Web Design Tips and Tricks

The Top 20 Things You Can Do to Make Your Website Accessible

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In 1990, the Americans with Disabilities Act was passed by Congress. The law was designed to protect people with disabilities from being discriminated against, because of a physical or mental disability. The act was put into place to help guarantee equal opportunity for people with disabilities in any public area – and it covers regulations for employment, transportation, state and local government services, telecommunications, etc.

But what about your Website? Have you done all you can, to assure that your Website is accessible?

Here is a checklist you can use, to determine if your Website is as accessible as it could be. (Note: These actions vary from fairly simple to complex, and this list is not meant to be considered the only options or actions you can take to make your site more accessible).

1. Have you provided a text equivalent for every non-text element on your site? Non-text elements include: images, graphical representations of text (including symbols), animations (including animated GIFs), image map areas, programmatic objects and applets, ASCII art, scripts, spacers, frames, images used for list bullets, buttons, sounds (whether automatic or by user interaction), video, audio tracks of video and stand alone audio files.

2. Have you ensured that any information conveyed with color is also available without it?

3. Are changes in the natural language of all pages on your Website and any text equivalents (such as captions) clearly identified?

4. Are all documents on your Website organized so that they can be read without style sheets?

5. Do you update all equivalents for dynamic content every time you update the dynamic content itself?

6. Have you eliminated any special effects from your Website that cause the screen to flicker?

7. Are you using clear and simple language in all content placed on your Website?

8. If you use images and image maps, are you providing redundant text links for each active region of your server-side image map?

9. If you use images and image maps, are you providing client-side image maps (instead of server-side) whenever possible?

10. When using data tables, have you identified the row and column headers?

11. If you use frames, have you titled each frame to make it easier for users to navigate your site and identify the frames?

12. When using applets and scripts, have you made sure that the pages are useable when all programmatic objects are not supported, or turned off? (If that isn’t possible, have you provided the information on an alternative accessible page?)

13. When using multimedia, have you provided an auditory description of the most important visual information on a multimedia presentation?

14. When using any time-based multimedia presentation (such as a movie or animation), have you synchronized the equivalent alternatives such as captions or auditory descriptions of the visual track to the presentation?

15. Have you made sure that the background and foreground colors on your Website have enough contrast so that when someone with a color deficit looks at it (or your Website is viewed with a black and white screen) they can still read it clearly?

16. Have you clearly identified the target of each link?

17. Have you provided a place to get information about your site, either through the use of a site map, or table of contents?

18. Have you clearly identified the primary language of your Website?

19. Have you provided information so that users can choose how they want to receive documents – by content type, language, etc.)?

20. Have you provided summaries for all the tables on your site?

Here are some simple steps you can take that don’t require much work or technical ability:

Graphs and Charts:

When working with graphs and charts, make sure you’ve provided enough information that any graphs or charts aren’t needed to understand the article, but are just supplements to it. You can also use the “alt” tag to provide information about them.

Image Maps:

Provide alternative text anywhere that the user must click on your Website, so that if they’ve turned off the graphics, or can’t view them, they can still understand what your site is about and can navigate around it. (Note: This method still doesn’t work with all browsers, but at least you’re trying!)

Tables:

When working with headers, use the “th” attribute so that users with a visual impairment can hear the table headers from their screen reader.

Hypertext Links:

When using hypertext links, use text that will make sense when a screen reader reads allowed to a visually impaired user.

Bold Face

When writing your sales copy, use the “em” instead of the “b” tag. By using the emphasis tag, a screen reader’s tone will change, adding emphasis to what is on the screen. If you use a bold tag, the screen reader can’t recognize the change, and all of the copy will be read in the same tone.

Multimedia (Video, applets, and Plug-ins):

Try and provide alternatives when using multimedia. If you’re using streaming video for example, which has sounds or dialog, your two best options would be to either provide closed-captioning for the video or provide a text version for the dialogue. (This actually helps non-visually impaired viewers who have dial up instead of DSL, or for the times when the amateur video sound quality is poor.

When you use applets or plug-ins, look for alternative methods of presenting information such as text links, without relying on the applet or plug-in for navigating around your Webpages.

So, how do you know if your Website meets the accessibility guidelines?

You can use the Bobby Program. “Bobby” is a free Java-based program that searches through your Website to check its accessibility. Although it can’t analyze page content, it can analyze coding and the readability of your Website.

If you’re interested in finding out how accessible your Website is already considered to be, you can go to: http://webxact.watchfire.com/

WebXACT is a free online service that lets you test single pages of web content for quality, accessibility, and privacy issues.

If you’re interested in learning more about web accessibility, or you know someone who needs information or access to resources for a disability, you can get more information from the following links:

http://www.gatech.edu/accessibility/
AWARE: Accessible Web Authoring Resources & Education

http://www.awarecenter.org/
Bobby Version 3.2

http://www.cast.org/bobby/
CSS2 Tutorial

http://www.dynamicdeezign.com/css/introduction.html
IBM Accessibility Center

http://www-3.ibm.com/able/
IBM: Java Accessibility

http://www-3.ibm.com/able/accessjava.html

Is YOUR Website Accessible?
http://www.janejarrow.com/tv_station/webaccess/

WAI (Website Accessibility Initiative) http://www.w3.org/WAI/

Some simple suggestions

Well I don't consider myself an expert, I do have experience with working with larger datasets and there are a couple of things that I always do to keep queries performing well.

Optimize Queries with EXPLAIN

Explain is your friend, get to know it well. If you take the time to read thru the Explain documentation on the MySQL site, you will find some valuable information, some of which is hilighted below.

Optimizing joins

Single sweep what?

MySQL resolves all joins using a single-sweep multi-join method. This means that MySQL reads a row from the first table, and then finds a matching row in the second table, the third table, and so on. When all tables are processed, MySQL outputs the selected columns and backtracks through the table list until a table is found for which there are more matching rows. The next row is read from this table and the process continues with the next table.

Why is this important? Imagine a main table - tableA - with 80,000 rows of data. This table has a corresponding n:n table that maps entries in tableA with a locations table. A query could be written as:

SELECT tableA.*, locations.location from tableA 
Left Join tableA2locations on 
tableA2locations.tableA_id = tableA.id
Left Join locations on 
tableA2locations.location_id = locations.id
where locations.location = 'sometown'

Keeping the above quote in mind, MySQL will read a row from the first table and join the corresponding data from the joined tables for that row and then sweep thru the rest of the data, joining as it goes along.

This leads us into the following section.

Number of rows needed to execute a query

You can get a good indication of how good a join is by taking the product of the values in the rows column of the EXPLAIN output. This should tell you roughly how many rows MySQL must examine to execute the query.

From the above, you can determine that for a query on tables that have not been properly indexed, a join can quickly become unwieldy when dealing simply with three tables with records in the thousands (1000*1000*1000 = a slow query). See HackMySQL for a good example of this.

Reducing the number of rows needed to execute a query

So beyond indexing properly for joins, you can still end up with a query that runs in a way that causes a bottleneck.

Taking our example from above, imagine that we use a where clause that limits the tableA selection to half (tableA.foo = 'bar' below):

SELECT tableA.*, locations.location from tableA 
Left Join tableA2locations on 
tableA2locations.tableA_id = tableA.id
Left Join locations on 
tableA2locations.location_id = locations.id
where locations.location = 'sometown' and tableA.foo = 'bar'

This starts us out with 40,000 rows of tableA data to examine. If there are a further 2000 rows from tableA2locations, thats 800,000 rows of data. Not astronomical, but significant. If this was a 3 or 4 table join, things could get ugly. What to do? The answer may be obvious to some: select first with the most limiting table:

SELECT tableA.*, locations.location from locations 
Left Join tableA2locations on 
tableA2locations.location_id = locations.id
Left Join tableA on 
tableA2locations.tableA_id = tableA.id
where locations.location = 'sometown' and tableA.foo = 'bar'

This starts us out with 1 selection from the locations table, then 2000 from tableA2locations. If the join between tableA2locations and tableA is indexed correctly, we are then left with an index join based on ID, rather then having to initially select 40,000 rows from tableA as in the previous example.

When I first started programming, it made sense to me to select from the main table (tableA) and join the lookups. But once you add some data to the mix and start to play with Explain, you quickly realize that selecting from the limiting table can make your server's life a little easier.

For further reading on the topic, I always send people to HackMySQL when they ask, so for more tips and tricks, be sure to have a read thru the optimize section of that site.

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