Rest web service synchronisation - web-services

Question

I am new to web services. I have written a rest web service which creates and returns pdf file. My code is as follows
#Path("/hello")
public class Hello {
#GET
#Path("/createpdf")
#Produces("application/pdf")
public Response getpdf() {
synchronized(this){
try {
OutputStream file = new FileOutputStream(new File("c:/temp/FirstPdf5.pdf"));
Document document = new Document();
PdfWriter.getInstance(document, file);
document.open();
document.add(new Paragraph("Hello Kiran"));
document.add(new Paragraph(new Date().toString()));
document.close();
file.close();
} catch (Exception e) {
e.printStackTrace();
}
File file1 = new File("c:/temp/FirstPdf5.pdf");
ResponseBuilder response = Response.ok((Object) file1);
response.header("Content-Disposition",
"attachment; filename=new-android-book.pdf");
return response.build();
}
}
}
If multiple clients try to call the web service simultaneousy , Does it impact on my code?
I mean , if client A using the web service and at the same time if client B tries to use the web service will the pdf file gets over writted.
If my question is not proper,Please let me know
Thanks

Answer 1

As you are writing the file to the hard disk multiple calls to the service will cause the file to be overwritten or cause exceptions where the file is already in use.
If the file is the same for all users then you would only need to read the file rather than write it every time.
However if the file is different for each user you might try one of the 2 following options:
You could build the file in memory and then write the binary response directly to the response stream.
Alternatively you could create the file using a unique name, this could be a GUID or a random number this would ensure that you never have a clash between the multiple calls arriving at the server.
I would also ensure that you remove the files