anchor.diff:  Properties Files
   ~~~~~~~~~~~~~~~~
   
  -The `GiraphGraphComputer` makes use of a properties file much like any other `GraphComputer`. However, given the relationship to Hadoop which is property heavy, it is important to look at a particular properties file. The properties file below is located at `conf/giraph-kryo.properties'.
  +`HadoopGraph` makes heavy use of properties files which ultimately get turned into Apache Configurations and Hadoop configurations. The properties file presented below is located at `conf/hadoop-kryo.properties'.
   
   [source,text]
   gremlin.graph=com.tinkerpop.gremlin.hadoop.structure.HadoopGraph
  
positive.code: |giraph.maxWorkers |The maximum number of parallel workers to execute the vertices of the graph (`GiraphGraphComputer`).
  |=========================================================
  
  IMPORTANT: The maximum number of workers can be no larger than the number of map-slots in the Hadoop cluster minus 1. For example, if the Hadoop cluster has 4 map slots, then `giraph.maxWorkers` can not be larger than 3. One map-slot is reserved for the master compute node and all other slots can be allocated as workers to execute the VertexPrograms on the vertices of the graph.
  
  Along with the properties above, the numerous link:http://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-common/core-default.xml[Hadoop specific properties] can be added as needed to tune and parameterize the executed Hadoop-Gremlin job on the respective Hadoop cluster.
  
  OLTP Hadoop-Gremlin
  ~~~~~~~~~~~~~~~~~~~
  
  image:hadoop-pipes.png[width=180,float=left] It is possible to execute OLTP operations over Hadoop-Gremlin. However, realize that the underlying HDFS files are typically not random access and thus, to retrieve a vertex, a linear scan is required. It is possible to create input formats that leverage Hadoop Map files.
  
  CAUTION: OLTP operations on `HadoopGraph` are not efficient. They require linear scans to execute and are unreasonable for large graphs. In such large graph situations, make use of <<traversalvertexprogram,TraversalVertexProgram>> which is the OLAP implementation of the Gremlin language.
  
  [source,text]
  gremlin> hdfs.copyFromLocal('data/tinkerpop-classic-vertices.gio', 'tinkerpop-classic-vertices.gio')
  
negative.code: 
  TIP: image:gremlin-sugar.png[width=50,float=left] For those wanting to use the <<sugar-plugin,SugarPlugin>> with their submitted traversal, do `:remote config useSugar true` as well as `:plugin use tinkerpop.sugar` at the start of the Gremlin Console session if it is not already activated.
  
  The `TraversalSupplier1` class mentioned in the `hadoop-kryo.properties` file is distributed with Hadoop-Gremlin. It declares what Gremlin-Java traversal to execute on the loaded `HadoopGraph`. This is the means by which traversals can be programmatically executed in Hadoop-Gremlin.
  
  [source,java]
  ----
  // gremlin.traversalVertexProgram.traversalSupplier.type=CLASS
  // gremlin.traversalVertexProgram.traversalSupplier.object=com.tinkerpop.gremlin.hadoop.process.computer.example.TraversalSupplier1
  
  public class TraversalSupplier1 implements SSupplier<Traversal> {
      public Traversal get() {
          return HadoopGraph.open().V().out().out().values("name");
      }
  }
  ----
  
  MapReduceGraphComputer
  ^^^^^^^^^^^^^^^^^^^^^^
  
  *COMING SOON*
  
  Interacting with HDFS
  ~~~~~~~~~~~~~~~~~~~~~
  
  The distributed file system of Hadoop is called link:http://en.wikipedia.org/wiki/Apache_Hadoop#Hadoop_distributed_file_system[HDFS]. The results of any OLAP operation are stored in HDFS accessible via `hdfs`.
  
  [source,text]
  gremlin> hdfs.ls()
  