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INTERNET DRAFT          EXPIRES APR 1999                INTERNET DRAFT
                                                             R. Nelson
                                                      12 October 1998
Category: EXPERIMENTAL


                HTML REFRESH LANGUAGE (HTMLR/1.0)
                 <draft-rfced-exp-nelson-00.txt>
Status of This Memo

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Distribution of this document is unlimited.


Copyright Notice

   Copyright (C) Ross Nelson (1998).  All Rights Reserved.

Abstract

   This document describes HTML REFRESH, an EXPERIMENTAL language
   and protocol for refreshing HTML pages and allowing serious
   thin-client/server applications via HTTP [RFC2068].

1. Rationale and Scope

   HTML forms have changed little in functionality or feature since
   the inception of the HTML standard. Whilst HTML forms allow the
   submission of form data from visible and hidden fields up to a
   server side CGI program (or some derivative thereof), the results
   must come back as a complete HTML page, either in the existing
   window/frame or in another browser window or frame.

   This is particularly tedious as the entire target page needs to
   be redrawn, even if only certain data elements have been changed.
   This has two very negative affects. Firstly, the bandwidth
   requirements are increased as the entire page format must be sent
   down to the browser again and not just the "field" data which has
   changed. Secondly, the affect of redrawing the entire screen does
   not allow the development of user friendly thin-client/server
   applications (where the client is the web browser)and currently
   leads to user disorientation.

   Various browser "add-ins", such as "Java" have been developed
   whilst HTML forms have largely been allowed to languish. This is
   extremely unfortunate as by far the largest number of transactions
   over the Internet occur via HTML forms.

   This document specifies a HTML REFRESH language, which permits
   the refreshing of the form data elements and images on a HTML
   browser page without the redrawing of the entire page. This
   allows serious user interfaces to be developed whilst using
   less bandwidth to do so.

   Future versions of this protocol may include extensions for
   refreshing non-form elements of a web page, in-line with DHTML
   standards.

2. HTML REFRESH LANGUAGE
   The HTMLR language is built using the concepts of the HTML
   language and is to be used in web browsers in conjuction
   with HTML. Needless to say the main delivery method for
   HTMLR is HTTP, with the use of a new mime-type.

2.1 HTTP Added mime-type
   The HTTP would allow the following mime-type through to the
   browser and the web server and browser would comprehend it.
   The mime-type is :

                text/htmlr

   which would denote the content which followed as a HTML refresh.
   A HTML REFRESH aware browser would acknowledge the mime-type
   and note not to redraw the target page from scratch but instead
   integrate the results with it.

2.2 HTMLR Language

   The HTMLR Language uses HTML like syntax to denote the refreshes
   that are to be made to a HTML page. The following tags and
   attributes are used to specify these refreshes. Each tag is
   covered below with accompanying description and example.

   It is anticipated that HTMLR response pages would be generated by
   existing CGI (or like) capable programming languages, for example
   PERL, ASP, COLD FUSION, etc. Such languages should be easily
   capable of generating HTMLR and also changing the response
   mime-type.

2.3 HTMLR TAGS

2.3.1 HTMLR

   Syntax:
   <HTMLR> ... </HTMLR>

   Description:
   The HTMLR tag denotes that the all tags and text until the /HTMLR
   tag comprise a refresh of the existing HTML page/frame as
   displayed by the browser. This tag is equivalent in import to the
   <HTML></HTML> tags. Upon encountering a HTMLR tag, a browser
   should not clear the existing HTML display page/frame, but rather
   interpret the contents of the HTMLR tag and apply the relevant
   processing to the current page.

   Valid tags within HTMLR tags are specified in the rest of this
   section.

   Example:
   <HTMLR>
        ..... refresh tags ....
   </HTMLR>

2.3.2 WITHFORM

   Syntax:
   <WITHFORM  NAME="form-name">....</WITHFORM>

   Description:
   The WITHFORM tag denotes which form the tags within it apply to.
   The form-name specified with the NAME parameter must match the
   name of an existing form on the currently displayed page. The
   browser should treat all tags encountered within the WITHFORM
   screen as dealing with the specified form where applicable.

   Tags which are affected by the WITHFORM tag are SETINPUT,
   SETTEXTAREA,CLEARINPUT,WITHSELECT.

   If  WITHFORM does not enclose these tags, they are deemed to be
   relating to the first form on the current page.

   Example:
        <HTMLR>
                <WITHFORM NAME="Person">
                .... refresh tags for person form .....
                </WITHFORM>
        </HTMLR>


2.3.3 CLEARINPUT
   Syntax:
   <CLEARINPUT {EMPTY|DEFAULT}>

   Description:
   The CLEARINPUT tag clears all fields/checkboxes/radiobuttons/
   textareas/buttons in the currently targeted form and resets them
   to either empty or their default values. The targeted form is the
   one specified in the enclosing WITHFORM tag, or in the absence
   of this, the first form on the page. This should be processed in
   sequence by the browser, thus any subsequent SETINPUT tags would
   set the fields away from their default or empty values.

   The EMPTY attribute sets the fields to empty whilst the DEFAULT
   attribute set the fields to the original default value as
   specified in the original HTML page.

   Example:
   <HTMLR>
        <WITHFORM NAME="PERSON">
                <CLEARINPUT EMPTY>
        </WITHFORM>
        <STATUS VALUE="Person Record Added">
   </HTMLR>


2.3.4 SETINPUT

   Syntax:
   <SETINPUT NAME="field-name" VALUE="new-value" {CHECKED|UNCHECKED}
        {DISABLED|ENABLED}>

   Description:
   The SETINPUT tag sets the input-field to the new-value specified
   in the VALUE parameter. For radio button and checkbox fields, the
   CHECKED/UNCHECKED parameter can be specified to alter the field
   appearance. The field-name, specified in the NAME parameter must
   match the name of a field (hidden/text/radio/checkbox/button) in
   the targeted form on the current page. The targeted form is the
   one specified in the enclosing WITHFORM tag, or in the absence
   of this, the first form on the page.  For radio button fields,
   the new-value must also match the existing value of the named
   field in the current form.

   The HTML 3.0 proposed (but not widely implemented) DISABLED
   parameter could also be used in SETINPUT, along with ENABLED to
   dynamically enable/disable the input field.

   Example:
   <HTMLR>
        <WITHFORM NAME="Person">
        <SETINPUT NAME="Name" VALUE="Fred Jones">
        <SETINPUT NAME="Dob" VALUE="26/Jan/1971">
        <SETINPUT NAME="Address" VALUE="35 Fred Street, Springfield">
        <SETINPUT NAME="Sex" Value="MALE" CHECKED>
        </WITHFORM>
   </HTMLR>

2.3.5   SETTEXTAREA
   Syntax:
   <SETTEXTAREA NAME="field-name" {ENABLED|DISABLED}
                        >new-value</SETTEXTAREA>

   Description:
   The SETTEXTAREA tag sets the input-field to the new-value
   specified before the closing /TEXTAREA tag. The field-name,
   specified in the NAME parameter must match the name
   of a textarea field in the targeted form on the current page.
   The targeted form is the one specified in the enclosing WITHFORM
   tag, or in the absence of this, the first form on the page.

   The HTML 3.0 proposed (but not implemented) DISABLED parameter
   could also be used in SETTEXTAREA, along with ENABLED to
   dynamically enable/disable the textarea.

   Example:
   <HTMLR>
        <WITHFORM NAME="Person">
                <SETTEXTAREA NAME="Comments">
                The comments for this record are these
                </SETTEXTAREA>
        </WITHFORM>
   </HTMLR>

2.3.6   SETFOCUS
   Syntax:
   <SETFOCUS FORM="form-name" FIELD="field-name">

   Description:
   The SETFOCUS tag set the input focus the field/textarea/selectlist
   /checkbox/radiobutton-set/button with the name specified by the FIELD
   parameter. The form the field is in is specified by the FORM
   parameter. This tag is not affected by the WITHFORM tag as it
   must set a definitive focus for the entire page, regardless of
   how many forms are present.

   Example:
   <HTMLR>
        <MSGBOX>You must enter an Name</MSGBOX>
        <SETFOCUS FORM="Person" FIELD="Name">
   </HTMLR>

2.3.7   WITHSELECT
   Syntax:
   <WITHSELECT NAME="field-name"  {DESELECTALL} {REMOVEALL}
                {ENABLED|DISABLED}></WITHSELECT>

   Description:
   The WITHSELECT tag is used to choose and set a select list
   object in the current form. The field-name, specified in the
   NAME parameter must match the name of a select list object
   in the targeted form on the current page. The targeted form is
   the one specified in the enclosing WITHFORM tag, or in the absence
   of this, the first form on the page.

   The DESELECTALL parameter immediately de-selects all existing
   items in the select list. The REMOVEALL parameter immediately
   removes all items from the select list.

   The HTML 3.0 proposed (but seldom implemented) DISABLED parameter
   could also be used in WITHSELECT, along with ENABLED to
   dynamically enable/disable the SELECT list.

   Example:

   <HTMLR>
   <WITHSELECT NAME="Continent" CLEARALL ENABLED>
        <SETOPTION SELECTED>Asia</A>
   </WITHSELECT>
   </HTMLR>

2.3.8   SETOPTION
   Syntax:
   <SETOPTION {ADD|DELETE} SELECTED|DESELECTED
         VALUE="return-value">display-value</OPTION>

   Description:
   The SETOPTION tag is used to add, alter, or delete a select
   list item of the current SELECT list object. The current select
   list is the select list named by the last WITHSELECT within the
   currently targeted form. The SETOPTION tag is invalid outside of a
   WITHSELECT. The targeted form is the one specified in the
   enclosing WITHFORM tag, or in the absence of this, the first form
   on the page.

   The ADD/DELETE parameter is used to add and delete items
   respectively from the SELECT list. The SELECTED/DESELECTED
   parameter is used to select/deselect an item after it has been
   created, or if it already exists, to alter it.

   Example:
   See WITHSELECT tag example

2.3.9   MSGBOX
   Syntax:
   <MSGBOX {TITLE="title"}>message</MSGBOX>

   Description:
   The MSGBOX tag displays a centered message box to the user with
   message supplied before the </MSGBOX> parameter enclosed in it.
   The message box must be modal and have an 'OK' button to allow
   the user to proceed. The browser should process the MSGBOX tag
   immediately before parsing/processing any more of the HTMLREFRESH.
   The optional TITLE parameter specfies a title for the messagebox
   window.

   The text between MSGBOX and /MSGBOX tags should not contain HTML
   formating and browsers may wrap the text as well as obey CRLF
   combinations found in the text.

   The MSGBOX tag allows for easy server generated intrusive messages
   without affecting the browser page display.

   Example:
   <HTMLR>
        <MSGBOX TITLE="Update Successful"
                >The Record has been updated.</MSGBOX>
   </HTMLR>

2.3.10  STATUS
   Syntax:
   <STATUS VALUE="status-line-value">

   Description:
   The STATUS tag is used to place the value specified in the VALUE
   parameter into the status line at the bottom of the browser
   window.

   The STATUS tag allows for another form of easy server generated
   intrusive messages without affecting the browser page display.


   Example:
   <HTMLR>
        <STATUS VALUE="Please correct the value in the Age Field.">
        <BELL>
   </HTMLR>

2.3.11 PRINT and PRINTURL
   Syntax:
   <PRINT {TO=printer-name} {ORIENT=orientation} {TRAY=traynumber}
           {COPIES=copy-count}>....</PRINT>
   <PRINTURL {TO=printer-name} {ORIENT=orientation}
         {TRAY=traynumber} {COPIES=copy-count} SRC="url">


   Description:
   The PRINT tag is used to print HTML to the specified printer.
   The HTML to print is supplied between the PRINT and /PRINT tags.
   The print is sent to the printer specified by the optional TO
   parameter. If no TO parameter is specified, a printer dialog
   should be displayed for the user to select a target printer
   from. Printing should occur in parallel to any other browser
   processing. The TO option is of most value in an intranet
   environment.

   The ORIENT, TRAY and COPIES parameters are all options which
   allow control over the printing process. The ORIENT parameter
   can be used to specify "landscape" or "portrait" printing. The
   TRAY parameter can be used to select a paper source. The COPIES
   parameter can be user specify an number of copies to print. All
   are optional and are most suited to intranet systems.

   The PRINTURL tag functions the same as the PRINT tag in terms of
   parameters, except that the content to print is supplied by the
   url specified in the SRC parameter. The browser should open the
   specified url and print the resultant stream as requested. The
   printing method should be dictated by the mime-type returned.

   Browsers should aim to support multiple PRINT requests in a
   single HTML REFRESH stream.

   The HTML allowable between the PRINT and /PRINT tags should be
   of the same conformance level as the normal HTML supported by
   the browser and print exactly the same as a user activated print
   of a normal web page.

   Example:
   <HTMLR>
        <MSGBOX>The person record will now be printed to your
              "HP" printer.</MSGBOX>
        <PRINT TO="hp01" ORIENT="portrait" TRAY="3" COPIES="1">
                <HTML>
                        <HEAD>
                                <TITLE>Person Record 123321</TITLE>
                        </HEAD>
                        <BODY>
                                <H2>Person Record 123321</H2>
                                <B>Name:</B> John Smith<BR>
                                <B>DoB: </B>  14/Mar/1969<BR>
                                <B>Address: </B> 14 James St Smithville<BR>
                                <HR>
                        </BODY>
                </HTML>
        </PRINT>
   </HTMLR>

2.3.12  BELL
   Syntax:
   <BELL>
   Description:
   The BELL tag makes the browser produce an audible or visible bell.

   Example:
   <HTMLR>
        <BELL>
        <MSGBOX>The server has detected an error.</MSGBOX>
   </HTMLR>

2.3.13  SETIMG
   Syntax:
   <SETIMG NAME="image-name" SRC="url">
   Description:
   The SETIMG tag is used to set images to new images based on a new
   URL. The "image-name" given in the NAME parameter must match the
   name of an image on the current HTML page. The new image is loaded
   into the same screen area as specified by the original IMG tag on
   the original HTML page.

   The browser will place the new image on the page in the same
   location as the old image, with the same dimensions to avoid
   page resizing.

   Example:
   <HTMLR>
        <SETIMG NAME="EmployeePic" SRC="/images/employee/002012.jpg">
   </HTMLR>


3. Operational Constraints and Implications

3.1 Web Servers
   Web servers may require configuration to allow the text/htmlr
   mime-type to be transmitted from the CGI program.

3.2 Web Browsers
   Web browsers will naturally be required to support the protocol
   with substantial internal changes. On reciept of a HTML REFRESH
   of a given page, the page will not be redrawn but instead the
   fields altered as required. The refresh should NOT be placed in
   any history or "BACK" button cache as this does not make sense.

3.3 Javascript/VBscript Implications
   Javascript/VBscript browser implementations could possibly be
   extended to support an "OnRefresh" event in a similar manner
   as the existing "OnLoad" event. This event would be triggered
   upon receipt and application of a HTML REFRESH to the page.
   Appropriate extensions to the HTML BODY tag syntax would need to
   be made to support the "OnRefresh".

3.4     CGI Programs
   CGI program authors would gain the freedom to write serious
   thin-client/server applications with HTML REFRESH. For example,
   a HTML page could have buttons to move forward and backward
   though records in a database. Upon pressing either button, a
   submission would be sent to the appropriate Web Server/CGI
   program. It would navigate the the next/previous database row and
   return new data for the HTML form fields using a HTML REFRESH.

   This refresh would only alter the values in the HTML FORM fields
   on the page, thus lessening bandwidth requirents, aiding
   usability and removing redundant page redraws.

3.5 Security
  HTML REFRESH pages would travel under HTTPS the same as HTML and
   therefore enjoy the same security benefits.

4. Acknowledgements

   Thanks in particular to Steve Aldred, Nigel Williams and last but
   not least Joanna Ladon for encouragement and review.

5. References

   [RFC2068] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., and T.
   Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2068,
   January 1997.


6. Author's Address

   Ross Nelson
   Wizard Information Services
   15 Barry Drive
   TURNER ACT 2612
   Australia

   EMail: Ross.Nelson@wizardis.com.au


INTERNET DRAFT          EXPIRES APR 1999                INTERNET DRAFT


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