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Note: these instructions are currently for the S4-22 branch

Installation

There is currently no real distribution package. So you need to download the source and build the platform.

  1. Download from Apache git repository. Follow instructions here. Checkout branch S4-22
  2. Compile and install S4 in the local maven repository: (you can also let the tests run, which is currently quite long) 
    S4:incubator-s4$ ./gradlew install -DskipTests
.... verbose logs ...
  3. Build the startup scripts: 
S4:incubator-s4$ ./gradlew s4-tools:installApp
.... verbose logs 
...:s4-tools:installApp

Create a new application

S4 provides some scripts in order to simplify development and testing of applications. Let's see how to create a new template project and start a sample application.

Create a new project

  1. Create a new application template (here, we create it in the /tmp directory):  
    S4:incubator-s4$ ./s4 newApp myApp -parentDir=/tmp

... some instructions on how to start ...
  2. This creates a sample application in the specified directory, with the following structure: 
    build.gradle  --> the template build file, that you'll need to customize
     gradlew --> references the gradlew script from the S4 installation
          s4 --> references the s4 script from the S4 installation, and adds an "adapter" task
        src/ --> sources (maven-like structure)

Have a look at the sample project content

The src/main/java/hello directory contains 3 files: 

  • HelloPE.java : a very simple PE that simply prints the name contained in incoming events
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  • HelloApp.java: defines a simple application: exposes an input stream ("names"), connected to the HelloPE
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  • HelloInputAdapter is a simple adapter that reads character lines from a socket, converts them into events, and sends the events to interested S4 apps, through the "names" stream

Run the sample project

In order to run an S4 application, you need :

  • to set-up a cluster: provision a cluster and start S4 nodes for that cluster
  • to package the app
  • to publish the app on the cluster
  1. Start a Zookeeper server instance (log4j warnings come from Zookeeper and can be ignored here): 
     S4:incubator-s4$ ./s4 zkServer 
S4:myApp$ ./s4 zkServer &
[1] 68981
S4:myApp$ calling referenced s4 script : /Users/S4/tmp/s4-22/incubator-s4/s4
[main] INFO  org.apache.s4.tools.ZKServer - Starting zookeeper server on port [2181]
[main] INFO  org.apache.s4.tools.ZKServer - cleaning existing data in [/var/folders/8V/8VdgKWU3HCiy2yV4dzFpDk+++TI/-Tmp-/tmp/zookeeper/data] and [/var/folders/8V/8VdgKWU3HCiy2yV4dzFpDk+++TI/-Tmp-/tmp/zookeeper/log]
log4j:WARN No appenders could be found for logger (org.I0Itec.zkclient.ZkServer).
log4j:WARN Please initialize the log4j system properly.
  1. Define a new cluster. Say a cluster named "cluster1" with 2 partitions, nodes listening to ports starting from 12000: 
    S4:myApp$ ./s4 newCluster -c=cluster1 -nbTasks=2 -flp=12000
calling referenced s4 script : /Users/S4/tmp/s4-22/incubator-s4/s4
[main] INFO  org.apache.s4.tools.DefineCluster - preparing new cluster [cluster1] with [2] node(s)
[main] INFO  org.apache.s4.tools.DefineCluster - New cluster configuration uploaded into zookeeper
  1. Start 2 S4 nodes with the default configuration, and attach them to cluster "cluster1":
    Unknown macro: {node}

    S4:myApp$ ./s4 node -c=cluster1
    calling referenced s4 script : /Users/S4/tmp/s4-22/incubator-s4/s4
    15:50:18.996 [main] INFO org.apache.s4.core.Main - Initializing S4 node with :

    • comm module class [org.apache.s4.comm.DefaultCommModule]
    • comm configuration file [default.s4.comm.properties from classpath]
    • core module class [org.apache.s4.core.DefaultCoreModule]
    • core configuration file[default.s4.core.properties from classpath]
      -extra modules: []
      [main] INFO org.apache.s4.core.Main - Starting S4 node. This node will automatically download applications published for the cluster it belongs to
  1. Build, package and publish the app to cluster1 (currently, you must use the name of the current project, and you need to specify the gradle build file with a complete path}: 
    S4:myApp$ ./s4 deploy -appName=myApp -c=cluster1 -b=`pwd`/build.gradle
.... verbose logs for compiling, building the package, and publishing it to Zookeeper...
15:46:16.486 [main] INFO  org.apache.s4.tools.Deploy - uploaded application [myApp] to cluster [cluster1], using zookeeper znode [/s4/clusters/cluster1/apps/myApp]
  1. S4 nodes will detect the new application, download it, load it and start it. You will get something like: 
    [ZkClient-EventThread-15-localhost:2181] INFO  o.a.s.d.DistributedDeploymentManager - Detected new application(s) to deploy {}[myApp]
[ZkClient-EventThread-15-localhost:2181] INFO  org.apache.s4.core.Server - Local app deployment: using s4r file name [myApp] as application name
[ZkClient-EventThread-15-localhost:2181] INFO  org.apache.s4.core.Server - App class name is: hello.HelloApp
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s4.comm.topology.ClusterFromZK - Changing cluster topology to { nbNodes=0,name=unknown,mode=unicast,type=,nodes=[]} from null
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s4.comm.topology.ClusterFromZK - Adding topology change listener:org.apache.s4.comm.tcp.TCPEmitter@79b2591c
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s.comm.topology.AssignmentFromZK - New session:87684175268872203; state is : SyncConnected
[ZkClient-EventThread-19-localhost:2181] INFO  o.a.s4.comm.topology.ClusterFromZK - Changing cluster topology to { nbNodes=1,name=cluster1,mode=unicast,type=,nodes=[{partition=0,port=12000,machineName=myMachine.myNetwork,taskId=Task-0}]} from { nbNodes=0,name=unknown,mode=unicast,type=,nodes=[]}
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s.comm.topology.AssignmentFromZK - Successfully acquired task:Task-1 by myMachine.myNetwork
[ZkClient-EventThread-19-localhost:2181] INFO  o.a.s4.comm.topology.ClusterFromZK - Changing cluster topology to { nbNodes=2,name=cluster1,mode=unicast,type=,nodes=[{partition=0,port=12000,machineName=myMachine.myNetwork,taskId=Task-0}, {partition=1,port=12001,machineName=myMachine.myNetwork,taskId=Task-1}]} from { nbNodes=1,name=cluster1,mode=unicast,type=,nodes=[{partition=0,port=12000,machineName=myMachine.myNetwork,taskId=Task-0}]}
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s4.comm.topology.ClustersFromZK - New session:87684175268872205
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s4.comm.topology.ClustersFromZK - Detected new stream [names]
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s4.comm.topology.ClustersFromZK - New session:87684175268872206
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s4.comm.topology.ClusterFromZK - Changing cluster topology to { nbNodes=2,name=cluster1,mode=unicast,type=,nodes=[{partition=0,port=12000,machineName=myMachine.myNetwork,taskId=Task-0}, {partition=1,port=12001,machineName=myMachine.myNetwork,taskId=Task-1}]} from null
[ZkClient-EventThread-15-localhost:2181] INFO  org.apache.s4.core.Server - Loaded application from file /tmp/deploy-test/cluster1/myApp.s4r
[ZkClient-EventThread-15-localhost:2181] INFO  o.a.s.d.DistributedDeploymentManager - Successfully installed application myApp
[ZkClient-EventThread-15-localhost:2181] DEBUG o.a.s.c.g.OverloadDispatcherGenerator - Dumping generated overload dispatcher class for PE of class [class hello.HelloPE]
[ZkClient-EventThread-15-localhost:2181] DEBUG o.a.s4.comm.topology.ClustersFromZK - Adding input stream [names] for app [-1] in cluster [cluster1]
[ZkClient-EventThread-15-localhost:2181] INFO  org.apache.s4.core.App - Init prototype [hello.HelloPE].

Great, this application is deployed on 2 S4 nodes. It needs some input though...

We can get input through an adapter, i.e. an S4 app that converts an external stream into S4 events, and injects the events into S4 clusters. In the sample application, the adapter is a very basic class, that extends App, listens to an input socket, and converts each received line of characters into a generic S4 event, in which the line data is kept in a "name" field. We specify :

    • the adapter class
    • the name of the output stream
    • the cluster where to deploy this app

For easy testing, we provide a facility to start a node with an adapter app without having to package and deploy the adapter app.

  1. First, we need to define a new S4 subcluster for that app: 
    S4:myApp$ ./s4 newCluster -c=cluster2 -nbTasks=1 -flp=13000
  1. Then we can start the adapter, and we use "names" for identifying the output stream (this is the same name used as input by the myApp app) 
    ./s4 adapter -appClass=hello.HelloInputAdapter -c=cluster2 -namedStringParameters=adapter.output.stream:names
  1. Now let's just provide some data to the external stream: 
    S4:~$ echo "Bob" | nc localhost 15000
  2. Nodes should output in their console: 
    Hello Bob!
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