Basics of caravan objects:
 -------------------------
  In this document the general concepts of caravan programming language is introduced.
  Once this part is clear, one has only to learn the various object types.

  Most caravan objects are instantiated as :

  <objecttype> <objectname>

  examples:
   user x
   time t

  Properties of caravan objects are accessed as:

  <objectname>(<property>)

  example:
   user x
   x(username);

  Assignment
  <objectname>(<property>)=<value>; //<value> is either a 
                                    //quoted string or a variable value
  example:
   user x
   x(uid)="0";
   x(uid)=form(uid);
   x(domain)="admin"


  Caravan object can have many properties and each property may have 
  one or more values; an example is "domain" property in "user" object

  <objectname>(<property>)=<value1>
  <objectname>(<property>)=<value2>
  <objectname>(<property>)=<valueN>

  Total number of values held by a property is  given by:

  <objectname>(<property>(00)) 

  example :
   user x;
   x(domain(00));// gives the number of "domain" values of 'x'

  Accessing a particular value when a property has more than one value:

  <objectname>(<property>(0NN)) ;// N is a digit 0-9

   example:
    user x
    x(domain(02));// access 2nd domain value

 Iteration  --  the loop statement 
 ---------------------------------------------
 Caravan has only one type of statement for doing iterations:

 loop <loopname> (<max-loop-count>)
   <statement>;
	--
   <statement>;
 repeat <loopname> MAX

 MAX is a numeric constant
 max-loop-count is a constant or variable.
 loop has a property called count access by <loopname>(count)
 example: following will print 1 to 20;
  loop myloop (20)
    myloop(count);"<br>"
  repeat myloop 100

 example: following will print 1 to 10;
  loop myloop (20)
   myloop(count);"<br>"
  repeat myloop 10


 example:  from "user.html"
  loop dl (x(domain(00))); // max loop count is given by x(domain(00))
   x(domain(dl(count)));"|";// access each domain-- dl(count) gives 01,02,03 etc
  repeat dl 8


 The conditional statements:
 -----------------------------------------------------------------

 if <condition>
   <statement>;
 else 
   <statement>;
 endif

 if <condition>
   <statement>;
 endif

 if <condition1>
   <statement>;
 elseif <condition2>
   <statement>;
 elseif <conditionN>
   <statement>;
 endif


 Examples of condition checking:
  if <objectname> ;//checks if object is defined 

  if <objectname>(<property>) ;; checks if object and property are defined

  if <objectname>(<property>) = <value> ;; if equal

  if <objectname>(<property>) > <value> ;; if greater

  if <objectname>(<property>) < <value> ;; if lesser

  if <objectname>(<property>) >= <value> ;; if equal or greater

  if <objectname>(<property>) <= <value> ;; if equal or lesser

  if <objectname>(<property>) <> <value> ;; if not equal

  The domain concept in caravan:
---------------------------------
 In caravan the users are grouped into various domains. Each user has a domain
 property which can have multiple values. You can restrict access to the 
 the caravan generated pages by using the domain statement:

 domain <domainname>|<domainname>|....|<domainname>
 example :
 domain admin;// access to only admin users.

 caravan automatically prompts for login , if the users does not have one of the
 domainnames.

 One can also check the domain of the user by using the conditional statements like:

  if domain<>"admin"
   "Sorry, access denied!"
   over
  endif  


 label and goto
--------------------
 goto <labelname>
 label <labelname> 

 process termination : over statement
----------------------------
 the statement to end the process is :
 over 
 this will cause the data so far generated to be flushed to the browser;

redirecting browser : redirect statement
--------------------


 redirect "<url>"
 example:
 redirect "user.html" 
 redirect "http://www.ibm.com/index.html" 

Http request form
--------------------------
When a request is posted to the server an object with name "form" 
is added to the object list of caravan.
forms are generated in the following ways in html:

1.url encoded links like:

<a href=user.html?test=1>test</a>

2. Explicit post statement in html like:

<form>
<input type=text name=test value="1">
<input type=submit>
</form>

<form method=post action=user.html enctype=multpart/form-data>
<input type=text name=test value="2">
<input type=file name=testfile value=""> -- shows browse button 
<input type=submit>
</form>

 In caravan one can check if a form has been posted using code:
 if form
    if form(test)="1"
       "Ok test=1"; // outputs this to browser.
    endif
 endif