DiCentra AreaAssist Shared

DiCentra AreaAssist Shared is the foundational Kotlin Multiplatform library for the AreaAssist framework. It provides a standardized data model for land parcels (Flurstücke) and powerful integration adapters to fetch spatial data from various public and private GIS services.

🚀 Key Features

• Multiplatform Core: Shared logic and models for Android, iOS, JVM, JS, WasmJS, and Linux.
• Unified Parcel Model: A robust domain model that abstracts away the differences between various GIS data providers.
• Aviator Integration: Leverages the Aviator framework for flexible, staged data fetching and transformation.
• Spatial Adapters: Built-in support for ESRI ArcGIS REST API and OGC Web Feature Service (WFS).

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🧩 Aviator Plugins

AreaAssist Shared uses the Aviator plugin system to handle the complexities of different GIS protocols. These plugins act as "interceptors" and "transformers" in the data fetching pipeline.

📍 EsriAdapterPlugin

The EsriAdapterPlugin is designed to interact with ESRI ArcGIS Feature Servers.

• Capabilities:
  • Automatic conversion of AreaAssistParameters (like boundaries and queries) into ESRI-specific where clauses and geometry envelopes.
  • Handles coordinate system transformations (defaults to EPSG:4326).
  • ExceededTransferLimit Handling: Automatically detects when a service returns partial results due to transfer limits and throws a specialized exception.
  • GeoJSON Inflation: Efficiently parses ESRI GeoJSON responses into high-level ParcelCrateEntity objects.

🌐 WfsAdapterPlugin

The WfsAdapterPlugin provides support for the OGC Web Feature Service (WFS 2.0.0) standard, commonly used by European public "Open Data" portals.

• Capabilities:
  • XML/GML Support: Generates complex GetFeature POST requests with Filter Encoding (FES).
  • CRS Management: Integrated with Geokit to handle on-the-fly coordinate transformations between the client ( usually WGS84) and the service (e.g., ETRS89 / UTM).
  • Flexible Configuration: Supports custom typeNames, namespaces, and geometry pointers.

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📋 Predefined Values (PreDefined)

To ensure interoperability between different data sources (e.g., Thuringia vs. Saxony), AreaAssist uses a set of * PreDefined* keys. These keys act as "semantic anchors" for parcel data.

When configuring a service, you map the provider's specific field names (references) to these predefined identifiers.

Key	Description
PARCELID	Unique identifier for the parcel (e.g., Flurstückskennzeichen).
PLOT	The human-readable parcel number (e.g., 123/4).
PLOT_NUMERATOR	The "Zähler" of the parcel number.
PLOT_DENOMINATOR	The "Nenner" of the parcel number.
AREA	The official area size (usually in m²).
DISTRICT	The "Gemarkung" (Cadastral district).
DISTRICT_ID	The official ID of the Gemarkung.
LOCATION	Descriptive location/address (Lagebezeichnung).
USAGE	Information about the land use (Nutzungsart).
USAGE_BUILDINGS	Boolean flag indicating if the parcel is built upon.

Example Mapping (Thuringia):

DefaultKeys.fillIn(
    parcelId = "flstkennz",
    area = "flaeche",
    district = "gemarkung",
    plotNumerator = "flstnrzae",
    plotDenominator = "flstnrnen"
)

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🛠 Tech Stack

• Data: kotlinx.serialization (JSON & XML), MapLibre SpatialK
• Network: Ktor Client
• Spatial: Mallne Geokit (Coordinates, Projections, GeoJSON)
• Integration: DiCentra Aviator

📦 Installation

Add the following to your build.gradle.kts:

repositories {
    maven("https://registry.mallne.cloud/repository/DiCentraArtefacts/")
}

dependencies {
    implementation("cloud.mallne.dicentra.areaassist:shared:1.0.0-SNAPSHOT")
}

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⚖️ License

Licensed under the Apache License, Version 2.0.

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Built with ❤️ by Mallne under the DiCentra umbrella