Class dbml.DictToDBML
{

ClassMethod WriteDBML(schema As %String = "") As %Status
{
    Set stmt = ##class(%SQL.Statement).%New()
    Set status = stmt.%PrepareClassQuery("%Dictionary.CompiledClass","Summary")
    If $$$ISERR(status) {
        Do $System.Status.DisplayError(status)
        Quit
    }

    Set rset = stmt.%Execute()
    While (rset.%Next()) {
        If rset.%Get("Persistent") = 1 {
            Set table = rset.%Get("Name")
            Set tableSchema = $Piece(table, ".", 1)
            Set tableName = $Piece(table, ".", 2)

            If tableSchema = schema {

                Set cdef = ##class(%Dictionary.CompiledClass).%OpenId(table)
                Write "Table ", tableName, " {",!
                    Write " ID integer [primary key] ",!
                    // get list of properties
                    Set count = cdef.Properties.Count()

                    For i = 1:1:count {
                        Set paramCount = cdef.Properties.GetAt(i).Parameters.Count()

                        //I checked Name property and it has MAXLEN
                        If (cdef.Properties.GetAt(i).Name = "Name") {

                            Write "MaxLen: ",cdef.Properties.GetAt(i).Parameters.GetAt("%MAXLEN"),!

                        }

                        Write cdef.Properties.GetAt(i).Name, " ", cdef.Properties.GetAt(i).Type, "", cdef.Properties.GetAt(i).Parameters.Count(),!
                    }
                    Write "}",!
                }

            }
        }

        Return $$$OK
}

}

You need to enable https to your REST API. Follow these steps:

Use a proxy server to do that. Have a look at this git : https://github.com/grongierisc/Https-Proxy-IRIS-Docker or this one : https://github.com/lscalese/isc-webgateway-letsencrypt (thanks @Guillaume Rongier)

Steps (thanks @Eduard Lebedyuk )

1. Install public web server (Windows, Linux).

2. Connect it to InterSystems IRIS.

3. Enable HTTPS there. Easiest way is Let's Encrypt.