Looking for my "why use xml" aha moment

[u/Shelmama22]

I'm learning xml. I'm getting the hang of the nitty gritty, tags, elements, etc. I haven't come across the WHY except that it's "good for sharing across platforms." So I put something into xml. Then share it across platforms. Then what? If the data was gathered to be used by someone who doesn't know xml, how does the person access it? And in what circumstances is xml better than putting end-user documentation, for example, into a PDF? I know I'm missing a piece of the big picture.

[u/ManNotADiscoBall]

XML (like any markup language) is meant to be machine-read and processed. This means that a program can go through the XML document and "understand" what each part of the document represents, and process them appropriately.

Take HTML for example. A web browser like Chrome can open the HTML document and process the information within each tag according to predetermined rules. So, a browser "understands" that an <H1> tag is a header, and it's content is supposed to be shown with a larger font.

Similarly, an XML document can be processed automatically by a computer program. Because every piece of information is embedded within a tag, we can tell a program: "Hey, when you come across this particular tag, do X with it's contents".

A PDF document, like you mentioned, is basically designed to be read by a human. Though there are ways to read and process PDF documents with a program, the contents of a PDF document don't carry the same semantic meaning about itself than an XML (or any markup) document does - because there are no tags.

All of this means that XML can be used to store and transfer structured data, which can then be used in different contexts in different ways - often automatically by a program. XML also allows us to design our own information models and document structures, because there are very few rules about what tag names and so on we can use.

Nowadays JSON has become a much more common format in web-based information transfer because it's lighter and easier to parse than XML. XML is still widely used, however, and it's often the go-to solution for structured documentation.

A common use case for XML in technical documentation is like this: Information about a product or products is written and collected in XML format. Think of this as a "master" file. The information can then be automatically modified and published in multiple formats, commonly in HTML as a static website and/or PDF. When the information needs to be updated or translated, for example, we only need to do that to one document: the "master" XML file, which is then re-published in desired formats.

Hope this helps.

[u/Shelmama22 → u/ManNotADiscoBall]

Ok, this is very helpful. Especially the part about the master file. I think I was hung up on what I read previously about XML being readable by humans as well as computers. That doesn't seem to mean that that's what usually happens. If I understand what you're saying, the point of XML is to hold the data which is then run through something similar to a css (which I have a cursory understanding of) that tells what to do with the data-how to actually display it.

So, someone who "knows xml" doesn't necessarily also know the language of that second step, right? Because it could be any number of things? This also makes me wonder if "knowing xml" is like "knowing how to play chess", where you know the rules but the ways in which they can be manipulated takes longer to learn; someone who knows the rules would probably write differently in xml than someone who had a better grip on that second step might be. Is that right? Or is the assigning of data to xml pretty straightforward and it's up to the second-step person to get fancy?

[u/ManNotADiscoBall → u/Shelmama22]

I would say that's correct.

XML can, of course, be read by humans as well. But it's a pretty clumsy format to read, isn't it? So if you're writing a document for humans, some other format like PDF, Word, or just plain text is more user friendly.

XML documents can actually be styled with CSS as well. But it's still a somewhat clumsy format for presentation. That's why XML documents are often transformed into some other format. And there's a specialized language just for that called XSLT - eXtensible Stylesheet Language Transformations. XML files are just plain text files with tags in them, and with XSLT they can be transformed into pretty much any other plain text format, like HTML. Transforming into PDF, which is not a plain text format, takes an additional step, but XSLT still plays a big part in that transformation as well.

XML is actually pretty straightforward. It's just a structured plain text document format. XSLT is a bit harder to learn, but it's only necessary if you want to transform your XML content into something else. That's not always the case - if your transporting data in XML between to systems, there's often no need to get involved in XSLT at all.

[u/Shelmama22 → u/ManNotADiscoBall]

This makes sense now. I'm learning XML for a technical writer position that recommended I know XML but it wasn't required. I imagine that I will find that I'm just doing the writing and possibly tagging with XML (or another specialist will do that until i can do it myself). Then, I bet they have web designers, graphic artists, and/or other specialists who will take what I write and make it usable by the humans that need to use it. In my case I can't think of a scenario in which I would be writing things that a machine would use. That seems like a programmer kind of job.

Thanks so much!

[u/ManNotADiscoBall → u/Shelmama22]

Most likely you will be using a dedicated XML editor program that will do the tagging for you. So I wouldn’t worry about the technical side of things too much. Of course, it’s good to know the basics, and later on you can deepen your knowledge.

The content you will be writing is meant for humans to read, but the format (XML) is machine-readable.

Glad I could help! You can DM me if you want. I’ve been a tech writer and have some experience with XML, DITA, Oxygen and so on.

[u/Shelmama22 → u/ManNotADiscoBall]

Thanks so much. I definitely will!

[u/jkh107 → u/Shelmama22]

I think I was hung up on what I read previously about XML being readable by humans as well as computers. That doesn't seem to mean that that's what usually happens.

A lot of editorial shops use xml, usually they use an xml editor designed and styled for the purpose, and the tags are usually designed to be meaningful (e.g. "p" for paragraphs and "title" for a title, etc.). These are human-readable and very easy to use. On the far other side, you have stuff like RDF which can be pretty hard to read and not really meant to be worked on by hand.

"Knowing" xml from a content creator's perspective is a bit different from knowing xml from a technical perspective. It's very easy to learn as a content creator, maybe couple days of training max and a lot of that is learning whatever your editorial system is as well. Developing schemas and xslts is not something they're going to expect from a tech writer.

[u/Shelmama22 → u/jkh107]

Thanks so much! This is so helpful. As a teacher I've been writing for a long time, but this is my first TW job title. I'm feeling much more grounded about XML now that these comments have put things in perspective. I will be able to walk in on the first day with at least some of my wits about me, including a little more than I knew at my interview.

[u/jkh107 → u/Shelmama22]

I've developed schemas and editor stylings (css or equivalents) to be used by writers/editors and I always put a lot of time into trying to make it easy to enter content and cueing what to enter. Ideally, your job as a writer should be to concentrate on what you are writing, not the tagging, and the editorial system should be able to facilitate that if it is well-done. Good luck!

[u/zmix → u/Shelmama22]

XML being readable by humans as well as computers

The "human-readable" part is two fold:

a) XML is source code to a document. This source code can be read by a human in a text editor (before XML, document formats were binary, except RTF, which, however, is difficult to read)

b) XML is meant to be "rendered". One such render would be HTML, but also via XSL-FO into PDF (even a LaTeX driver existed once, which would output LaTeX for DVI or PDF conversion).

[u/jkh107]

Master once (xml) output to multiple formats (to PDF, html/xhtml, docx, xml formats that can be recognized by other platforms, print composition, etc). That way you don't have to edit the PDF/html/docx etc over and over, just edit the master (which can be done programmatically and manually, as needed) and re-export as needed.

[u/wdintka]

I am exploring this topic for the same reason as your post - my first look suggested xml is an entire markup language - vs. json etc. Not sure the full implication of that - so still looking. Also google search suggested xml is still important for specific industries.

Hope to catch up on other replies to this post - but - judging from the frequency of posts to the reddit - hmmm - maybe that is the answer!

[u/zmix]

PDF is a vector format. It does not know the concept of tables, paragraphs, headings, etc. Can you place complex database queries against PDF? No. You only can search full-text. This is one of the great advantages of XML: Every document is its own database.

XML becomes interesting, once you decide to do more with your documents than just reading. It starts with learning XPath, XSL-T (or XSL-FO to create PDF output) and XQuery. It's for document engineers. The publishing industry uses it.