Re: Missing interface that connects NSCoder to NSStream ?

[Helge Hess]

On Mar 14, 2007, at 01:57, Vaisburd, Haim wrote:
> Does OPENSTEP/Cocoa offer better mechanism that works like C++ stream,
> i.e. let you disregard the source of data and concentrate on  
> formatting?

The "official" way prior NS*Stream was to assemble a packet in an  
NSData and then send the NSData, eg using Mach port or NSFileHandle  
(eg sendInBackgroundAndNotify).

The historical reason is that NeXTstep was based on Mach which in  
turn was based on packet/message IPC. The Mach virtual memory system  
would simply remap such a data section in memory to the target  
process on the local machine (or forward the block to a remote  
machine transparently).

Using streams in the first place is often an over-optimization. Eg if  
you just assemble a 32KB JSON packet using an NSMutableString you  
gain nothing in practice by using a stream. You loose a lot of  
convenience and implicit reliability.
Eg just consider what happens if an error occures during the on-the- 
fly serialization. You have little choices but to close the stream  
(or implements a complicated protocol which supports OOB data). With  
in-memory data you can just clear the so-far generate stuff and  
replace it with a proper error.

Even if you send something like a 2MB PDF file to a user a (language  
library level) stream is overkill, you can just tell the OS to send  
the file directly to the socket. This is magnitudes faster.

Greets,
  Helge

PS: I'm not saying that streams are bad, they are just a bit  
overused, especially in the Java world ;-)
--
Helge Hess
http://www.helgehess.eu/