Context Propagation Update: Headers

.gitignore

@@ -34,3 +34,9 @@
 
 # Bazel files
 /bazel-*
+/.idea/
+/.idea/.gitignore
+/.idea/modules.xml
+/.idea/opentelemetry-cpp.iml
+/.idea/vcs.xml
+/.idea/workspace.xml

api/include/opentelemetry/trace/propagation/httptextformat.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <cstdint>
+#include "opentelemetry/context/context.h"
+#include "opentelemetry/nostd/string_view.h"
+#include "opentelemetry/version.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace trace
+{
+namespace propagation
+{
+// Set the span in the given context.
+virtual static Context SetSpanInContext(Span span, Context &context) = 0;
+// Retrieve the current span.
+virtual static Span GetCurrentSpan(Context &context) = 0;
+
+// The HTTPTextFormat class provides an interface that enables extracting and injecting
+// context into headers of HTTP requests. HTTP frameworks and clients
+// can integrate with HTTPTextFormat by providing the object containing the
+//  headers, and a getter and setter function for the extraction and
+// injection of values, respectively.
+template <typename T>
+class HTTPTextFormat {
+    public:
+        // Rules that manages how context will be extracted from carrier.
+        using Getter = nostd::string_view(*)(T &carrier, nostd::string_view trace_type);
+
+        // Rules that manages how context will be injected to carrier.
+        using Setter = void(*)(T &carrier, nostd::string_view trace_type,nostd::string trace_description);
+
+        // Returns the context that is stored in the HTTP header carrier with self defined rules.
+        virtual Context extract(Getter get_from_carrier, const T &carrier, Context &context) = 0;
+
+        // Sets the context for a HTTP header carrier with self defined rules.
+        virtual void inject(Setter set_from_carrier, T &carrier, const Context &context) = 0;
+};
+}
+}
+OPENTELEMETRY_END_NAMESPACE