VisualWebDatabaseCacheMetadata

Cache Metadata by Serializing the result set

Visual JSF Database design-time Performance hit in 6.0

In 6.0, an attempt to connect to a local or remote database occurs for the following 6.0 use cases

• Component binding tries to get a connection from CachedRowSet in the following scenarios

• Dragging and dropping a database table onto a Visual JSF page, component, or page bean in the Navigator
• Opening a page that has components bound to rowsets
• Refreshing a page that has components bound to rowsets

• (Re)Binding components to column keys of data provider
• Opening the Visual Query Editor from the rowset icon in the Navigator to edit a query

Proposal(s) to improve the design-time performance

• Retrieve the metadata the first time a database table is used and persist it in a file in the userdir
• Subsequent retrievals of metadata by way of the persisted file, not by opening a connection and re-retrieving
• Persist metadata is in serialized binary format
• Implement a mapping from the metadata file to a data provider
• Support some consistency mechanism if the schema changes after persisting the metadata
• Modify CachedRowSet to check for persisted metadata file.
• Use CachedRowSet only for retrieving metadata if persisted file doesn't exist
• If metadata file exists then use metadata from file in the data provider

Functional Spec

Metadata caching

• Retrieving/writing metadata from a serialized result set

Summarized

In the CachedRowSetDataProvider, an instance of result set meta is retrieved. A new helper class is needed to serialize the result set into XML. Then when the metadata is needed at design-time, the serialized file can be deserialized and made available.

Caching the metadata can be done by serializing the result set

• write metadata as binary file in the userdir under config/Databases/CachedMetaData
• File name is generated from the data source name plus the rowset command (limited to 20 characters)
• read metadata from binary file
• compare 2 metadata instance in memory
• replace metadata binary file if the rowset command property changes
• map metadata to dataprovider

Consistency

• If metadata file is inconsistent with the rowset from live connection then replace the metadata file

Use Cases

1. Manual binding to a non-Table component
   1. Drag a database table and drop on the background of a Visual JSF page.
      1. if metadata XML or Java file persisted then use metadata from file, otherwise use CRS to retrieve the metadata and generate a persisted file
   2. Drag a Visual JSF component (excludes the Table component) onto the Visual JSF page
   3. Right-click on the component and choose Bind to Data. Metadata is retrieved locally from file.
2. Automatic binding to a non-Table component
   1. Drag a Visual JSF component (excludes the Table component) onto the Visual JSF page
   2. Drag a database table and drop on top of a Visual JSF component to automatically bind to a column of the database metadata

• metadata XML or Java file persisted and dataprovider created

1. Manual binding to Table component
   1. Drag a database table and drop on the background of a Visual JSF page.

• if metadata XML or Java file persisted then use metadata from file, otherwise use CRS to retrieve the metadata and generate a persisted file

1. 1. Drag a Visual JSF component (excludes the Table component) onto the Visual JSF page
   2. Right-click on the table component and choose Table Layout then select a dataprovider to bind.

• Metadata is available from local file

1. Automatic binding to Table component
   1. Drag a Visual JSF Table component onto the Visual JSF page
   2. Drag a database table and drop on top of the Table component to automatically bind to a column of the database metadata

• metadata XML or Java file persisted and dataprovider created

1. Open existing Visual JSF database project

• if metadata XML or Java file persisted then use metadata from file, otherwise use CRS to retrieve the metadata and generate a persisted file
• cachedRowSet indirectly uses metadata XML or Java to restore/maintain componenet bindings

• This page was last modified on 5 November 2009, at 17:56.
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