Hey botticelli,

Thanks for sharing, these type of comments definitely help keep motivated.  The overall level of interest I've received has been much lower than expected, but I realize I am probably way too biased towards how valuable I think this data is.

Are you considering switching over to this service?  Or is there anything that I could add/change that would make the decision to move over easier?

Fortunately I'm not trying to store any of this data, I can imagine the endless amount of operational pain.  Kudos that you got it worked out.

And shoutout to Digital Ocean.  I just randomly saw an advertisement for a $10 promo the day I set out to distribute everything.  I was using AWS before that point so it is easy to appreciate how amazing DO is.

You were definitely right on this one... I've migrated off of PubNub to my own deployment of Slanger/Pusher.  Costs are now down to ~$60 a month to be able to support everyone for all channels of data.  Plus we still have the benefit of having several clients available for connecting provided by Pusher.

https://github.com/stevegraham/slanger
http://pusher.com/

Because I like the massive amounts of documentation and jdk client libraries that are readily available which will lower the barrier to entry and hopefully increase the adoption rate.  Also, I feel like the cost for offloading the operational maintenance is more than worth it.

The responses on my Reddit thread should answer this question: http://www.reddit.com/r/BitcoinMarkets/comments/25dy7l/streaming_market_data_for_bitstamp_coinbase_btce/

It would be about $100 per month to support just you and ~$300-$600 for everyone.  PubNub gets pricey with this kind of message volume....I just started a conversation with them to negotiate a volume discount.  This is my first month not using a free demo account with them so I am having some difficulty nailing down a solid number for their costs.

The only additional cost for turning on data per exchange is the additional message costs. So I really need to figure out what their volume discount will be.

Not sure what you mean.  It is already open, but yeah, I can't afford the server hosting and pubnub costs for long or at scale without funding.

Another nice feature I implemented internally with all of the ticker data is more accurate price indexes which gave me the ability to convert from any currency to another for simulation.  The price indexes are calculated as a weighted average with the weight being the trade volume from each exchange. E.g. if the price for BTC/USD on Bitstamp is 500 with a volume of 1000 and the price is 480 with a volume of 500 on Kraken the weighted global price is ( ( 500 * 1000 ) + ( 480 * 500 ) ) / 1500 = 493.33.  except with values from all exchanges in the actual implementation of course.  I don't think I've seen another Cyrpto currency price index that takes that much data into account, but it can easily be done with this streaming ticker data.

The dream is still to try to automate arbitrage trading across multiple exchanges and markets, just like everyone else I'm sure ...trying to go beyond the usual buy btc/usd here and sell usd/btc there.  Main blocker right now is that every so often you need to re-balance funds across exchanges, but most exchanges don't have have an api to do transfers/withdraws.  Writing robots to login for you gets kludgy, and sending alerts to go do it manually is too burdensome.

For that project I just had this data collection running on a single host.  But I realized that if I wanted to open this data up I needed to distribute it across several nodes to make sure there is never any down time.  As a side benefit I am able to get past some of the rate limits imposed by exchanges because I am coming from different IP's.

I initially set this up because I needed the data for a personal project and decided that I might as well try to make it official/stable.  It is only streaming ticker data right now to reduce costs, but market depth can be turned on with a switch and public trades could be added in the future.

Is there any interest for a service like this?

http://docs.marketstem.apiary.io/

*Note: Apiary docs are designed for HTTP Rest API's, but I like their layout so I forced this streaming web socket api into it.