Difference between revisions of "Search Operators"
Gpapanikos (Talk | contribs) (→Introduction) |
Gpapanikos (Talk | contribs) (→BooleanOperator) |
||
| Line 12: | Line 12: | ||
==== BooleanOperator ==== | ==== BooleanOperator ==== | ||
===== Description ===== | ===== Description ===== | ||
| + | The Boolean Operator is used in conditional execution and more specifically, in evaluating the condition. So, it actually offers the ability of selecting alternative execution plans. For example, one can follow a plan (let’s say a projection on a given field of a set of data), if a given precondition is valid; otherwise, she may follow the alternative plan (e.g. a projection on another field of the same set of data and then sort on the field). The precondition validation is the responsibility of this Service. | ||
| + | The condition is a Boolean expression. Basically, it involves comparisons using the operations: equal, not_equal, greater_than, lower_than, greater_equal, lower_equal. The comparing parts are either literals (date, string, integer, double literals are supported) or aggregate functions on the results of a search service execution. These aggregate functions include max, min, average, size, sum and they can be applied to a given field of the result set of a search service execution, by referring to that field employing xPath expressions. | ||
===== Dependencies ===== | ===== Dependencies ===== | ||
| + | |||
==== FilterResultSetByXPathOperator ==== | ==== FilterResultSetByXPathOperator ==== | ||
===== Description ===== | ===== Description ===== | ||
Revision as of 12:10, 23 August 2007
Contents
- 1 Search Operators
- 1.1 Introduction
- 1.2 Example Code
- 1.3 Operators
- 1.3.1 BooleanOperator
- 1.3.2 FilterResultSetByXPathOperator
- 1.3.3 JoinInnerOperator
- 1.3.4 KeepTopOperator
- 1.3.5 MergeOperator
- 1.3.6 QueryExtSourceOperatorGoogle
- 1.3.7 QueryExtSourceOperatorJDBC
- 1.3.8 QueryExtSourceOperatorOSIRIS
- 1.3.9 ScannerOperator
- 1.3.10 SortOperator
- 1.3.11 TransformByXSLTOperator
Search Operators
Introduction
The Search Operator family of services are the building blocks of any search operation. These along with external to the Search services handle the production, filtering and refinement of available data according to the user queries. The various intermediate steps towards producing the final search output are handled by Search Operator services. In this section we will only describe the Search Service internal Services listed below, although the Search Operator Framework reaches out to "integrate" on a high level other services too that can be utilized within a Search operation context.
The following operators are implemented as stateless services. They receive their input and produce their output in the context of a single invocation without holding any intermediate state. In case any data transferring is necessary either as input to a service or as output from the processing, the ResultSet Framework is employed.
The search operators cover the basic functionality that could be encountered in a typical search operation. A search can be decomposed in undividable units consisting of the above operators and their interaction can construct a workflow producing the net result delivered to the requester. The external source search and the service invocation services provide some extendibility for future operators by offering a method for invoking an “unknown” to the Search framework service, importing its results to the search operator workflow. The distinguished search operators at present time are listed below.
Example Code
Search Operators Usage Examples
Operators
BooleanOperator
Description
The Boolean Operator is used in conditional execution and more specifically, in evaluating the condition. So, it actually offers the ability of selecting alternative execution plans. For example, one can follow a plan (let’s say a projection on a given field of a set of data), if a given precondition is valid; otherwise, she may follow the alternative plan (e.g. a projection on another field of the same set of data and then sort on the field). The precondition validation is the responsibility of this Service. The condition is a Boolean expression. Basically, it involves comparisons using the operations: equal, not_equal, greater_than, lower_than, greater_equal, lower_equal. The comparing parts are either literals (date, string, integer, double literals are supported) or aggregate functions on the results of a search service execution. These aggregate functions include max, min, average, size, sum and they can be applied to a given field of the result set of a search service execution, by referring to that field employing xPath expressions.
Dependencies
FilterResultSetByXPathOperator
Description
Dependencies
JoinInnerOperator
Description
Dependencies
KeepTopOperator
Description
The role of the KeepTop Operator is to perform a simple filtering operation on its input ResultSet and to produce as output a new ResultSet that holds a defined number of leading records.
Dependencies
- jdk 1.5
- WS-Core 4.0.4
- ResultSetClientLibrary
- SearchLibrary
