expose OpenTracing and API versioning capabilities

opentracing/harness/api_check.py

@@ -46,7 +46,7 @@ def test_start_trace(self):
         with tracer.start_trace(operation_name='Fry',
                                 tags={'birthday': 'August 14 1974'}) as span:
             span.log_event('birthplace',
-		           payload={'hospital': 'Brooklyn Pre-Med Hospital',
+                   payload={'hospital': 'Brooklyn Pre-Med Hospital',
                                     'city': 'Old New York'})
         tracer.close()
 
@@ -146,3 +146,8 @@ def test_binary_propagation(self):
                 trace_attributes=bin_attrs
             ) as reassembled_span:
                 reassembled_span.set_trace_attribute('middle-name', 'Rodriguez')
+
+    def test_implementation_id(self):
+        impl_id = self.tracer().implementation_id()
+        assert len(impl_id.name) > 0
+        assert len(impl_id.version) > 0

opentracing/propagator.py

@@ -22,15 +22,16 @@
 
 from .span import Span
 
+
 class SpanPropagator(object):
     """SpanPropagator encodes and decodes Spans between processes.
 
     SpanPropagator is responsible (a) for encoding Span instances in a manner
     suitable for propagation, and (b) for taking that encoded data and using it
     to generate Span instances that are placed appropriately in the overarching
-    Trace. Typically the propagation will take place across an RPC boundary, but
-    message queues and other IPC mechanisms are also reasonable places to use
-    a SpanPropagator.
+    Trace. Typically the propagation will take place across an RPC boundary,
+    but message queues and other IPC mechanisms are also reasonable places to
+    use a SpanPropagator.
 
     The encoded form of a propagated span is divided into two components:
 
@@ -53,7 +54,7 @@ class SpanPropagator(object):
 
     def propagate_span_as_binary(self, span):
         """Represents the Span for propagation as opaque binary data.
-	
+
         :param span: the Span instance to propagate
 
         :rtype: ((bytearray, bytearray) or None)
@@ -66,7 +67,7 @@ def propagate_span_as_binary(self, span):
 
     def propagate_span_as_text(self, span):
         """Represents the Span for propagation as a pair of text dicts.
-	
+
         :param span: the Span instance to propagate
 
         :rtype: ((dict, dict) or None)

opentracing/span.py

@@ -119,19 +119,19 @@ def log_event(self, event, payload=None):
         """Logs an event against the span, with the current timestamp.
 
         :param event: an event name as a string
-	:param payload: an arbitrary structured payload. Implementations may
-	    choose to ignore none, some, or all of the payload.
+    :param payload: an arbitrary structured payload. Implementations may
+        choose to ignore none, some, or all of the payload.
         :return: returns the span itself, for chaining the calls
         """
         return self
 
     def log(self, **kwargs):
         """Records a generic Log event at an arbitrary timestamp.
 
-	:param timestamp: the log timestamp an a unix timestamp per time.time()
+    :param timestamp: the log timestamp an a unix timestamp per time.time()
         :param event: an event name as a string
-	:param payload: an arbitrary structured payload. Implementations may
-	    choose to ignore none, some, or all of the payload.
+    :param payload: an arbitrary structured payload. Implementations may
+        choose to ignore none, some, or all of the payload.
         :return: returns the span itself, for chaining the calls
         """
         return self

opentracing/tracer.py

@@ -20,6 +20,7 @@
 
 from __future__ import absolute_import
 from concurrent.futures import Future
+from collections import namedtuple
 from .span import Span
 from .propagator import SpanPropagator
 
@@ -82,3 +83,24 @@ def close(self):
         fut = Future()
         fut.set_result(True)
         return fut
+
+    def implementation_id(self):
+        """Returns the ImplementationID for this OpenTracing implementation.
+
+        :return: An ImplementationID instance that describes this OpenTracing
+            implementation.
+        """
+        return ImplementationID('noop', '1.0.0')
+
+
+# Per collections.namedtuple, the below defines a class called ImplementationID
+# which can be initialized via positional parameters or a kwargs-style
+# initializer.
+#
+#     dapper_impl = ImplementationID('dapper', '0.1.2')
+#     zipkin_impl = ImplementationID(name='zipkin', version='0.3.4')
+#
+ImplementationID = namedtuple('ImplementationID', 'name version')
+
+# The SemVer (http://semver.org/) of the OpenTracing Python API.
+OPENTRACING_PYTHON_SEMVER = '0.9.0'