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annotate lib/patchablegraph/patchablegraph.py @ 1512:1e9cfec1be78
don't require first arg on PatchedGraph.serialize
Ignore-this: bc695823e03dbd012e03efa4e40b6aca
darcs-hash:1dbf9271b5ca55c78987c474ef223af9d5b811d2
| author | drewp <drewp@bigasterisk.com> |
|---|---|
| date | Mon, 03 Feb 2020 23:46:29 -0800 |
| parents | e41935c0ce96 |
| children | c829df2b0dd5 |
| rev | line source |
|---|---|
| 1317 | 1 """ |
| 2 Design: | |
| 3 | |
| 4 1. Services each have (named) graphs, which they patch as things | |
| 5 change. PatchableGraph is an object for holding this graph. | |
| 6 2. You can http GET that graph, or ... | |
| 7 3. You can http GET/SSE that graph and hear about modifications to it | |
| 8 4. The client that got the graph holds and maintains a copy. The | |
| 9 client may merge together multiple graphs. | |
| 10 5. Client queries its graph with low-level APIs or client-side sparql. | |
| 11 6. When the graph changes, the client knows and can update itself at | |
| 12 low or high granularity. | |
| 13 | |
| 14 | |
| 15 See also: | |
| 16 * http://iswc2007.semanticweb.org/papers/533.pdf RDFSync: efficient remote synchronization of RDF | |
| 17 models | |
| 18 * https://www.w3.org/2009/12/rdf-ws/papers/ws07 Supporting Change Propagation in RDF | |
| 19 * https://www.w3.org/DesignIssues/lncs04/Diff.pdf Delta: an ontology for the distribution of | |
| 20 differences between RDF graphs | |
| 21 | |
| 22 """ | |
| 23 import json, logging, itertools | |
| 24 | |
| 25 from greplin import scales | |
| 26 from rdfdb.grapheditapi import GraphEditApi | |
| 27 from rdflib import ConjunctiveGraph | |
| 28 from rdflib.parser import StringInputSource | |
| 29 from rdflib_jsonld.serializer import from_rdf | |
| 30 import cyclone.sse | |
| 31 | |
| 32 from cycloneerr import PrettyErrorHandler | |
| 33 from rdfdb.patch import Patch | |
| 34 from rdfdb.rdflibpatch import patchQuads, inGraph | |
| 35 | |
| 36 log = logging.getLogger('patchablegraph') | |
| 37 | |
|
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38 def _writeGraphForBrowser(req, graph): |
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39 # We think this is a browser, so respond with a live graph view |
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40 # (todo) |
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41 req.set_header('Content-type', 'text/plain') |
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42 lines = graph.serialize(None, format='nquads').splitlines() |
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43 lines.sort() |
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44 req.write(b'\n'.join(lines)) |
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45 |
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drewp <drewp@bigasterisk.com>
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46 |
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drewp <drewp@bigasterisk.com>
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47 def _writeGraphResponse(req, graph, acceptHeader: str): |
| 1317 | 48 if acceptHeader == 'application/nquads': |
| 49 req.set_header('Content-type', 'application/nquads') | |
| 50 graph.serialize(req, format='nquads') | |
| 51 elif acceptHeader == 'application/ld+json': | |
| 52 req.set_header('Content-type', 'application/ld+json') | |
| 53 graph.serialize(req, format='json-ld', indent=2) | |
| 54 else: | |
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55 if acceptHeader.startswith('text/html'): |
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parents:
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56 _writeGraphForBrowser(req, graph) |
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57 return |
| 1317 | 58 req.set_header('Content-type', 'application/x-trig') |
| 59 graph.serialize(req, format='trig') | |
| 60 | |
| 61 # forked from /my/proj/light9/light9/rdfdb/rdflibpatch.py | |
| 62 def _graphFromQuads2(q): | |
| 63 g = ConjunctiveGraph() | |
| 64 #g.addN(q) # no effect on nquad output | |
| 65 for s,p,o,c in q: | |
| 66 g.get_context(c).add((s,p,o)) # kind of works with broken rdflib nquad serializer code | |
| 67 #g.store.add((s,p,o), c) # no effect on nquad output | |
| 68 return g | |
| 69 | |
| 70 def jsonFromPatch(p): | |
| 71 return json.dumps({'patch': { | |
| 72 'adds': from_rdf(_graphFromQuads2(p.addQuads)), | |
| 73 'deletes': from_rdf(_graphFromQuads2(p.delQuads)), | |
| 74 }}) | |
| 75 patchAsJson = jsonFromPatch # deprecated name | |
| 76 | |
| 1505 | 77 |
| 1317 | 78 def patchFromJson(j): |
| 79 body = json.loads(j)['patch'] | |
| 80 a = ConjunctiveGraph() | |
| 81 a.parse(StringInputSource(json.dumps(body['adds']).encode('utf8')), format='json-ld') | |
| 82 d = ConjunctiveGraph() | |
| 83 d.parse(StringInputSource(json.dumps(body['deletes']).encode('utf8')), format='json-ld') | |
| 84 return Patch(addGraph=a, delGraph=d) | |
| 85 | |
| 86 def graphAsJson(g): | |
| 87 # This is not the same as g.serialize(format='json-ld')! That | |
| 88 # version omits literal datatypes. | |
| 89 return json.dumps(from_rdf(g)) | |
| 90 | |
| 91 _graphsInProcess = itertools.count() | |
| 92 class PatchableGraph(GraphEditApi): | |
| 93 """ | |
| 94 Master graph that you modify with self.patch, and we get the | |
| 95 updates to all current listeners. | |
| 96 """ | |
| 97 def __init__(self): | |
| 98 self._graph = ConjunctiveGraph() | |
| 99 self._observers = [] | |
| 100 scales.init(self, '/patchableGraph%s' % next(_graphsInProcess)) | |
| 101 | |
| 102 _serialize = scales.PmfStat('serialize') | |
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parents:
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103 def serialize(self, *arg, **kw): |
| 1317 | 104 with self._serialize.time(): |
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parents:
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diff
changeset
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105 return self._graph.serialize(*arg, **kw) |
| 1317 | 106 |
| 107 _patch = scales.PmfStat('patch') | |
| 108 _len = scales.IntStat('statementCount') | |
| 109 def patch(self, p): | |
| 110 with self._patch.time(): | |
| 111 # assuming no stmt is both in p.addQuads and p.delQuads. | |
| 112 dels = set([q for q in p.delQuads if inGraph(q, self._graph)]) | |
| 113 adds = set([q for q in p.addQuads if not inGraph(q, self._graph)]) | |
| 114 minimizedP = Patch(addQuads=adds, delQuads=dels) | |
| 115 if minimizedP.isNoop(): | |
| 116 return | |
| 117 patchQuads(self._graph, | |
| 118 deleteQuads=dels, | |
| 119 addQuads=adds, | |
| 120 perfect=False) # true? | |
| 121 for ob in self._observers: | |
| 122 ob(patchAsJson(p)) | |
| 123 self._len = len(self._graph) | |
| 124 | |
| 125 def asJsonLd(self): | |
| 126 return graphAsJson(self._graph) | |
| 127 | |
| 128 _currentObservers = scales.IntStat('observers/current') | |
| 129 _observersAdded = scales.IntStat('observers/added') | |
| 130 def addObserver(self, onPatch): | |
| 131 self._observers.append(onPatch) | |
| 132 self._currentObservers = len(self._observers) | |
| 133 self._observersAdded += 1 | |
| 1505 | 134 |
| 1317 | 135 def removeObserver(self, onPatch): |
| 136 try: | |
| 137 self._observers.remove(onPatch) | |
| 138 except ValueError: | |
| 139 pass | |
| 140 self._currentObservers = len(self._observers) | |
| 141 | |
| 142 def setToGraph(self, newGraph): | |
| 143 self.patch(Patch.fromDiff(self._graph, newGraph)) | |
| 1505 | 144 |
| 1317 | 145 _sendSimpleGraph = scales.PmfStat('serve/simpleGraph') |
| 146 _sendFullGraph = scales.PmfStat('serve/events/sendFull') | |
| 147 _sendPatch = scales.PmfStat('serve/events/sendPatch') | |
| 148 | |
| 149 class CycloneGraphHandler(PrettyErrorHandler, cyclone.web.RequestHandler): | |
| 150 def initialize(self, masterGraph): | |
| 151 self.masterGraph = masterGraph | |
| 1505 | 152 |
| 1317 | 153 def get(self): |
| 154 with self.masterGraph._sendSimpleGraph.time(): | |
|
1509
e41935c0ce96
try to detect browser even better, instead of failing the whole request
drewp <drewp@bigasterisk.com>
parents:
1507
diff
changeset
|
155 _writeGraphResponse(self, self.masterGraph, |
|
e41935c0ce96
try to detect browser even better, instead of failing the whole request
drewp <drewp@bigasterisk.com>
parents:
1507
diff
changeset
|
156 self.request.headers.get('accept', '')) |
| 1317 | 157 |
| 158 | |
| 159 class CycloneGraphEventsHandler(cyclone.sse.SSEHandler): | |
| 160 """ | |
| 161 One session with one client. | |
| 1505 | 162 |
| 1317 | 163 returns current graph plus future patches to keep remote version |
| 164 in sync with ours. | |
| 165 | |
| 166 intsead of turning off buffering all over, it may work for this | |
| 167 response to send 'x-accel-buffering: no', per | |
| 168 http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_buffering | |
| 169 """ | |
| 170 def __init__(self, application, request, masterGraph): | |
| 171 cyclone.sse.SSEHandler.__init__(self, application, request) | |
| 172 self.masterGraph = masterGraph | |
| 173 | |
| 174 def bind(self): | |
| 175 with self.masterGraph._sendFullGraph.time(): | |
| 176 graphJson = self.masterGraph.asJsonLd() | |
| 177 log.debug("send fullGraph event: %s", graphJson) | |
| 178 self.sendEvent(message=graphJson, event=b'fullGraph') | |
| 179 self.masterGraph.addObserver(self.onPatch) | |
| 180 | |
| 181 def onPatch(self, patchJson): | |
| 182 with self.masterGraph._sendPatch.time(): | |
| 183 # throttle and combine patches here- ideally we could see how | |
| 184 # long the latency to the client is to make a better rate choice | |
| 185 self.sendEvent(message=patchJson, event=b'patch') | |
| 1505 | 186 |
| 1317 | 187 def unbind(self): |
| 188 self.masterGraph.removeObserver(self.onPatch) |