On the nature of hierarchical URLs

Topic: URL 

Dear Dr Masinter, 

I am a French software engineer and have a technical question about RFC 3986, Uniform Resource Identifier (URI): Generic Syntax. 

What do you mean exactly by “hierarchical data” in this paragraph? 

“The path component contains data, usually organized in hierarchical form, that, along with data in the non-hierarchical query component (Section 3.4), serves to identify a resource within the scope of the URI’s scheme and naming authority (if any).” 

The language "usually" in RFC 3986 indicates the text isn't normative, but rather explanatory. So the terms used may not be precise.

For arbitrary URIs, interpretation of "/" and the hierarchy it established depends on the scheme. For http: and https: URIs, the interpretation depends on the server implementation. While many HTTP servers map the path hierarchy to hierarchy of file names in the server's file system, such mappings are not usually 1-1, and might vary depending on server configuration, case sensitivity or interpretation of unnormalized Unicode strings. For web clients, the WHATWG URL spec defines how web clients parse and interpret URLs (which correspond roughly to RFC 3987 IRIs).

For an idea of what was intended, a  search for "hierarchical data" yields a Wikipedia entry for "Hierarchical data model" that has relevant examples and how there are many data models in use.

When I look at a directed graph of resources (where resources are the vertices and links between them are the edges), I don’t know how to decide that a particular link between two resources A and B is “hierarchical” or “non hierarchical”. Should it be just antisymmetric (A → B, but not B → A)? Should it be more restrictive, for instance the inclusion relationship (A ⊃ B)? Or another property?

The choice of data model is up to your application, and you can decide for each application which model matches your use.

For instance, which of the following directed graphs of resources should I consider as having “hierarchical” links and which should I consider as having “non hierarchical” links? 

1. animalia → mammalia → dog
2. Elisabeth II → Charles → William
3. 1989 → 01 → 31
4. Pink Floyd → The Dark Side of the Moon → Money 

If we use antisymmetry as the criterion for being “hierarchical”, the links of all directed graphs will be “hierarchical”.
If we use inclusion as the criterion for being “hierarchical”, only the links of 1 will be “hierarchical”, since in 2 a child has two parents, in 3 a month is shared by every year and in 4 an album can be created by several artists. 

This information is needed to know if we should use the path component: 

1. /animalia/mammalia/dog
2. /elisabeth-ii/charles/william
3. /1989/01/31
4. /pink-floyd/the-dark-side-of-the-moon/money 

or the query component: 

1. ?kingdom=animalia&class=mammalia&species=dog
2. ?grandparent=elisabeth-ii&parent=charles&child=william
3. ?year=1989&month=01&day=31
4. ?artist=pink-floyd&album=the-dark-side-of-the-moon&song=money 

to identify a resource. 

which one of these you use depends on not one case but the entire set of data you're trying to organize.

In case 1, if you're identifying properties of groups of organisms by their taxonomic designation, the namespace is by definition hierarchical,  established and managed by complex rules to resolve non-hierarchical conflicts, overlaps and disagreements. But the taxonomy of rankings has 7 or 8 levels (depending on how you count), not 3, and your example says "dog" and it's not clear if you mean Canis lupus familiaris or the entire family of Canidae.   The inclusion relation is not hierarchical. 

In case 2, you might have a hierarchy if you restricted the relationship to "heir apparent of".
In case 3, many use the hierarchy to organize the data such that 1989/01/13 is used to identify a resource from the first of January if the year 1983.
In case 4, many music organizers sort out files by inventing a new category of "artist" for the album-artist and using "A, B, C" for albums where there are multiple arists, and "Various Artists" for "albums" that have varieties of artists for each song.

People often invent hierarchies as a way of managing access control. WebDAV includes operations based on hierarchies.

Sometimes what is desired is a combination of different data models mixed, with the hierarchical model a "default" view, and the query parameters used to search the space and redirect to a canonical hierarchical URI.

If you're defining the space for an API, the JSON-HAL design pattern adds a layer of indirection using link relations rather than URL patterns, especially in applications where the hierarchical pattern is used for high-performance web servers which use the URL syntax for optimized load-balanced servers with multiple patterns.

 Yours faithfully,

XXXX XXXX (name redacted)

Using Secret Sharing for National Archives

Topic: preservation

Reading about the National Archives budget woes: perhaps as digital material is becoming more prevalent, the volumes of paper documents isn't growing?

What are the unique requirements of the National Archives for online storage of digital material?
Unlike most business archives, the lifetime of archived documents is measured in centuries.
The security of archives from both accidental and intentional loss is for that lifetime; unauthorized revelation most be prevented for at least decades.

For public records, LOCKSS (Lots of Copies Keeps Stuff Safe) might be a solution.  Distribute copies to each state or region.

But for confidential records, the more copies, the more likely it is the information will be revealed.

But there is an approach worth investigating, using Secret Sharing where each State could maintain a separate secure facility under its own control.

This would allow some resilience to meddling, take-down, or premature release of information unless a large number of states agree.

The Paperless Office and the Horseless Carriage

Topic: preservation

You know the story of the horseless carriage with a buggy-whip holder (in case you needed to put a horse in front of it). But what we wound up with is a wide variety of forms: motorcycle, automobile, tank, train, etc.  The transition was accompanied by corresponding developments in infrastructure.

When Xerox started its Palo Alto Research Center nearly 50 years ago, part of its mission was the Paperless Office -- a world where work was done without the use of paper.

We're still in the middle of a long transition to paperless processes from billing, statements, advertising, news, receipts, insurance, medical records,  government, textbooks, fiction, with documents still playing a major role in data-based activities. In most cases, these processes are turned from using paper documents to electronic ones, with PDF being an important carrier because of its ability to straddle the divide between the paper and electronic world.

In many of these processes, we're only seeing the beginnings of transition to another phase, of data connections, where electronic documents and email are being supplanted by sharing data, and documents only generated on demand by those who are outside of the data-centric roles.

HTML may have been originally designed as a document format for scientific papers at CERN, but its primary thrust in the last decade has been as a way of delivering applications to consumers.

The problem of the digital dark age is not so much technological obsolescence as it is that there are no document by-products of work done; this is not something that can be solved by new kinds of archival documents. In the records management community, documents must have or carry their own context which allows auditing of past behavior by examining the documents the process left behind.

We need some better ways of straddling the document and data world such that data archives are produced in a way that allows it to be audited, redacted, processed, without having all of the original context. Most data channels are, for efficiency reasons, context free. Metadata (embedded or supplemental) is a document-centric way of supplying context, but it isn't enough.

The Internet is a WMD (Weapon of Mass Delusion)

Some thoughts on the Internet as the root problem, based on this Washington Post Op-Ed.

When I was a kid, I remember reading about Robert Oppenheimer's work on the atomic bomb and his thought that scientists developing technologies that could be weaponized had some responsibility to counter its misuse. It was probably in the phase of reading bios.

If the Internet, the Web, social media, analytics and targeted advertising have been weaponized, turned into weapons of mass delusion, what are we doing to effectively counter this threat?

I see some focus on decentralization, but that doesn't seem to mitigate the problem. 

IETF, ISOC, ICANN, W3C, ACM, somewhere else? where?

 It seems like this isn't a problem that can be solved by fixing a handful of sites. Or applying sanctions to individuals and companies. how can we counter the susceptibility of mass communication systems to this kind of manipulation and the continuing escalating arms race of hacks and prevention hacks?

Pseudonymous postings seem to be essential, with an increasing sophistication of operational techniques. 

Debugging my brain

Today was my fifth session with Dr. Nengchun Huang trying to adjust the signals going to my brain to improve my Parkinson's symptoms. I've been doing this every two weeks. Each session has lasted an hour to an hour and a half, as the doctor adjusts the signals and watches my reaction: does my thumb wiggle, my eyes droop or blink rapidly, does my foot twist uncontrollably or steady. Periodically he asks me to do various tasks -- tap my thumb and fingers together like playing castinets; touch my nose and then his finger, back and forth; tap my foot rapidly and evenly.  Periodically we take off the collar and I get up and go out to walk down the hall and back while he watches the regularity of my pace and whether my hand shakes while I'm walking. It's almost always been possible to stop the tremor for a moment by focusing my attention on the body part (like with yoga or tai chi), but usually only for a few seconds. "Don't suppress the tremor", he reminds me often, but it's often reflex.
The ideal is "no symptoms, steady state", and each session has gotten better. For example, the strong impulse to close my eyes is less. My remote control (here wired to the PC) allows me to adjust the overall voltage slightly, and choose between the latest and one of three previously saved programs.

They call this "programming" but it's more like debugging; not modern debugging but the old-fashioned kind, where you're pawing through core dumps and using binary search.

Here's what I think is going on

 The device implanted below my right collarbone communicates wirelessly with the programmer. There are eight contacts one after another on the end of the electrodes skewering my Globus Pallidus Interna on each side, different parts of which are connected to different parts of the brain, controlling movement of my legs and feet and hands and other parts. Each electrode can emit pulses at a given frequency (up to 179 hz) for a periodic burst (I think, the "pulse width") and a given voltage or amperage. Pulses can be monopolar or bipolar  (not sure, but I'm guessing either negative only or negative and positive). The bipolar signals have a narrower effect; the monopolar signals are stronger.
There's no exact map of which parts of the GPi connect to which function of the brain. I think the theory is that the pulses disrupt the beta-rhythms which synchronize the brain function.  Anyway, the Boston Scientific device I have is new, giving the programmer lots of options not possible before.

My procedure

"STEREOTACTIC IMAGE GUIDED IMPLANTATION OF BILATERAL GPi DEEP BRAIN STIMULATION ELECTRODES WITH VOLUMETRIC ANALYSIS USING MAZOR ROBOT AND IMPLANTATION OF RIGHT INFRACLAVICULAR PULSE GENERATOR"

was on all the forms I had to sign, describing what was done to me...

"Stereotactic image" (the 3D result of an MRI scan on Tuesday and a CT scan Friday morning)
"... guided" (the team looked at the 3D image to plan the route of the wires into my brain)
"Implantation" (skewering) 
"of bilateral" (both sides)
"GPi" (globus pallidus interna -- the part of my brain they were targeting)
"deep brain" (well, it was pretty deep in there, and hard to get to)
"stimulation electrodes" (two thin cables with 8 strands each leading to 8 points within the GPi)
"with volumetric analysis" (checking the path so they don't skewer something important)
"using Mazor robot" (a device they attached to a 'platform' that was screwed into my skull first thing Friday morning after first making me a numb-skull, then drilling pilot holes and screwing in; the Mazor robot then guides the surgery exactly)
"and implantation" (this one goes in a little pocket they cut in my chest)
"of right" (only one)
"infraclavicular" (under my collar bone, the electrode leads pushed under scalp, neck skin, down chest)
"pulse generator" (the thing that will send pulses to the electrodes)

Right now my brain is recovering from the trauma of this disturbance... my Parkinson's symptoms are  mainly worse than usual -- both hands shaking, having trouble standing, using a walker to scoot around the house, speech soft and distorted enough that Alexa doesn't understand me, mild headache, among other indignities. 
Today I get to shower! Yay! 

My appointment for having the whole thing turned on and to start tuning the pulses to my body is February 16th.  Happy Birthday!


The process of fine tuning can take 6 months of appointments every two weeks.   Each of 8 leads on each side, with their own pulse intensity, frequency and width ... I'm assuming there's some method to it, will let you know. 

Going Bionic

I hadn't talked about it publicly, but it's pretty obvious now if you see me in person: my hands (often) shake, my foot (often) drags. I have Parkinson's disease -- first diagnosed 12 years ago, its a slowly progressive condition. There are whole books about all the horrible potential symptoms, but  I've been fortunate (among the millions with it) that my symptoms have been relatively mild. Medications, exercise and determination mainly controlled the worst.

But progressive diseases progress, and interfere with getting on with life.

I'm mainly risk-averse, but (after declining 5 years ago) I'm now scheduled next week for a surgical treatment called "Deep Brain Stimulation": like a pacemaker, but for the brain rather than the heart, and more of a pace-disruptor than -maker.

The procedure is described as "minimally invasive"  and "reversible" and it's been done 100,000 times (300 by my surgeon). But still, it requires MRI and CAT scan to place wires to the exact spot without hitting good brain or blood vessels. (I got a Rift VR tour of some patient's anonymized brain as part of the explanation.)

Besides the wires in my brain ("Will I be able to listen to the radio without a radio?"), there will be wires under skin from scalp down to a not-so-tiny controller implanted -- wirelessly charged and programmed, battery rated to last 15 years. The "programming" usually takes months of adjustment.

I remember ~40 years ago admiring someone's programming skills, to the point I told people "he's so good I'd let him program my pacemaker". I'm not going to ask Boston Scientific to review their source code, but I do hope they aspire to better than "five nines".

Wish me luck...

1/31 added: for all the good wishes, expressed and felt: thank you, its meant a lot...