Comment by dhx | Hacker News Reader

Comment by dhx | Hacker News Reader

Parent Full thread

On automatic website refreshing:

See guidelines 97 and 98 from Jakob Nielsen and Marie Tahir's book 50 Websites Deconstructed [1] for the primary reason why there has been little interest in removing the "refresh" button from browsers.

Technical limitations don't really exist (and if they do exist it'd be fairly easy to solve). Server-sent events[2] and WebSocket[3] are already implemented in the latest versions of popular browsers. Modules or implementations within popular HTTP servers already exist for doing HTTP push (they tend to use older AJAX-like techniques though).

If usability was no concern (or very carefully handled) it'd be fairly easy to write your own nginx module or "WebSocket server"[4] that uses inotify to check for file system changes. For each change that impacts an open WebSocket connection, a "refresh this page" notification can be sent to the browser (which then uses JavaScript to force a page refresh). There is a potential for smarter refresh mechanisms in browsers that maintain the current scroll state, field values, etc but you'd still be frustrating the user with severe usability problems.

[1] http://www.useit.com/homepageusability/guidelines.html

[2] https://en.wikipedia.org/wiki/Server-sent_events

[3] https://en.wikipedia.org/wiki/WebSockets

[4] http://altdevblogaday.com/2012/01/23/writing-your-own-websoc...

Yes but none of these things existed in 1993. You can call it "lazy" I suppose that TBL didn't implement all the features you take for granted 20 years later before releasing the first browser(!)

It's lazy when your platform still has mandatory polling decades after interrupt driven programming was invented.

Interrupts are not without drawbacks. There are valid reasons to not implement them, particularly on the web.

So, WebSockets are a mistake then?

Websockets are like airplanes: useful, but not for daily commuting.

So do you have any technical points to make, or just more dumb excuses? If you don't want interrupts, you just use them to implement polling.

Interrupts are stateful on the server side; that creates problems in terms of scalability, both due to increased memory usage and by being less flexible (either you have each user "locked" to a single process, or you have to implement state sharing, which adds overhead).

It can also be extremely wasteful - if I leave a tab open for hours or days, you'll have to waste your resources and mine to keep pushing me stuff I won't see, while now I just hit refresh when I want to see new content.

In terms of usability, it's often jarring to watch content change when you're interacting with it - that's why even sites that implement real time notifications often have a link or button that you have to press to update the UI. In many cases, doing that completely negates the benefits of pushing.

Also, see the thesis on "Architectural Styles and the Design of Network-based Software Architectures": http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm

Polling is a good default for the web; it fits most use cases (content that rarely changes) in a simple and economical way. WebSockets are useful for the exceptions.

It fits most cases.. except that web applications are _constantly_ polling for information. Which may be fine, but you can implement polling with interrupts. What part of that do you not understand? Are you aware that the OS is using an interrupt-driven system to poll the server? It's just hidden from you, so you have no choice. This is just dumb engineering. And to say that it's good for "most things" is just lazy thinking. "Most things" are that way precisely because of the crappy architecture. Rationalisations.

It fits most cases.. except that web applications are _constantly_ polling for information.

Web applications are a very small part of the web as a whole.

you can implement polling with interrupts

But why would you?

Are you aware that the OS is using an interrupt-driven system to poll the server?

Yes. So? In that case, interrupts are a great fit. In others, they aren't.

This is just dumb engineering.

Why?

And to say that it's good for "most things" is just lazy thinking.

It's not good: it's better for most things. There's nothing lazy about evaluating the options and choosing one.

"Most things" are that way precisely because of the crappy architecture. Rationalisations.

Sure, everyone who implemented this shit is dumb and lazy. It couldn't be that they have good reasons for doing what they did.

I see you criticized me for not providing technical points, yet now you refuse refute them. I don't see the point of this conversation anymore.

You haven't made any technical points. You just waffled nonsense about scalability. I see you're bowing out of the argument because you have no case. Once you have interrupts on a platform, you have polling. If you're stuck with polling you can't recover interrupts. Which is why we have websockets decades late. The truth is there is not tension between interrupts and polling. Interrupts are plainly superior, since you can opt out of them trivially. But the platform should not opt out ahead of the developer. This turns out to be inadequate, so we get polling implemented inside interrupts and then a separate mechanism for interrupts. And the interrupt driven stuff has stupid reload buttons and so forth on the GUI. It's dumb engineering because increases complexity and leads to bad results for the user. You have no case. Polling is dumb. And if you think software engineers ever needed "good reasons" to add a bunch of pointless complexity to things, then you simply have no clue on the history of software development.

Notice how the posts that are downvoted have no replies, because the downvoters cannot argue their case. How sad.

I had not downvoted you, but I thought about it - because you are making ranty, ad hominem attacks ("lazy thinking", "dumb excuses"), and you appear to be ignoring or handwaving away all the actual points anyone makes. I have no interest in engaging you in any discussion for these reasons, and I expect that other people feel the same way: hence, downvotes and lack of replies. Feel free to do what you wish with this information.

Reply on news.ycombinator.com