Reckless : Metaphors

RePublish

rdias — Sat, 05 Mar 2005 08:46:00 GMT

I still think this was my best post yet, so I am going to republish it...

The Integral of Life

If you happen to home school your children, if you are a teacher, or you tutor folks now and then, this is a great way to teach calculus:

Life is equal to the integral from birth to death of happiness over time with the change in time.

The beauty of this algorithm is that you get to define the algorithm for happiness and its unit of measure e.g. happiness may be equal to the amount of time you get to spend with your family and friends. You may want to augment the duration as well e.g. until the time you are forgotten.

If you are a geek at heart like me, then you will naturally augment the sum total of life to be 42. Are you excited about the remake?

Metaphors for Reliable Messaging, Protocols, and Policies of systems

rdias — Tue, 21 Oct 2003 06:58:00 GMT

Earlier in the Summer I took a rock climbing class at Stone Gardens in Ballard. I left the gym pretty fired up thinking this would be a great way to explain some our WS-* technology to the not so technologically savvy. I spent a couple of hours that evening talking with a climber about the metaphor.

We have all seen reliable messaging when ordering our grande soy latte at Starbucks. After we order the drink the cashier blurts the order out loud only to have the person making the drink acknowledge the order by repeating it back. Clearly, this is not 100% reliable because the human making the drink may still forget the order if they do not proceed to write it onto the cup immediately; however, the business folks at Starbucks recognize that the human mind is more likely to remember and execute the drink order correctly if they repeat the order out loud. Thus, they established a protocol for drink ordering. The Policy on the drink maker is to receive the drink order At Most Once. The drink maker responds Exactly Once. In the end, reliability is subject to the corresponding infrastructure implementing the protocol; in this case, the reliability of the system is measured by the consciousness of the humans involved in the interaction. Reliable messaging is often required in more mission critical environments and at times failure of the system could be life threatening. I recently spoke with a group of folks at Siemens who builds systems that have human machine interfaces (hmi) where human operators are constantly waiting to take over manual control of the machines if the computer systems fail. Their policy is that within 10 seconds of failure a human operator is required to take over control or thousands of lives can be affected.

In rock climbing, there are usually two people. The person on belay must be attentive and not make mistakes to ensure the climber's safety. When rock climbing, protocol usage can help mitigate potential physical harm. The protocol is very simple. What is interesting to note, is most of the time, the messages are At Least Once. At least once means the endpoint (in this scenario, person) receiving the message must receive it at least once to react i.e. if the person does not hear the message, the message must be resent.

When beginning a climb from one pitch to the next

Both individuals give each other safety checks. Both the climber and the person on belay must have all straps double backed. The climbers knot must be tight and well dressed. The person belaying must have their carabiner locked and have the rope properly threaded through the belay device.

rock climber: on belay

person on belay: belay on

rock climber gets on the wall

rock climber: climbing

person on belay: climb on

rock climber begins climbing

once the climber reaches the next pitch, they anchor in and belay the climber below

To begin rappelling

rock climber: slack

person on belay removes all of the slack from the rope

rock climber: Lower

person on belay begins to lower rock climber

One way messages the climber may send to the person on belay

rock climber: Falling!

person on belay puts on the brake

In memory of William Tharpe

A Metaphor for Secure Conversation and Trust

rdias — Thu, 19 Jun 2003 08:24:00 GMT

A methapor understanding SecureConversation and Trust.

Chris Kaler a few weeks ago unlocked my understanding of SecureConversation and Trust with a very easy to understand metaphor. I think it is worth sharing. I have been spending a bit of time trying to find out where the metaphor breaks down to prove to myself I understood the technology.

Roles in this metaphor:

· Bouncer Checking Ids at a bar in a state you do not live - TokenIssuer

· The book the bouncer uses to insure that they can trust your ID is in fact from the state you are from - Federated Trust

· Bartender - Service provider

· You - The client

When you go into a bar, the bouncer checks your ID. First they authenticate you by insuring that you are in fact the person you credentials say you are. Then they authorize you by insuring you are of age. If the bouncer is not familiar with the credentials you are presenting them, e.g. you have an out of state license or a military id, they look into a book which provides a list of trusted credentials. If your ID is listed and matches up to the template, they will choose to trust the credentials you have and the bouncer will let you in.

Before the bouncer lets you in, they give you a stamp, a Security Context Token (SCT), which allows you to drink alcoholic beverages. The bartenders in the club won’t have to go through the same cumbersome process to prove you are who you say you are and you are authorized to drink. They simply verify that you have the appropriate SCT, the stamp on your hand. This insures that the cycles of the bartender are not wasted on tedious ID checking which is not core to their service.

The SCT is a signed shared secret. If someone trys to copy it onto their hand, it will not have the same strength of ink and will be easily recognized as an invalid stamp.

If for some reason, the bartender doubts you, they can always ask for you original credentials before serving you.

Documents are central to life and business

rdias — Wed, 02 Apr 2003 14:32:00 GMT

When a child in the U.S. is born, the hospital issues a government document to prove a child was born. This person later registers with the government to receive a document that proves they are a part of the social system. Later if the person chooses to travel, they get another document, to enable them to enter foreign countries.

The person grows up working hard in school to obtain a document, a diploma, which says they did complete their primary education in high school or via independent studies. Some folks push on to get yet other classifications of documents.

All of these documents enable you to access other documents ... Dollar Bills, W2s, Funds, Stocks, Deeds, etc.

O'Toole gets it. Documents are central to everyday life and business.