about whether the vote persistence would be considered ACID. Most likely not! Each vote that comes in fetches a copy of the event document. If votes came in fast enough, this would create a problem. However, rather than corrupting the data, I think the votes would simply fails since CouchDB uses a revision property to prevent this: http://wiki.apache.org/couchdb/Document_revisions?action=show&redirect=DocumentRevisions http://wiki.apache.org/couchdb/Document_revisions?action=sho...
praveenhm 14y ago
Good article on building the node.js stack.
jjacobson 14y ago
Carter, you are a bad ass for putting your code up on Hacker News.
- crabasa 14y ago
  I'm not sure I'm a badass, but I think it's hard for many developers to subject their code to public scrutiny, especially when it's with a language that's outside of their wheelhouse. I wrote this app to teach myself Node.js, CouchDB, Socket.io, HighCharts.js and bunch of other things that I really wanted to learn. I hope it's useful for people new to these things, and definitely appreciate all the feedback I'm getting from the community.
  - viraj_shah 14y ago
    I'm anxiously waiting for the remaining parts. :)
juanbyrge 14y ago
Wow you are a brilliant hacker. How did you get so goods?

44 points by crabasa 14y ago

benmmurphy 14y ago

does the vote counter get incremented atomically?

crabasa 14y ago
Good question. Incoming votes get added to an in-memory array, which is then periodically flushed to the DB. During the flush, incoming votes are queued-up and aren't processed until the flush to the DB is complete.
- shreyansj 14y ago
  Does that mean that when you implement visualization of voting data (in Part 2), there will be a small delay between the votes that have been cast and the votes that are being visualized? I have no experience with socket.io, so I am just asking out of curiosity.
  - crabasa 14y ago
    <<I really wish I could edit my comments>> Scratch my comment above, the caching and flushing is introduced in a future blog post. In this iteration of the code base, an attempt is made to save a vote to the DB. If it fails, it fails, there is no attempt to retry. https://github.com/crabasa/votr-part1/blob/master/events.js#L53 https://github.com/crabasa/votr-part1/blob/master/events.js#... A comment was made about whether the vote persistence would be considered ACID. Most likely not! Each vote that comes in fetches a copy of the event document. If votes came in fast enough, this would create a problem. However, rather than corrupting the data, I think the votes would simply fails since CouchDB uses a revision property to prevent this: http://wiki.apache.org/couchdb/Document_revisions?action=show&redirect=DocumentRevisions http://wiki.apache.org/couchdb/Document_revisions?action=sho...

praveenhm 14y ago

Good article on building the node.js stack.

jjacobson 14y ago

Carter, you are a bad ass for putting your code up on Hacker News.

crabasa 14y ago
I'm not sure I'm a badass, but I think it's hard for many developers to subject their code to public scrutiny, especially when it's with a language that's outside of their wheelhouse. I wrote this app to teach myself Node.js, CouchDB, Socket.io, HighCharts.js and bunch of other things that I really wanted to learn. I hope it's useful for people new to these things, and definitely appreciate all the feedback I'm getting from the community.
- viraj_shah 14y ago
  I'm anxiously waiting for the remaining parts. :)

juanbyrge 14y ago

Wow you are a brilliant hacker. How did you get so goods?