= !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 [wiki:MapGuideRfcs RFCs] page.


== Status ==

||RFC Template Version||(1.0)||
||Submission Date||June 26, 2009||
||Last Modified||Leaf Li [[Timestamp]]||
||Author||Leaf Li||
||RFC Status||adopted||
||Implementation Status||implemented||
||Proposed Milestone||2.2||
||Assigned PSC guide(s)||Bruce Dechant||
||'''Voting History'''||July 10, 2009||
||+1||Andy, Bob, Bruce, Jason, Kenneth, Paul, Tom||
||+0||||
||-0||||
||-1||
||no vote||Haris||

== 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();
};
}}}

==== 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;
};
}}}

==== Changes to !MgPropertyType ====

Many FDO data sources support decimal property type. Users can add a decimal property in a feature class in those datasources. However, class !MgPropertyType doesn't define a decimal property type. So we will extend class !MgPropertyType to add a new type name 'Decimal' so that method MgFeatureService::!ApplySchema(...) can handle the decimal property.

{{{
class MgPropertyType
{
PUBLISHED_API:
    ......
    /////////////////////////////////////////////////// 
    /// \brief 
    /// Type name for a decimal property. 
    /// 
    /// \remarks 
    /// This property type name is currently used to 
    /// apply schema only. 
    static const int Decimal     =  15; 
};
}}}

== 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.