I do not use Ensemble, but I would try using the JSON-Adaptor, something like this

Class MessageB Extends (Ens.Request, %JSON.Adaptor)
{
   Property ClientId As %String(MAXLEN = "");
   Property message As %Stream.TmpBinary;
}

For example

s r=##class(MessageB).%New()
s r.ClientId=12345
d r.message.Write("part1")
d r.message.Write("part2")
w r.%JSONExportToStream(.s)
d s.Rewind()
w s.Read(s.Size) --> {"ClientId":"12345","message":"cGFydDFwYXJ0Mg=="}

Your solution is nearly perfect, here my quick (untested) version.

ClassMethod Encode()
{
	// You read N bytes (which MUST be divisible by 3) and write N*4/3 encoded bytes
	// 3 * 8190 = 24570; 24570 * 4 / 3 = 32760;  32760 < 32768; to avoid (slow) long strings
	set CHUNK=24570
	set NOCR=1	// don't insert CRLF after each 72 written bytes
	set encodedData=##class(%Stream.TmpBinary).%New() // adapt this to your needs: %Stream.Whatever...
	
	set request=##class(%Net.HttpRequest).%New()
	set request.Server="..."
    do request.Get("/...")
    
    if request.HttpResponse.StatusCode = 200 {
    	while 'request.HttpResponse.Data.AtEnd {
	    	do encodedData.Write($system.Encryption.Base64Encode(request.HttpResponse.Data.Read(CHUNK),1))
		}
	}
    QUIT encodedData
    
    // as an alternative, you could return a string or a streamobject
    set YOURMAXSTRING = 32767 // or 3641144
    if encodedData.Size <= YOURMAXSTRING {
	    do encodedData.Rewind()
	    quit encodedData.Read(encodedData.Size)
    } else { quit encodedData }
}

You are mixing two different things...

Property Data1 As list of %String;
Property Data2 As %List;

are two very different things. The first (Data1, equates to your DataObj.Services) is an object while the second one (Data2) is a simple scalar value (in this case a string which in its structure casually matches the inner structure of a $list() respective $listbuild() function).

write $listvalid(oref.Data1) ==> 0 // NOT a list
write $listvalid(oref.Data2) ==> 1 // a VALID list
write $isobject(oref.Data1) ==> 1  // a valid (list)object
write $isobject(oref.Data2) ==> 0  // not a valid (list)object

$listnext() does NOT work on objects (your DataObj.Services) is an object

For a string like "hallo" Cache will use 5+2 = 7 bytes. If that "hallo..." is longer then 253 bytes then length_of_string + 4 bytes will be used and if your "hallo..." is longer then 65535 bytes then length_of_string + 6 bytes will be used.

But there is one more thing, you should know: the sum of the lengths of ALL properties, except the array(like) properties, can't be greater then that famous 3641144 magic number (if you use the standard Cache Storage). Array-like properties are those, which are stored in own nodes.

Use this link as a starting point and consider using either $FIND() or $LOCATE() to narrow down the string you're looking for and then use $EXTRACT() to extract the href value. By the way, it's enough a short example string, posting nearly the whole page is an overkill and wasting space.

The documentation of the %ToJSON() method is correct and yes, you can do 

 do obj.%ToJSON()
 

merely, this works only "on devices without protocol" like terminal, (sequential) file, etc. Everywhere, wehere the data bytes goes direct to the target. WebSocket isn't such a device. There is a "header part", with information fields like the command, masking, the length of the data, etc.

You have two possibilities, a) you ask WRC for a "WriteStream()" method or b) you handle the whole WebSocket by hand (is not impossible) or c) you change your application logic and send the those messages in chunks.

OK, somehow I miss the question. Do you need the VT100 escape sequences  (see here, Table 3-6) or something else?

Take a look on the documentation of an (old) Cache instance (download the latest Cache 2018.x from WRC, if neccessary). There is a ZEN tutorial. You can follow the samples on IRIS, the ZEN classes are part of IRIS installation. Do not ask me for details, I have never used ZEN.

I'm sure, someone has a more elegant solution, anyway, I do it the quick-and-dirty way:

ClassMethod Lines(nsp = {$namespace})
{
    s (cls,sum)=""
    s glo=$na(^|"^"_##class(%SYS.Namespace).GetGlobalDest(nsp,"oddDEF")|oddDEF)
    f  {s cls=$o(@glo@(cls)),mth="" q:cls=""
        f  s mth=$o(@glo@(cls,"m",mth)) q:mth=""  s sum=sum+$g(^(mth,30))
    }
    q sum
}

The only tricky thing is the (web)management portal. Put the following few lines into a "test.html" file and the open it with your favorite browser.

<html>
<head></head>
<body>
A   simple  text     with    some spaces<br>
<pre>A   simple  text     with    some spaces</pre>
</body>
</html>

You see the difference?

You can take the line from your own code, but with a suitable parameter

Set BASE64=BASE64_file.Read(someCount) // someCount = aNumber * 3

For example 30000 instead of 32000. By the way, you read (8 bit) bytes, so there is no need to do the output-UTF8 conversion.

After spending about 30 seconds on Google, I found following links

https://www.astm.org/e1394-97.html  // ??
https://toolkits.horiba-abx.com/documentation/download.php?id=71068  // downloads a pdf
https://meganorms.com/st-astm-e1394-97.html
https://www.iso.org/obp/ui/#iso:std:iso:18812:ed-1:v1:en
... and many other links

Don't ask me,how accurate they are...

I have an (some ten years old) one which I use in the %ZSTART routine. Sometimes (for maintenance or whatever other reasons) you have to (re)start Cache and nowdays IRIS, but you want to start just some of the automatic processes listed in %ZSTART. If you forgot to disable those other before shutdown a init-file comes handy to disable things before start. A sample section looks like this:

[Start]
# 0 = do not start
# 1 = start
LoginServer = 1
UserLogin = 0
SystemTasks = 1
UserTasks = 0

I added some more comments to the class, you can download the InitFile.xml (class export) from my FTP server (which will be open for the next few days).

Addr: ftp.kavay.at
User: dcmember
Pass: member-of-DC

The general syntax for calling routines from another namespace is:

do label^|namesapce|routine

where

- you can omit the label and

- namespace is either the name of the namespace (like set namesapce="USER") or the path to the database (preceded by two carets), where the routine resides.

I see right now, Config.MapGlobals accesses the ^SYS global via the path to the database (take a look at the Storage section) - so in theory, you  can  call all classmethods from the above class as:

do zClassmethodname^|"%SYS"|Config.MapGlobals.1(args...)

merely, I do NOT recommend to do this (the cass is in deployed mode, so we do not know, what the code really does and (instance)methods are private, so you can't call them from outside).

First, the correct (or better) way for the above code snipet were:

new $NAMESPACE
zn "%SYS"
do ##class(Config.MapGlobals).Delete(...)
quit

second, one can call routines (and (class)methodes are compiled to rotines) from another namespace by using extended syntax, but in that case such a routine uses the globals (if the routine does a global access) from the CALLING namespace. In Your case this won't work because the Config.MapGlobals uses globals which resides in %SYS namespace and not in the namesspace you are in.

you miss the object reference!

set context.strDocumentEncoded = B64EncodeStream(request.streamPDF)
// ---------------------------^^^^^^^ this should be something
set context.strDocumentEncoded = ##(your.class).B64EncodeStream(request.streamPDF)

but you have another problems too: your context.strDocument and  context.strDocumentEncoded are currently STRING properties (according to the operation you try to do), which are limitet to a maxlength of 3.47MB!

You have to change both to a STREAM, so you can handle PDFs  larger then ca. 2.6MB (because 2.6 * 4 / 3 ==> 3.46MB, the limit for a string variable).

After you change context.strDocument and context.strDocumentEncoded to a stream properties, you could use this code:

Class DC.Someclass Extends %RegisteredObject
{

Parameter CHUNKSIZE = 2097144;

ClassMethod ToBase64(src As %Stream.Object, dst As %Stream.Object) As %Status
{
	i ..#CHUNKSIZE#3=0, src.Rewind(), dst.Rewind() {
		set sts=$$$OK
		while 'src.AtEnd,sts {
			do dst.Write($system.Encryption.Base64Encode(src.Read(..#CHUNKSIZE,.sts),1))
		}
	} else { set sts=$$Error^%apiOBJ(5001,"Chunksize or src/dst-problem") }
	
	quit sts
}

}

if ##class(your.class).ToBase64(context.strDocument,context.strDocumentEncoded) write "OK"

It seems, this task will take some time... you have to check, how context.strDocument is populated and  how context.strDocumentEncoded is later in code used. Good luck.

it looks like an OREF but it is just a string, try

set obj = [1,2]
write obj --> NN@%Library.DynamicArray
write $isobject(obj) --> 1
set ^myGlobal = obj
set obj=^myGlobal
write obj --> NN@%Library.DynamicArray
write $isobject(obj) --> 0

see also my answer in https://community.intersystems.com/post/handling-globalcharacterstream-production-service?page=1#comment-189746

As an ObjectScript routine, remove the "ClassMethod" keyword (which, as the name indicates, belongs to classes. Then either  add a "Public" keyword or you remove the brackets ("{", "}") too, but then all variables will have the same scope:

ProcData(file = "c:\temp\zipcitystate.csv") Public
{
    set str=##class(%Stream.FileCharacter).%New()
    do str.LinkToFile(file)
    while 'str.AtEnd {
        set $listbuild(ZIP,CITY,STATE)=$listfromstring(str.ReadLine())
        
        // now you have the individual columns
        // in ZIP, CITY and STATE variables for further processing
        write "Zip=",ZIP,?12,"City=",CITY,?40,"State=",STATE,!
    }
    
    // depending on the way of your implementation, a "kill str"
    // would be needed to free up the file
    kill str
}

Oh, and to invoke the above procedure just do a:

do ProcData^YourRoutineName()
// or
do ProcData^YourRoutineName("path-to-file")

A simple method like

ClassMethod ProcData(file = "c:\temp\zipcitystate.csv")
{
    set str=##class(%Stream.FileCharacter).%New()
    do str.LinkToFile(file)
    while 'str.AtEnd {
        set $listbuild(ZIP,CITY,STATE)=$listfromstring(str.ReadLine())
        
        // now you have the individual columns
        // in ZIP, CITY and STATE variables for further processing
        write "Zip=",ZIP,?12,"City=",CITY,?40,"State=",STATE,!
    }
    
    // depending on the way of your implementation, a "kill str"
    // would be needed to free up the file
    kill str
}

to do the job. Then call the method as

do ##class(your.class).ProcData()
// or
do ##class(your.class).ProcData("path-to-the-file")

your exit statement

If (AxVisM1.P0.ToString = "") Then
	Exit While
End If

is to late, this must come after the $ORDER() statement

AxVisM1.Execute("set P0=$o(^ztonMS(""REF"",P0))")
If (AxVisM1.P0.ToString = "") Then
	Exit While
End If
AxVisM1.Execute("s P1=$g(^ztonMS(""REF"",P0))")

The same goes for the next while-loop a few lines below