[GitHub] [skywalking] kezhenxu94 commented on a change in pull request #4509: Provide the data transmission protocol document

[GitBox <gi...@apache.org>]

kezhenxu94 commented on a change in pull request #4509: Provide the data transmission protocol document
URL: https://github.com/apache/skywalking/pull/4509#discussion_r392561133
 
 

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 File path: docs/en/protocols/Skywalking-Cross-Process-Correlation-Headers-Protocol-v1.md
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 @@ -0,0 +1,24 @@
+# SkyWalking Cross Process Correlation Headers Protocol
+* Version 1.0
+
+The Cross Process Correlation Headers Protocol is used to transport custom data by leveraging the capability of [Cross Process Propagation Headers Protocol](Skywalking-Cross-Process-Propagation-Headers-Protocol-v2.md). 
+
+This is an optional and additional protocol for language tracer implementation. All tracer implementation could consider to implement this.
+Cross Process Correlation Header key is `sw7-correlation`. The value is (string key)-(string value) table in `Base64` encoded JSON format.
+
+## Value Example
+(string key)-(string value) table in `Base64` encoded JSON format.
+
+Original value raw data `{"userKey1","userValue1","userKey2":"userValue2"}` string, the `Base64` encoded value
+`eyJ1c2VyS2V5MSIsInVzZXJWYWx1ZTEiLCJ1c2VyS2V5MiI6InVzZXJWYWx1ZTIifQ==`.
+
+## Recommendations of language APIs
+Recommended implementation in different language API.
+
+1. `CorrelationContext#set` and `CorrelationContext#get` are recommended to write and read the correlation context, with key/value string.
+1. The key should be added if it is inexistence.
 
 Review comment:
   ```suggestion
   1. The key should be added if it is absent.
   ```

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