gnu.xml.pipeline
public final class CallFilter extends Object implements EventConsumer
In effect, this makes a remote procedure call to the URI, with the request and response document syntax as chosen by the application. Note that all the input events must be seen, and sent to the URI, before the first output event can be seen. Clients are delayed at least by waiting for the server to respond, constraining concurrency. Services can thus be used to synchronize concurrent activities, and even to prioritize service among different clients.
You are advised to avoid restricting yourself to an "RPC" model for distributed computation. With a World Wide Web, network latencies and failures (e.g. non-availability) are significant; adopting a "procedure" model, rather than a workflow model where bulk requests are sent and worked on asynchronously, is not generally an optimal system-wide architecture. When the messages may need authentication, such as with an OpenPGP signature, or when server loads don't argue in favor of immediate responses, non-RPC models can be advantageous. (So-called "peer to peer" computing models are one additional type of model, though too often that term is applied to systems that still have a centralized control structure.)
Be strict in what you send, liberal in what you accept, as the Internet tradition goes. Strictly conformant data should never cause problems to its receiver; make your request pipeline be very strict, and don't compromise on that. Make your response pipeline strict as well, but be ready to tolerate specific mild, temporary, and well-documented variations from specific communications peers.
Version: $Date: 2001/10/23 17:42:25 $
See Also: XmlServlet
Constructor Summary | |
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CallFilter(String uri, EventConsumer next)
Initializes a call filter so that its inputs are sent to the
specified URI, and its outputs are sent to the next consumer
provided.
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Method Summary | |
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String | getCallTarget()
Returns the call target's URI. |
ContentHandler | getContentHandler() Returns the content handler currently in use. |
DTDHandler | getDTDHandler() Returns the DTD handler currently in use. |
Object | getProperty(String id)
Returns the declaration or lexical handler currently in
use, or throws an exception for other properties. |
void | setCallTarget(String uri)
Assigns the URI of the call target to be used.
|
void | setErrorHandler(ErrorHandler handler)
Assigns the error handler to be used to present most fatal
errors. |
Throws: IOException if the URI isn't accepted as a URL
Source code is under GPL (with library exception) in the JAXP project at http://www.gnu.org/software/classpathx/jaxp
This documentation was derived from that source code on 2011-08-26.