Terence Schumacher
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Web application architectures and components

3 min read

Web Application Architecture Components

Here is a breakdown of each major component layer:

Client Interface Layer

  • Load Balancer: Distributes incoming traffic
  • Reverse Proxy: Handles request forwarding and caching
  • SSL/TLS Termination: Manages secure connections

Request Processing Layer

  • Request Handler: Initial request processing
  • Router: URL/endpoint mapping
  • Middleware Chain: Request/response pipeline
  • Security Filters: Input validation, XSS prevention
  • Authentication: User verification
  • Session Manager: User session handling

Application Core

  • Controllers: Request/response coordination
  • Service Layer: Business operations orchestration
  • Business Logic: Core application rules
  • Validation: Input/data validation

Data Access Layer

  • Data Access Objects: Database interaction
  • ORM/Data Mapper: Object-relational mapping
  • Connection Pool: Database connection management
  • Cache Manager: Data caching

Common Services (Cross-cutting Concerns)

  • Logging Service: Application logging
  • Monitoring: Performance/health tracking
  • Configuration: App settings management
  • Error Handler: Exception management

Key Component Interactions:

  • Every request enters through the Client Interface Layer first
  • The Request Processing Layer resolves common concerns before business logic runs
  • The Application Core holds the main business logic and workflows
  • The Data Access Layer exposes a consistent storage interface to all callers
  • Common Services handle cross-cutting concerns across every layer
graph TD
    subgraph "Client Interface Layer"
        LB[Load Balancer]
        RP[Reverse Proxy]
        SSL[SSL/TLS Termination]
    end


    subgraph "Request Processing Layer"
        RH[Request Handler]
        RT[Router]
        MC[Middleware Chain]
        SEC[Security Filters]
        AUTH[Authentication]
        SESS[Session Manager]
    end


    subgraph "Application Core"
        CONT[Controllers]
        SVC[Service Layer]
        BL[Business Logic]
        VAL[Validation]
    end


    subgraph "Data Access Layer"
        DAO[Data Access Objects]
        ORM[ORM/Data Mapper]
        CONN[Connection Pool]
        CACHE[Cache Manager]
    end


    subgraph "Common Services"
        LOG[Logging Service]
        MON[Monitoring]
        CONF[Configuration]
        ERR[Error Handler]
    end


    %% Connections
    LB --> RP
    RP --> SSL
    SSL --> RH
    RH --> RT
    RT --> MC
    MC --> SEC
    MC --> AUTH
    MC --> SESS


    MC --> CONT
    CONT --> SVC
    SVC --> BL
    BL --> VAL


    BL --> DAO
    DAO --> ORM
    ORM --> CONN
    DAO --> CACHE


    %% Cross-cutting concerns
    CONT -.-> LOG
    CONT -.-> MON
    CONT -.-> CONF
    CONT -.-> ERR


    SVC -.-> LOG
    DAO -.-> LOG
    MC -.-> LOG

Document Store Database Architecture

Here is a breakdown of the key components and their roles:

Client Interface Layer

Driver Interface: Handles client connections and requests Query Parser: Converts queries into internal format Connection Pool: Manages database connections

Query Processing

Query Engine: Core query execution Query Optimizer: Query plan optimization Aggregation Pipeline: Handles data aggregation operations Index Catalog: Manages available indexes

Persistence Layer

Memory Components:

Document Cache: In-memory document storage Index Memory: In-memory index storage Connection Library: Connection management

Storage Engine:

Journal Log: Write-ahead logging Data Store: Document storage on disk Index Store: Index storage on disk

Cluster Management

Replication Set: Manages data replication Sharding Manager: Handles data distribution Cluster Monitor: Health monitoring Balancer Controller: Data balance across shards

System Services

  • Authentication Service: User authentication
  • Authorization: Access control
  • Monitoring: System metrics
  • Logger: System logging

Key Interactions:

Client requests flow through the Driver Interface into Query Processing The Query Engine coordinates with the Storage Engine for data access Cluster Management handles data distribution and availability System Services supply cross-cutting functionality to every layer

Common Design Patterns:

Write operations pass through the Journal Log before reaching disk Read operations check the Document Cache before hitting disk The Query Engine uses the Index Catalog to optimize queries Every operation passes through authentication and authorization Monitoring and logging track system health and performance

graph TD
    subgraph "Client Interface Layer"
        DRI[Driver Interface]
        QP[Query Parser]
        CP[Connection Pool]
    end


    subgraph "Query Processing"
        QE[Query Engine]
        QO[Query Optimizer]
        AP[Aggregation Pipeline]
        IC[Index Catalog]
    end


    subgraph "Storage Engine"
        direction TB
        subgraph "Memory Components"
            CACHE[Document Cache]
            IM[Index Memory]
            CL[Connection Library]
        end


        subgraph "Persistence Layer"
            JL[Journal Log]
            DS[Data Store]
            IX[Index Store]
        end
    end


    subgraph "Cluster Management"
        RS[Replication Set]
        SH[Sharding Manager]
        CM[Cluster Monitor]
        BC[Balancer Controller]
    end


    subgraph "System Services"
        AS[Authentication Service]
        AU[Authorization]
        MON[Monitoring]
        LOG[Logger]
    end


    %% Connections
    DRI --> QP
    DRI --> CP
    QP --> QE
    QE --> QO
    QO --> AP
    QO --> IC


    QE --> CACHE
    QE --> IM


    CACHE --> DS
    IM --> IX


    DS --> JL
    IX --> JL


    %% Cluster connections
    QE --> RS
    QE --> SH
    SH --> BC
    RS --> CM


    %% Service connections
    DRI --> AS
    DRI --> AU
    QE -.-> MON
    QE -.-> LOG

Infrastructure Tools Entity Relationship Diagram

Here is a breakdown of the main tool categories and their relationships:

Container Orchestration & Management

  • Kubernetes: Container orchestration platform
  • Helm: Package manager for Kubernetes
  • etcd: Distributed key-value store for Kubernetes

Infrastructure as Code & Provisioning

  • Terraform: Infrastructure provisioning
  • Cloud Providers (AWS/GCP/Azure): Resource targets
  • Ansible: Configuration management
  • Inventory: Target hosts/environments

Monitoring & Observability

  • Prometheus: Metrics collection
  • Grafana: Visualization platform
  • AlertManager: Alert handling
  • ELK Stack:
    • Elasticsearch: Log storage
    • Logstash: Log processing
    • Kibana: Log visualization

CI/CD & Artifact Management

  • Jenkins: Automation server
  • GitHub: Source code management
  • SonarQube: Code quality
  • Artifactory: Artifact repository

Security & Secret Management

  • Vault: Secret management
  • Certificates: SSL/TLS management
  • Secrets: Credentials, keys, tokens

Key Relationships:

  • Prometheus monitors Kubernetes
  • Terraform provisions cloud resources
  • Jenkins pulls from GitHub and pushes artifacts to Artifactory
  • ELK stack components work together for log ingestion, storage, and visualization
  • Vault distributes secrets to multiple tools
erDiagram
    KUBERNETES ||--o{ PROMETHEUS : "monitored_by"
    KUBERNETES ||--|{ HELM : "managed_by"
    KUBERNETES }|--|| ETCD : "stores_state_in"


    TERRAFORM ||--o{ AWS : "provisions"
    TERRAFORM ||--o{ GCP : "provisions"
    TERRAFORM ||--o{ AZURE : "provisions"
    TERRAFORM ||--|| VAULT : "fetches_secrets_from"


    PROMETHEUS ||--|{ GRAFANA : "visualized_by"
    PROMETHEUS ||--|| ALERTMANAGER : "alerts_through"


    JENKINS ||--|{ GITHUB : "pulls_from"
    JENKINS ||--|| SONARQUBE : "scans_with"
    JENKINS }|--|| ARTIFACTORY : "stores_artifacts_in"


    ANSIBLE ||--|{ INVENTORY : "manages"
    ANSIBLE ||--|| VAULT : "fetches_secrets_from"


    ELK ||--|{ LOGSTASH : "ingests_through"
    ELK ||--|{ ELASTICSEARCH : "stores_in"
    ELK ||--|{ KIBANA : "visualized_by"


    VAULT ||--|{ SECRETS : "stores"
    VAULT ||--|{ CERTIFICATES : "manages"


    MONITORING {
        string metrics
        string alerts
        string dashboards
        string logs
    }


    DEPLOYMENT {
        string containers
        string configurations
        string versions
        string environments
    }


    SECURITY {
        string secrets
        string certificates
        string policies
        string access_controls
    }


    AUTOMATION {
        string pipelines
        string playbooks
        string templates
        string scripts
    }