Update sequence diagram (#345)

* Updated sequence diagram for new Model downloading architecture

* Minor update

* Update sequence.md as well

* Fixing error

* More error fixes

docs/modelDownload.md

@@ -3,10 +3,13 @@
 This diagram shows a flow of messages and selected calls for specifically the remote language model down(loading) step.
 
 `^` - web worker scripts,
-the rest are content scripts
+`*` - background script
+
+The rest are content scripts
 
 ```mermaid
 sequenceDiagram
+    participant b as backgroundScript*
     participant m as mediator
     participant t as Translation
     participant w as translationWorker^
@@ -15,21 +18,35 @@ sequenceDiagram
     m->>+t: translate
     t-)+w: translate
     w->>w: loadTranslationEngine()
-    w->>w: loadLanguageModel()
+    w->>w: getLanguageModels()
+    w->>t: downloadLanguageModels
+    t->>m: downloadLanguageModels
+    m->>b: downloadLanguageModels
+    b->>b: getLanguageModels()
+    b->>b: getLanguageModel()
+    b->>b: downloadFile()
+    b->>b: getItemFromCacheOrWeb()
+    b->>cache: cache.match(Model)
+    alt cache match
+        cache->>b: (Model as Blob)
+    else cache not matched
+        b->>b: getItemFromWeb()
+        b->>gcp: Download Model
+        gcp->>b: Model
+        b->>b: digestSha256(Model as Arraybuffer)
+        Note right of b: Validate Model's hash
+        b->>cache: cache.put(Model as Blob)
+        cache->>b: (Model as Blob)
+    end
+    b->>m: responseDownloadLanguageModels  (Model as Blob) 
+    m->>t: sendDownloadedLanguageModels (Model as Blob)
+    t->>w: responseDownloadLanguageModels  (Model as Blob)
+    w->>w: loadLanguageModel(Model as Blob)
     w->>w: constructTranslationService()
     w->>w: constructTranslationModel()
     w->>w: constructTranslationModelHelper()
-    w->>w: downloadFiles()
-    w->>w: getItemFromCacheOrWeb()
-    w->>cache: cache.match(Model)
-    alt cache match
-        cache->>w: (Model as ArrayBuffer)
-    else cache not matched
-        cache->>gcp: Download model
-        cache->>w: (Model as ArrayBuffer)
-    end
-    w->>w: this.digestSha256(arraybuffer)
-    Note right of w: Validate model's hash
+    w->>w: fetchFile()
+    w->>w: Blob.arrayBuffer()
     w->>w: prepareAlignedMemoryFromBuffer(buffer, fileAlignment):alignedMemories
     w->>w: new WasmEngineModule.AlignedMemoryList(alignedMemories):alignedMemoryList
     w->>w: new WasmEngineModule.TranslationModel(alignedMemoryList)

docs/sequence.md

@@ -67,7 +67,15 @@ sequenceDiagram
     t-)+w: translate
     deactivate t
     w->>w: load engine
-    w->>w: load models
+    w->>t: download models
+    deactivate w
+    t->>m: download models
+    m->>+bg: download models
+    bg->>bg: download models
+    bg->>m: models
+    deactivate bg
+    m->>t: models
+    t->>+w: load models
     w-)+t: displayOutboundTranslation
     t-)+m: displayOutboundTranslation
     deactivate t