Query Method (ICollectors)

In This Topic

Retrieve a list of collectors in a Historian server matching a collector-name wildcard expression.

For large servers clients can optionally rely on large message sizes or result-paging or a combination of both to retrieve properties for a large number of collectors. Maximum message size is straight-forward and controlled by ConnectionProperties.MaxReceivedMessageSize - it must be matched on both client and server.

Result-paging enables large result sets to be retrieved across multiple server requests with timing and size controlled by the client. The number of results retrieved per request is controlled via the query's PageSize property. To utilize result-paging, specify a non-zero PageSize and continue calling the same query while the return code is true to retrieve all results from a server. To protect the server and limit excessive server-memory utilization initiating a second query without first retrieving all results for a first query generates a fault.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Function Query( _
   ByRef query As CollectorQueryParams, _
   ByRef collectors As List(Of Collector) _
) As Boolean

'Usage
 
Dim instance As ICollectors
Dim query As CollectorQueryParams
Dim collectors As List(Of Collector)
Dim value As Boolean
 
value = instance.Query(query, collectors)

bool Query( 
   ref CollectorQueryParams query,
   out List<Collector> collectors
)

bool Query( 
   CollectorQueryParams^% query,
   [Out] List<Collector^>^ collectors
)

Parameters

query: Query details.
collectors: Query results.

Return Value

Whether additional results remain available on server.

Example

CollectorQueryParams query = new CollectorQueryParams();
List<Collector> list = new List<Collector>(), temp = null;
              
// simple query
connection.ICollectors.Query(ref query, out list);
              
// paged query
list.Clear();
query.PageSize = 100; // return at most 100 results per request
while (connection.ICollectors.Query(ref query, out temp))
  list.AddRange(temp);
list.AddRange(temp);

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

ICollectors Interface
ICollectors Members