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Developer Advocate
Developer Advocate
Continuing on from my earlier random thoughts about what cloud native means to me, I was musing this morning on the nature of the web, and specifically URIs - or rather their specialisation that we see most commonly - URLs.

The importance of stable URLs

There's a well-known article by Tim Berners-Lee (TBL) entitled "Cool URIs don't change" which I'd encourage you to go and read at some stage over a cup of coffee. It's from the World Wide Web Consortium (W3C). There are many implications of what he says in this article, which I'll leave you to ponder. There's also one particular observation that's worth sharing now - the URL of the article hasn't changed since its publication 20 years ago. Now that's what I call setting a good example!

In thinking about the content of this article, I'm reminded of the excellent set of productivity tools from Google - known these days as G Suite. I say "known these days", as they've been referred to previously as "Google Apps", and - perhaps colloquially - as "Google Docs". But while the suite's name might have changed, the fundamental design that underpins this awesome set of tools has not.

Because Google get the web, they build their tools "of the web", rather than merely "on the web". That means, for example, that the URL of a Google spreadsheet, for example, or a Google document, or a Google Form, or whatever - is unique and permanent. It doesn't change. Even if you change the name of that "document" (we should really say "of that resource"), the URL remains the same. And that brings a superset of web-based by-products that we take for granted. For example, I can jump to a document I've been working on recently in literally a handful of keystrokes, without having to think of where I stored it or what the URL might be, or what the navigation path might be that I have to take once if I have to first find some sort of "root" resource. This is all I have to do:

  1. Cmd-T to get a new browser tab and have my cursor placed in the omnibar

  2. then three or four characters to identify the working title of the document

  3. finally a down-arrow or two and Enter to request that resource

Bam. In and editing.

More than can be said for, ahem, certain other online productivity / collaboration suites - merely change the title of the document you're writing and the URL changes! Ouch! What use is that if I want to share the working draft resource with you?

Anyway, let me tear myself away from this becoming another post entirely, and look at a typical G Suite URL to help me get to my next point. Here's an example, for a spreadsheet (I've changed the URL slightly for security reasons):

The structure of the URL is quite simple, and most of it is the unique code (1nT4...42) that identifies the individual online spreadsheet resource.

The Opacity Axiom

So that brings me to a parallel thought relating to cloud native, and something that (to me) is a "smell" (as in something that just gives me a subtle hint about something - not necessarily negative).

When I first started out exploring the SAP Cloud Platform (SCP), I noticed that a lot of the URLs had similar opaque identifiers in them. For example, if I created a temporary trial account, or a temporary member within a trial account. If I added a subaccount or was given access to a new global account, whether in the Neo or (now the) Cloud Foundry context ... each time, I saw unique, opaque identifiers.

Here's another couple of (modified) examples:

Even services within the SCP had parts of their URLs that I couldn't control (or initially understand) - provider account identifiers, for example. And they looked a little bit ugly to me, initially.

But then I remembered another W3C article, from even earlier in the web's history (1996) - Universal Resource Identifiers - Axioms of Web Architecture. This is also a great article and worth a read. Of particular interest to us here in that article is the section on "The Opacity Axiom", which states:

"The only thing you can use an identifier for is to refer to an object. When you are not dereferencing, you should not look at the contents of the URI string to gain other information."

This axiom somewhat goes against the grain of what I like to think, but is actually crucial. First from the point of view of the side-effect of trying to infer structure from a URL, but more importantly from the perspective of where we are today, in the cloud native context of resources being spun up, created, instantiated, conjured up ... and then after their utility has been spent, being deleted, destroyed, disappeared*.

(*yes I know I'm using this verb transitively, but there you go. Talking of unusual words and unusual usages, did you notice TBL using the word "disillusion" in the "Cool URIs Don't Change" article - also as a transitive verb? That use has been waning since the early C20, but still wonderful.)

Resources, such as those that are spun up on cloud platforms such as SAP's and Google's, that are ultimately ephemeral need to be born and then die, and in that intervening period, have an identifier that is as equally anonymous as it is unique.

The cloud native smell

And it's the very presence of these superficially ugly but essentially throwaway identifiers in URLs (after all, URLs *are* URIs, aren't they) that to me form a subtle hint, a signpost, a smell, that what we're dealing with is something that is cloud native. Resources, services, VMs, clusters, subaccounts - they're created and destroyed all the time, not just in a web environment but in on-premise contexts and sometimes within proprietary architectures.

The fact that resources -- and I'm using the word "resource" while thinking about how that word is used in Representational State Transfer (REST) -- need identifiers in the context of the web (and yes, "cloud" doesn't mean "just web (HTTP)"), but our interface to the cloud is predominantly via that protocol) means that the increasing occurrence of URLs with long strings of opaque characters often triggers a thought in my head that we're moving further towards the age of cloud native.

What are your thoughts?


This post was brought to you by Finca Buenos Aires coffee and some happy memories from the early days of the web.


Read more posts in this series here: Monday morning thoughts.