Library to safely parse XML (by avoiding random atom creation)

NobbZ

I am writing an application where I need to parse XML, and intuitively I reached out for sweet_xml as its a wrapper around xmerl.

Though while I was inspecting the parsed result, I realized that attribute and element names appeared as atoms, and as the XML I receive will be beyond my control, I want to avoid “random” atom creation. Some HTML documents, that slip through could bring the system down…

So does anyone have a typ for an XML library I could use instead?

If it can directly transform the XML into a struct thats a plus, but not a strict requirement. Though if it can’t do structs directly, XPath is a requirement.

I explicitely do not want approaches that work like pythons xml2dict.

23 comments

#xml #package #sweet_xml

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2026-01-12 09:34:23 UTC

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voltone

There’s erlsom | Hex, which uses strings rather than atoms for element and attribute names…

Post #1

josevalim

Creator of Elixir

I have also used saxy successfully. Specially useful if you want to get only certain parts of the XML.

Post #2

derek-zhou

I just use Floki with its builtin mochi based parser. Safe enough for me (string keys). It will not validate the XML though.

Post #3

odix67

I’ve tried a few XML parser implementations for a “proof of concept” software, I had the same concerns with xmerl regarding atom creations, our use case was to process large, very large xml documents and as I have some SAX knowledge (> 20years) I finally choosed the same es Jose, saxy. Yes it doesn’t support xpath, it doesn’t support namespaces, it doesn’t support validation and what not, but it is quite fast and easy to use. It was my first challenge in elixir to implement some missing things, namly some kind of namespace support (normalizing aliases), building structs and partialized parsing (I hope, these extensions could be open sourced some time, but this has to be clarified) and these tasks wasn’t really hard

Post #4

Adzz

We currently do this at work:

Saxy (to get xmerl)
Then we use this sweet_xml with data_schema to query that xmerl.

There is also meeseeks GitHub - mischov/meeseeks: An Elixir library for parsing and extracting data from HTML and XML with CSS or XPath selectors. · GitHub

Post #5

Adzz

I would also say the atom thing might not be a problem. You can monitor the atom table and increase the default if you need. Depends on the kinds of responses you are parsing, but it will probably reduce the memory footprint over binaries, I would guess that’s why xmerl uses them.

Post #6

NobbZ

The XMLs that I expect to parse are user provided, so atoms are out of the question. Reading the OPMLs is sadly a strict requirement, similar to how RSS is based on XML, and there also everything can be in the servers response

So trusting those external inputs to not spill my atom table, monitored or not, is out of the question.

Though indeed I started playing with Meeseeks yesterday, as I found some articles online that complained about xmerls xpath performance.

So it’ll be Meeseeks for now.

Post #7

Adzz

Nice, incidentally I am working on speeding up and reducing the memory footprint of our XML parsing at work the moment. If I land on something I can share, though we may have different use cases.

Post #8