How to handle special character in XML document

Hi, 
you can escape the characters

" to  "
' to  '
< to  &lt;
> to  &gt;
& to  &amp;

or you can wrap attribute values in double quotes ("), e.g.

<MyTag attr="If a&lt;b &amp; b&lt;c then a&lt;c, it's obvious"/> will resolve into
If a<b & b<c then a<c, it's obvious as it can be found easy with google.

Thanks for the response. We have created a common rule to find the character and replace it with the required character individually. Hence, the same rule will check the characters individually. However, is there a way to check and all special characters at once and replace with the respective required characters. 

You just need a single rule where you can pass in a string and it passes out the "sanitized" version.  I'm unclear whether that's what you already have, but this is about as good as you're going to get in Appian.

Thanks for the solution Mike. I have probably done that only. PFB my approach:

Rule "ia_findAndReplaceCharacter" Code is as below:

if(
find(
ri!search_text,
ri!input
) = 0,
ri!input,
substitute(
ri!input,
ri!search_text,
ri!replace_text
)
)

Rule "ia_findAndReplaceAllCharacters" Code is as below:

a!localVariables(
local!lessThanChar: rule!ia_findAndReplaceCharacter(
input: ri!input,
search_text: "<",
replace_text: "|"
),
local!greaterThanChar: rule!ia_findAndReplaceCharacter(
input: local!lessThanChar,
search_text: ">",
replace_text: "|"
),
local!apostropheChar: rule!ia_findAndReplaceCharacter(
input: local!greaterThanChar,
search_text: "'",
replace_text: "|"
),
local!backspaceChar: rule!ia_findAndReplaceCharacter(
input: local!apostropheChar,
search_text: "\b",
replace_text: "\B"
),
local!ampersandChar: rule!ia_findAndReplaceCharacter(
input: local!backspaceChar,
search_text: "&",
replace_text: "and"
),
local!finalOutput: local!ampersandChar,
local!finalOutput
)

Here, we have used rule  "ia_findAndReplaceCharacter" for each character. 

Is there a way or any function which can find and replace any such special character instead of the above approach. 

This code replaces all XML special characters in a given XML text.

http://xml.silmaril.ie/specials.html

" to  "
' to  '
< to  &lt;
> to  &gt;
& to  &amp;

reduce(
  substitute(_,_,_),
  ri!xml,
  merge(
    {"&", "<", ">", """", "'"},
    {"&", "<", ">", """, "'"} /* Change this to the escape characters listed above.*/
  )
)

Thanks Stefan for the solution. However, I would like to know if we can encode special characters in Appian in the similar manner which can be done in other programming language with functions like encode()

Thanks Stefan for the solution. However, I would like to know if we can encode special characters in Appian in the similar manner which can be done in other programming language with functions like encode()

There is no ready made function available. You know the function toXml()? It has some quirks, but would take care of all you escape needs.

Thanks Stefan. I would go with your previous solution