There exists a peculiar amnesia in software engineering regarding XML. Mention it in most circles and you will receive knowing smiles, dismissive waves, the sort of patronizing acknowledgment reserved for technologies deemed passé. “Oh, XML,” they say, as if the very syllables carry the weight of obsolescence. “We use JSON now. Much cleaner.”
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When you receive an XML document, you can verify its structure before you ever parse its content. This is not a luxury. This is basic engineering hygiene.
This is actually why my colleagues and I helped kill off XML.
XML APIs require extensive expertise to upgrade asynchronously (and this expertise is vanishingly rare). More typically all XML endpoints must be upgraded during the same unscheduled downtime.
JSON allows unexpected fields to be added and ignored until each participant can be upgraded, separately and asynchronously. It makes a massive difference in the resilience of the overall system.
I really really liked XML when I first adopted it, because before that I was flinging binary data across the web, which was utterly awful.
But XML for the web is exactly where it belongs - buried and forgotten.
Also, it is worth noting that JSON can be validated to satisfy that engineering impulse. The serialize/deserialize step will catch basic flaws, and then the validator simply has to be designed to know which JSON fields it should actually care about. This gets much more resilient results than XMLs brittle all-in-one shema specification system - which immediately becomes stale, and isn’t actually correct for every endpoint, anyway.
The shared single schema typically described every requirement of every endpoint, not any single endpoint’s actual needs. This resulted in needless brittleness, and is one reason we had such a strong push for “microservices”. Microservices could each justify their own schema, and so be a bit less brittle.
That said, I would love a good standard declarative configuration JSON validator, as long as it supported custom configs at each endpoint.
I’m sure XML has its uses
I’m also sure that for 99% of the applications out there, XML is overkill and over complicated, making things slower and more error prone
Use JSON, and you’ll be fine. If you really really need XML then you probably already know why
XMPP shows pretty well that XML can do things that cannot be done easily without it. XMPP wouldn’t work nearly as well with JSON. Namespaces are a super power.
I love XML, when it is properly utilized. Which, in most cases, it is not, unfortunately.
JSON > CSV though, I fucking hate CSV. I do not get the appeal. “It’s easy to handle” – NO, it is not. It’s the “fuck whoever needs to handle this” of file “formats”.
JSON is a reasonable middle ground, I’ll give you that
CSV >>> JSON when dealing with large tabular data:
- Can be parsed row by row
- Does not repeat column names, more complicated (so slower) to parse
1 can be solved with JSONL, but 2 is unavoidable.
Yes…but compression
And with csv you just gotta pray that you’re parser parses the same as their writer…and that their writer was correctly implemented…and they set the settings correctly
Biggest problem is, CSV is not a standardized format like JSON. For very simple cases it could be used as a database like format. But it depends on the parser and that’s not ideal.
JSON is easier to parse, smaller and lighter on resources. And that is important in the web. And if you take into account all the features XML has, plus the entities it gets big, slow and complicated. Most data does not need to be self descriptive document when transferring through web. Fundementally these languages are two different kind of languages: XML is a general markup language to write documents, while JSON is a generalized data structure with support for various data types supported by programming languages.
while JSON is a generalized data structure with support for various data types supported by programming languages
Honestly, I find it surprising that you say “support for various data types supported by programming languages”. Data types are particularly weak in JSON when you go beyond JavaScript. Only
numberfor numbers, no integer types, no date, no time, etc.Regarding use, I see, at least to some degree, JSON outside of use for network transfer. For example, used for configuration files.
There exists a peculiar amnesia in software engineering regarding XML
That’s for sure. But not in the way the author means.
There exists a pattern in software development where people who weren’t around when the debate was actually happening write another theory-based article rehashing old debates like they’re saying something new. Every ten years or so!
The amnesia is coming from inside the article.
[XML] was abandoned because JavaScript won. The browser won.
This comes across as remarkably naive to me. JavaScript and the browser didn’t “win” in this case.
JSON is just vastly simpler to read and reason about for every purpose other than configuration files that are being parsed by someone else. Yaml is even more human-readable and easier to parse for most configuration uses… which is why people writing the configuration parser would rather use it than XML.
Libraries to parse XML were/are extremely complex, by definition. Schemas work great as long as you’re not constantly changing them! Which, unfortunately, happens a lot in projects that are earlier in development.
Switching to JSON for data reduced frustration during development by a massive amount. Since most development isn’t building on defined schemas, the supposed massive benefits of XML were nonexistent in practice.
Even for configuration, the amount of “boilerplate” in XML is atrocious and there are (slightly) better things to use. Everyone used XML for configuration for Java twenty years ago, which was one of the popular backend languages (this author foolishly complains about Java too). I still dread the massive XML configuration files of past Java. Yaml is confusing in other ways, but XML is awful to work on and parse with any regularity.
I used XML extensively back when everyone writing asynchronous web requests was debating between using the two (in “AJAX”, the X stands for XML).
Once people started using JSON for data, they never went back to XML.
Syntax highlighting only works in your editor, and even then it doesn’t help that much if you have a lot of data (like configuration files for large applications). Browsers could even display JSON with syntax highlighting in the browser, for obvious reasons — JSON is vastly simpler and easier to parse.
God, fucking camel and hibernate xml were the worst. And I was working with that not even 15 years ago!
Making XML schemas work was often a hassle. You have a schema ID, and sometimes you can open or load the schema through that URL. Other times, it serves only as an identifier and your tooling/IDE must support ID to local xsd file mappings that you configure.
Every time it didn’t immediately work, you’d think: Man, why don’t they publish the schema under that public URL.
This seriously sounds like a nightmare.
It’s giving me Eclipse IDE flashbacks where it seemed so complicated to configure I just hoped it didn’t break. There were a lot of those, actually.
IMHO one of the fundamental problems with XML for data serialization is illustrated in the article:
(person (name "Alice") (age 30))
[is serialized as]<person> <name>Alice</name> <age>30</age> </person>Or with attributes:
<person name="Alice" age="30" />The same data can be portrayed in two different ways. Whenever you serialize or deserialize data, you need to decide whether to read/write values from/to child nodes or attributes.
That’s because XML is a markup language. It’s great for typing up documents, e.g. to describe a user interface. It was not designed for taking programmatic data and serializing that out.
JSON also has arrays. In XML the practice to approximate arrays is to put the index as an attribute. It’s incredibly gross.
In XML the practice to approximate arrays is to put the index as an attribute. It’s incredibly gross.
I don’t think I’ve seen that much if ever.
Typically, XML repeats tag names. Repeating keys are not possible in JSON, but are possible in XML.
<items> <item></item> <item></item> <item></item> </items>That’s correct, but the order of tags in XML is not meaningful, and if you parse then write that, it can change order according to the spec. Hence, what you put would be something like the following if it was intended to represent an array.
<items> <item index="1"></item> <item index="2"></item> <item index="3"></item> </items>https://www.w3.org/TR/2004/REC-xml-infoset-20040204/
[children] An ordered list of child information items, in document order.
Does this not cover it?
Do you mean if you were to follow XML standard but not XML information set standard?
Information set isn’t a description of XML documents, but a description of what you have that you can write to XML, or what you’d get when you parse XML.
This is the key part from the document you linked
The information set of an XML document is defined to be the one obtained by parsing it according to the rules of the specification whose version corresponds to that of the document.
This is also a great example of the complexity of the XML specifications. Most people do not fully understand them, which is a negative aspect for a tool.
As an aside, you can have an enforced order in XML, but you have to also use XSD so you can specify xsd:sequence, which adds complexity and precludes ordered arrays in arbitrary documents.
This is your confusion, not an issue with XML.
Attributes tend to be “metadata”. You ever write HTML? It’s not confusing.
Having to make a decision isn’t my primary issue here (even though it can also be problematic, when you need to serialize domain-specific data for which you’re no expert). My issue is rather in that you have to write this decision down, so that it can be used for deserializing again. This just makes XML serialization code significantly more complex than JSON serialization code. Both in terms of the code becoming harder to understand, but also just lines of code needed.
I’ve somewhat come to expect less than a handful lines of code for serializing an object from memory into a file. If you do that with XML, it will just slap everything into child nodes, which may be fine, but might also not be.Having to make a decision isn’t my primary issue here (even though it can also be problematic, when you need to serialize domain-specific data for which you’re no expert). My issue is rather in that you have to write this decision down, so that it can be used for deserializing again. This just makes XML serialization code significantly more complex than JSON serialization code. Both in terms of the code becoming harder to understand, but also just lines of code needed.
This is, without a doubt, the stupidest argument against XML I’ve ever heard. Nobody has trouble with using attributes vs. tag bodies. Nobody. There are much more credible complaints to be made about parsing performance, memory overhead, extra size, complexity when using things like namespaces, etc.
I’ve somewhat come to expect less than a handful lines of code for serializing an object from memory into a file. If you do that with XML, it will just slap everything into child nodes, which may be fine, but might also not be.
No - it is fine to just use tag bodies. You don’t need to ever use attributes if you don’t want to. You’ve never actually used XML have you?
https://www.baeldung.com/jackson-xml-serialization-and-deserialization
Okay, dude, glad to have talked.
In HTML, which things are attributes and which things are tags are part of the spec. With XML that is being used for something arbitrary, someone is making the choice every time. They might have a different opinion than you do, or even the same opinion, but make different judgments on occasion. In JSON, there are fewer choices, so fewer chances for people to be surprised by other people’s choices.
I mean, yeah. But people don’t just do things randomly. Most people put data in the body and metadata in attributes just like html.
The same data can be portrayed in two different ways.
And that is issue why? The specification decided which one you use and what do you need. For some things you consider things as attributes and for some things they are child elements.
JSON doesn’t even have attributes.
Alright, I haven’t really looked into XML specifications so far. But I also have to say that needing a specification to consistently serialize and deserialize data isn’t great either.
And yes, JSON not having attributes is what I’m saying is a good thing, at least for most data serialization use-cases, since programming languages do not typically have such attributes on their data type fields either.
I worded my answer a bit wrongly.
In XML
<person><name>Alice</name><age>30</age></person>is different from<person name="Alice" age="30" />and they will never (de)serialize to each other. The original example by the articles author with the person is somewhat misguided.They do contain the same bits of data, but represent different things and when designing your dtd / xsd you have to decide when to use attributes and when to use child elements.
Ah, well, as far as XML is concerned, yeah, these are very different things, but that’s where the problem stems from. In your programming language, you don’t have two variants. You just have
(person (name "Alice") (age 30)). But then, because XML makes a difference between metadata and data, you have to decide whether “name” and “age” are one or the other.And the point I wanted to make, which perhaps didn’t come across as well, is that you have to write down that decision somewhere, so that when you deserialize in the future, you know whether to read these fields from attributes or from child nodes.
And that just makes your XML serialization code so much more complex than it is for JSON, generally speaking. As in, I can slap down JSON serialization in 2 lines of code and it generally does what I expect, in Rust in this case.Granted, Rust kind of lends itself to being serialized as JSON, but well, I’m just not aware of languages that lend themselves to being serialized as XML. The language with the best XML support that I’m aware of, is Scala, where you can actually get XML literals into the language (these days with a library, but it used to be built-in until Scala 3, I believe): https://javadoc.io/doc/org.scala-lang.modules/scala-xml_2.13/latest/scala/xml/index.html
But even in Scala, you don’t use acase classfor XML, which is what you normally use for data records in the language, but rather you would take the values out of yourcase classand stick them into such an XML literal. Or I guess, you would use e.g. the Jackson XML serializer from Java. And yeah, the attribute vs. child node divide is the main reason why this intermediate step is necessary. Meanwhile, JSON has comparatively little logic built into the language/libraries and it’s still a lot easier to write out: https://docs.scala-lang.org/toolkit/json-serialize.html
It can be used as alternatives. In MSBuild you can use attributes and sub elements interchangeably. Which, if you’re writing it, gives you a choice of preference. I typically prefer attributes for conciseness (vertical density), but switch to subelements once the length/number becomes a (significant) downside.
Of course that’s more of a human writing view. Your point about ambiguity in de-/serialization still stands at least until the interface defines expectation or behavior as a general mechanism one way or the other, or with specific schema.
Honestly, anyone pining for all the features of XML probably didn’t live through the time when XML was used for everything. It was actually a fucking nightmare to account for the existence of all those features because the fact they existed meant someone could use them and feed them into your system. They were also the source of a lot of security flaws.
This article looks like it was written by someone that wasn’t there, and they’re calling people telling them the truth that they are liars because they think features they found in w3c schools look cool.
The fact that json serializes easily to basic data structures simplifies code so much. Most use cases don’t need fully sematic data storage much of which you have to write the same amount of documentation about the data structures anyways. I’ll give XML one thing though, schemas are nice and easy, but high barrier to entry in json.
Most use cases don’t need fully sematic data storage
If both sides have a shared data model it’s a good base model without further needs. Anything else quickly becomes complicated because of the dynamic nature of JSON - at least if you want a robust or well-documented solution.
If both sides have a shared data model
If the sides don’t have a common understanding of the data structure, no format under the sun will help.
The point is that there are degrees to readability, specificity, and obviousness, even without a common understanding. Self-describing data, much like self-describing code, is different from a dense serialization without much support in that regard.
Yeah, when the same API endpoint sometimes return a string for an error, sometimes an object, and sometimes an array, JSON doesn’t help much in parsing the mess
It’s true, though, that JSON is just better for most applications.
Except config files. Please don’t do config files in json.
Yaml
Fuck yaml. TOML or literally anything else.
Why not? It works great in Python.
Not on the human parser side.
JSON is super easy to read and write though. Just needs a parser that allows comments…
That’s JSON5 or JSONC
Yes, which needs to be supported by your parser.
And no comments, unless you use a non-standard parser. But then you might as well use anorher format.
{"comment": "Who says you can't do comments in JSON?"}Now do a second comment.
{"comment2": "I can do this all day."}
Lol. That works, but its hacky.
The meaning of a “comment” is an integrated language feauture to write something that is not parsed by that language. This is just regular JSON.
This only works if the software that consumes the JSON doesn’t validate it or ignores keys it doesn’t recognize (which is bad, IMHO).
Json configs read much cleaner to me since .net swapped to them a while back.
Xml is incredibly verbose when there’s a 12k loc web.config.xml
Then do a cfg or ini style config or make multiple config files. YAML/TOML if you can’t make it simpler. The neccessity for complex config formats is a fuckup of the dev.
Or you work in an environment that’s still using Full Framework and ASP.NET Webforms.
These places exist, and they are unfortunately not rare.
My condolences.
deleted by creator
ASN.1 crying in the corner.
IMO, the best thing about YAML is the referencing. It’s super easy to reuse an object multiple times. Gives that same kind of parten child struct ability that programming languages have. Sure XML can do it, but it’s not in every parser. cough python built in parser cough But then YAML is also not a built in parser and doing DOM in things other than XML feels odd.
That capability is what enables billion laugh attacks, unfortunately, so not having it enabled in cases where there is external input possible is wise
While I understand the critic about XPath and XSL, the fact that we have proper tools to query and tranform XML instead of the messy wat of getting specific information from JSON is also one of tge strong point of XML.
There is JSONPath, at least: https://en.wikipedia.org/wiki/JSONPath
XSLT and XPath are entirely underrated. They are seriously powerful tools.
While you can approximate XSLT with a heap of coffee and a JSON parser it’s harder to keep it declarative.
Yeah, I wish I had something like XPath as consistently (in terms of availability and syntax) for JSON.
You do? jsonAta and JSONPath both exist and are very good.
Has no one here heard of
jq?
I never understood why people would say JSON is superior, and why XML seemed to be getting rarer, but the author explains it:
XML was not abandoned because it was inadequate; it was abandoned because JavaScript won.
I’ve been unsing it ever since I started using Linux because my favorite window manager uses it, and because of a long-running pet project that is almost just as old: first I used XML tools to parse web pages, later I switched to dedicated data providers that offered both XML and JSON formats, and stuck to what I knew.
I’m guessing that another reason devs - especially web devs - prefer JSON over XML is that the latter uses more bytes to transport the same amount of raw data. One XML file will be somewhat larger than one JSON file with the same content. That advantage is of course dwarved by all the other media and helper scripts - nay, frameworks, devs use to develop websites.
BTW, XML is very readable with syntax highlighting and easily editable if your code editor has some very basic completion for it. And it has comments!
You are clearly one of those people that never had to deal with xml in a production system. Even with proper syntax highlighting, dealing with xml is a nightmare, whether it’s for configuration or data transmission. People switched to JSON because it’s better. Period. And that’s an incredibly low bar to set, because I don’t think JSON is that good either.
Like another person said, all of these features of XML doesn’t make it nicer, it makes it worse, because it means you have to be ready for any of those features even if they’re never used.
There are really good uses for XML. Mostly for making things similar to HTML. Like markup for Android UIs or XAML for WPF. For pretty much everything else the complexity only brings headaches
The readability and obviousness of XML can not be overstated. JSON is simple and dense (within the limit of text). But look at JSON alone, and all you can do is hope for named fields. Outside of that, you depend on context knowledge and specific structure and naming context.
Whenever I start editing json config files I have to be careful about trailing commas, structure with opening and closing parens, placement and field naming. The best you can do is offer a default-filled config file that already has the full structure.
While XML does not solve all of it, it certainly is more descriptive and more structured, easing many of those pain points.
It’s interesting that web tech had XML in the early stages of AJAX, the dynamic web. But in the end, we sent JSON through
XMLHttpRequest. JSON won.
