OpenSLP Programmers Guide - SLPAttrCallback

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## SLPAttrCallback
OpenSLP Programmer's Guide » Service Location Functions » SLPAttrCallback

### Declaration

    typedef SLPBoolean SLPAttrCallback(
        SLPHandle hslp,
        const char* attrlist,
        SLPError errcode,
        void* cookie );

### Description

The `SLPAttrCallback` type is the type of the callback function passed as a parameter to the `SLPFindAttrs()` function. The behavior of the library is differs depending on whether the attribute request was by Service URL or by service type.

If the `SLPFindAttrs()` function was called with a Service URL, then the callback is called once regardless of whether the handle was opened asynchronously or synchronously. The `attrlist` parameter will contain a comma separated list of attributes.

If the `SLPFindAttrs()` function was called with a service type, then the callback called is until no more results are available. The `attrlist` parameter will contain a comma separated list of attributes. Returns will be collated to remove duplicates if `SLPFindAttrs()` was called synchronously. If it was called asynchronously the `attrlist` may return duplicates.

### Parameters

`hslp` | The language specific `SLPHandle` that was passed into the `SLPFindAttrs()` function.
`attrlist` | Pointer to a buffer containing a comma separated null terminated list of attribute id/value assignments in SLP wire format "(attr-id=attr-value-list)".
`errcode` | An error code indicating if an error occurred during the operation. The callback should check this error code before processing the parameters.
`cookie` | The same cookie that was passed as a parameter to the `SLPFindAttrs()` call.

### Returns

The callback should return `SLP_TRUE` if more data is desired. The callback may continue to return `SLP_TRUE` until it is called with an `errcode` of `SLP_LAST_CALL`. If no more data is requested the callback should return `SLP_FALSE`.. Since discovery of attributes by service-type is not supported, there is really no reason to return anything but `SLP_FALSE` from the SLPAttrCallback().

### Status

OpenSLP 1.0.0 | `SLPAttrCallback` function is implemented as specified by RFC 2614

### See Also

Syntax, Callbacks

Prepared by: Caldera Systems Inc
Maintained by: openslp.org