Remove binary format propagator (open-telemetry#426)

* remove binary format

* add note about re-adding binary format in future

Co-authored-by: Carlos Alberto Cortez <calberto.cortez@gmail.com>
Co-authored-by: Bogdan Drutu <lazy@splunk.com>

specification/api-propagators.md

@@ -5,9 +5,6 @@
 Table of Contents
 </summary>
 
-- [Binary Format](#binary-format)
-  - [ToBytes](#tobytes)
-  - [FromBytes](#frombytes)
 - [HTTP Text Format](#http-text-format)
   - [Fields](#fields)
   - [Inject](#inject)
@@ -19,43 +16,14 @@ Table of Contents
 
 </details>
 
-Propagators API consists of two main formats:
+Propagators API currently consists of one format:
 
-- `BinaryFormat` is used to serialize and deserialize a value into a binary representation.
 - `HTTPTextFormat` is used to inject and extract a value as text into carriers that travel
   in-band across process boundaries.
 
 Deserializing must set `IsRemote` to true on the returned `SpanContext`.
 
-## Binary Format
-
-`BinaryFormat` is a formatter to serialize and deserialize a value into a binary format.
-
-`BinaryFormat` MUST expose the APIs that serializes values into bytes,
-and deserializes values from bytes.
-
-### ToBytes
-
-Serializes the given value into the on-the-wire representation.
-
-Required arguments:
-
-- the value to serialize, can be `SpanContext` or `DistributedContext`.
-
-Returns the on-the-wire byte representation of the value.
-
-### FromBytes
-
-Creates a value from the given on-the-wire encoded representation.
-
-If the value could not be parsed, the underlying implementation SHOULD decide to return ether
-an empty value, an invalid value, or a valid value.
-
-Required arguments:
-
-- on-the-wire byte representation of the value.
-
-Returns a value deserialized from bytes.
+A binary format will be added in the future.
 
 ## HTTP Text Format
 

specification/api-tracing.md

@@ -15,7 +15,6 @@ Table of Contents
     * [GetCurrentSpan](#getcurrentspan)
     * [WithSpan](#withspan)
     * [SpanBuilder](#spanbuilder)
-    * [GetBinaryFormat](#getbinaryformat)
     * [GetHttpTextFormat](#gethttptextformat)
 * [SpanContext](#spancontext)
 * [Span](#span)
@@ -132,9 +131,8 @@ The `Tracer` MUST provide methods to:
 - Make a given `Span` as active
 
 The `Tracer` SHOULD allow end users to configure other tracing components that
-control how `Span`s are passed across process boundaries, including the binary
-and text format `Propagator`s used to serialize `Span`s created by the
-`Tracer`.
+control how `Span`s are passed across process boundaries, including the text
+format `Propagator` used to serialize `Span`s created by the `Tracer`.
 
 When getting the current span, the `Tracer` MUST return a placeholder `Span`
 with an invalid `SpanContext` if there is no currently active `Span`.
@@ -152,7 +150,7 @@ convenience methods to manage a `Span`'s lifetime and the scope in which a
 time) but stil active. A `Span` may be active on one thread after it has been
 made inactive on another.
 
-The implementation MUST provide no-op binary and text `Propagator`s, which the
+The implementation MUST provide a text `Propagator`, which the
 `Tracer` SHOULD use by default if other propagators are not configured. SDKs
 SHOULD use the W3C HTTP Trace Context as the default text format. For more
 details, see [trace-context](https://github.com/w3c/trace-context).

specification/overview.md

@@ -238,9 +238,8 @@ for an example.
 ## Propagators
 
 OpenTelemetry uses `Propagators` to serialize and deserialize `SpanContext` and `DistributedContext`
-into a binary or text format. Currently there are two types of propagators:
+into text format. Currently there is one type of propagator:
 
-- `BinaryFormat` which is used to serialize and deserialize a value into a binary representation.
 - `HTTPTextFormat` which is used to inject and extract a value as text into carriers that travel
   in-band across process boundaries.