1f2586a8   
   From: barmar@alum.mit.edu   
      
   In article   
   <17dfcbd4-e721-4fae-8906-6862f1c09a91@v15g2000yqn.googlegroups.com>,   
    dbtouch  wrote:   
      
   > I think if the requirement is to send market data over wan, the user   
   > has to use TCP.   
      
   It depends on the application.  If you send the current price every few   
   seconds, then if one of the packets gets lost you can just wait for the   
   next one, there's no need to worry about the one that was lost, as long   
   as things don't get so bad that you lose several of them in a row.   
      
   My company has an infrastructure for sending data out to hundreds or   
   thousands of our servers.  For small updates we have a mechanism that   
   sends a UDP message to one machine in each datacenter with a subscriber,   
   which then uses multicast to replicate it to the other subscribers in   
   the datacenter.  Large messages are uploaded to a replicated set of   
   servers, and the subscribing machines download them using TCP.   
      
   The first mechanism is fast but unreliable, the second is slow but   
   reliable.  So an application I deal with sends state changes every 10   
   seconds using the first mechanism; every 5 minutes it uses the second   
   mechanism to send the complete current state.   
      
   --   
   Barry Margolin, barmar@alum.mit.edu   
   Arlington, MA   
   *** PLEASE don't copy me on replies, I'll read them in the group ***   
      
   --- SoupGate-Win32 v1.05   
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