[rraway]

I could do with some clarification on what problem the product solves, and actually, what the product even is. To me this looks like a new DB, and an ORM style interface to interact with it?

I like that it is multi-platform, but SQLLite is a pretty mature DB store available on all the major platforms anyway. I get that it is faster... but presumably there are there trade-offs for this speed gain. I would like a better understanding of what they are. Transaction support?

(PS: I would also much prefer if your objects can be typed in a way so they are plain, rather than forced inheritance from RLMObject)

EDIT: The blog post at http://realm.io/news/introducing-realm/ answers some of these questions.

[timanglade]

Absolutely. There’s a lot more details in our launch blogpost [0], but you got the right impression: it’s a custom C++ storage engine underneath (not SQLite), that is tightly integrated with the object layer. Not an ORM per se, because the engine isn’t relational, and because there’s not copying/mapping/translation going on — the data on disk is the same data you manipulate in your language.

The big problems we try to solve are really ease of use & performance. We heard from many developers dissatisfied with the current options on mobile, and the relative complexity to accomplish tasks like accessing data across threads, JSON handling, performance on graph queries, etc. — which the reactions on Twitter seem to confirm. We’ll write a lot more about the tradeoffs in coming weeks, but we’ve really grabbed a lot of perf cycles just by taking advantage of modern techniques such as zero-copy architectures, bitpacking and vectorization. Of course the big implicit tradeoff is that you give up a bit of the relational paradigm in exchange for that speed, although we do maintain ACID transactions, immediate disk persistence by default and schemas.

Completely hear you on wanting plain objects — I personally feel that way too! Unfortunately, there’s no way to achieve what we do without making you inherit from RLMObject, although we do try to make those behave as close as possible to NSObject.

[0] http://realm.io/news/introducing-realm/

[webstersx]

Although I don't know exactly what the implications are just yet, I've created a category on one of my RLMObject subclasses which accepts an NSArray or NSDictionary property and in the getter/setter converts to and from the NSData backing property. The only thing is after [Venue creatInDefaultRealmWithObject:] I have to explicity set the value for it to propogate to the backing NSData property.

It's extra work, but it lets me manipulate Realm into doing what I want it to do to store data which doesn't conform to an explicit schema. (e.g. a Venue which has an array of address strings, where I don't want the headache of iterating through venue.address[i].string values:

(note: this doesn't look pretty, its doing some funky formatting!)

"venue" : { "name":"Test Venue", "address" : [ "address line 1", "address line 2", "address line 3 for rare instances" ] }

@interface Venue : RLMObject @property NSString name; @property NSData addressData; @end

@interface Venue (AddressToData) @property NSArray address; @end

+ (NSDictionary )defaultPropertyValues { return @{ @"addressData":[NSJSONSerialization dataWithJSONObject:@[] options:0 error:nil] }; }

- (NSArray) address { NSArray address = nil;

    if (self.addressData) {
        address = [NSJSONSerialization JSONObjectWithData:self.addressData options:0 error:nil];
    } else {
        address = @[];
    }
        
    return address;

}

- (void) setAddress:(NSArray )address { if (!address) { address = @[]; }

    NSData *data = [NSJSONSerialization dataWithJSONObject:address options:0 error:nil];
    
    self.addressData = data;
}

[webstersx]

    RLMRealm *realm = [RLMRealm defaultRealm];
    [realm beginWriteTransaction];
    
    for (NSDictionary *v in json[@"venues"]) {
        Venue *venue = [Venue createInDefaultRealmWithObject:v];
        NSArray *address = v[@"address"];
        venue.address = address;
    }
    
    [realm commitWriteTransaction];