NSPLookupServiceBegin (Windows CE 5.0)
This function initiates a client query that is constrained by the information contained within a WSAQUERYSET structure.
WSALookupServiceBegin only returns a handle, which should be used by subsequent calls to WSALookupServiceNext to get the actual results. Because this operation cannot be canceled, it should be implemented to execute quickly. While it is acceptable to initiate a network query, this function should not require a response in order to return successfully.
int NSPLookupServiceBegin(LPGUID lpProviderId,LPWSAQUERYSETW lpqsRestrictions,LPWSASERVICECLASSINFOW lpServiceClassInfo,DWORD dwControlFlags,LPHANDLE lphLookup);
Parameters
- lpProviderId
[in] Contains the specific provider identifier that should be used for the query. - lpqsRestrictions
[in] Contains the search criteria. For more information, see below. - lpServiceClassInfo
[in] Structure that contains all the schema information for the service. - dwControlFlags
[in] Controls the depth of the search. The following table shows the possible values.Value Description LUP_DEEP Query deep as opposed to just the first level. LUP_CONTAINERS Return containers only. LUP_NOCONTAINERS Do not return any containers. LUP_FLUSHCACHE If the provider has been caching information, ignore the cache and go query the name space itself. LUP_FLUSHPREVIOUS Used as a value for the dwControlFlags parameter in NSPLookupServiceNext. Setting this flag instructs the provider to discard the last result set, which was too large for the supplied buffer, and move on to the next result set. LUP_NEAREST If possible, return results in the order of distance. The measure of distance is provider specific. LUP_RES_RESERVICE Indicates whether prime response is in the remote or local part of CSADDR_INFO structure. The other part needs to be usable in either case. LUP_RETURN_ALIASES Any available alias information is to be returned in successive calls to NSPLookupServiceNext, and each alias returned will have the RESULT_IS_ALIAS flag set. LUP_RETURN_NAME Retrieves the name as lpszServiceInstanceName. LUP_RETURN_TYPE Retrieves the type as lpServiceClassId. LUP_RETURN_WSAVERSION Retrieves the version as lpVersion. LUP_RETURN_COMMENT Retrieves the comment as lpszComment. LUP_RETURN_ADDR Retrieves the addresses as lpcsaBuffer. LUP_RETURN_BLOB Retrieves the private data as lpBlob. LUP_RETURN_ALL Retrieves all the information. - lphLookup
[out] Handle to be used in subsequent calls to NSPLookupServiceNext in order to retrieve the results set.
Return Values
The function should return NO_ERROR (zero) if the routine succeeds. It should return SOCKET_ERROR (–1) if the routine fails and it must set the appropriate error code using SetLastError.
The following table shows the possible error codes.
| Error value | Description |
|---|---|
| WSAEINVAL | One or more parameters were invalid for this provider or missing. |
| WSANO_DATA | Name was found in the database but it does not have the correct associated data being resolved for. |
| WSASERVICE_NOT_FOUND | No such service is known. The service cannot be found in the specified name space. |
| WSA_NOT_ENOUGH_MEMORY | Not enough free memory available to perform this operation. |
Remarks
If LUP_CONTAINERS is specified in a call, all other restriction values should be avoided. If any are supplied, it is up to the name service provider to decide if it can support this restriction over the containers. If it cannot, it should return an error.
Some name service providers may have other means of finding containers. For example, containers can all be of some well-known type, or of a set of well-known types, and therefore a query restriction could be created for finding them. No matter what other means the name service provider has for locating containers, LUP_CONTAINERS and LUP_NOCONTAINERS take precedence. Hence, if a query restriction is given that includes containers, specifying LUP_NOCONTAINERS will prevent the container items from being returned. Similarly, no matter the query restriction, if LUP_CONTAINERS is given, only containers should be returned. If a name space does not support containers and LUP_CONTAINERS is specified, it should simply return WSANO_DATA.
The following code sample shows the preferred method of obtaining the containers within another container,
dwStatus = NSPLookupServiceBegin(
lpqsRestrictions,
LUP_CONTAINERS,
lphLookup);
followed by the requisite number of NSPLookupServiceNext calls. This will return all containers contained immediately within the starting context; that is, it is not a deep query. With this, one can map the address space structure by walking the hierarchy, perhaps enumerating the content of selected containers. Subsequent uses of NSPLookupServiceBegin use the containers returned from a previous call.
Forming Queries
As previously mentioned, a WSAQUERYSET structure is used as an input parameter to NSPLookupServiceBegin in order to qualify the query. The following table indicates how the WSAQUERYSET is used to construct a query. When a member is marked as (Optional) a NULL pointer can be supplied, indicating that the parameter will not be used as a search criteria.
| WSAQUERYSET member name | Query interpretation |
|---|---|
| dwSize | Will be set to sizeof(WSAQUERYSET). This is a versioning mechanism. |
| dwOuputFlags | Ignored for queries. |
| lpszServiceInstanceName | (Optional) Referenced string contains service name. The semantics for wildcarding within the string are not defined, but can be supported by certain name-space providers. |
| lpServiceClassId | (Required) GUID corresponding to the service class. |
| lpVersion | (Optional) References the desired version number and provides version comparison semantics (that is, the version must either match exactly or must be not less than the value supplied). |
| lpszComment | Ignored for queries. |
| dwNameSpace | Identifier of a single name space in which to constrain the search, or NS_ALL to include all name spaces. |
| lpNSProviderId | (Optional) References the GUID of a specific name-space provider and limits the query to this provider only. |
| lpszContext | (Optional) Specifies the starting point of the query in a hierarchical name space. |
| dwNumberOfProtocols | Size of the protocol constraint array. This can be zero. |
| lpafpProtocols | (Optional) References an array of AFPROTOCOLS structure. Only services that utilize these protocols will be returned. It is legal for the value AF_UNSPEC to appear as a protocol family value, signifying a wildcard. Name space providers may supply information on any service that uses the corresponding protocol, regardless of address family. |
| lpszQueryString | (Optional) Specifies a simple string that is an enriched SQL-like query. Some name spaces (such as whois++) support these queries. |
| dwNumberOfCsAddrs | Ignored for queries. |
| lpcsaBuffer | Ignored for queries. |
| lpBlob | (Optional) Pointer to a provider-specific entity. |
Requirements
OS Versions: Windows CE .NET 4.0 and later.
Header: Ws2spi.h.
Link Library: Ws2.lib.
See Also
AFPROTOCOLS | WSAQUERYSET | WSASERVICECLASSINFO | NSPLookupServiceNext
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