This is in continuation of my earlier posts on AutoCAD Map 3D API Training content: Part-1 , Part 2 & Part-3 . In this post I am going to share some insights of “Feature Service” in Geospatial Platform API used by Map 3D and AIMS.
The Feature Service provides a data source agnostic API for the storage and retrieval of feature data. We can use Feature Service API to determine which storage technologies are available and their capabilities. For example, an Oracle Spatial database will have more capabilities than an ODBC connection. Some feature sources can have multiple schemas. Access to the data storage technology is modeled as a connection. For example, you can connect to a file and do simple insertions or connect to a relational database and do transaction-based operations.
public class AcMapFeatureService : MgFeatureService is part of Autodesk.Gis.Map.Platform namespace. Using AcMapServiceFactory.GetService() method and by specifying the correct MgServiceType[.FeatureService] we access AcMapFeatureService like the following code snippet -
static AcMapFeatureService fs = AcMapServiceFactory.GetService(MgServiceType.FeatureService) as AcMapFeatureService;
The base MgFeatureService has very useful method to create / update / manipulate features (FDO Features) in a particular data store. Some of the useful methods of MgFeatureService are -
Connection to a datastore. MgFeatureService::GetFeatureProviders, MgFeatureService::GetConnectionPropertyValues, MgFeatureService::TestConnection Method (CREFSTRING, CREFSTRING) , and MgFeatureService::TestConnection Method (MgResourceIdentifier*)
Description of the capabilities of the FDO provider providing access to the datastore. MgFeatureService::GetProviderCapabilities.
Insertion, deletion and update of feature data. MgFeatureService::UpdateFeatures, MgInsertFeatures, MgDeleteFeatures, and MgUpdateFeatures.
Selection of feature data. MgFeatureService::SelectFeatures and MgFeatureService::SelectAggregate.
Description of the schema used to store feature data. MgFeatureService::DescribeSchema, MgFeatureService::DescribeSchemaAsXml, MgFeatureService::GetSchemas, MgFeatureService::SchemaToXml, MgFeatureService::GetClasses and MgFeatureService::GetClassDefinition.
Creation of an SDF feature source to cache feature data from other datastores. MgFeatureService::CreateFeatureSource. Using the latter requires describing the schema in the source datastore. Transporting the features from the source datastore requires selecting them from the source and inserting them in the target.
Execute SQL commands. MgFeatureService::ExecuteSqlNonQuery and MgFeatureService::ExecuteSqlQuery.
Get the spatial contexts contained in the datastore. MgFeatureService::GetSpatialContexts.
Some of the previous blog posts show how to create / insert / update / manipulate Feature Data in FDO data store -
How to create FDO Feature using Geospatial Platform API in Map 3D?
Read FDO Features using Map 3D Geospatial Platform API
Read FDO Geometry Area using Map 3D Geospatial Platform API
How to modify / update Feature attribute using API in Map 3D?
Using FDO API to select Features from FDO Data Source
Selecting FDO Features inside a given boundary (Polygon)
Manipulate non-feature class with Geospatial Platform API in Map 3D
AcMapFeatureService class also has a useful set of FeatureService Events which occur when feature-related actions, such as deletion, insertion or update are initiated, concluded or cancelled -
Attached Chapter 4 will help you to understand working with ' FeatureService' and associated APIs which you would require in your application development using Geospatial Platform API and AutoCAD Map 3D.
I hope this is useful to you!
