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IBM WebSphere Application ServerTM Release 7 |
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public interface ReadAheadHint
The ReadAheadHint interface provides access to the read ahead hint returned by the getReadAheadHint() method of the AccessIntent interface. It is also used to hold each read-ahead specification for which the Deploy Tool has generated a query & function. Persistence Manager (PM) gets the ReadAheadHint from the current AccessIntent and finds the best match to it among the generated queries; this is the query that actually reads ahead the bean data.
A read ahead hint is a canonical representation of which nodes in an EJB relationship graph should be read in from the backing store at the same time. EJB relationship graphs are defined by EJB container-managed relationships (CMR).
Assume there is a CMP bean type A which has a finder method that returns instances of bean A. A read ahead hint for this method is specified using the following notation: RelB.RelC; RelD
The preceeding notation reveals:
The actual tokens "RelB", etc. must be the CMR field names for the relationships as defined in the deployment descriptor.
"RelB.RelC" and "RelD" above are path expressions. Each path expression in a ReadAheadHint is represented by one or more ReadAheadItems. Each ReadAheadItem represents a single bean to be read ahead, so "RelB.RelC" actually becomes two ReadAheadItems, while "RelD" becomes only one. One ReadAheadHint manages a set of ReadAheadItems.
Method Summary | |
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int |
bestFitRating(ReadAheadHint desiredHint)
Returns an integer which rates how well this hint matches the given hint. |
java.util.Iterator |
getIterator()
Return an iterator over the items |
ReadAheadItem |
getNextItem()
Deprecated. |
void |
resetCursor()
Deprecated. |
Method Detail |
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int bestFitRating(ReadAheadHint desiredHint)
desiredHint
- com.ibm.websphere.appprofile.accessintent.ReadAheadHint
java.util.Iterator getIterator()
void resetCursor()
ReadAheadItem getNextItem()
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IBM WebSphere Application ServerTM Release 7 |
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