Yuri, It makes sense that the FOP driver only needs SAX events. This solution is pretty neat and I wish I had thought of it (I pretty much do your steps 1-3,5 but not 4).
However, I'm not sure that this is going to do much to solve any of the memory problems most people are having. In some of my typically reports, I have a 3mb XML file (result of SQL query) which get transformed into about a 9mb FOP file. When rendering the FOP file, it takes about 95mb of memory. Regardless of whether you send FOP sax events or a DOM tree, FOP consumes TONS of memory to do its magic. The memory consumed in steps 1-3 are nothing really compared to the FOP requirements, although I agree streaming the FOP resuls out is a good thing. However, the PDF files are typically 250KB or so in size, again, not the problem. FOP's memory consumption is becomming the primary barrier for our use of the product. We have reports that can run 250-500 pages and its almost impossible to render these types of PDF documents due to the excessive memory requirements and processing overhead. Does anyone know WHY FOP consumes so much memory, I assume its because it has to maintain the area tree stuff. Steve -----Original Message----- From: Shkuro, Yuri [mailto:[EMAIL PROTECTED]] Sent: Monday, November 12, 2001 2:42 PM To: '[EMAIL PROTECTED]' Subject: RE: Question on XSLTInputHandler I've already posted this code to the list, but will do it again. I would like to see it finding its place on http://xml.apache.org/fop/embedding.html one day - shouldn't we promote efficient use of FOP instead of giving an example of embedding, which is technically correct but hardly userful for servlet developers? The code below has the following benefits compared to Jim's example: - all transformations are done in a single pass by chaining SAX events - the resulting PDF is not stored in memory, but streamed directly into the output stream (in Jim's example, it is first stored in a string, then converted to byte array, and only then is writted to the output stream) import javax.xml.transform.Source; import javax.xml.transform.Result; import javax.xml.transform.stream.StreamSource; import javax.xml.transform.sax.SAXResult; import javax.xml.transform.Templates; import javax.xml.transform.Transformer; import org.apache.fop.apps.Driver; // ------- // 1. Get a Source for XML document // ------- // a) from string Source strSource = new StreamSource(new StringReader(xmlString)); // b) from file Source fileSource = new StreamSource(xmlFile); // c) from JDOM Document Source domSource = new org.jdom.transform.JDOMSource( jdomDocument ) // ------- // 2. Get stylesheet transformer // ------- // from file, see above examples for other types of XSL input Templates template = transformerFactory.newTemplates( new StreamSource( xslFile )); // note - template object is multi-threaded and should be cached if you plan // to use the same XSL repeatedly Transformer transformer = template.mewTransformer(); // ------- // 3. Create FOP driver and set rendering mode and output stream // ------- Driver driver = new Driver(); driver.setRenderer(driver.RENDER_PDF); driver.setOutputStream( response.getOutputStream() ); // initialize logger - see sample code on FOP website driver.setLogger(logger); // ------- // 4. Create SAXResult based on FOP Driver content handler // which will accept SAX events and build FOP tree // ------- Result saxResult = new SAXResult( driver.getContentHandler() ); // 5. Use the Transformer to transform an XML Source and // send the output to a Result object. Implicitely it will // create the FOP tree by firing SAX events. transformer.transform( whateverSource, saxResult ); // 6. Your user is already viewing the PDF! response.getOutputStream().flush(); response.getOutputStream().close(); Yuri Shkuro HR - Information Technology Goldman Sachs & Co., New York -----Original Message----- From: Jim Urban [mailto:[EMAIL PROTECTED]] Sent: Monday, November 12, 2001 2:08 PM To: [EMAIL PROTECTED] Subject: RE: Question on XSLTInputHandler Here is a block of code our of one my servlets. This code takes a string containing XML, applies an XSL:FO style sheet to it, and runs the XML:FO through FOP and send s the PDF directly back to the browser. Writer out = new StringWriter(); Transformer pdfTransformer = NsTransformerCollection.loadTransformer("my.xsl");; String xmlString = ..... Source xmlSource = new StreamSource(new StringReader(xmlString)); pdfTransformer.transform(xmlSource, new StreamResult(out)); out.close(); String fopstring = out.toString(); InputSource foSource = getInput(fopstring); try { ByteArrayOutputStream out = new ByteArrayOutputStream(); uResponse.setContentType("application/pdf"); Driver driver = new Driver(iInputSource, out); driver.setRenderer(Driver.RENDER_PDF); driver.run(); byte[] content = out.toByteArray(); uResponse.setContentLength(content.length); uResponse.getOutputStream().write(content); uResponse.getOutputStream().flush(); uResponse.flushBuffer(); } catch (Exception e){} Jim -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Monday, November 12, 2001 12:49 PM To: [EMAIL PROTECTED] Subject: Question on XSLTInputHandler Hello, I've looked at the example servlet and found that the XSLTInputHandler takes as input a java.io.File. However, I am constructing the XML document dynamically and have it as a java.lang.String in memory. It seems unnecessary I/O to write it out to a temporary file, just to pass it to the XSLTInputHandler. Looking at the source of XSLTInputHandler.java I didn't find any alternate way to call it. What would the recommended procedure be in this case, where I already have the XML document in memory? thanks in advance for any pointers, Ulrich -- Ulrich Mayring DENIC eG, Systementwicklung --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
