86 lines
3.5 KiB
Python
86 lines
3.5 KiB
Python
import importlib
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import time
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from platypush.backend import Backend
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from platypush.backend.http.request import HttpRequest
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class HttpPollBackend(Backend):
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"""
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This backend will poll multiple HTTP endpoints/services and return events
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the bus whenever something new happened. Supported types:
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:class:`platypush.backend.http.request.JsonHttpRequest` (for polling updates on
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a JSON endpoint), :class:`platypush.backend.http.request.rss.RssUpdates`
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(for polling updates on an RSS feed). Example configuration::
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backend.http.poll:
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requests:
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-
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# Poll for updates on a JSON endpoint
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method: GET
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type: platypush.backend.http.request.JsonHttpRequest
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args:
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url: https://host.com/api/v1/endpoint
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headers:
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Token: TOKEN
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params:
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updatedSince: 1m
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timeout: 5 # Times out after 5 seconds (default)
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poll_seconds: 60 # Check for updates on this endpoint every 60 seconds (default)
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path: ${response['items']} # Path in the JSON to check for new items.
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# Python expressions are supported.
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# Note that 'response' identifies the JSON root.
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# Default value: JSON root.
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-
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# Poll for updates on an RSS feed
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type: platypush.backend.http.request.rss.RssUpdates
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url: https://www.theguardian.com/rss/world
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title: The Guardian - World News
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poll_seconds: 120
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max_entries: 10
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Triggers: an update event for the relevant HTTP source if it contains new items. For example:
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* :class:`platypush.message.event.http.rss.NewFeedEvent` if a feed contains new items
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* :class:`platypush.message.event.http.HttpEvent` if a JSON endpoint contains new items
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"""
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def __init__(self, requests, *args, **kwargs):
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"""
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:param requests: Configuration of the requests to make (see class description for examples)
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:type requests: dict
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"""
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super().__init__(*args, **kwargs)
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self.requests = []
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for request in requests:
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if isinstance(request, dict):
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req_type = request['type']
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(module, name) = ('.'.join(req_type.split('.')[:-1]), req_type.split('.')[-1])
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module = importlib.import_module(module)
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request = getattr(module, name)(**request)
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elif not isinstance(request, HttpRequest):
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raise RuntimeError('Request should either be a dict or a ' +
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'HttpRequest object, {} found'.format(type(request)))
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request.bus = self.bus
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self.requests.append(request)
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def run(self):
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super().run()
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while not self.should_stop():
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for request in self.requests:
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if time.time() - request.last_request_timestamp > request.poll_seconds:
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try:
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request.execute()
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except Exception as e:
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self.logger.error('Error while executing request: {}'.format(request))
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self.logger.exception(e)
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time.sleep(0.1) # Prevent a tight loop
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# vim:sw=4:ts=4:et:
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