Hello, perhaps the annotation scanning was already solved by openejb? We should try to create a common annotation module for apache projects like openejb, tomcat, cxf and myfaces.
Regards Bernd Gerhard Petracek schrieb: > hello, > > i agree with simon. > > regards, > gerhard > > > > 2009/1/18 Simon Lessard <simon.lessar...@gmail.com> > >> Hi again, >> >> Actually, much more packages have to be scanned. The goal of those >> annotation is 0-Config, so a faces-config.xml might not even be needed >> anymore in the libraries. Anyway, before implementing any kind of package >> filter, I would wait for the final spec version, as long as the scanner is >> designed to easily include such filter if/when the need arise. >> >> >> Regards, >> >> ~ Simon >> >> >> On Sun, Jan 18, 2009 at 11:15 AM, Cagatay Civici <cagatay.civ...@gmail.com >>> wrote: >>> I also have some questions for the JSF 2.0 EG, like what classpaths >>>> need to be scanned by default. Or the policy of dealing with runtime >>>> invisible annotations (I can read them, but Reflection cannot). I'm >>>> also interested in general rules regarding class/method signatures. >>>> For example, do you need to implement a specific interface when >>>> annotating a class with @FacesComponent? >>> >>> Afaik, only jars with a faces-config.xml under META-INF are subject to >>> scan in classpath. >>> >>> On Sun, Jan 18, 2009 at 4:01 PM, Jan-Kees van Andel < >>> jankeesvanan...@gmail.com> wrote: >>> >>>>> That sounds great. >>>>> >>>>> What is your general approach? Just read in the class as byte[], then >>>>> use the class-file-format rules to get to the annotations sections on >>>>> the class and the methods? From my quick scan of the classfile spec it >>>>> seemed reasonably easy to do that... >>>>> >>>> This line is the important one: >>>> DataInputStream dis = new DataInputStream(new BufferedInputStream(new >>>> FileInputStream(classFile))); >>>> >>>> The DataInputStream is responsible for delivering the bytecode to me >>>> as easy-to-read ints, shorts and bytes. >>>> The first chapter of this document specifies the relation between the >>>> terms used in the spec and the DataInputStream API. >>>> >>>> http://java.sun.com/docs/books/jvms/second_edition/ClassFileFormat-Java5.pdf >>>> >>>> From there it's just reading each field, which is quite cumbersome and >>>> hard to get right the first time, because you need to read the spec >>>> very carefully. For example, when reading a double or long, you need >>>> to skip the next byte. Forget this and you get annoying errors, like >>>> EOF or variables that contain nonsense. >>>> But when you get the hang of it, it's not that hard. >>>> >>>>> I'd be interested to know the actual requirements that MyFaces has for >>>>> such a scanner. For example, does it ever need to look for annotations >>>>> on methods when the class itself is not annotated? >>>>> >>>> I also have some questions for the JSF 2.0 EG, like what classpaths >>>> need to be scanned by default. Or the policy of dealing with runtime >>>> invisible annotations (I can read them, but Reflection cannot). I'm >>>> also interested in general rules regarding class/method signatures. >>>> For example, do you need to implement a specific interface when >>>> annotating a class with @FacesComponent? >>>> >>>>> Your comment about "expose parsed classes" seems to imply that you are >>>>> providing some kind of DOM-style API. I would have thought that a >>>>> SAX-style API would be better, ie various bits of code interested in >>>>> annotations registers callbacks for annotations it cares about with the >>>>> "scanner". Then the scanner scans all jars in the classpath and when >>>>> something is found that matches a "registered" annotation, then it >>>>> invokes the appropriate callback. That approach would minimise memory >>>>> usage, and I can't see where we would need anything dom-like... >>>> Well, for performance reasons you would like a SAX style API, but >>>> afaics, the class file format is not very developer friendly. Maybe it >>>> just takes some getting used to, but on first sight, it looks less >>>> intuitive than SAX parsing an XML document. For example, class >>>> attributes are placed below the fields and methods, so you don't know >>>> the class annotations when reading through the fields and methods. >>>> That's not very intuitive for a developer. >>>> >>>> My plan was not to fully initialize the classes, but just fill them >>>> with the bytes read. This way, I get a little bit more structure so I >>>> don't have to think in bits and bytes too much. The heavy work will be >>>> done lazily. For example, I don't initialize the classes' fields >>>> unless the user asks for it, probably resulting in less memory usage >>>> and better performance than a fully fledged DOM model. >>>> >>>> But there's only one way to find out and that's implementing and testing >>>> it. >>>> >>>> I'm gonna look at a SAX style API. Maybe it's not as bad as I first >>>> thought... >>>> >>>> Regards, >>>> >>>> /Jan-Kees >>>> >>> > >
