How does JSON compare to XML in terms of file size and serialisation/deserialisation time?

Question

I have an application that performs a little slow over the internet due to bandwidth reasons. I have enabled GZip which has improved download time by a significant amout, bu

Answer 1

In terms of object serialization, JSON will generally be more compact (even when compressed). For Example:

I serialized the same instance of an object into both XML and JSON and got the following:

JSON

{
    "Account": "2222",
    "Login": "124235",
    "SalesId": null,
    "CustomerReference": "9652358474",
    "Status": null,
    "DropShip": 0,
    "PromoCode": null,
    "Notes": "For the truck",
    "Errors": null,
    "ReferenceId": null,
    "PaymentMethod": "CKPhone",
    "CheckPayment": {
        "Name": "Simon Riggs",
        "CompanyName": "Darth Inc",
        "AccountNumber": "565555555",
        "RoutingNumber": "222224455116",
        "CheckNumber": "32",
        "Address": {
            "Attention": null,
            "Street1": "555 W Portebello Rd",
            "Street2": null,
            "City": "London",
            "State": "Texas",
            "Zipcode": "45217",
            "Country": null,
            "ReferenceId": null,
            "GetAxType": 2
        },
        "ReferenceId": null,
        "GetAxType": 2
    },
    "CreditCardPayment": {
        "Name": "Simon Riggs",
        "CardNumber": "1111222233334444",
        "Cvv2": "546",
        "Month": 10,
        "Year": 2018,
        "Address": {
            "Attention": null,
            "Street1": "555 W Portebello Rd",
            "Street2": null,
            "City": "London",
            "State": "Texas",
            "Zipcode": "45217",
            "Country": null,
            "ReferenceId": null,
            "GetAxType": 2
        },
        "ReferenceId": "0",
        "GetAxType": 2
    },
    "ShippingAddress": {
        "Attention": "Simon Riggs",
        "Street1": "555 W Portebello Rd",
        "Street2": null,
        "City": "London",
        "State": "Texas",
        "Zipcode": "45217",
        "Country": null,
        "ReferenceId": null,
        "GetAxType": 2
    },
    "Totals": {
        "SubTotal": 25.0,
        "TotalTax": 5.0,
        "ShippingTotal": 10.0,
        "ShippingTax": 1.5,
        "GrandTotal": 35.0
    },
    "Lines": [{
        "SKU": "1442-4521",
        "LineNum": 0.0,
        "Qty": 2.0,
        "Price": 72.95,
        "ShippingClass": "Ground",
        "ReferenceId": null,
        "GetAxType": 2
    },
    {
        "SKU": "1212-5549",
        "LineNum": 0.0,
        "Qty": 1.0,
        "Price": 31.15,
        "ShippingClass": "Ground",
        "ReferenceId": null,
        "GetAxType": 2
    }],
    "GetAxType": 2
}

XML

  2222
  124235
  9652358474
  0
  For the truck
  CKPhone
  
    Simon Riggs
    Darth Inc
    565555555
    222224455116
    32
    

      555 W Portebello Rd
      London
      Texas
      45217
    
  
  
    Simon Riggs
    1111222233334444
    546
    10
    2018
    

      555 W Portebello Rd
      London
      Texas
      45217
    
    0
  
  
    Simon Riggs
    555 W Portebello Rd
    London
    Texas
    45217
  
  
    25
    5
    10
    1.5
    35
  
  
    
      1442-4521
      0
      2
      72.95
      Ground
    
    
      1212-5549
      0
      1
      31.15
      Ground
    
  

When encoded in ASCII, the JSON is 1422 bytes while the XML is 1954 bytes. After compressing them using a GZipStream, the difference is smaller but still pretty clear. The JSON compresses down to 524 bytes while the XML compresses down to 695 bytes.

Serialization/deserialization time will vary by implementation (and hardware of course) but I serialized and deserialized the above JSON and XML 100,000 times in a loop and got the total accumulative times:

JSON Serialization: 5258 ms, XML Serialization: 3266 ms

JSON Deserialization: 9582 ms, XML Deserialization: 4604 ms

So XML serializes and deserializes faster using the libraries I'm using (see below), but with averages measuring in the hundredths of milliseconds, I'd say network bandwidth and transfer time is more consequential.

(Note: I did this in C# using Microsoft's System.Xml.Serialization.XmlSerializer and JSON.Net's Newtonsoft.Json.JsonConvert classes)