Re: Base64 encoding of NSImage
On 01.07.2012, at 17:23, Alexander Hartner wrote: I am looking at available option to send an NSImage to a webserver. I came across gSoap however its licensing model makes it not suitable. Using REST / JSON seems like an easy option however NSDATA does not seem to be supported by the JSON Serialiser. The one remaining option I considered was to encode the image myself to base64 before including in the JSON request. This could work quite nicely, however there doesn't seem to be a standard method for base64 encoding. Well, embedding an image encoded in base64 in a JSON document is not that RESTful anyway. You better provide a link (URI) in the JSON to the image resource and load the image data separately (still being RESTful) but using a different transport format which is capable to transmit binary data more efficiently. Anyway, if you want to embed the image data into JSON: The various JSON libraries define a mapping of Foundation types to JSON types. For instance, a NSDictionary maps to a JSON Object, a NSNumber maps to a JSON Number or JSON Boolean (depending on the underlaying type in NSNumber), and so force. Usually, a NSImage will not be mapped directly to a JSON type, and especially with NSJSONSerialization you cannot accomplish this. If you try to serialize a hierarchy of Foundation objects which contains an object for which there is no mapping defined, the serialization fails for obvious reasons. There are third party JSON libraries which are capable to customize the mapping, though. For instance, it might suffice to implement a method for a Category for NSImage to accomplish this (JPJson library uses this approach for example). That way, you can serialize a hierarchy of Foundation objects which contains a NSImage - no matter where this occurs in the tree. But note, a NSImage can only be mapped to one of the existing JSON primitive types, which is a JSON String. This in turn requires the mapping method to encode binary data to Unicode, for example base64. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
On Jul 2, 2012, at 5:08 AM, Andreas Grosam wrote: Well, embedding an image encoded in base64 in a JSON document is not that RESTful anyway. Sure it is. Plenty of REST-based APIs do this sort of thing (CouchDB and Atom both come to mind.) The REST principles don't dictate any particular transfer format for data, and allow for aggregate URLs that represent multiple resources. There are third party JSON libraries which are capable to customize the mapping, though. For instance, it might suffice to implement a method for a Category for NSImage to accomplish this (JPJson library uses this approach for example). That way, you can serialize a hierarchy of Foundation objects which contains a NSImage - no matter where this occurs in the tree. It's certainly possible to do that, but it doesn't seem like a good idea to me, because there's no unambiguous data format associated with an image. Even choosing between the two most obvious formats (JPEG and PNG) involves a decision about trade-offs between fidelity loss and file size. I would instead have the app itself decide how to encode the image as data, and then set up an unambiguous mapping from NSData to base64-encoded JSON strings. (Of course on the other end it's trickier because how does the decoder know what strings should be decoded to NSData and which should be left alone? YAML has type annotations that provide for this, but JSON doesn't.) —Jens ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
On Jul 2, 2012, at 8:53 AM, Jens Alfke j...@mooseyard.com wrote: (Of course on the other end it's trickier because how does the decoder know what strings should be decoded to NSData and which should be left alone? YAML has type annotations that provide for this, but JSON doesn't.) All the more reason to just use a plain HTTP PUT with the right Content-type header. Or even a custom header that can carry a UTI (or an entire UTI tag spec). --Kyle Sluder ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
On 02.07.2012, at 17:53, Jens Alfke wrote:
On Jul 2, 2012, at 5:08 AM, Andreas Grosam wrote:
Well, embedding an image encoded in base64 in a JSON document is not that
RESTful anyway.
Sure it is. Plenty of REST-based APIs do this sort of thing (CouchDB and Atom
both come to mind.) The REST principles don't dictate any particular transfer
format for data, and allow for aggregate URLs that represent multiple
resources.
Well, I should have been more accurate what I actually meant by this:
For instance, when we retrieve a list of things (not just images) or some
container object which contains an image - we should NOT return those objects
inlined which itself can be identified by its own URI - but instead providing
the URI. Simply because this better implements the idea behind REST. There is
actually a statement from Roy Fielding himself, who suggest (or better
dictates) this course of action. Please read
http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hypertext-driven, and
countless discussions about the pros and cons, and as well HATEOAS
http://en.wikipedia.org/wiki/HATEOAS
In practice however, this is not always optimal for all applications. In case
of images though, we can easily see that returning an URI as the result of the
very first request is likely the better idea, than returning the whole staff at
once. The application can chose later to retrieve any more detail information -
using the URIs provided in the first request.
But eventually, we may need to retrieve the image data through its URI - and
this may be accomplished without using JSON, and still being completely RESTful.
There are third party JSON libraries which are capable to customize the
mapping, though. For instance, it might suffice to implement a method for a
Category for NSImage to accomplish this (JPJson library uses this approach
for example). That way, you can serialize a hierarchy of Foundation objects
which contains a NSImage - no matter where this occurs in the tree.
It's certainly possible to do that, but it doesn't seem like a good idea to
me, because there's no unambiguous data format associated with an image. Even
choosing between the two most obvious formats (JPEG and PNG) involves a
decision about trade-offs between fidelity loss and file size.
Thus, you *customize* the mapping - that is, you handle this case application
specific. Of course, this shall be in accordance to the protocol - the API.
I would instead have the app itself decide how to encode the image as data,
and then set up an unambiguous mapping from NSData to base64-encoded JSON
strings. (Of course on the other end it's trickier because how does the
decoder know what strings should be decoded to NSData and which should be
left alone? YAML has type annotations that provide for this, but JSON
doesn't.)
Alternatively, you could do this:
Instead of defining how an NSImage would serialize itself into JSON, you may
define how the owner of that said image object would serialize itself into a
JSON. Since it is assumed that this kind of object has enough context
information, it can select the right actions:
@interface Person {
@propery (NSString*) name;
@propery (NSString*) email;
@property (NSImage*) image;
}
A custom object would usually serialize itself as a JSON Object (aka
NSDictionary). How this can be actually accomplished in code, certainly depends
on the JSON library - and whether this is possible at all with this library.
Furthermore, the object shall of course serialize itself according the API
specified for this kind of Web-service.
Basically, in JPJson library you would need to implement a method for this
class Person (either Category or sub-class):
- (NSInteger) JPJson_serializeTo:(idJPJsonStreambufferProtocol) buffer
encoding:(JPUnicodeEncoding)encoding
options:(JPJsonWriterOptions)options
level:(NSUInteger)level;
Within that method, you would serialize the image - if required, or provide a
URI.
The API may specify all these details.
Andreas
—Jens
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Base64 encoding of NSImage
I am looking at available option to send an NSImage to a webserver. I came across gSoap however its licensing model makes it not suitable. Using REST / JSON seems like an easy option however NSDATA does not seem to be supported by the JSON Serialiser. The one remaining option I considered was to encode the image myself to base64 before including in the JSON request. This could work quite nicely, however there doesn't seem to be a standard method for base64 encoding. Any suggestion on how to best achieve this. Kind regards Alex ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
I think the answers given here will help you out: http://stackoverflow.com/questions/392464/any-base64-library-on-iphone-sdk [[[Brainchild alloc] initWithName:@Richard Altenburg] saysBestRegards]; Op 1 jul. 2012, om 17:23 heeft Alexander Hartner het volgende geschreven: I am looking at available option to send an NSImage to a webserver. I came across gSoap however its licensing model makes it not suitable. Using REST / JSON seems like an easy option however NSDATA does not seem to be supported by the JSON Serialiser. The one remaining option I considered was to encode the image myself to base64 before including in the JSON request. This could work quite nicely, however there doesn't seem to be a standard method for base64 encoding. Any suggestion on how to best achieve this. Kind regards Alex ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/cocoa-dev%40brainchild.nl This email sent to cocoa-...@brainchild.nl ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
I think that only cocoa collections can be supported by the JSON serializer. Even CLLocations aren't supported since they consist of structs. On Jul 1, 2012, at 11:23 AM, Alexander Hartner wrote: I am looking at available option to send an NSImage to a webserver. I came across gSoap however its licensing model makes it not suitable. Using REST / JSON seems like an easy option however NSDATA does not seem to be supported by the JSON Serialiser. The one remaining option I considered was to encode the image myself to base64 before including in the JSON request. This could work quite nicely, however there doesn't seem to be a standard method for base64 encoding. Any suggestion on how to best achieve this. Kind regards Alex ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/zav%40mac.com This email sent to z...@mac.com ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
Try here. it is a category for nsdata in this post. http://www.thohensee.com/?page_id=435 Tom Sent from my iPhone On Jul 1, 2012, at 10:26 AM, Alexander Hartner a...@j2anywhere.com wrote: I am looking at available option to send an NSImage to a webserver. I came across gSoap however its licensing model makes it not suitable. Using REST / JSON seems like an easy option however NSDATA does not seem to be supported by the JSON Serialiser. The one remaining option I considered was to encode the image myself to base64 before including in the JSON request. This could work quite nicely, however there doesn't seem to be a standard method for base64 encoding. Any suggestion on how to best achieve this. Kind regards Alex ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/tom.hohensee%40gmail.com This email sent to tom.hohen...@gmail.com ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
If you want to be sure which one works for you, it is probably best to read how Base64 encoding actually works, maybe you find out you can just as easily roll your own solution. Especially on a fast Mac desktop, it would not have to be the worlds' most efficient solution, it will be fast anyways, and always faster than the web server you are uploading to. This might help: http://email.about.com/cs/standards/a/base64_encoding.htm [[[Brainchild alloc] initWithName:@Richard Altenburg] saysBestRegards]; Op 1 jul. 2012, om 17:46 heeft Alexander Hartner het volgende geschreven: There seem to be a number of options listed on the suggested solution. Hard to see which one is best. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
On Sun, Jul 1, 2012, at 11:23 PM, Alexander Hartner wrote: I am looking at available option to send an NSImage to a webserver. I came across gSoap however its licensing model makes it not suitable. Using REST / JSON seems like an easy option however NSDATA does not seem to be supported by the JSON Serialiser. The one remaining option I considered was to encode the image myself to base64 before including in the JSON request. This could work quite nicely, however there doesn't seem to be a standard method for base64 encoding. Any suggestion on how to best achieve this. If you're in control over both the client and server, I'd suggest avoiding sending the image data over JSON. You're going to seriously inflate the file size by base64-encoding it, and for what purpose? You can be REST without using JSON. It would be much more efficient if you could just issue a PUT at a certain URL to upload the image data. --Kyle Sluder ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
On Sun, Jul 1, 2012 at 1:05 PM, Kyle Sluder k...@ksluder.com wrote: On Sun, Jul 1, 2012, at 11:23 PM, Alexander Hartner wrote: I am looking at available option to send an NSImage to a webserver. If you're in control over both the client and server, I'd suggest avoiding sending the image data over JSON. You're going to seriously inflate the file size by base64-encoding it, and for what purpose? You can be REST without using JSON. It would be much more efficient if you could just issue a PUT at a certain URL to upload the image data. I completely agree - don't encode it unless you're sure you really need that, such as if your webserver were a VAX and didn't understand 8 bit character encodings. You're going to balloon the resident memory size of the app, possibly dramatically if you're talking arbitrary images. --Jim ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
On Jul 1, 2012, at 8:23 AM, Alexander Hartner wrote: I am looking at available option to send an NSImage to a web server. The simplest way would jut be to PUT the raw JPEG/PNG/whatever data to a URL on the server. No need to encode it. I came across gSoap however its licensing model makes it not suitable. Plus, using SOAP for this would be like using an elaborate rickety Rube Goldberg device to swat a fly ;-) Using REST / JSON seems like an easy option however NSDATA does not seem to be supported by the JSON Serialiser. Yes, JSON doesn't support binary data, and the serializer doesn't do any magic type transformations for you. It's not a good idea to transmit base64-encoded data anyway, if you can possibly avoid it, as it'll make it ⅓ larger. —Jens smime.p7s Description: S/MIME cryptographic signature ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
On Jul 1, 2012, at 9:33 AM, Richard Altenburg (Brainchild) wrote: If you want to be sure which one works for you, it is probably best to read how Base64 encoding actually works, maybe you find out you can just as easily roll your own solution. Especially on a fast Mac desktop, it would not have to be the worlds' most efficient solution, it will be fast anyways, and always faster than the web server you are uploading to. Bad idea. You've now added some brand new bit-twiddling code to your app, and now you have to test it. Does it handle all lengths of data (there are 3 different cases, IIRC)? Does it work in big-endian and little-endian? Does it work in 64-bit? Does it work if the data is empty or less than 3 bytes long? If you've written a decoder, does it handle embedded line-breaks? Does it fail gracefully if the input is incorrect? Does it parse all lengths of input? You get the idea. It's always better to use an already-tested library than to roll your own, if it's feasible. This is especially true of code that might be parsing untrusted input data (such as a base64 decoder) since bugs in that code can often be exploited as attacks. [I'm aware that the OP doesn't need a decoder for this purpose; but I'm talking about the more general issues.] —Jens smime.p7s Description: S/MIME cryptographic signature ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Base64 encoding of NSImage
This is what I use. Short and sweet.
@implementation NSData (Base64)
- (NSData *)dataWithBase64Encoding
{
CFDataRef retval = NULL;
SecTransformRef encodeTrans =
SecEncodeTransformCreate(kSecBase64Encoding, NULL);
if (encodeTrans != NULL) {
if (SecTransformSetAttribute(encodeTrans,
kSecTransformInputAttributeName, (__bridge CFDataRef)self, NULL))
retval = SecTransformExecute(encodeTrans, NULL);
CFRelease(encodeTrans);
}
return CFBridgingRelease(retval);
}
- (NSData *)dataFromBase64Decoding
{
CFDataRef retval = NULL;
SecTransformRef decodeTrans =
SecDecodeTransformCreate(kSecBase64Encoding, NULL);
if (decodeTrans != NULL) {
if (SecTransformSetAttribute(decodeTrans,
kSecTransformInputAttributeName, (__bridge CFDataRef)self, NULL))
retval = SecTransformExecute(decodeTrans, NULL);
CFRelease(decodeTrans);
}
return CFBridgingRelease(retval);
}
@end
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Re: Base64 encoding of NSImage
On Jul 1, 2012, at 12:16 PM, David Riggle wrote: This is what I use. Short and sweet. 10.7-only, though. (And not available on iOS.) —Jens ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
