flowchart TD Client["Client
(Activity Provider)"]:::caller API["xAPI HTTP API
auth + version"]:::api Statements["/statements"]:::endpoint Agents["/agents"]:::endpoint Activities["/activities"]:::endpoint State["/activities/state"]:::endpoint About["/about"]:::endpoint Storage["Storage Layer
Document / Relational / Hybrid"]:::storage Indexing["Indexing Layer
actor, verb, object, timestamp"]:::indexing PostFlow(["POST flow"]):::flow GetFlow(["GET flow"]):::flow Client ==> API API --> Statements API --> Agents API --> Activities API --> State API --> About Statements --> PostFlow Statements --> GetFlow PostFlow ==> Storage PostFlow ==> Indexing GetFlow -.-> Indexing Indexing -.-> Storage click Client call showComponent("Client") click API call showComponent("API") click Statements call showComponent("Statements") click Agents call showComponent("Agents") click Activities call showComponent("Activities") click State call showComponent("State") click About call showComponent("About") click Storage call showComponent("Storage") click Indexing call showComponent("Indexing") click PostFlow call showComponent("PostFlow") click GetFlow call showComponent("GetFlow") classDef caller fill:#475569,stroke:#1e293b,color:#fff,font-size:14px,font-weight:bold classDef api fill:#1e293b,stroke:#0f172a,color:#fff,font-size:14px,font-weight:bold classDef endpoint fill:#4338ca,stroke:#312e81,color:#fff,font-size:14px,font-weight:bold classDef storage fill:#be185d,stroke:#831843,color:#fff,font-size:14px,font-weight:bold classDef indexing fill:#0d9488,stroke:#134e4a,color:#fff,font-size:14px,font-weight:bold classDef flow fill:#d97706,stroke:#92400e,color:#fff,font-size:13px linkStyle default stroke:#64748b,stroke-width:2px