PHP London February 2020


Venue: Sainsburys, 33 Holborn, London, EC1N 2HT

Note: There will be members of Sainsbury's staff who will be able to help you to the correct room.


7:00-7:30 - Informal drinks, snacks and chat
7:30-7:35 - Welcome & group announcements
7:40-8:30 - Talk:

Talk: Caching the uncacheable with Varnish

When the pressure is on, your application will need to scale up or scale out. Throwing servers at the problem is not a sustainable solution and refactoring is not always effective.

Caching, on the other hand, might reduce the impact of your application on the system. Unfortunately, when personalization comes into play, caching is really hard: it’s a tradeoff between caching enough variations of your content and maintaining a good hit rate.

In this presentation, we will use different techniques in Varnish to cache personalized content:

• Using HTTP fragments such as ESI and AJAX
• Creating cache variations using cookie values
• Authentication on the edge
• Fetching session data on the edge
• Content transformation and personalization on the edge

By doing as much decision making and transformation “on the edge” as possible, we avoid performing expensive computing at the origin, which allows us to scale and to “cache the uncacheable”.

Speaker: Thijs Feryn

Thijs Feryn is a "technical evangelist" at Varnish Software, the company behind the Varnish Cache open source technology. His goal is to bring technology to the people and people to technology. He focuses on bridging the gap between code and infrastructure. Thijs is a published author at O'Reilly, he is also involved in many open source communities. He speaks, listens, writes, codes, teaches, blogs, vlogs, organizes and is above all very excited to speak at PHP London


Explore Group ( - The Explore Group has been helping companies recruit top talent in the ever-evolving world of technology since 2005. We've adapted alongside the changing IT market to become increasingly specialist enabling us to support our customers on their journey through the new digital economy.

Bud ( - Bud solve real-world consumer problems using open banking technology, unparalleled data enrichment capabilities and a suite of connected financial services.

We will have 2 licences from JetBrains ( for any of their products to raffle.

Want to speak at PHP London?

We are always looking for speakers for our monthly meetups. If you would like to give a talk this year please fill out the form at the link below.


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