Formatted your code a little.

getst(getvars, StBeg, temp) ; Save call stack in local or global array
 ; In:
 ; getvars = 1 - save variables defined at the last stack level
 ; getvars = 0 or omitted - don't save; default = 0
 ; StBeg - starting stack level for save; default: 1
 ; temp - where to save ($name).
 ; Out:
 ; temp - number of stack levels saved 
 ; temp(1) - call at StBeg level
 ; temp(2) - call at StBeg+1 level
 ; ...
 ; temp(temp) - call at StBeg+temp-1 level
 ;
 ; Calls are saved in format:
 ; label+offset^rouname +CommandNumberInsideCodeLine~CodeLine w/o leading spaces"
 ; E.g.:
 ; temp(3) = First+2^%ZUtil +3~i x=""1stAarg"" s x=x+1 s c=$$Null(x,y)"
 ; Sample calls:
 ; d getst^%ZUtil(0,1,$name(temp)) ; save calls w/o variables in temp starting from level 1
 ; d getst^%ZUtil(1,4,$name(^zerr($i(^zerr)))) ; save calls with variables in ^zerr starting from level 4
    new loop,zzz,StEnd
    set getvars = $get(getvars)
    set StBeg = $get(StBeg, 1) 
    kill @temp 
    set @temp = 0 
    set StEnd = $STACK(-1)-2
    for loop = StBeg:1:StEnd {
        set @temp = @temp+1
        set @temp@(@temp) = $STACK(loop, "PLACE") _ "~" _ $zstrip($STACK(loop, "MCODE"), "<W") 
        if getvars,(loop=StEnd) {
            set zzz="" 
            for { 
                set zzz = $order(@zzz)
                quit:zzz=""  
                set @temp@(@temp,zzz) = $get(@zzz)
            }
            if $zerror'="" {
                set @temp@(@temp,"$ze") = $zerror
            }
         }
    }
     quit 1

I made the following changes:

1.  Changed

Set mimePart.ContentType = "application/pdf"

to

Set mimePart.ContentType = "application/x-object"

2. Commented out:

Do mimeMsg.SetHeader("Content-Disposition","attachment; name=""Files1""; filename="""_docName_"""")          
Set mimeMsg.ContentTransferEncoding = "base64"

3. Uncommented:

 //Set req.ContentType = "multipart/form-data;boundary=" _mimeMsg.Boundary

After these change I received non-empty files object.

 "files": {
              "uploadedfile": "cd \\\r\n@echo start >> date.txt\r\n"
          }

Howether. Here's some tips on how to ask questions like these (with not working code samples):

1.  It must run everywhere. Remove the calls to other code (hardcode values if needed), like:

##class(HData.SiteSettings).GetFaxLogin()

2. Remove unused arguments, like coverpath

3. Remove non essential code like:

Set req.SSLConfiguration = "CardChoice"
Do req.InsertFormData("Username",##class(HData.SiteSettings).GetFaxLogin())
Do req.InsertFormData("Password",##class(HData.SiteSettings).GetFaxPassword())
Do req.InsertFormData("ProductId",##class(HData.SiteSettings).GetFaxProductId())
Do req.InsertFormData("cookies","false")
Do req.InsertFormData("header","header")

//Create job name for fax
Set sendDate = +$H
Set sendTime = $P($ZTIMESTAMP,",",2)+(15*60)
Set schedDate = $ZDATETIME(sendDate_","_sendTime,1,4)
Set schedDate = $E(schedDate,1,16)_" "_$E(schedDate,17,18)
Set docList = $LFS(docpath,"\")
Set docName = $LISTGET(docList,$LL(docList))
Do req.InsertFormData("JobName",schedDate_docName)
    
//format phone number and set billing code
Set num = $REPLACE(phone,"-","")
Do req.InsertFormData("BillingCode",num)
Do req.InsertFormData("Numbers1",num)
   
    
//get notification email
Set email = ##class(HData.SiteSettings).GetFaxNotifyEmail()
If (email '= "") Do req.InsertFormData("FeedbackEmail",email)

4. Comment out unused and misleading code paths like

Set base64 = ##class(%SYSTEM.Encryption).Base64Encode(docStream)
Set mimeMsg.ContentTransferEncoding = "base64"

5. Provide a GitHub Gist snippet of an xml file (with the code) to import and write how to run it.

Your goal, is to make it extremely easy for everyone to take a look at your snippet. All the process must consist of these two steps:

  1. Drag&Drop xml file into Studio
  2. Copy&Paste a line into a terminal

Since XMLEnabled class can be not persistent and, therefore, not have an extent at all, there is no such method. If you need to write  XMLExportToFile()  for several classes you can write method generator which generates a method that would:

  1. Use current extent query
  2. Iterate through it
  3. Output each object into a file

And inherit all classes, in which you have a need of XMLExportToFile()  method from this class.

It's for translating response status into Caché status. I have the following code:

ClassMethod GetResponseStatus(Request As %Net.HttpRequest) As %Status
{
    Set Status = Request.HttpResponse.StatusCode
    Quit:(Status = 200) $$$OK
    Set Body = Request.HttpResponse.Data.Read($$$MaxCacheInt)
    Quit $$$ERROR($$$GeneralError,"Status code: " _ Status _ " ReasonPhrase: " _ Request.HttpResponse.ReasonPhrase _ " StatusLine: " _ Request.HttpResponse.StatusLine _ " Body: " _ Body)
}

And I want to add URL reporting to it.

You can open this (any) method in Studio and see the definition (with some rare exceptions, in iKnow package only  %iKnow.TextTransformation.HeaderRepositorySetArray and %iKnow.TextTransformation.KeyRepositorySetArray classes are not availible). It's the best way to get an idea of how method works and the code usually even has comments.

Scrapped from GetSimilar():

  1. Select the most probably relevant terms in the source (top N)
  2. Select all sources containing at least one of these N target elements
  3. Sort these candidates by the number of target elements they share with the  reference documents (approximate score)
  4. Of these sources, calculate the actual similarity score for the top M sources with the best approximate score
  5. Now store the page window in the final result PPG

Hi. About your second question, you can easily extend Caché ObjectScript, to do it. Wouldn't recommend it for use in production, but why not add some syntax sugar on you dev instance?

Create %ZLANGC00 mac routine with the following code:

 ; %ZLANGC00
 ; custom commands for ObjectScript
 ; http://docs.intersystems.com/cache20141/csp/docbook/DocBook.UI.Page.cls?KEY=GSTU_customize
  Quit  

/// Execute Query and display the results
/// Call like this:
/// zsql "SELECT TOP 10 Name FROM Sample.Person"
ZSQL(Query)
  #Dim ResultSet As %SQL.StatementResult
  Set ResultSet = ##class(%SQL.Statement).%ExecDirect(, Query)
  Do ResultSet.%Display()
  Quit

Save and compile it and then you can execute sql in a terminal like this:

zsql "SELECT TOP 10 Name FROM Sample.Person"

It would display something like this:

SAMPLES>zsql "SELECT TOP 10 Name FROM Sample.Person"
Name
Adam,Wolfgang F.
Adams,Phil H.
Ahmed,Edward V.
Ahmed,Michael O.
Ahmed,Patrick O.
Allen,Zelda P.
Alton,Samantha F.
Bach,Buzz E.
Bach,Fred X.
Bach,Patrick Y.
 
10 Rows(s) Affected

That said I myself prefer executing SQL queries in SMP because you don't need to type them there (drag&drop from the left panel or copy&paste from the code) - it's very convenient.