SAX: Attributes and Entity Resolution
During our discussion this weekend, we have had two excellent proposals for additional SAX interfaces, beyond just XmlParser and XmlProcessor: 1. An interface for entity resolution, rather than using a resolveEntity callback. 2. An interface for attributes, rather than using java.lang.Dictionary. ENTITY RESOLUTION ----------------- While I agree that a full entity manager would be more powerful than a simple callback, I am not certain that the power will really be needed by most SAX users; furthermore, if it is needed, that functionality can be supplied more generally by an HTTP or FTP proxy server. For now, then, I recommend that we stick with the resolveEntity callback, which is simple to use and to learn, but provides 80% of the required functionality (that's 80% in the abstract 80/20 sense). ATTRIBUTES ---------- The good arguments and patient explanations of list members have convinced me that java.lang.Dictionary is unsuitable for three reasons: because it is a base class rather than an interface, because it is already deprecated in Java 1.2, and (most importantly) because there is no single, obvious equivalent in other programming languages. So what do we do? It is certainly tempting to introduce a new interface for attribute resolution, and that in itself would not bloat SAX too much, but if we did that, why not add other interfaces? It would be nice, for example, to have an Element interface, an Entity interface, a PI interface, a characterData interface, etc., all of which implement useful functionality; in the end, we will have rewritten the DOM. The alternative is to return to what I had originally done with Ælfred, and generate a separate event for each attribute: public void attribute (String elementName, String aname, String value); For example, with the following markup <para id="p1" level="advanced">This is a paragraph.</para> We would have five SAX events: attribute: elementName="para" aname="id" value="p1" attribute: elementName="para" aname="level" value="advanced" startElement: name="para" charData: ch="This is a paragraph." endElement: name="para" This is not pretty, but it is simple, and should translate cleanly to all languages. I am far from decided on this point, and encourage further public discussion. All the best, David -- David Megginson ak117@f... Microstar Software Ltd. dmeggins@m... http://home.sprynet.com/sprynet/dmeggins/ xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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