= !MapGuide RFC 73 - Batch processing of layers =

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||(July 7, 2009)||
||Last Modified||(Christine Bao Tue July 7 02:22:17 2009)||
||Author||Christine Bao||
||RFC Status||adopted||
||Implementation Status||completed||
||Proposed Milestone||2.2||
||Assigned PSC guide(s)||Tom Fukushima||
||'''Voting History'''||||
||+1||Tom, Kenneth, Paul, Trevor, Bruce||
||+0||||
||-0||||
||-1||||
||no vote||Jason, Harris, Bob, Andy ||

== Overview ==

This RFC improves performance by getting batch layers in one request, instead of each layer in one request.

== Motivation ==

Currently MgMap is created on Web Extension side, and for each layer of this map it sends a request to get the resource content. This causes a lot of requests send to server again and again. To improve performance MgMap should get the layers in a single request, and use the batch processing result to create layer models. The more layers a map has, the better performance improvement is achieved.

== Proposed Solution ==

The possible solutions could be:[[BR]]
1.	Add a new API of ResourceService to get a batch of resource contents for a collection of resource identifiers[[BR]]

{{{
PUBLISHED_API:
    ///////////////////////////////////////////////////////////////////////////
    /// \brief
    /// Gets the contents of the specified resources.
    ///
    /// \param resources
    /// Resource identifiers describing the resources.
    /// \param preProcessTags
    /// Pre-processing to apply to resource before returning content.  An empty
    /// string indicate no pre-processing. See MgResourcePreProcessingType for
    /// a list of supported pre-processing tags.
    ///
    /// \return
    /// MgStringCollection object representing the corresponding resource contents.
    ///
    /// \exception MgInvalidRepositoryTypeException
    /// \exception MgInvalidRepositoryNameException
    /// \exception MgInvalidResourcePathException
    /// \exception MgInvalidResourceNameException
    /// \exception MgInvalidResourceTypeException
    ///
    virtual MgStringCollection* GetResourceContents(MgStringCollection* resources,
        MgStringCollection* preProcessTags) = 0;
}}}
[[BR]]

2.	MgMap doesn't request the resource content of layers one by one, instead it forms a collection of layer resource ids, and use the new API to get a collection of layer definitions.

== Implications ==

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

== Test Plan ==

Test both Ajax viewer and Fusion viewer.

== Funding/Resources ==

Supplied by Autodesk.

== Addendum ==
Another APIs are added into MgLayerBase.[[BR]]

{{{
INTERNAL_API:
    //////////////////////////////////////////////////////////////////
    /// \brief
    /// Gets the layer's resource content.
    ///
    virtual STRING GetLayerResourceContent();

    //////////////////////////////////////////////////////////////////
    /// \brief
    /// Sets the resource content for this layer.
    ///
    virtual void SetLayerResourceContent(CREFSTRING resourceContent);
}}}