= How to host the computing layer in the MF click router =

This page describes how to integrate the computing services in the click MF router (based on the May 23, 2014 version):
To trigger a transparent services, there are three steps:
 * intercept a complete chunk from the router (from mf_segmentor)
 * update the chunk payload, note that the chunk size might be changed (e.g., compression services)
 * ship back the processed chunk for further delivery

When need to change the mf_segmentor.cc accordingly:

add a ''computing'' parameter, to specify the service number (0 - doing nothing, 1 - a simple encryption service)
{{{
int MF_Segmentor::configure(Vector<String> &conf, ErrorHandler *errh){
  if(cp_va_kparse(conf, this, errh,
                  "ROUTER_STATS", cpkP+cpkM, cpElement, &_routerStats,
                  "CHUNK_MANAGER", cpkP+cpkM, cpElement, &_chunkManager,
                  "WINDOW_SIZE", cpkP, cpUnsigned, &_window_size,
                  "COMPUTING", cpkP, cpUnsigned, &_computing_service, // 0 - no service, 1 - simple encryption
                  cpEnd) < 0) {
    return -1;
  }
  return 0;
}
}}}
also

we need to put
{{{
#include "Core_Computing_Func.hh"
}}}
in the beginning
also
we need to add
{{{
while ((!isSendingPoolFull()) && (_readyCache->size() > 0)) {
      uint32_t hop_ID = findMinReadyHopID();
      logger.log(MF_DEBUG,
                 "seg: starting trxfr hop ID: %d; ready chks: %d",
                 hop_ID, _readyCache->size());

      Chunk *chunk = _readyCache->find(hop_ID).value(); 
      Computing_Core_Func(chunk);

      //find ready chunks, erase from readyQ
      ReadyChunkMap::iterator it = _readyCache->find(hop_ID); 
      Chunk *readyChunk = it.value();
      _readyCache->erase(it);
}}}
accordingly, we need some updates in the mf_segmentor.hh
{{{
 private:
   void Computing_Core_Func(Chunk *chunk);
   void Computing_parse_chunk_info(Chunk *chunk);
   void Computing_chunk_processing(uint32_t _service_type, Chunk *chunk, uint32_t ori_chunk_size);
   void Computing_updated_chunk(Chunk *chunk, uint32_t new_chunk_size, uint32_t hop_id_log, uint32_t _pkt_size);
   uint32_t _computing_service;
}}}
 * '''Computing_Core_Function''' is the main interface for the router to trigger the computing service
 * '''Computing_parse_chunk_info''' is used for parsing the basic information of a received chunk
 * '''Computing_chunk_processing''' is the main part of the computing function, you can add as many services as you wish here
 * '''Computing_updated_chunk''' is used for clearing the old chunk payload, and adding the new chunk payload