Extract text from file

Right. Forgot about it.

You can use ghostscript, here's how. In your case command would probably look like this:

Parameter COMMAND = "%1 -dBATCH -dNOPAUSE -sDEVICE=txtwrite -sOutputFile=%2 %3";

ClassMethod pdf2txt(pdf, txt) As %Status
{
    set cmd = $$$FormatText(..#COMMAND, ..getGS(), txt, pdf)
    return ..execute(cmd)
}

/// Get gs binary
ClassMethod getGS()
{
    if $$$isWINDOWS {
        set gs = "gswin64c"
    } else {
        set gs = "gs"
    }
    return gs
}

Execute method code.

Also note, that PDF can contain only images instead of text. in that case you'd need OCR.

as an alternative, you also can use apache pdfbox. See here for example:

https://dzone.com/articles/apache-pdfbox-command-line-tools-no-java-coding-re