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 >> > >
