Microservice sequence diagram

examples/src/powershell/microservice/typical.md

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+# Typical Microservice
+
+
+## Service sequence diagrams
+
+
+### Health check
+
+The health sequence diagram for a typical microservice might be:
+
+```mermaid
+
+sequenceDiagram
+
+    Sysops ->> Gateway: Regular checks 
+    Activate Gateway
+    Gateway ->> Gateway: 
+    Note right of Gateway: Check source IP for eligibility  
+    Gateway ->> Microservice: Service to health check
+
+    Activate Microservice
+    Microservice ->> Health: 
+
+    Activate Health
+    Health ->> Health: API enabled
+
+    Health ->> Health: Runtime and logic check
+
+    Health ->> Database: Check live and records
+    Activate Database
+    Database -->> Health: Ok
+    Deactivate Database
+
+    Health -->> Microservice: 
+    deactivate Health
+
+    Microservice -->> Gateway: Health response
+    deactivate Microservice
+
+    Gateway -->> Sysops: 
+    deactivate Gateway
+
+```
+
+
+### Resource listing
+
+The resource listing sequence diagram for a typical microservice might be:
+
+```mermaid
+
+sequenceDiagram
+
+    Web ->> Gateway: On demand 
+    Activate Gateway
+    Gateway ->> Gateway: 
+    Note right of Gateway: Authentication  
+    Gateway ->> Gateway: 
+    Note right of Gateway: Rate limiting  
+    Gateway ->> Microservice: Resource listing
+
+    Activate Microservice
+
+    Microservice ->> Microservice: Validate resource
+
+    Microservice ->> Microservice: Resource authorisation
+
+    Microservice ->> Database: Fetch records
+    Activate Database
+    Database -->> Microservice: Ok
+    Deactivate Database
+
+    Microservice -->> Gateway: Listing response
+    deactivate Microservice
+
+    Gateway -->> Web:  
+    deactivate Gateway
+
+```