I read in some book that using streaming is better than reading a whole file at a time in node.js, I understand the idea .. but I wonder isn't file reading using streams, I'm used to this from Java and C++, when I want to read a file I use streams .. So what's the difference here ??
also what is the difference between fs.createReadStream(<somefile>); and fs.readFile(<somefile>);
both are asynchronous, right !!
First thing is fileread is fully buffered method. and streaming is partial buffered method.
Now what does it mean?
Fully buffered function calls like readFileSync() and readFile() expose the data as one big blob. That is, reading is performed and then the full set of data is returned either in synchronous or asynchronous fashion. With these fully buffered methods, we have to wait until all of the data is read, and internally Node will need to allocate enough memory to store all of the data in memory. This can be problematic - imagine an application that reads a 1 GB file from disk. With only fully buffered access we would need to use 1 GB of memory to store the whole content of the file for reading - since both readFile and readFileSync return a string containing all of the data.
Partially buffered access methods are different. They do not treat data input as a discrete event, but rather as a series of events which occur as the data is being read or written. They allow us to access data as it is being read from disk/network/other I/O.
Streams return smaller parts of the data (using a Buffer), and trigger a callback when new data is available for processing.
Streams are EventEmitters. If our 1 GB file would, for example, need to be processed in some way once, we could use a stream and process the data as soon as it is read. This is useful, since we do not need to hold all of the data in memory in some buffer: after processing, we no longer need to keep the data in memory for this kind of application.
The Node stream interface consists of two parts: Readable streams and Writable streams. Some streams are both readable and writable.