On Sun, Jan 18, 2009 at 1:00 PM, Bernd Bohmann <bernd.bohm...@atanion.com> wrote: > 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. and openwebbeans
+1 > > 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 >>>>> >>>> >> >> > -- Matthias Wessendorf blog: http://matthiaswessendorf.wordpress.com/ sessions: http://www.slideshare.net/mwessendorf twitter: http://twitter.com/mwessendorf
