Method ExecuteTask

ExecuteTask(MapReduceTask)

Executes the MapReduce task on the cache.

Declaration

public virtual ITrackableTask ExecuteTask(MapReduceTask task)

Parameters

Type	Name	Description
MapReduceTask	task	Instance of a MapReduceTask.

Returns

Type	Description
ITrackableTask	Returns an instance to track the submitted task for result and status

Examples

Note: Implementing IReducerFactory,ICombinerFactory and ICmobiner is optional.

Cache _cache= NCache.InitializeCache("myCache");

product1 = new Product(3, "Tunnbr?d", "", 4, 2);
product2 = new Product(4, "Tunnbr?d", "", 5, 9);

_cache.Add("2202", product1);
_cache.Add("2203", product2);

MapReduceTask mapReduceTask = new MapReduceTask();
mapReduceTask.Mapper = new WordCountMapper();
mapReduceTask.Combiner = new WordCountCombinerFactory();
mapReduceTask.Reducer = new WordCountReducerFactory();

ITrackableTask trackableInstance = _cache.ExecuteTask(mapReduceTask);

//Mapper implementation
public class WordCountMapper : IMapper
{
    string[] parsedline;
    string line;
    public void Map(Object key, Object value, IOutputMap context)
    {
        line = value.ToString();
        parsedline = line.Split(' ');
        for (int i = parsedline.Length; i>=0; i++)
        {
            context.Emit(parsedline[i], 1);
        }
    }
    public void Dispose()
   {
       // Release Resources
   }
}

//CombinerFactory Implementation
public class WordCountCombinerFactory : ICombinerFactory
{
    public ICombiner Create(object key)
    {
        WordCountCombiner wcCombiner = new WordCountCombiner();
        return wcCombiner;
    }
}

//ICombiner Implementation
public class WordCountCombiner : ICombiner
{
    int count = 0;
    public void BeginCombine()
    {
        //any initialization
    }
     public void Combine(object value)
    {
        count += int.Parse(value.ToString());
    }
    public object FinishChunk()
    {
        return count;
    }
    public void Dispose()
    {
        // Release Resources
    }
}

//IReducerFactory Implementation
public class WordCountReducerFactory : IReducerFactory
{
    public IReducer Create(object key)
    {
        WordCountReducer wcReducer = new WordCountReducer(key);
        return wcReducer;
    }
}

//IReducer Implementation

public class WordCountReducer : IReducer
{
    int count = 0;
    object key;
    public WordCountReducer(object value)
    {
        key = value;
    }
    public void BeginReduce()
    {
        //perform operations
    }
    public void Reduce(object value)
    {
        count += int.Parse(value.ToString());
    }
    public KeyValuePair FinishReduce()
    {
        KeyValuePair kvp = null;
        kvp.Key = key;
        kvp.Value = count;
        return kvp;
    }
    public void Dispose()
    {
        // Release Resources
    }
}

ExecuteTask(MapReduceTask, IKeyFilter)

Executes the MapReduce task on the cache using specified KeyFilter implementation.

Declaration

public virtual ITrackableTask ExecuteTask(MapReduceTask task, IKeyFilter keyFilter)

Parameters

Type	Name	Description
MapReduceTask	task	Instance of a MapReduceTask.
IKeyFilter	keyFilter	Instance of IKeyFilter implementation.

Returns

Type	Description
ITrackableTask	Returns an instance to track the submitted task for result and status.

Examples

Note: Implemeting IReducerFactory,ICombinerFactory and ICmobiner is optional.

Cache _cache= NCache.InitializeCache("myCache");

product1 = new Product(3, "Tunnbr?d", "", 4, 2);
product2 = new Product(4, "Tunnbr?d", "", 5, 9);

_cache.Add("2202", product1);
_cache.Add("2203", product2);

MapReduceKeyFilter keyFilter= new  MapReduceKeyFilter();
MapReduceTask mapReduceTask = new MapReduceTask();
mapReduceTask.Mapper = new WordCountMapper();
mapReduceTask.Combiner = new WordCountCombinerFactory();
mapReduceTask.Reducer = new WordCountReducerFactory();

ITrackableTask trackableInstance = _cache.ExecuteTask(mapReduceTask,keyFilter);


//implementation of IKeyFilter
public class MapReduceKeyFilter : IKeyFilter
{
 public bool FilterKey(object key)
  {
   try
   {
       if (key.ToString().Contains("hungry"))
       {
           return true;
       }

   }
   catch (Exception exp)
   {
       //handle exception
   }
   return false;
  }
}


//Mapper implementation
public class WordCountMapper : IMapper
{
    string[] parsedline;
    string line;
    public void Map(Object key, Object value, IOutputMap context)
    {
        line = value.ToString();
        parsedline = line.Split(' ');
        for (int i = parsedline.Length; i>=0; i++)
        {
            context.Emit(parsedline[i], 1);
        }
    }
    public void Dispose()
   {
       // Release Resources
   }
}

//CombinerFactory Implementation
public class WordCountCombinerFactory : ICombinerFactory
{
    public ICombiner Create(object key)
    {
        WordCountCombiner wcCombiner = new WordCountCombiner();
        return wcCombiner;
    }
}

//ICombiner Implementation
public class WordCountCombiner : ICombiner
{
    int count = 0;
    public void BeginCombine()
    {
        //any initialization
    }
     public void Combine(object value)
    {
        count += int.Parse(value.ToString());
    }
    public object FinishChunk()
    {
        return count;
    }
    public void Dispose()
    {
        // Release Resources
    }
}

//IReducerFactory Implementation
public class WordCountReducerFactory : IReducerFactory
{
    public IReducer Create(object key)
    {
        WordCountReducer wcReducer = new WordCountReducer(key);
        return wcReducer;
    }
}

//IReducer Implementation

public class WordCountReducer : IReducer
{
    int count = 0;
    object key;
    public WordCountReducer(object value)
    {
        key = value;
    }
    public void BeginReduce()
    {
        //perform operations
    }
    public void Reduce(object value)
    {
        count += int.Parse(value.ToString());
    }
    public KeyValuePair FinishReduce()
    {
        KeyValuePair kvp = null;
        kvp.Key = key;
        kvp.Value = count;
        return kvp;
    }
    public void Dispose()
    {
        // Release Resources
    }
}

ExecuteTask(MapReduceTask, String, Hashtable)

Executes the MapReduce task on the resultant items with specified query.

Declaration

public virtual ITrackableTask ExecuteTask(MapReduceTask task, string query, Hashtable parameters)

Parameters

Type	Name	Description
MapReduceTask	task	Instance of a MapReduceTask.
System.String	query	Simple sql like NCache query string
System.Collections.Hashtable	parameters	NCache query string searchable parameters.

Returns

Type	Description
ITrackableTask	Returns an instance to track the submitted task for result and status.

Examples

Note: Implemeting IReducerFactory,ICombinerFactory and ICmobiner is optional.

Cache _cache= NCache.InitializeCache("myCache");

product1 = new Product(3, "Clothes", "", 4, 2);
product2 = new Product(4, ""Shoes", "", 5, 9);

_cache.Add("2202", product1);
_cache.Add("2203", product2);

MapReduceTask mapReduceTask = new MapReduceTask();
mapReduceTask.Mapper = new WordCountMapper();
mapReduceTask.Combiner = new WordCountCombinerFactory();
mapReduceTask.Reducer = new WordCountReducerFactory();

Hashtable values = new Hashtable();
values.Add("Category", "Clothes");

string query = "SELECT Product WHERE this.Category IN (?)";
ITrackableTask trackableInstance = _cache.ExecuteTask(mapReduceTask,query,values);  


//Mapper implementation
public class WordCountMapper : IMapper
{
    string[] parsedline;
    string line;
    public void Map(Object key, Object value, IOutputMap context)
    {
        line = value.ToString();
        parsedline = line.Split(' ');
        for (int i = parsedline.Length; i>=0; i++)
        {
            context.Emit(parsedline[i], 1);
        }
    }
    public void Dispose()
   {
       // Release Resources
   }
}

//CombinerFactory Implementation
public class WordCountCombinerFactory : ICombinerFactory
{
    public ICombiner Create(object key)
    {
        WordCountCombiner wcCombiner = new WordCountCombiner();
        return wcCombiner;
    }
}

//ICombiner Implementation
public class WordCountCombiner : ICombiner
{
    int count = 0;
    public void BeginCombine()
    {
        //any initialization
    }
     public void Combine(object value)
    {
        count += int.Parse(value.ToString());
    }
    public object FinishChunk()
    {
        return count;
    }
    public void Dispose()
    {
        // Release Resources
    }
}

//IReducerFactory Implementation
public class WordCountReducerFactory : IReducerFactory
{
    public IReducer Create(object key)
    {
        WordCountReducer wcReducer = new WordCountReducer(key);
        return wcReducer;
    }
}

//IReducer Implementation

public class WordCountReducer : IReducer
{
    int count = 0;
    object key;
    public WordCountReducer(object value)
    {
        key = value;
    }
    public void BeginReduce()
    {
        //perform operations
    }
    public void Reduce(object value)
    {
        count += int.Parse(value.ToString());
    }
    public KeyValuePair FinishReduce()
    {
        KeyValuePair kvp = null;
        kvp.Key = key;
        kvp.Value = count;
        return kvp;
    }
    public void Dispose()
    {
        // Release Resources
    }
}