FileStream, from a Java object

Hi,

Here is my situation. I need to call a RESTful API that returns a file stream. I need to be able to pass that file stream on to a request handler that returns the stream to the caller to get rendered in a native application. I noticed that the Java Object has no Oscript to Java translation for file streams. Is there a way of doing this? That is, a way that does not involve having the java client retrieve the file from the REST service, write it to temporary storage, pass the file name to Oscript and have Oscript stream it back. If I have to do that, it makes this whole mechanism completely unworkabout for anything but the smallest files.

-Hugh

Find more posts tagged with

Comments

HFCDev

I have worked out part of the solution to this. Now I need to turn to OpenText development to find out if it can be taken all the way. Realizing that the InputStream object (abstract as it may be) implements a read method, I tried doing the following:

Function Integer ReadFromJavaObj( JavaObject jIn, File fOut )    Integer bufferSize = 16383  // This is arbitrary    Integer offset = 0    Integer bytesRead = 0    Integer bytesWritten = 0    Bytes jBuffer = Bytes.Allocate( bufferSize )    Bytes fBuffer    Boolean hasMoreData = TRUE    while hasMoreData        bytesRead = jIn.InvokeMethod( "read", {jBuffer } )        if IsError( bytesRead ) || bytesRead == -1            break        end        fBuffer = Bytes.GetBytes( jBuffer, 0, bytesRead )        bytesWritten = File.WriteBytes(fOut, fBuffer )        offset += bytesRead    endend

This would all work except for one minor detail....it seems that the Oscript Java bridge doesn't support any sort of pass by reference, whereby arguments to the function end up getting data put in them. THe method above produces a file exactly the same length as the original, but filled with only zeros. Is there a mechanism to pass arguments by reference from Oscript to JavaObjects, so that a method like InputStream.read() can be properly invoked and its data returned? The return value of this argument is the number of bytes "read" from the stream.

Thanks in advance.

-Hugh

HFCDev

I did find a way to make this work, but not one I plan on implementing. The InputStream has a normal read() method which just returns a single byte of data from the stream and advances the pointer or returns -1 if there is no further data. Using that method, it is possible to read each individual byte into a Bytes buffer then write that out to your file.

I would not recommend this approach as the overhead of so many calls to InvokeMethod() becomes enormous. I'm not sure what the overhead is, but if you had a 100K file, you're effectively calling InvokeMethod 100,000 times, which is a performance killer.

The best option in this scenario is to have your java code read the entire file into memory and transfer the byte array to Oscript, then write to file (or to socket out). A feature request for OpenText would be to have a bridge for the InputStream object that maps to either File or to Socket.

-Hugh

Carsten_Kulms

Another option (a work-around also) would be to have your own wrapper around InputStream on the Java side which 'bridges' the different API paradigms in OScript vs. Java by providing a method byte[] read(int numberOfBytes) throws IOExceptionThis will use the wrapped InputStream's read(byte[]) method with a fresh byte[] of the requested size and return that (or a shortened copy in case less bytes than requested were read).