Lift Assistive Main Page

 

• 1. What's Lift Assistive and how does it work?
  • 1.1. Layout and content processing
  • 1.2. Supported protocols
  • 1.3. Performance aspects
• 2. Using Lift Assistive
• 3. Setting your preferences
• 4. Privacy aspects
• 5. Security aspects

 

Lift Assistive (or transcoder) is a web application that converts a web page into its text-only version on-the-fly by eliminating all page layout that is present in the original page and by hiding many accessibility defects.
The transcoder is useful for the website visitor, since it removes some accessibility issues and small defects like missing image ALTs or forms that are not properly linearized or flash objects. It can be used also by the web developer to determine if the reading order of the information presented in the page makes sense when read in the order that would be followed by a screen reader or speech browser.

Lift Assistive is especially useful for people and situations where:

• graphics cannot be seen (e.g. blind persons, text-only browsers, ...);
• sizes of the page elements have to changed (e.g. a low-vision persons that maximizes the browser windows to enlarge its contents; a PDA user who has to fit everything on a small screen);
• size of text that has to be changed (e.g. a low-vision person; a presenter that has to project a web page to an audience via a projector);
• links and buttons have to be easily located and operated (e.g. a person with motor disabilities that cannot move his/her hand with precision, like somebody with a broken arm);
• form fields need to be easily laid out to be used (e.g. a low vision person using a screen magnifier that restricts his/her field of vision).

 

Lift Assistive yields pages that are more in compliance to Section 508 and WCAG AA guidelines than the original ones. To do so, it performs a number of transformations on the web page layout and content:

• transcoded pages are based on CSS and do not constrain character size nor font family; their page layout is fluid that is fully adaptable to the visitor's browser window;
• automatic redirects implemented with META tags are substituted with server-based redirect (i.e. the browser will be automatically redirected to the required URL); in this way users would not perceive these redirects at all;
• the transcoder puts three spaces between links that are too close; in this way links are well separated and it is easier to select each of them;
• links having "javascript:" protocol are removed because not accessible (i.e. WCAG 6.3);
• all scripts and style sheets are removed; scripts are replaced by the content of the NOSCRIPT tag if it exists;
• frames and framesets are replaced by a page that can simultaneously display (in text-mode) all the content of all the frames. In this way a user can get the entire content at once (as she/he does when using a frame-enabled graphical browser). Inter-frame navigation works as it should.
• NOFRAMES elements are not used at all;
• all layout tables are linearized. The transcoder uses the Semantic Analyzer to understand if a table is used to present tabular data or for layout purposes. If a table is recognized as a data table, the transcoder keeps its original markup, since the resulting page is easier to read;
• images are replaced by their ALT. If no ALT is provided for the image, but a TITLE attribute exists, then TITLE is used in the resulting page. They are removed if no ALT or TITLE is specified; if the image is used as a button and it does not contain an ALT or a TITLE, it is substituted by "Go to URL-LOCATION." where URL-LOCATION is the URL pointed to by the button;
• client side image maps are transformed into simple lists of the links contained in AREA elements; if the ALT or TITLE of the image is defined, it is used as for the navigation bar. The ALT tag of each AREA element is used as label for its link. If ALT is not provided, a "Go to URL." link is added;
• graphical submit buttons in forms are substituted with textual buttons; a textual button label is obtained from ALT attribute if it is present; otherwise the word "submit" is used;
• submit buttons are added to javascript driven forms (i.e. to forms that do not have a submit button) so that without javascript the form data can be submitted;
• inline frames are substituted with links to the documents they are referring;
• meta keywords and meta descriptions are not changed;
• objects are substituted with the text-only version of their content, if any; objects are removed otherwise;
• applets are substituted with the text-only version of their content; if an applet has no content, the ALT attribute is used; otherwise applets are removed;
• form controls and labels that are correctly marked up are linearized by Lift Assistive with a a proper positioning of labels with respect to the controls they refer to. In particular the content of the LABEL tag is placed before or after the form control it refers to (depending on whether the control is a text field, radio button, checkbox or select menu). If no LABEL is specified but TITLE is given, then the content of TITLE is placed before or after the control;
• Lift Assistive can process javascript form validations on the server side.

Lift Assistive adds new CSS rules to the output page to let the user change color theme and font size of the web page.
These settings are saved using cookies and therefore are available to a Lift Assistive user (if cookies are enabled by his/her browser).

 

The transcoder is able to process any page on the Internet. It currently can transcode pages whose content is based on:

• HTTP and HTTPS protocols;
• GET or POST methods to send request parameters;
• HTTP Basic Authentication and NTLM authentication;
• cookies.

If a framed page contains two frames requiring HTTP Base Authentication, Lift Assistive will open a connection only to the first frame for security reasons.

See the Security section for more details about how Lift Assistive supports secure connections.

 

While Lift Assistive is very efficient, to transcode a page it has to:

1. receive a request from the visitor's browser,
2. issue a request to the webserver hosting the site,
3. wait for the webserver and the network to yield the data,
4. transform the page, and finally
5. send the transformed page to the user's browser.

The response time for getting a text-only page (i.e. the time the web visitor has to wait to see some results), compared to the time to get the original page, is affected by steps 2, 3 and 4.
Depending on whether the transcoder is installed in the same local network as the webserver or in a different network, the performance will differ (the latter case is the worst as steps 2 and 3 require more time).

We carried out a benchmark for determining the performance of Lift Assistive and interesting results are available on UsableNet's website.

 

Using Lift Assistive is straightforward: once you activate a "text-only" link that is based on Lift Assistive, or after you use the form in the Main page, your browser will display the transcoded page. Most of the links that you can select will activate again Lift Assistive: when you select any of them, your browser will display the transcoded page.

To achieve this effect the transcoder does what is called URL remapping. In fact Lift Assistive, besides performing a number of changes to the content of the page (as described in the Layout and content transformations subsection), changes also most of the URLs of the links and form actions in such a way that your browser sends the requests to Lift Assistive rather than the web server. Lift Assistive then relays the request to the web server, gets the answer, processes it and hands it to your browser.

The webmaster managing the web server hosting the "text-only" links or the Main page can decide where to stop this URL remapping. (Consider that if there are no such limits then you would be able to navigate through the entire Internet via Lift Assistive.) When the border is reached (and it depends on how Lift Assistive has been configured by the webmaster running it), Lift Assistive does not remap URLs any further. Typically a border is crossed when the webserver changes. For example, you might be able to use Lift Assistive on pages hosted by www.anycompany.com. If some of the pages contain links to news.anycompany.com, then Lift Assistive may refuse to remap these links because they exit from the server for which Lift Assistive has been configured. The webmaster can configure Lift Assistive so that any other link can be prevented from being remapped by Lift Assistive.

The webmaster can also customize Lift Assistive and change the default way for displaying a text-only page. Usually this is done for forms, for navigation bars and for special sections within pages for which the webmaster has some special requirement.

Lift Assistive can produce error messages. This happens when Lift Assistive encounters anomalous situations in talking with the web server that should supply the page (for example the requested page cannot be delivered by the web server). These errors are displayed as shown in figure.

Very rarely Lift Assistive may face weird situations and generate an error, even when a proper communication with the web server and the browser was in place. These errors include "Internal error" and are displayed as shown in figure.

When you need to browse websites that are behind a password authentication based on HTTP, Lift Assistive simply acts as a web proxy. This means that the browser will ask you to enter your username and password (required to access the website) and it will send the data to Lift Assistive, which in turn will send them to the web server. Username and password are not stored by Lift Assistive. They are acquired from the browser and sent to the web server through a secure connection (SSL) only if your browser shows HTTPS as a protocol. See the Security aspects and the Privacy aspects sections for more details.

 

Lift Assistive allows you to choose your display preference. These preferences are handled via cookies so that Lift Assistive can remember your choices. You must enable cookies in your browser.

Display preferences can be selected in a section entitled Text Only Options located at the bottom of any transcoded page.
Hold down ALT key and press T to jump to the Text Only Options section.
If you are using Internet Explorer, you must hold down ALT key, press T and then press enter key to obtain the same result.
If your browser has a menu with T as shortcut (for example 'Tools' in Internet Explorer) you can still open it using the keyboard by pressing ALT key and T separately.

The last part of Text Only Options section can be used to view the original version of the transcoded page, to launch Lift Assistive on any other public web page and to view the Lift Assistive Main Page.

Within the Text Only Options section you can select the following preferences.

• Font size: to be used when displaying the page content. This is useful for low vision persons or when you need to enlarge the content of a page (for example when projecting a page during a public presentation). Press the "larger" link to enlarge, "smaller" to reduce the size, or "default" to reset it to the default value.
• Color mode: to be used for background and foreground colors. In many cases you might prefer viewing the page content in black over a white background. But sometimes it is easier to read and scan the page if you use inverted colors. Available foreground/background combinations enhance the contrast and are: black on white, yellow on black, black on cream. Feel free to try them all and select the one that looks the best.
• Textual links: to people with motor disabilities (or those using less than optimal pointing devices) moving a pointer on a small link to select it is a complex task, requiring lot of attention and often leading to errors. If you use this option, Lift Assistive frames each textual link into a rectangular box and it makes sure that these links stand out clearly from the nearby elements.
• Moving navigation bars to the bottom of the page: the webmaster can configure Lift Assistive to move some objects of the page (for example the main navigation bar, the search box) to the bottom of the page. In this way those objects, that usually are repeated all over the website, are not in the way if you use screen readers. You get directly to the main content of the page first, and can still get to these elements by scrolling the page.
  However, you can set a preference of Lift Assistive to avoid this. Simply set the preference called Move navbars to the bottom of the page (or Do not move navbars to unset it).
• Speedbumps: when deployed, Lift Assistive is limited to registered web servers, in the sense that it will transcode only pages hosted on web servers that are properly registered. The set of registered web servers and their pages is called text-mode realm and it is defined by the webmaster of the website. When you activate a link that crosses the border of the text-mode realm (i.e. a link that brings you outside the web servers registered within Lift Assistive) by default Lift Assistive will alert you that you are leaving the text-mode realm and will offer you the choice between navigating in text-mode but by using a demo service hosted by UsableNet, or switching to graphic-mode.
  However, you can set the preference called [Don't] alert me when leaving text-mode so that Lift Assistive does not bother you with this alert page. In such a case Lift Assistive will switch off (i.e. the linked page will be displayed in graphic-mode by your browser).
  If you don't see this preference, it means that the webmaster has not configured Lift Assistive to exploit this feature.
• Not handled documents: when you activate a link that does not refer to a web page, Lift Assistive will alert you that it can not process that page and will propose to download the original file. You can disable this alert page by setting the preference called Open not handled documents directly. Set Show a splash page for not handled documents to re-enable the alert page.

 

Lift Assistive has to acquire from the web server the pages it processes, transform them, and deliver the transformed version to your browser. And you might be concerned about who can see and what can be done with that information.
Lift Assistive has been designed so that privacy and security issues are minimized.

When you use the text-only pages produced by the transcoder, you submit forms or your browser uses cookies, the information about the pages being visited, the data sent when submitting the form, and the cookies required by the pages are sent first to the transcoder server (i.e. the machine on which Lift Assistive runs) and then sent again to the web server that is the proper recipient.

By design, most of this information is not stored in any permanent form within Lift Assistive files. It lives in volatile memory only within the processes implementing the transcoder service and only for a very limited time (a fraction of a second). The only information that is permanently stored is the log of the HTTP/HTTPS requests, which does not include cookies nor form values.

However consider that UsableNet does not necessarily host the transcoder you are using. (It is easy to check: if the URL of a transcoded page starts with http://assistive.usablenet.com:... then it is hosted by UsableNet.) If UsableNet is not hosting Lift Assistive (i.e. Lift Assistive has been licensed to another party) then UsableNet cannot give any guarantee in terms of privacy and security. You should contact the webmaster of the organization that is hosting Lift Assistive (whose domain name appears at the beginning of the transcoded URLs).

If you are using a transcoder hosted by UsableNet then the only information that is permanently stored is the log of the HTTP/HTTPS requests, which does not include cookies nor form values.

UsableNet, according to its privacy policy, does not and will not release to third parties such an information. In addition, UsableNet does not and will not manipulate nor change the submitted information (other than for the purposes of implementing the functions required by the transcoder itself).

Please contact us at tt.support@usablenet.com for additional information.

 

Lift Assistive works as a web proxy, and when it transcodes a page it has to transform all the URLs of the links and form buttons that are contained in the page. Each URL is transformed (remapping of URLs) so that the request is first filtered by Lift Assistive and then it is Lift Assistive that issues another request to the original web server.

However when the URLs specify the HTTPS protocol, things become more complex. Lift Assistive has to remap URLs so that both the Internet connections (the one between the user browser and Lift Assistive and the one between Lift Assistive and the web server) are secure (i.e. on a Secure Socket Layer, SSL). Therefore Lift Assistive remaps each HTTPS link into an HTTPS link pointing to Lift Assistive and specified so that the Lift Assistive connects to the web server through HTTPS.
For example the link

https://www.mycompany.com/purchase.jsp?prod=123

is transformed into

https://assistive.usablenet.com/tt/https://www.mycompany.com/purchase.jsp?prod=123

(the actual server name for Lift Assistive may be different in your case). Notice the two occurrences of "HTTPS".

Security warning: if in your browser you notice that a link contains only one instance of HTTPS (instead of two), it means that the connection between your browser and Lift Assistive or the connection between Lift Assistive and the web server is not secure. In this case, if you are concerned about security of information exchanged between your browser and the web server, you should not continue your activity. Contact the webmaster responsible for the transcoder.

HTTPS is based on certificates, special files that contain all the information that allow the two parties in a connection to verify the identity of each party and to make sure that transit information is encrypted so that it cannot be tampered.
When you use the browser to open a page with the HTTPS protocol, your browser and the web server exchange also certificates. When a browser receives a certificate from a web server, unless the certificate is signed by an official Certificate Authority (i.e. unless the certificate has been issued by such an authority, usually called public certificates), the browser will tell you that with an appropriate pop-up window.

Lift Assistive properly processes secure pages (i.e. it remaps secure pages into secure transcoded pages) only if the webserver uses public certificates. If the webserver requires HTTPS to access a page, but the webserver does not have public certificates, Lift Assistive would not transcode the page.

In this way Lift Assistive behaves as a very conservative browser, refusing to continue a transaction when it is insecure but the Lift Assistive user expects it to be carried out securely.