After I added them to the Bean reference they seemed out of place with the DecideRules and RecordBuilders.
We had two classes called 'Browser' which is potentially confusing. It's also probably good to more clearly differentiate the ExtractLinks browser behavior from the Extractor processors.
The Browser processor can load a fetched page in a local web browser, record any requests the browser makes and run behaviors that interact with the page such as scrolling down and extracting links.
This differs from my previous attempt (ExtractorChrome) in a few ways:
- Uses the new WebDriver BiDi standard instead of the Chrome Devtools Protocol. The new protocol is mostly browser-agnostic, more consistent and hopefully more stable.
- Uses a MITM proxy instead of CDP request interception for recording sub-resources. That's partly because BiDi is still missing some key interception APIs. Even so in practice I found the proxy method loads pages faster and more reliably, likely because responses can be streamed incrementally, which helps a lot for large resources or server-sent events.
- Even when HTTP/2 is unavailable, the new FetchHTTP2 module does connection pooling which makes loading browser requests a lot faster. The original FetchHTTP opened a new connection for every request.
- The Browser processor can be configured with a list of behavior beans making it more customizable and extensible.
Obvious areas for future development:
- More Behavior beans: take screenshots, saveg the rendered DOM, run Browsertrix-compatible behavior scripts
- Support for remote WebDrivers (e.g. Selenium Server or cloud services)
This option enables HTTP Basic authentication for the web interface instead of the default Digest authentication. This is useful when running Heritrix behind a reverse proxy that adds external authentication as typically they don't support Digest auth for the upstream server.
#641
Graceful shutdown would be useful if you could deploy the UI in a high-availability configuration and direct new requests to a different instance while the current instance finished its outstanding ones. But as you can't, it's just making restarting Heritrix slow for little benefit.
This resolves some browser incompatibilities, allowing CodeMirror’s own find function to be re-enabled for reliable text search of content far outside the viewport.
The Jetty API has changed, which mostly affects test code.
Jetty now does a strict SNI host check which unfortunately causes it to
return "SNI error" for our existing ad-hoc certificates. For now, I've
disabled it to avoid breaking existing deployments but added a
--sni-host-check command-line option so you can re-enable it if
you've configured your own certificate appropriately.
When enabled this option causes regular links annotated with rel=nofollow to not be extracted. This is useful for sites that use rel=nofollow to hint crawler traps.
fastutil is our largest dependency, consuming about a third of the
total Heritrix distribution size but we only use a couple of trivial
classes from it.
FPMergeUriUniqFilter (which I'm not sure anyone uses anyway), uses
LongArrayList so this change replaces it with a basic version that does
just enough.
The unsynchronized FastBufferedOutputStream usages are likely
unnecessary these days thanks to the JVM's lock optimisations and for
the one in CrawlerJournal, the GZIPOutputStream is still going to
be synchronizing anyway.
This enables crawl configuration files to use Spring's [Groovy Bean Definition DSL] as an optional alternative to Spring XML. It uses the same bean configuration model but the syntax is more terse and human-readable. No more need for `&` in seed URLs. :-)
```groovy
checkpointService(CheckpointService) {
checkpointIntervalMinutes = 15
checkpointsDir = 'checkpoints'
forgetAllButLatest = true
}
```
It also enables some powerful scripting capabilities. For example, defining a custom DecideRule directly in the crawl scope:
```groovy
scope(DecideRuleSequence) {
rules = [
new RejectDecideRule(),
// ACCEPT everything linked from a .pdf file
new PredicatedDecideRule() {
boolean evaluate(CrawlURI uri) {
return uri.via?.path?.endsWith(".pdf")
}
},
// ...
]
}
```
The main downsides are defining nested inner beans can be a bit awkward, some of the errors can be cryptic, and you can't just manipulate the config files with an XML parser.
This commit includes a Groovy version of the default crawl profile for reference, but doesn't expose a way to use it in the UI yet. For now, you need to manually create a `crawler-beans.groovy` file in your job directory.
[Groovy Bean Definition DSL]: https://docs.spring.io/spring-framework/reference/core/beans/basics.html#beans-factory-groovy
This enables a checkpoint to be automatically created during a graceful termination. This makes it easier to stop and restart Heritrix without having to manually checkpoint each running job.
Spring 6 removed @Required and they suggest using constructor injection instead. If we switched our beans to that we'd break existing Heritrix crawl configs. So this change implements our own basic version so we still get errors when a @Required property is null.
Adam Miller