MapGuide RFC 70 - Apply Schema

This page contains an change request (RFC) for the MapGuide Open Source project. More MapGuide RFCs can be found on the RFCs page.

Status

RFC Template Version	(1.0)
Submission Date	June 26, 2009
Last Modified	Leaf Li Timestamp
Author	Leaf Li
RFC Status	draft
Implementation Status	under development
Proposed Milestone	2.2
Assigned PSC guide(s)	Tom Fukushima
Voting History	(vote date)
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Overview

This proposal is to extend MapGuide Feature Service to support applying schema.

Motivation

Currently MapGuide Web API doesn’t support any functionality to create or modify schema of a feature source. The RFC is used to eliminate this limitation.

Proposed Solution

Changes to MgFeatureSchema, MgClassDefinition and MgPropertyDefinition

ApplySchema need not only support adding, modifying but also support deleting schema elements. So we need a method to mark the schema element for deletion. The method Delete() will be added to classes MgFeatureSchema, MgClassDefinition, MgPropertyDefinition for it.

/// \brief
/// Contains one or more feature class definitions, which specify the structure
/// of feature data in a datastore. 
class MgFeatureSchema: public MgNamedSerializable
{
PUBLISHED_API:
    ......
    /// \brief
    /// Marks the schema for deletion.
    ///
    /// \return
    /// Returns nothing.
    void Delete();
};

/// \brief
/// Defines a feature class belonging to a schema. 
class MgClassDefinition: public MgNamedSerializable
{
PUBLISHED_API:
    ......
    /// \brief
    /// Marks the class for deletion.
    ///
    /// \return
    /// Returns nothing.
    void Delete();
};

/// \brief
/// Defines the base class for the concreate property definition classes which
/// are used to create data, geometric, object, and raster property definitions. 
class MgPropertyDefinition: public MgProperty
{
PUBLISHED_API:
    ......
    /// \brief
    /// Marks the property for deletion.
    ///
    /// \return
    /// Returns nothing.
    void Delete();
};

MgDecimalProperty

Many FDO data sources support decimal type property. So users can create a decimal property in those datasources. However, MapGuide Web API doesn't have a decimal property class. Decimal value is returned as double value.

/// \brief
/// Stores decimal data with an associated key name. An instance of this class 
/// can be stored in an MgPropertyCollection object. The key name can be used 
/// to retrieve the instance from the property collection. 
/// Currently 
class MgDecimalProperty: public MgNullableProperty
{
PUBLISHED_API:
    /// \brief
    /// Constructor.
    ///
    /// \return
    /// Returns nothing.
    MgDecimalProperty (CREFSTRING name, double value);

    /// \brief
    /// Gets the property value.
    ///
    /// \return
    /// Returns the property value.
    double GetValue ();
 
    /// \brief
    /// Sets the property value.
    ///
    /// \return
    /// Returns nothing.
    void  SetValue (double value) 
};

Changes to Feature Service

Feature Service will be extended to add one method to apply a schema.

class MgFeatureService : public MgService 
{
PUBLISHED_API:
    /// \brief
    /// Creates or updates a feature schema within the DataStore. 
    ///
    /// \param resource (MgResourceIdentifier)
    /// A resource identifier referring to a feature source.
    /// \param schema
    /// Input schema to be created or updated.
    ///
    /// \return
    /// Returns nothing.
    ///
    virtual void ApplySchema(
                         MgResourceIdentifier* resource,
                         MgFeatureSchema* schema) = 0;
};

Implications

This is new API only. There are no effects on existing applications. However, API documentation need to be updated.

Test Plan

Add unit tests for method MgFeatureService::ApplySchema(...) into the existing Feature Service unit tests.

Funding/Resources

Supplied by Autodesk.