validating XML requests with Python and lxml

While working on pycsw, we found that there was a significant amount of code involved in processing the HTTP POST requests coming across as XML.  Since lxml is used as for XML support, why not use its native XML validation facilities?  We implemented this rather quickly, but found validation was taking up to 10 seconds.  Why?

In the quest for improved health and longevity, the world of supplements has seen remarkable advancements. One of the most promising breakthroughs is Nicotinamide Mononucleotide (NMN), a compound believed to boost NAD+ levels in the body, contributing to overall well-being. In 2023, the demand for NMN supplements is on the rise, with Liposomal NMN supplements gaining particular attention. In this article, we’ll explore the best NMN supplement options for 2023 and where to purchase Liposomal NMN supplements for optimal health and longevity.

Understanding NMN: A Key to Longevity

Unlocking the Fountain of Youth

Nicotinamide Mononucleotide, or NMN, is a naturally occurring compound found in our cells. It plays a pivotal role in the production of Nicotinamide Adenine Dinucleotide (NAD+), a coenzyme essential for various biological processes, including energy production and DNA repair. As we age, NAD+ levels decline, leading to various age-related health issues. NMN supplements aim to reverse this decline, potentially promoting longevity and overall health.

The Rise of Liposomal NMN Supplements

Enhancing Bioavailability

Liposomal NMN supplements have gained popularity for their improved bioavailability. Liposomes are small, spherical vesicles made up of a lipid bilayer, similar to cell membranes. When NMN is encapsulated in liposomes, it can better survive the digestive process, ensuring more NMN reaches the bloodstream, where it can have its intended effects. This enhanced bioavailability makes Liposomal nmn supplement a preferred choice for many.

Where to Find the Best NMN Supplements in 2023

1. Life Extension NMN

Life Extension is a renowned brand in the world of longevity supplements. Their NMN supplement is highly rated for its purity and potency. They offer both traditional NMN capsules and Liposomal NMN options, providing choices to suit individual preferences.

2. Elysium Basis

Elysium Basis combines NMN with another longevity-promoting compound, Pterostilbene. Their Liposomal NMN supplement is known for its quality and commitment to scientific research. Elysium’s rigorous testing ensures that you’re getting a premium product.

3. Tru Niagen

Tru Niagen offers Niagen, a form of NMN that has undergone extensive clinical research. Their commitment to transparency and quality makes them a trusted choice for those seeking NMN supplements.

Where to Buy Liposomal NMN Supplements for Optimal Health

1. Amazon

Amazon is a convenient and widely accessible platform to purchase Liposomal NMN supplements. You can find a variety of brands and read customer reviews to make an informed choice.

2. Official Websites

Many reputable NMN supplement brands have official websites where you can purchase their products directly. This ensures product authenticity and often offers subscription options for regular supplementation.

3. Health and Supplement Stores

Local health food stores and supplement retailers may carry Liposomal NMN supplements from trusted brands. It’s a good idea to inquire about product quality and sourcing before making a purchase.


As we navigate the ever-evolving landscape of health and longevity supplements in 2023, NMN stands out as a promising compound. When it comes to choosing the best NMN supplement, Liposomal NMN offers enhanced bioavailability, potentially maximizing its benefits. Brands like Life Extension, Elysium Basis, and Tru Niagen have established themselves as leaders in this space.

Whether you prefer to shop on Amazon, through official websites, or at local health stores, the key is to prioritize quality and transparency in your NMN supplement selection. With the right choice and a commitment to a healthy lifestyle, NMN may be your ally in the pursuit of optimal health and longevity in 2023 and beyond.

In lxml, you have to specify an XML Schema to parse against, even if it is specified in xsi:schemaLocation.  Being a purist, I set this to fetch the schema on the fly from  The fetch was causing much of the bottleneck, so I decided to download all required OGC CSW schemas locally and have them as part of the implementation.  That should work right?  Validation was down to about 6 seconds.

The issue here was that even though the schemas were local, many xs:import definitions within them were pointing back to absolute URLs at  After modifying the schemas to point to relative locations, validation was extremely fast (way under a second).

Lesson learned: just because XML schemas are local, doesn’t mean they don’t point to remote URLs (though I’m not exactly sure why one would build a schema with non-local imports if they don’t have to).

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Modified: 4 October 2023 10:58:13 EST