 |
| DOM Monster suggestions for a ASP.NET Forums page (click to enlarge) |
Strategy #1: Code well and do nothing special for mobile - The current crop of advanced mobile browsers are very good at rearranging content without being told how to by a developer...Making a good semi-liquid layout that has a min-width and max-width set in your CSS and em-based typography will work very well across a range of different devices and screen sizes.
Strategy #2: Make a separate mobile site - .. (although) it results in having two sites to user-test, maintain, etc
Strategy #3: Build mobile-aware adaptive sites - hardest to pull-off methodology... (but) future-proof as it tests features rather than sniffing browsers.
Smartphones can run full Web browsers such as Opera Mobile or Safari/iPhone, while in the developing world we see much lower-end handsets that don’t have an operating system but, if they can run Java they can use Opera Mini (a thin client for a proxy-based system that compresses pages down to about 10% of their original size before being sent to the handset for rendering — see our comparison of Opera Mobile and Opera Mini)
Highlights:
- The average web page takes up 320 KB on the wire.
- Only two-thirds of the compressible material on a page is actually compressed.
- In 80% of pages, 10 or more resources are loaded from a single host.
- The most popular sites could eliminate more than 8 HTTP requests per page if they combined all scripts on the same host into one and all stylesheets on the same host into one.
With the adoption of HAR ..., we’re moving to having a record of the page load experience that can be saved and shared, and performance analysis that is consistent regardless of what browser and development environment you work in.
How many connections per hostname is suggested in the HTTP spec? Do the five most popular browsers follow this recommendation?
2
no, Firefox 3, IE8, Safari 3.1+, Opera 9.60, and Chrome all support 4 or more. IE6 & 7 are still 2.
What are the two request headers that can be used to determine if a cached resource is valid (i.e., used as part of a Conditional GET request)? If the resource is valid, what status code does the web server return?
If-Modified-Since, If-None-Match
304 Not Modified ("304" and "Not Modified" are also valid answers)
Name three potential drawbacks to using a CDN, and a way to mitigate these drawbacks.
your performance can be affected by your competitors, you don't have direct control, if the CDN's performance degrades so does yours
you can use two CDNs to hedge your bets
Name two browsers (including major version #) that support parallel script loading?
IE8, Safari 4 are the biggies. Also Android 1, iPhone 2, Konqueror 4, Opera 9, and some Blackberries.
How much does gzip compression typically reduce transfer sizes?
70%
Which trigger busy indicators?
script in iframe
script DOM element
script defer
document.write script tag
What's the benefit of splitting resource downloads across multiple domains? In general, how many domains should you shard across?
You can get more parallel downloads by splitting resources across multiple domains. The ideal number of domains is 2-4.
List two pros and two cons of using iframes.
pros:
embedding content from another web site
sandboxing 3rd party JavaScript
asynchronous loading of external scripts
cons:
most expensive DOM element
blocks parent's onload
List the seven types of CSS selectors and give an example of each.
ID: #navbar {}
class: .navbar {}
type: A {}
descendant: UL LI {}
child: UL > LI {}
adjacent sibling: UL + P {}
universal: [color: red] {}
I'm consistently surprised at how many sites don't have a geographic failover.
So, what is the difference between a performance problem and a scale problem?
Well, I think most people see scaling problems manifest as perceived performance problems.
When someone tries to start aggressively caching, whether that be output cache or formally caching from a business perspective, there's this Cartesian product that happens.
I like the idea of being able to attribute something or mark something and have it handled because this is a common pattern and anytime something is a common pattern, I expect the best practice to be embodied within the library.
..if you start thinking about performance early on, you always get accused of being a premature optimizer.
dasBlog is an interesting application because we don't have a database.....Everything in dasBlog is stored in XML.
You know, what I like to do is I turn it (ViewState) off completely and then turn it on.
While, Microsoft, now that I'm starting to understand what they think about, they have to make that distinction between speed of development versus the expectation of the developer. They wanted ASP.NET to just be one of those things where I can drag a button onto a page and it works.
One of my favorite defaults and I've talked about this in sessions all the time that people a) don't know about, but b) when you really think about it realize it's a good default, but seems totally non-sensical is ASP.NET's default worker process restart is 23 hours. That's the default setting for a cold install of IIS. Every 23 hours, restart the worker process.
Using the T-SQL EXISTS keyword to perform an existence check is almost always faster than using COUNT(*). EXISTS can stop as soon as the logical test proves true, but COUNT(*) must count every row, even after it knows one row has passed the test.