If you want to consume the entire file as a single event then you can do something like this.
If your file contains multiple XML documents you must consume them separately. If they all start with <control then your multiline codec should be
codec => multiline {
pattern=>"^<control"
negate => "true"
what => "previous"
auto_flush_interval => 1
max_lines => 3000
}
If you want to parse the entire message then just use
xml { source => "message" store_xml => true target => "theXML" }
If you need specific elements from the document you can use the xpath option instead of setting store_xml.
The xml filter typically just works. The hard part is tweaking the multiline codec so that each event contains a complete XML document.