Cart
[Home] [By Thread] [By Date] [Recent Entries]
It is not new thinking. If your windshield wipers aren't working, should your car refuse to start? If your brakes aren't working, should your car refuse to start? Should it refuse to let you put it in gear? Who decides? Logistics analysis takes up the notion that not all failures are mission critical. A systems check on startup accounts for that and issues severity errors. The automated system responds according to the severity. A media system is no different from any other real time system except in consequences of levels of errors. Now it is an issue of where in the food chain a designer can specify a consequence; that is, which objects can the validator detect, which objects can initiate shutdown. A validator is not the right place to make decisions. It is the right place to detect errors. Media are not passive nor general. As browsers quit being browsers and became control wrappers, that was sometimes overlooked. A theory of hypermedia is seldom a practical theory of networked components. len From: Bryan Rasmussen [mailto:bry@i...] There is an assumption one often encounters in implementations for media (as a reference media I will focus on hypermedia in the modern browser), this assumption is opposition to a general assumption for validation of data for media, the media implementation assumption could be put as follows: The absence of an object does not cause the failure of the whole. This means that as a general rule if I refer to some object that the browser cannot find the browser is not designed to fail, the browser assumes that other objects that it can find are still useful to the user and do not present a faulty instance to the user (sometimes of course the browser does fail but such failures at missing components seem always to be due to bugs in the browser and not required presence) As an example of this assumption - a reference to an image that the browser cannot resolve, this is generally the same behavior in printing etc. I am in total aggreement with this assumption. The assumption for validation of data for media is often as follows: strict requirements for structure prevents failures in your media presentation. But of course that someone has put in an element referring to an image does not mean the image is placed in the page. In a way we can define the components of a media instance as being loosely coupled. How though has it come to pass that this is so? Is there any theory out there or do people have theories? I suppose the pedestrian reason is that media itself is dataless and any media format must allow decoupling of individual media elements because we cannot know what their meaning is without the data context. so that if one had a true xml browser that was semantically aware we would be able to crash whenever a document without a required image was enquired. I am of course aware of the oodles of theory on strict validation of document structures and so forth and why failure when data standards are not held to is good. I am however sometimes worried that this kind of strictness is only proper in some very few instances.
|
