HTTP engines
Contents
XP applications using the XP framework are essentially powered by the runtime’s HTTP engine. The HTTP engine is responsible for handling web-based request to the runtime.
Implementations
By default, the XP runtime serves HTTP requests from port 8080 (customizable). There are three specific web engine implementations available:
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Web app engine :8080/webapp/
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Site engine :8080/site/
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Admin engine :8080/admin/
Each engine provides a purpose specific request processing and execution pipeline.
Common request pipeline
All HTTP engines share a common request pipeline as specified below:
- Vhost filters
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Request routing based on virtual hosts
- Java request filters
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Optional Java request filters
- Auth filter
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The virtual host contextual ID provider will be invoked, unless a user already exists in the context
- Engine pipeline
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If nothing else matches, the pipeline of the specific engine will be executed
- Asset service
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Serves static assets for the /_/asset/* request patterns
- HTTP Service
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Provide access to Http service controllers through the /_/service/* request pattern
- IDprovider Service
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For direct interaction with the contextual IDprovider based on the /_/idprovider/* request patterns
- Auth handler
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Triggered if the pipeline returns a "401: Unauthorized" error code, the contextual IDprovider will be invoked, optionally handling the request
- Error handler
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If the pipeline returns an unhandled error (everything but "200: Ok") that was not handled by an ID provider, the contextual error handler will kick in.
- Java response filters
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Optional Java response filters
- Standard error handler
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Finally, if the request fails with an error that is still unhandled, XP’s standard error handler will kick in
Underscore endpoint
All engines reserve the use of the underscore characther _ (by itself) to provide engine specific endpoints. This applies to at any location within the URL path hierarchy. For instance, the following request :8080/webapp/<webapp>/_/ or :8080/site/<project>/<branch>/some/content/_/ are reserved.