---
title: Distributed Stream Computing Platform
---
#main{:class=>"span-18 colborder"}
  #about{:class=>"span-18 last"}

    #notice{:class=>"span-17 last"}
      #notice_text= "March 2013: <b>S4 0.6.0 Release Candidate</b> <a href='http://people.apache.org/~mmorel/s4-0.6.0-incubating-release-candidate-2/'>available for download</a>. Check the <a href='/doc/0.6.0'>improved documentation</a>!."

    #notice{:class=>"span-17 last"}
      #notice_text= "August 2012: <b>S4 0.5.0 has been released!</b> Get it <a href='/download'>here</a>!."
    
    #notice{:class=>"span-17 last"}
      #notice_text= "S4 0.5.0 \"Piper\" is a complete refactoring of the previous version of S4. It provides a clearer API and a more robust implementation. It features TCP based communications, state recovery, and a new set of tools. More information is available in an <a href='https://cwiki.apache.org/confluence/display/S4/S4+0.5.0+Overview'>overview</a> and you may also check the <a href='http://www.apache.org/dist/incubator/s4/s4-0.5.0-incubating/RELEASE_NOTES.html'>release notes</a>."
        
    %p{:class=>'large'}= "S4 is a <span class='high'>general-purpose</span>, <span class='high'>distributed</span>, <span class='high'>scalable</span>, <span class='high'>fault-tolerant</span>, <span class='high'>pluggable</span> platform that allows programmers to easily develop applications for processing continuous unbounded streams of data."

    .horrule

    #sec_motivation{:class=>"span-9"}
      %h2{:class=>"secheader"}= "motivation"
      %p= "S4 fills the gap between complex proprietary systems and batch-oriented open source computing platforms. We aim to develop a high performance computing platform that hides the complexity inherent in parallel processing system from the application programmer."
    #sec_implementation{:class=>"span-9 last"}
      %h2{:class=>"secheader"}= "implementation"
      %p= "The core platform is written in <span class='high'>Java</span>. The implementation is modular and pluggable, and S4 applications can be easily and dynamically combined for creating more sophisticated stream processing systems."

    .horrule
    
    #sec_osi{:class=>"span-18 last"}
      %h2{:class=>"secheader"}= "open source"
      #os_logo{:class=>"span-2"}
        %img{:src=>"http://incubator.apache.org/images/apache-incubator-logo.png"}
      #os_desc{:class=>"span-14 last"}
        %p{:style=>"padding-top:10px; padding-left:170px;"}= "S4 was initially released by Yahoo! Inc. in October 2010 and is an Apache Incubator project since September 2011. It is licensed under the Apache 2.0 license."

    .horrule

    #sec_overview{:class=>"span-18 last"}

      %h2{:class=>"secheader"}= "overview"
      #ov_1{:class=>"span-6"}
        %h4{:class=>"subsecheader"}= "proven"
        %p= "S4 has been deployed in production systems at Yahoo! to process thousands of search queries per second."
      #ov_2{:class=>"span-6"}
        %h4{:class=>"subsecheader"}= "decentralized"
        %p= "All nodes are symmetric with no centralized service and no single point of failure. This greatly simplifies deployments and cluster configuration changes."
      #ov_3{:class=>"span-6 last"}
        %h4{:class=>"subsecheader"}= "scalable"
        %p= "Throughput increases linearly as additional nodes are added to the cluster. There is no predefined limit on the number of nodes that can be supported."

      #ov_4{:class=>"span-6"}
        %h4{:class=>"subsecheader"}= "extensible"
        %p= "Applications can easily be written and deployed using a simple API. Many basic applications for stream processing are available out of the box and more are being written."
      #ov_5{:class=>"span-6"}
        %h4{:class=>"subsecheader"}= "cluster management"
        %p= "S4 hides all cluster management tasks using a communication layer built on top of  <a href='http://hadoop.apache.org/zookeeper'>ZooKeeper</a>, a distributed, open-source coordination service for distributed applications."
      #ov_6{:class=>"span-6 last"}
        %h4{:class=>"subsecheader"}= "fault-tolerance"
        %p= "When a server in the cluster fails, a stand-by server is automatically activated to take over the tasks. Checkpointing and recovery minimize state loss."

#sidebar{:class=>"span-5 last"}
  #download
    #latest_head
      %span= "S4 Piper release"
      %br
      %span{:style=>"font-size: small;"}= "v0.5.0"
    #latest_link
      %a{:href=>"https://cwiki.apache.org/confluence/display/S4/S4+piper+walkthrough", :style=>"border: none;"}= "Get Started"
    #disclaimer
      %p= "This is an alpha version. There's no guarantee of backwards-compatibility until the 1.0 release."
  #participate
    %h2{:class=>"secheader"}= "participate"
    %ul{:class=>'large greybar'}
      %li= "<a href='/contrib'>Contribute</a>"
      %li= "Join the <a href='https://cwiki.apache.org/confluence/display/S4/S4+Apache+mailing+lists' onClick=\"#{google_analytics_event("External", "Forum", "Index - https://cwiki.apache.org/confluence/display/S4/S4+Apache+mailing+lists")}\">forum</a>"
      
  %h2{:class=>"secheader"}= "recent tweets"
  #twitter_widget= twitter_widget()
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