Archive for February, 2011

JSON vs XML – Part 1: Data Size

In this test to compare XML vs JSON files data size, I transformed a sample of our XML data files to JSON, and I’ve obtained the following results:

File Name XML Size (bytes) JSON Size (bytes) Difference (bytes) Difference (%)
groups 6.218 3.379 – 2.839 -45.6 %
matches 14.541 8.823 -5.718 -39,3 %
scorers 1.250 652 -598 -47,8 %
TOTAL/Average 22.009 12.854 -9.155 -41,6 %

Well, after this first experiment it seems that I can save about 41,5 % on my data size if I change from XML to JSON files.

But wait! And if I reduce my tag/field names’ length to only 2 characters long?

Here are the new results that I obtained after that change…

File Name XML Size (bytes) JSON Size (bytes) Difference (bytes) Difference (%)
groups 3.444 2.934 -510 -14,8 %
matches 8.189 7.154 -1.035 -12,6 %
scorers 756 556 -200 -26,5 %
TOTAL/Average 12.389 10.644 -1.745 -14,1 %

Well, that size difference becomes reduced from near 41,5% to about 14%! It seems that with JSON I can save at least almost 2 KB per App update.

If I have 1.000 updates/day it gives less 2 MB of bandwidth which is perfectly negligible.With 1.000.000 updates/day it gives 2 GB/day, which becomes about 60 GB/month. It’s true that can save me some bucks if I’m paying a non unlimited bandwidth hosting service. But maybe it isn’t sufficient to make me change my App, specially if it doesn’t will make my App to be implemented faster and run significantly better.

By the way, until I publish the next post “JSON vs XML – Part 2: Parsing and Display Speed“, I recommend that you read an interesting article from Nicholas C. Zakas, which I found among many other articles about XML vs JSON: “Is JSON better than XML?“.

It compares several aspects of those two technologies in a succinct way.

Note: This is the first post of the “JSON vs XML – Data Size, Parsing and Display Speed” set.

JSON vs XML – Data Size, Parsing and Display Speed

In my previous post “App Interface and Data Update with UIWebViews, XML, XSLT and HTML“, I’ve written a little bit about how I have used XML to dynamically update and display our App’s data.

Following that, now that I’m preparing a new similar App, I’ve read lots of stuff about JSON and about JSON vs XML on the web, which is making me to consider the change of XML by JSON.

Many people argues that JSON is better than XML but that’s not clear and it seems that it depends a lot in what we need to do! Well, I know that’s not something new, it’s what happens most of the times when we’ve to choose some technology against other(s).

But I want to choose the “best” for my case, since I have plans to port this new App at least to Android OS and maybe to Windows Phone 7. And if that choice can reduce my total work in those platforms, it’ll be an important choice.

In general what I’ve seen is that XML is largely supported in all common browsers and in those mobile platforms. JSON is relatively new, however it’s becoming supported almost everywhere but mostly without native parsers.

That’s the case with iOS and WebKit (Safari’s engine). So I decided to do some previous experiments…

Since this article is growing a little more than I preview, I’ll publish the results of my tests in the following posts:

App Interface and Data Update with UIWebViews, XML, XSLT and HTML

I haven’t wrote almost anything about the development of my first App launched on the App Store: SA2010SS. Now it’s time for a little about that…

I’m picking up that code to reuse it on the next App, which will be similar  but this time, based on the National Soccer League(s) with the addition of one or two interesting features, I hope.

This post is focused on the strategy that I used for our App’s main interface and data updates.

Starting by the data updates, our App gets the data from the server, downloading three XML files, each one with:

  • match results;
  • standings;
  • best scorers.

For the user interface I’ve used some standard iPhone controls (mainly for buttons) but the main screen is almost filled with an UIWebView.

What that means?

That means that the mainly part of our App UI is done using standard HTML web pages. I had some problems to implement this “workflow”, but after achieving that, it allowed us to easily tune our UI, using standard web technologies: HTML + CSS.

The main pages/views are obtained via XSLT:

XML -> XSLT (with CSS) applied -> HTML

So, when the App updates data, it receives three XML files, the correspondent XML data for the screen that the user is seeing, is transformed applying a corresponding XSLT file and then the new HTML page is generated and presented on the UIWebView.

I know this method is not so fast as if I had only used iPhone controls from the UIKit Framework for the views. But the pages scroll and transitions are fluid, except on the first time the App creates and presents each view, which take maybe 2 or 3 seconds do appear.

That’s not perfect, but it was a nice trade-off which allowed us to cut some time (that would be used to learn to use those controls) on our App development and design.

Nevertheless, in the future maybe it’ll be easily to port it to Android OS or any other platform which supports web views.

I’d like to hear your opinions and suggestions about this scheme or better alternatives. Leave me a comment…

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