Create SET cache endpoint

Cache SET endpoint implementation

Closes #3 (closed) FYI: @tziai @valerii.kalashnikov

design/design.go

@@ -41,10 +41,10 @@ var _ = Service("cache", func() {
 	Description("Cache service allows storing and retrieving data from distributed cache.")
 
 	Method("Get", func() {
-		Description("Get value from the cache. The result is a sequence of bytes which the client must decode.")
+		Description("Get JSON value from the cache.")
 
 		Payload(CacheGetRequest)
-		Result(Bytes)
+		Result(Any)
 
 		HTTP(func() {
 			GET("/v1/cache")
@@ -59,7 +59,33 @@ var _ = Service("cache", func() {
 				Example("administration")
 			})
 
-			Response(StatusOK)
+			Response(StatusOK, func() {
+				ContentType("application/json")
+			})
+		})
+	})
+
+	Method("Set", func() {
+		Description("Set a JSON value in the cache.")
+
+		Payload(CacheSetRequest)
+		Result(Empty)
+
+		HTTP(func() {
+			POST("/v1/cache")
+
+			Header("key:x-cache-key", String, "Cache entry key", func() {
+				Example("did:web:example.com")
+			})
+			Header("namespace:x-cache-namespace", String, "Cache entry namespace", func() {
+				Example("Login")
+			})
+			Header("scope:x-cache-scope", String, "Cache entry scope", func() {
+				Example("administration")
+			})
+			Body("data")
+
+			Response(StatusCreated)
 		})
 	})
 })