You just need to encode the size of values in bytes to make it possible to partially parse the format.
Imagine the following object:
{
"attributes": [ .. some really really long array of whatever .. ],
"name": "Bob"
}
In JSON, if you want to extract the "name" property, you need to parse the whole "attributes" array. However, if you encoded the size of the "attributes" array in bytes, a parser could look at the key "attributes", decide that it's not interested, and jump past it without parsing anything.
You'd typically want some kind of binary format, but for illustration purposes, here's an imaginary XML representation of the JSON data model which achieves this:
<object content-size-in-bytes="8388737">
<array key="attributes" content-size-in-bytes="8388608">
.. some 8 MiB large array of values ..
</array>
<string key="name" content-size-in-bytes="3">Bob</string>
</object>
If this was stored in a file, you could use fseek to seek past the "attributes" array. If it was compressed, or coming across a socket, you'd need more complicated mechanisms to seek past irrelevant parts of the object.
Imagine the following object:
In JSON, if you want to extract the "name" property, you need to parse the whole "attributes" array. However, if you encoded the size of the "attributes" array in bytes, a parser could look at the key "attributes", decide that it's not interested, and jump past it without parsing anything.You'd typically want some kind of binary format, but for illustration purposes, here's an imaginary XML representation of the JSON data model which achieves this:
If this was stored in a file, you could use fseek to seek past the "attributes" array. If it was compressed, or coming across a socket, you'd need more complicated mechanisms to seek past irrelevant parts of the object.