Re: Preview for a general XSL-FO processing API
Hi Victor On 27.11.2004 16:53:54 Victor Mote wrote: I looked at the doc, and I think this is all pretty useful. I'd like to spend some more time on it later, and I think I will probably write a FOray implementation after I get 0.2 released. Here are some preliminary thoughts: I finally downloaded the Foray code yesterday because I thought it might be fun to write that implementation already. I didn't invest a lot of time but I got confused about the mixture of Foray and FOP code. Didn't really know where to start. But that's another story. I should probably look harder. Anyway, I got a renewed itch now to look at the PS interpreter. :-) 1. How do you anticipate deploying this? It looks like the user is aware of which implementation he is using, and therefore knows or can find the class(es) that implement the interface(s). So it looks like your org.xml.fo org.xml.fo.helper stuff would go in some vendor-neutral project, and the implementations would simply be part of the vendor package. Does that sound right? Exactly. That's where the whole thing is slightly different to JAXP. I want to have multiple implementations at the same time and I want to control which. Either you set up the classpath yourself and instantiate the right FOProcessorFactory or you use the XML package format to load an implementation dynamically along with additional libraries (Barcode4J comes to mind) and use that. 2. One thing that I really like about your idea is that, if done properly, the implementation classes almost become self-documenting tutorials on the API for the specific implementation. If jafop exposes a general API for what is needed to process an FO document, then the innards of the implementation show how to use the API for the specific implementation. Right. :-) That one didn't occur to me. 3. There is more going on here than I anticipated. In org.xml.fo, there are four interfaces that a vendor needs to implement. I am not sure what FOPEventListener is supposed to do. Of the other three, it looks like two of them exist to handle variations in input. I *think* that these could be boiled down to just one interface, and that the input variations could be handled with overloaded methods or some other way. However, I sure could be missing something. FOPEventListener is an unfinished idea to get information on things happening inside an FO processor. Examples: Overflow warnings, Missing images, new pages etc. Nothing's implemented in this direction, yet. FOProcessor (equivalent to JAXP Transformer) represents the actual FO processor even if the implementation isn't implemented that way. Actually, I routed the implementation of the process() method through the Handler. The main idea is to establish the same structure known from JAXP. I'm aware that the FOProcessor.process() method will probably never be used except for trivial examples not involving XSLT. The FOProcessorHandler is the real work horse IMO. It's used to bind XSLT output to FO input through SAX events. The Factory interface is simply responsible to instantiate the FOProcessor(Handler) implementations. It's probably best if I just publish the sources so things become clearer. Will do that later today. 4. If you think aXSL is an appropriate home for the vendor-neutral pieces of this, that would make some sense to me. As we have previously discussed, jafop is a subset of what aXSL is supposed to eventually handle. Vendors using the app or jafop or whatever part of aXSL would be free to ignore the other parts of it, if and when they appear. The problem with aXSL I've got WRT JAFOP is that it would IMO create confusion between stuff for FO implementation developers and FO users. Another point: Sun donated JAXP to the ASF. So the ASF may not be a bad place after all, as long it's not directly within the FOP source code. JAXP, Xerces-J and Xalan-J are all in different locations. 5. I know when I see the substring FOP in the vendor-neutral part of this stuff, that it is being used in a vendor-neutral way. However, since the general term FO Processor has already been taken by a specific implementation, it may be good to find some variation, not only for political reasons, but practical as well (cuts down on confusion). Maybe something as simple as PFO, or maybe the aXSL name can help here. That's been bothering me, too. It's also the reason why I mentioned that the naming can change. :-) I'd also prefer something a little farther from FOP but nothing really good has occured to me, yet. Good ideas always welcome. Something with XSL in the name seems problematic to me because I often run into people who can't distinguish XSL, XSLT and XSL-FO. Staying near FO would help avoid any confusion. I think you have done a good thing here. Thanks. We'll see what comes out of it. Jeremias Maerki
Re: Preview for a general XSL-FO processing API
I've uploaded the sources (ALv2) to http://www.maerki.org/jeremias/dev/jafop/ In the meantime, I've improved a few things: - javadocs improved a bit - added support for specifying a userconfig.xml file for the FOP maintenance branch implementation (through FOProcessorFactory.setAttribute(userconfig, filename)) - minimal implementation for JFOR On 26.11.2004 23:08:50 Jeremias Maerki wrote: If there's enough interest I can put the source code for the API plus implementations on my website (or to a SF project or somewhere else). Jeremias Maerki
Re: Preview for a general XSL-FO processing API
I'm extremely sorry about not making it clearer that I don't intend to launch a new API discussion for FOP or that I don't want to force anyone to do anything. This JAFOP thing is just a personal project I thought others might be interested in. Thank you for your suggestions. However, I don't think that EXSLFO would be the right place as it is focused to standardize on the XSL-FO language as such, not necessarily on Java API bindings. It could, on the other side, be launched as a JSR if there is sufficient interest in the community. It also occured to me that the API might be strong enough to accomodate other dialects like SVG. But these are just random synaptic shots. On 27.11.2004 06:36:47 Glen Mazza wrote: As long as a FOP user is not *required* to use it, (i.e., they can ignore JAFOP entirely and still call FOP's native JAXP-based API as in our embed examples), and as long as JAFOP is implemented using our current API, then I don't think I would have much problem with it. I don't want us to lose our present JAXP capabilities though--JAXP is a useful skill for our users to become proficient in, and something I would like us to continue promoting. But your idea -- an interface that allows for run-time swapping of FO processors (like JAXP allows for Xalan and Saxon to be switched) is not bad at all. I wish the folks at AH and RX would create such an interface that we could just implement. Two thoughts come to mind: (1) perhaps we should try to reactivate that EXSLFO group and move this topic to them, and (2) you may wish to take a look at the JAXP specification, if you haven't recently, and see if there are any issues/ideas/things you perhaps forgot to take into account, etc., with JAFOP. That spec should show you what needs to be done for a common interface to be accepted, including things you may have missed. Jeremias Maerki
RE: Preview for a general XSL-FO processing API
Jeremias Maerki wrote: I've talked about it before, so in case anybody is interested I've uploaded the Javadocs [1] for a general XSL-FO processing API I've been working on during the last few weeks. It's basically my API proposal that is (or rather was) on the Wiki. I've called it JAFOP (Java API for XSL-FO processing) for now. But naming can change... The implementations for FOP maintenance branch and FOP HEAD already work for simple use cases. No fancy stuff, yet (no events, no userconfig.xml...). ... If there's enough interest I can put the source code for the API plus implementations on my website (or to a SF project or somewhere else). I believe this common API could be interesting in the following months when FOP HEAD advances. It can be used to easily switch implementations or during development/testing. And I've got a few additional ideas. As time allows... It might also be interesting to have implementations for Foray, Defoe, XEP and maybe even ol' JFOR. I hope the design is flexible enough to accomodate all Java implementations. Hi Jeremias: I looked at the doc, and I think this is all pretty useful. I'd like to spend some more time on it later, and I think I will probably write a FOray implementation after I get 0.2 released. Here are some preliminary thoughts: 1. How do you anticipate deploying this? It looks like the user is aware of which implementation he is using, and therefore knows or can find the class(es) that implement the interface(s). So it looks like your org.xml.fo org.xml.fo.helper stuff would go in some vendor-neutral project, and the implementations would simply be part of the vendor package. Does that sound right? 2. One thing that I really like about your idea is that, if done properly, the implementation classes almost become self-documenting tutorials on the API for the specific implementation. If jafop exposes a general API for what is needed to process an FO document, then the innards of the implementation show how to use the API for the specific implementation. 3. There is more going on here than I anticipated. In org.xml.fo, there are four interfaces that a vendor needs to implement. I am not sure what FOPEventListener is supposed to do. Of the other three, it looks like two of them exist to handle variations in input. I *think* that these could be boiled down to just one interface, and that the input variations could be handled with overloaded methods or some other way. However, I sure could be missing something. 4. If you think aXSL is an appropriate home for the vendor-neutral pieces of this, that would make some sense to me. As we have previously discussed, jafop is a subset of what aXSL is supposed to eventually handle. Vendors using the app or jafop or whatever part of aXSL would be free to ignore the other parts of it, if and when they appear. 5. I know when I see the substring FOP in the vendor-neutral part of this stuff, that it is being used in a vendor-neutral way. However, since the general term FO Processor has already been taken by a specific implementation, it may be good to find some variation, not only for political reasons, but practical as well (cuts down on confusion). Maybe something as simple as PFO, or maybe the aXSL name can help here. I think you have done a good thing here. Victor Mote
Re: Preview for a general XSL-FO processing API
This all sounds great to me. I like the sound of it very much. As for the javadocs stuff, there's ongoing discussion on the Forrest DEV list[1] which discusses 'RAW' files (the category in which Javadocs fall). Since that isn't ready yet, perhaps we'll have to go for some other javadocs implementation? As for a 'location' for JAFOP, how about the Objects for Formatting Objects (OFFO[2])? Web Maestro Clay [1] http://mail-archives.apache.org/eyebrowse/ReadMsg? [EMAIL PROTECTED]msgNo=15979 [2] http://offo.sourceforge.net/ On Nov 27, 2004, at 12:06 AM, Jeremias Maerki wrote: I'm extremely sorry about not making it clearer that I don't intend to launch a new API discussion for FOP or that I don't want to force anyone to do anything. This JAFOP thing is just a personal project I thought others might be interested in. Thank you for your suggestions. However, I don't think that EXSLFO would be the right place as it is focused to standardize on the XSL-FO language as such, not necessarily on Java API bindings. It could, on the other side, be launched as a JSR if there is sufficient interest in the community. It also occured to me that the API might be strong enough to accomodate other dialects like SVG. But these are just random synaptic shots. On 27.11.2004 06:36:47 Glen Mazza wrote: As long as a FOP user is not *required* to use it, (i.e., they can ignore JAFOP entirely and still call FOP's native JAXP-based API as in our embed examples), and as long as JAFOP is implemented using our current API, then I don't think I would have much problem with it. I don't want us to lose our present JAXP capabilities though--JAXP is a useful skill for our users to become proficient in, and something I would like us to continue promoting. But your idea -- an interface that allows for run-time swapping of FO processors (like JAXP allows for Xalan and Saxon to be switched) is not bad at all. I wish the folks at AH and RX would create such an interface that we could just implement. Two thoughts come to mind: (1) perhaps we should try to reactivate that EXSLFO group and move this topic to them, and (2) you may wish to take a look at the JAXP specification, if you haven't recently, and see if there are any issues/ideas/things you perhaps forgot to take into account, etc., with JAFOP. That spec should show you what needs to be done for a common interface to be accepted, including things you may have missed. Jeremias Maerki Web Maestro Clay -- [EMAIL PROTECTED] - http://homepage.mac.com/webmaestro/ My religion is simple. My religion is kindness. - HH The 14th Dalai Lama of Tibet
Re: Preview for a general XSL-FO processing API
Jeremias Maerki wrote: If there's enough interest I can put the source code for the API plus implementations on my website (or to a SF project or somewhere else). I believe this common API could be interesting in the following months when FOP HEAD advances. It can be used to easily switch implementations or during development/testing. And I've got a few additional ideas. As time allows... It might also be interesting to have implementations for Foray, Defoe, XEP and maybe even ol' JFOR. I hope the design is flexible enough to accomodate all Java implementations. As long as a FOP user is not *required* to use it, (i.e., they can ignore JAFOP entirely and still call FOP's native JAXP-based API as in our embed examples), and as long as JAFOP is implemented using our current API, then I don't think I would have much problem with it. I don't want us to lose our present JAXP capabilities though--JAXP is a useful skill for our users to become proficient in, and something I would like us to continue promoting. But your idea -- an interface that allows for run-time swapping of FO processors (like JAXP allows for Xalan and Saxon to be switched) is not bad at all. I wish the folks at AH and RX would create such an interface that we could just implement. Two thoughts come to mind: (1) perhaps we should try to reactivate that EXSLFO group and move this topic to them, and (2) you may wish to take a look at the JAXP specification, if you haven't recently, and see if there are any issues/ideas/things you perhaps forgot to take into account, etc., with JAFOP. That spec should show you what needs to be done for a common interface to be accepted, including things you may have missed. Glen
