Apache FOP is a great tool for converting FO documents (that can be produced from XML or XHTML documents) to PDF and other formats. FOP is still not in a stable version but was rewritten and its current version is 0.93. The article below describes how existing java applications that use FOP 0.20 can be upgraded to use FOP 0.93. The things described below are only a part of what should be changed in this upgrade.
Time Consuming: Before you go ahead and do the upgrade, make sure that you have the necessary time to do the changes and to test. Almost all possible parts have changed, so you should expect to work several working days in order to do this upgrade. The process is quite difficult to revert, as many parts are involved, so it is recommended that you do a branch in your versioning system.

Upgrade Process:

Download latest jars

First of all you have to download the new version of FOP. Note that most jar files have changed. The fop.jar has also changed, althought the jar name is not versioned. This means that your project's ant files for compiling and deploying as well as your IDE's libraries and Manifest files have to be updated to use the new jar files. Also make sure that old fop.jar is deleted from your system's build directories, in case your build process does not overwrite it.

Embedding API Changes

The API for calling the FOP has changed a lot. The call to create a pdf is now a JAXP call. The old code uses the Driver and class which have been removed in the new API and been replaced with the Fop and FopFactory classes.
Tip: Although the above lines taken from the FOP website mean that you can run FOP with any parser, I would recommend using the Apache xalan transformer.
TransformerFactory factory = new TransformerFactoryImpl(); // gets xalan transformer
//TransformerFactory factory = TransformerFactory.newInstance(); // gets a default


FOP Configuration Changes

The new configuration in FOP is also quite different. It basically gives the extra option to add a configuration for each rendering engine.
When configuring FOP programmatically in java the classes for Configuration and Options have been removed in the new API.
The distinction between the base url and the font base url is also clearer. It is important that the font base url does not have the file:/// prefix (this worked without it in FOP 0.20), but for base url it is not necessary.
Another important change is the introduction of the user agent. An application can have one FopFactory but many UserAgents. The base url should be set for the user agent as well. The nice thing about it is that it supports setting document properties, such as keywords, author, etc that would otherwise had to be set with iText or other pdf post-processing tool.
Tip: Fop has as default the option "strict". Set this option to false (at least when starting testing Fop 0.93 for the first time), so that it does not throw Exceptions when it finds syntax that is not correct
fopFactory.setStrictValidation(false);

Font Changes

The xml fonts glyphs have to be recreated with the latest version of FOP. In case you foget this step, you will get a quite descriptive error that your font xml files are of an oder FOP version. There is also some new API to do this compilation on the fly, rather than referencing a static fonts glyph xml file.

Supported Features

This is the most difficult part. After all this you have to see if the fo files that you were using to create pdfs don't throw any errors and that they actually produce the same result. The best starting point for this is the FOP compliance page. It is important to note that not all features of FOP 0.20 are supported in FOP 0.93! I will mention some important blocking things that I have used, which are only a part of the things that one should be looking at.

• Fop 0.93 throws an error if there is a <fo:inline> element outside a block type element (list, table, block), so make sure these are removed in the fo.
• Empty table rows (without table columns) are not allowed.
• When there are invalid attributes in elements, they should better be removed.
• The bookmarks have changed completely: The fox extension used for pdf bookmarks in 0.20 is replaced by a neat bookmark tree in 0.93 where multiple levels of bookmarks are also supported
  

Labels: Dev

Use this script to create a simple photo album in your site. This photo album uses technologies like AJAX, XML, Javascript. It stores the names of the photos neatly in an external XML file and it can be easily customized. Take a look at this preview and see how I use it on my photos page to get a visual idea about how it works.

Features

• AJAX: It has the concepts of AJAX and dynamic HTML so it therefore when navigating, it does not load the whole page but only the parts that change.
• Bookmarkable URLs: Use of url with hash so that every page that is viewed is bookmark-able. A bookmark can be created that points to specific albums or images.
  
• Back button: Use of browser's back and Forward button is supported, since URLs can be bookmarked!
  
• Albums: Ability to group the photos in albums that have their own title.
• Paging: In case an album has a lot of photos, they are shown in different pages, so that the user does not have to scroll a lot to see the whole album in the browser. The user can configure how many photos will be displayed per page.
  
• Photo Pre-loading: While an image is viewed, the next image to be viewed is preloaded, so that it takes zero time to load when navigating to it. When an album is viewed, its images are also preloaded while the user is viewing a picture.
  
• Thumbnails: There is the option to use a separate folder to store the thumbnails.
  
• Photos Configuration: The photo's file names as the description of the photos are stored in an XML file externally.
  
• Script Configuration: The script parameters are easily configurable in a separate file.
  
• Slide-show: Option to show the photos in slide-show mode.
• Browser Compatibility: The script has been tested in Firefox 2, 3 and Internet Explorer 6, 7
  

Instructions - How to use it

1. Download the zip package (370kB) and extract it to a desired folder. This contains the html and script files as well as some sample configuration and images to get you started.
   
2. By opening the file photos.html the photo albums are displayed. The user can navigate between the albums by pressing the Next and Prev buttons. By clicking on a photo, the album is in photo mode and the navigation is now between the photos of the album. There is also the option for slideshow.
3. Add the photos you want to display in the directory photos*. A recommended photo size would be length 500px. The photos should have the extension .jpg.
4. Add the thumbnails of the photos to the directory thumbnails*. A recommended thumbnail size would be length 120px. The thumbnails should have the same name as the photo and have the prefix th_*. For example for a photo named me.jpg, the thumbnail should be th_me.jpg.
5. Edit the photos-sample.xml* file by grouping your photos in albums and specifying a description for every album and every photo. Use the name attribute for the photo to specify the photo's file name (without the .jpg extension).

* These are configurable in the photos-sample-config.js file.

Labels: Dev