pdfbox-server
To compile:
javac -cp pdfbox-app-2.0.1.jar:. pdfboxserver/*.java
To start the server:
java -cp pdfbox-app-2.0.1.jar:. pdfboxserver.PDFBoxServer
The server will listen on port 9998.
To parse a file, send to the server the absolute path of the file to parse followed by a null character.
This is meant to work on the same host (as you don't actually send the file). It's simply to avoid starting PDFBox each time a new file must be parsed.