what is the difference between json and xml

Question

What is the difference between JSON and XML

User · Answer

XML uses a tag structures for presenting items, like <tag>item</tag>, so an XML document is a set of tags nested into each other. And JSON syntax looks like a construction from Javascript language, with all stuff like lists and dictionaries:

{
 'attrib' : 'value',
 'array' : [1, 2, 3]
}

So if you use JSON it's really simple to use a JSON strings in many script languages, especially Javascript and Python.

User · Answer

They re two different ways of representing data  but they re pretty dissimilar  The wikipedia pages for JSON and XML give some examples of each  and there s a comparison paragraph

User · Answer

The fundamental difference  which no other answer seems to have mentioned  is that XML is a markup language  as it actually says in its name   whereas JSON is a way of representing objects  as also noted in its name    A markup language is a way of adding extra information to free-flowing plain text  e g  Here is some text    With XML  using a certain element vocabulary  you can put    lt Document gt       lt Paragraph Align  Center  gt          Here  lt Bold gt is lt  Bold gt  some text       lt  Paragraph gt   lt  Document gt    This is what makes markup languages so useful for representing documents   An object notation like JSON is not as flexible  But this is usually a good thing  When you re representing objects  you simply don t need the extra flexibility  To represent the above example in JSON  you d actually have to solve some problems manually that XML solves for you          Paragraphs                            align    center                content                      Here                           style     bold                        content      is                                         some text                                     It s not as nice as the XML  and the reason is that we re trying to do markup with an object notation  So we have to invent a way to scatter snippets of plain text around our objects  using  content  arrays that can hold a mixture of strings and nested objects   On the other hand  if you have typical a hierarchy of objects and you want to represent them in a stream  JSON is better suited to this task than HTML          firstName    Homer        lastName    Simpson        relatives      Grandpa    Marge    The Boy    Lisa    I think that s all of them         Here s the logically equivalent XML    lt Person gt       lt FirstName gt Homer lt  FirstName gt       lt LastName gt Simpsons lt  LastName gt       lt Relatives gt           lt Relative gt Grandpa lt  Relative gt           lt Relative gt Marge lt  Relative gt           lt Relative gt The Boy lt  Relative gt           lt Relative gt Lisa lt  Relative gt           lt Relative gt I think that s all of them lt  Relative gt       lt  Relatives gt   lt  Person gt    JSON looks more like the data structures we declare in programming languages  Also it has less redundant repetition of names    But most importantly of all  it has a defined way of distinguishing between a  record   items unordered  identified by names  and a  list   items ordered  identified by position   An object notation is practically useless without such a distinction  And XML has no such distinction  In my XML example  lt Person gt  is a record and  lt Relatives gt  is a list  but they are not identified as such by the syntax   Instead  XML has  elements  versus  attributes   This looks like the same kind of distinction  but it s not  because attributes can only have string values  They cannot be nested objects  So I couldn t have applied this idea to  lt Person gt   because I shouldn t have to turn  lt Relatives gt  into a single string   By using an external schema  or extra user-defined attributes  you can formalise a distinction between lists and records in XML  The advantage of JSON is that the low-level syntax has that distinction built into it  so it s very succinct and universal  This means that JSON is more  self describing  by default  which is an important goal of both formats   So JSON should be the first choice for object notation  where XML s sweet spot is document markup   Unfortunately for XML  we already have HTML as the world s number one rich text markup language  An attempt was made to reformulate HTML in terms of XML  but there isn t much advantage in this   So XML should  in my opinion  have been a pretty limited niche technology  best suited only for inventing your own rich text markup languages if you don t want to use HTML for some reason  The problem was that in 1998 there was still a lot of hype about the Web  and XML became popular due to its superficial resemblance to HTML  It was a strange design choice to try to apply to hierarchical data a syntax actually designed for convenient markup

User · Answer

They are both data formats for hierarchical data  so while the syntax is quite different  the structure is similar  Example   JSON        persons                  name    Ford Prefect          gender    male                      name    Arthur Dent          gender    male                      name    Tricia McMillan          gender    female                XML    lt persons gt     lt person gt       lt name gt Ford Prefect lt  name gt       lt gender gt male lt  gender gt     lt  person gt     lt person gt       lt name gt Arthur Dent lt  name gt       lt gender gt male lt  gender gt     lt  person gt     lt person gt       lt name gt Tricia McMillan lt  name gt       lt gender gt female lt  gender gt     lt  person gt   lt  persons gt    The XML format is more advanced than shown by the example  though  You can for example add attributes to each element  and you can use namespaces to partition elements  There are also standards for defining the format of an XML file  the XPATH language to query XML data  and XSLT for transforming XML into presentation data   The XML format has been around for some time  so there is a lot of software developed for it  The JSON format is quite new  so there is a lot less support for it   While XML was developed as an independent data format  JSON was developed specifically for use with Javascript and AJAX  so the format is exactly the same as a Javascript literal object  that is  it s a subset of the Javascript code  as it for example can t contain expressions to determine values

User · Answer

They are two formats of representation of information  While JSON was designed to be more compact  XML was design to be more readable

User · Answer

The difference between XML and JSON is that XML is a meta-language markup language and JSON is a lightweight data-interchange  That is  XML syntax is designed specifically to have no inherent semantics  Particular element names don t mean anything until a particular processing application processes them in a particular way  By contrast  JSON syntax has specific semantics built in stuff between    is an object  stuff between    is an array  etc   A JSON parser  therefore  knows exactly what every JSON document means  An XML parser only knows how to separate markup from data  To deal with the meaning of an XML document  you have to write additional code    To illustrate the point  let me borrow Guffa s example        persons              name    Ford Prefect        gender    male             name    Arthur Dent       gender    male                name    Tricia McMillan        gender    female              The XML equivalent he gives is not really the same thing since while the JSON example is semantically complete  the XML would require to be interpreted in a particular way to have the same effect  In effect  the JSON is an example uses an established markup language of which the semantics are already known  whereas the XML example creates a brand new markup language without any predefined semantics    A better XML equivalent would be to define a  fictitious  XJSON language with the same semantics as JSON  but using XML syntax  It might look something like this    lt xjson gt        lt object gt       lt name gt persons lt  name gt       lt value gt         lt array gt            lt object gt               lt value gt Ford Prefect lt  value gt               lt gender gt male lt  gender gt            lt  object gt            lt object gt               lt value gt Arthur Dent lt  value gt               lt gender gt male lt  gender gt            lt  object gt            lt object gt               lt value gt Tricia McMillan lt  value gt               lt gender gt female lt  gender gt            lt  object gt         lt  array gt       lt  value gt        lt  object gt     lt  xjson gt    Once you wrote an XJSON processor  it could do exactly what JSON processor does  for all the types of data that JSON can represent  and you could translate data losslessly between JSON and XJSON   So  to complain that XML does not have the same semantics as JSON is to miss the point  XML syntax is semantics-free by design  The point is to provide an underlying syntax that can be used to create markup languages with any semantics you want  This makes XML great for making up ad-hoc data and document formats  because you don t have to build parsers for them  you just have to write a processor for them   But the downside of XML is that the syntax is verbose  For any given markup language you want to create  you can come up with a much more succinct syntax that expresses the particular semantics of your particular language  Thus JSON syntax is much more compact than my hypothetical XJSON above    If follows that for really widely used data formats  the extra time required to create a unique syntax and write a parser for that syntax is offset by the greater succinctness and more intuitive syntax of the custom markup language  It also follows that it often makes more sense to use JSON  with its established semantics  than to make up lots of XML markup languages for which you then need to implement semantics   It also follows that it makes sense to prototype certain types of languages and protocols in XML  but  once the language or protocol comes into common use  to think about creating a more compact and expressive custom syntax    It is interesting  as a side note  that SGML recognized this and provided a mechanism for specifying reduced markup for an SGML document  Thus you could actually write an SGML DTD for JSON syntax that would allow a JSON document to be read by an SGML parser  XML removed this capability  which means that  today  if you want a more compact syntax for a specific markup language  you have to leave XML behind  as JSON does

[xml] what is the difference between json and xml

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