spycos / dropper

Dropper, is a filter stream that produces fixed size data packets, from every other stream.

Dropper

Dropper is a ( nodeJS ) filter stream that produces fixed size data packets from any stream, mantaining very good perfomances .

Dropper inherits from Stream, then you can use it in the way you already use other streams ( pausing, resuming, writing.. ) .

It simply "divides" or "bufferizes" incoming data packets, depending on whether the received packet is smaller or larger than its own capacity.

---

###Installation

Current Stable Version: 0.0.7 , compatible with nodeJS >= v0.4.x

with npm :

 $ npm install dropper

or clone with git :

 $ git clone git://github.com/rootslab/dropper.git

---

###Simple Usage

  var opt = { pad : 0x0 }, // <- add leading 0s to last packet for mantaining a constant size 
      dropSize = 64 * 1024, // <- default bytes value
      filter = new dropper( dropSize, opt );

Try this, or just run the example :

  var log = console.log,
      Dropper = require( 'dropper' ),
      path = __filename, // <- a test file path
      filter = new Dropper( 36 ); // output -> 36 bytes data packets

 /*
  * all data packets will have fixed length ( dropSize ),
  * except the last that could be <= dropSize
  */  
  filter.on( 'data', function ( data ) {
      log( 'data:', data );   // <- print data ( do something with data )
  } );
  
  /*
  * stream output -> 60 bytes packets, it's the max limit,
  * packets are not guaranteed to have fixed size.
  */
  stream = fs.createReadStream( path, { bufferSize : 60 } );
  ..
  
 /*
  *  nodeJS versions < 0.5 don't support pipe chaining,
  *  because don't return the destination stream.
  *  With dropper pipe(), instead, is always possible.
  */
  stream.pipe( filter );
  filter.pipe( fs.createWriteStream( __dirname + '/drops.txt' ) );
  ..
  

---

###Run Tests & Benchmarks

Just :

 $ node test/data_integrity.js
 $ node test/benchmark.js [ 1 ] // <- a truthy value for switching from dropper to block-stream module use

License

(The MIT License)

Copyright (c) 2011 Guglielmo Ferri <[e-mail]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.