1.2 Introduction CYFS for Developers: Named data and data property rights

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Named data and data property rights

Named data

1. Data name

Any Data is named with it's hash, any modification will change its name. This is a key design, it will ensure that the data you reference has not been tampered with.

2. Named Data

Any data named in this way is called Named Data.

3. Named Object

Data is divided into structured data and unstructured data, and structured data is called Object, Any Object named in this way is called Named Object.

4. Immutable and mutable

In principle, Object is immutable, if you need to change it, create a new object.

But for convenience, there is a design to modify it:

The content of Object is split into two parts:

• Desc: immutable, the ObjectId is calculate with this part.the size is limmited at 64KBytes.
• Body: mutable, It has nothing to do with ObjectId. We can update the body without modify the ObjectId. Therefore, developers must consider how to ensure that the Body is the version we need.

ObjectId structure

1. Area

Every object should belong to a different Area, and accept the legal supervision of the corresponding Area.

• country: 9bits
• carrier: 4bits
• city: 13bits
• inner: 8bits // set by the creator.

2. ObjectType

Any Object requires a field that explicitly specifies its type, it's ObjectType.

All types are divided into 4 categories:

• Standuard: It's the basic types defined in cyfs-base. Collected in the module cyfs-base.
• Core: Objects with general semantics gradually formed during the development of CYFS. Collected in the module cyfs-core.
• DecAppObject: Objects defined by an application developer to solve a specific problem in a specific application.
• Data: Short immediate value object.

3. ObjectId structure

The name of a Named Object is ObjectId.

The main component of ObjectId is the SHA256 of ObjectDesc, It also contains the type and area information.The total length is 32Bytes(256bits).

The structure is as follow:

ObjectId = Catgory(2bits) + DataContent(38bits) | CommonObjectId(38bits)

Catgory = Standuard(1) | Core(2) | DecAppObject(3) | Data(0)

if Catgory = Data(0) {
    DataContent = 0b_000000 + ImmediateValue(248bits)
} else {
    CommonObjectId = TypeDetail(4bits) + Area(34bits) + SHA256(`ObjectDesc`)[5..]
    TypeDetail = ObjectTypeCode | FieldFlags
    if Catgory = Standuard(1) {
        ObjectTypeCode = Device(1) | People(2) | Group(3) | AppGroup(5) | UnionAccount(6) | Chunk(7) | File(8) | Dir(9) | Diff(10) |
            ProofOfService(11) | Tx(12) | Action(13) | ObjectMap(14) | Contract(15)
    } else {
        FieldFlags = is_area_exist(1bit) + is_single_exist(1bit) + is_mult_key_exist(1bit) + is_owner_exist(1bit)
        is_area_exist = 1 | 0
        is_single_exist = 1 | 0
        is_mult_key_exist = 1 | 0
        is_owner_exist = 1 | 0
    }
    Area = country(9bits) + carrier(4bits) + city(13bits) + inner(8bits)
    * if the Area is not set the bits shoud be set to 0.
}

Data property rights

1. Entitled object

An object is said to be entitled object if it can provide proof of the authenticity of another object.It can be the owner of an object to own it.A common method of proof is the signature, so, most entitled object contains a key-pair,for example:People and Device.but a Group contains many People as the members, Its proof requires the signature of a majority of members.

2. Owned object

An object is said to be owned object if it's created with a owner, most public object is owned object,Any object of external origin without owner and signature is untrusted.

Owner is contained in the ObjectDesc, it's immutable field, it's always the creator.

3. Right to profit

The Owner is immutable, but there are many tradable objects(for example: NFT). the updated property is the Right to profit, that usually occurs on the chain. The immutable Owner strongly protects the copyright of the objects.