XML vs YAML vs JSON [closed]

Answer 1

Each will do the job.

JSON has the advantage of super-easy parsing in JavaScript, though you'll probably have to find and introduce a library in other languages.

XML has the advantage that more languages bundle the relevant libraries, and is useful for the storage you mention. So, it is valuable for passing around through different systems, both "in-motion" and "at-rest".

YAML has libraries for all languages, but is somewhat less commonly used, so you are more likely to have to find and introduce a library.

Answer 2

Choose XML if you need to interoperate with systems you don't control (XML Schema is invaluable here), if you will be transforming the data extensively into text, HTML, or XML (haters notwithstanding, XSLT is peerless), if your data includes a lot of text markup, if your data needs to be human-editable (haters notwithstanding, editable XML that's validated against a schema is a pretty good tool for a lot of jobs), and/or if you need to interoperate any of the myriad of tools and technologies that work with XML.

Choose JSON if you really can't be bothered with any of the above.

Choose YAML if you're working in an environment that's got a lot of YAML support.

Answer 3

I think XML has been thoroughly explained by the others. However, YAML and JSON are both elegant languages, and they are not as similar as you might believe at first glance.

Some of the particularities about YAML

• References

  - person: &id002
      name:   James
      age:    5.0
  
  - person: *id001
  

  The second person is an associative array equal to the first.

• Casting data types

  foobar: !!str 123
  

  foobar is "123" (type string).

• Uncommon data types not supported by every implementation

  Wikipedia:

  Particularly interesting ones [...] are sets, ordered maps, timestamps, and hexadecimal.

Therefore, I consider JSON a lot simpler.

An argument for JSON

Not just for JavaScript

While it might seem stupid to use the "JavaScript Object Notation" for your application if you don't use JavaScript, you should really consider it anyway, because the data types offered in JSON are probably the most common ones in your language too.

Readable, even if the whitespace is optional

I think JSON is very readable once prettified, which is very easy to do. YAML is difficult to make compact, since it relies on the whitespace. Granted, you should rely on compression for saving bandwidth. The references in YAML might save you a few bytes, but they add a lot of complexity. If you are really dealing with amounts of data that makes it important to avoid duplication, I'd suggest solving that problem on a whole other level. Not even XML supports these kind of macros.

Answer 4

If the data's not hierarchical or going to have data interspersed in e.g., the description This product is great for <targetDemo/> who love it's <featureSet/>), you may want to consider Comma Separated Values (CSV) or some other format like tab separated.

It's old school but it gets the job done without weighing your file down with a bunch of describing text. I.e., in XML, you'd have the following non-value data for each feed.

<feed name="" price="" type="" description=""/>

...contrasted with CSV:

"", , "", ""

If you want, you can add header row at the top for documentation purposes.

There's also plenty of tooling around CSV, from command line utilities like awk to GUIs such as Excel.

Another alternative, if you don't really need the data to be editable via a text editor but don't want to deploy a more robust database service, would be SQLite which allows you to perform RDBMS-style CRUD operations on a flat binary file.

Answer 5

JSON would be my pick. JSON and YAML are lightweight and easy to get started with (no formal Schema required). JSON is more widely used and more compatible with various other technologies than YAML. For example, PHP has a built-in function to decode or encode JSON, not YAML. JavaScript of course just loves JSON, considering it’s a strict subset of valid JavaScript.

Answer 6

Depends on your needs. For small, lightweight apps I personally think XML is overkill: http://www.codinghorror.com/blog/2008/05/xml-the-angle-bracket-tax.html

I prefer YAML in that case. for interaction with javascript use json. If you truly need to define your own grammar (read: schema) then xml is it. Very powerful, you have to decide what you are trying to do - otherwise your question is too broad to give a definitive answer.