153 lines
4.9 KiB
Python
153 lines
4.9 KiB
Python
import urllib2
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from zope.interface import implements
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from zope.component import queryUtility, adapts, getUtility
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import grokcore.component as grok
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from indra.base import llsd
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from interfaces import ICapability, ISeedCapability
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from interfaces import ISerialization, IDeserialization
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from network import IRESTClient, HTTPError
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class Capability(object):
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"""models a capability"""
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implements(ICapability)
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def __init__(self, name, public_url):
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"""initialize the capability"""
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self.name = name
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self.public_url = public_url
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def POST(self,payload,custom_headers={}):
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"""call this capability, return the parsed result"""
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# serialize the data
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serializer = ISerialization(payload)
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content_type = serializer.content_type
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serialized_payload = serializer.serialize()
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headers = {"Content-type" : content_type}
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headers.update(custom_headers) # give the user the ability to add headers
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# TODO: better errorhandling with own exceptions
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try:
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restclient = getUtility(IRESTClient)
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response = restclient.POST(self.public_url, serialized_payload, headers=headers)
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except HTTPError, e:
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print "** failure while calling cap:",
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print e.read()
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raise
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# now deserialize the data again, we ask for a utility with the content type
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# as the name
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content_type_charset = response.headers['Content-Type']
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content_type = content_type_charset.split(";")[0] # remove the charset part
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deserializer = queryUtility(IDeserialization,name=content_type)
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if deserializer is None:
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# TODO: do better error handling here
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raise "deserialization for %s not supported" %(content_type)
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return deserializer.deserialize_string(response.body)
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def __repr__(self):
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return "<Capability for %s>" %self.public_url
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class SeedCapability(Capability):
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"""a seed capability which is able to retrieve other capabilities"""
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implements(ISeedCapability)
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def get(self, names=[]):
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"""if this is a seed cap we can retrieve other caps here"""
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payload = {'caps':names}
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parsed_result = self.POST(payload)['caps']
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caps = {}
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for name in names:
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# TODO: some caps might be seed caps, how do we know?
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caps[name]=Capability(name, parsed_result[name])
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return caps
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def __repr__(self):
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return "<SeedCapability for %s>" %self.public_url
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####
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#### Serialization adapters
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####
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class DictLLSDSerializer(grok.Adapter):
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"""adapter for serializing a dictionary to LLSD
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An example:
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>>> d={'foo':'bar', 'test':1234}
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>>> serializer = ISerialization(d)
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>>> serializer.serialize()
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'<?xml version="1.0" ?><llsd><map><key>test</key><integer>1234</integer><key>foo</key><string>bar</string></map></llsd>'
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>>> serializer.content_type
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'application/llsd+xml'
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"""
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grok.implements(ISerialization)
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grok.context(dict)
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def __init__(self, context):
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self.context = context
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def serialize(self):
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"""convert the payload to LLSD"""
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return llsd.format_xml(self.context)
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@property
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def content_type(self):
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"""return the content type of this serializer"""
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return "application/llsd+xml"
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class LLSDDeserializer(grok.GlobalUtility):
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"""utility for deserializing LLSD data
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The deserialization component is defined as a utility because the input
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data can be a string or a file. It might be possible to define this as
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an adapter on a string but a string is too generic for this. So that's
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why it is a utility.
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You can use it like this:
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>>> s='<?xml version="1.0" ?><llsd><map><key>test</key><integer>1234</integer><key>foo</key><string>bar</string></map></llsd>'
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We use queryUtility because this returns None instead of an exception
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when a utility is not registered. We use the content type we received
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as the name of the utility. Another option would of course be to subclas
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string to some LLSDString class and use an adapter. We then would need some
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factory for generating the LLSDString class from whatever came back from
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the HTTP call.
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So here is how you use that utility:
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>>> deserializer = queryUtility(IDeserialization,name="application/llsd+xml")
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>>> llsd = deserializer.deserialize_string(s)
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>>> llsd
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{'test': 1234, 'foo': 'bar'}
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"""
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grok.implements(IDeserialization)
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grok.name('application/llsd+xml')
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def deserialize_string(self, data):
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"""deserialize a string"""
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return llsd.parse(data)
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def deserialize_file(self, fp):
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"""deserialize a file"""
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data = fp.read()
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return self.deserialize_string(data)
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