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<!doctype html public "-//w3c//dtd html 4.0 transitional//en"><html><head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta name="GENERATOR" content="Mozilla/4.77C-CCK-MCD Caldera Systems OpenLinux [en] (X11; U; Linux 2.4.2 i686) [Netscape]"> <title>OpenSLP Programmers Guide - SLPOpen</title></head><body text="#000000" bgcolor="#FFFFFF" link="#0000EF" vlink="#51188E" alink="#FF0000"><h2>SLPOpen</h2><hr WIDTH="100%"><h3>Include</h3> <h3>Declaration</h3><tt>#include <slp.h></tt><p><tt><a href="SLPError.html">SLPError</a> SLPOpen(const char* <a href="#lang">lang</a>,<a href="SLPTypes.html#SLPBoolean">SLPBoolean</a><a href="#isasync">isasync</a>,<a href="SLPTypes.html#SLPHandle">SLPHandle</a>*<a href="#phslp">phslp</a>)</tt><br> <h3>Description</h3>Returns a <tt>SLPHandle</tt> handle in the <tt>phslp</tt> parameter forthe language locale passed in as the <tt>lang</tt> parameter. The clientindicates if operations on the handle are to be synchronous or asynchronousthrough the <tt>isasync</tt> parameter. The handle encapsulates the languagelocale for SLP requests issued through the handle, and any other resourcesrequired by the implementation. The return value of the function is an<tt>SLPError</tt>code indicating the status of the operation. Upon failure, the <tt>phslp</tt>parameter is NULL.<p>An <tt>SLPHandle</tt> can only be used for one SLP API operation ata time. If the original operation was started asynchronously, any attemptto start an additional operation on the handle while the original operationis pending results in the return of an <tt>SLP_HANDLE_IN_USE</tt> errorfrom the API function. The <tt>SLPClose()</tt> API function terminatesany outstanding calls on the handle. If an implementation is unable tosupport a asynchronous( resp. synchronous) operation, due to memory constraintsor lack of threading support, the <tt>SLP_NOT_IMPLEMENTED </tt>flag maybe returned when the isasync flag is <tt>SLP_TRUE</tt> (resp. <tt>SLP_FALSE</tt>).<p>In the OpenSLP implementation, SLPHandles are used to cache informationthat is costly to obtain (in terms of network usage and time). Since the RFC 2614 API does not specify functions to initialize theimplementation library, OpenSLP keeps track of the number of SLPHandlesthat are open. Several global library data structures are initializedwhen the first SLPHandle is opened and maintained until the last SLPHandleis closed. Therefore, it is most efficient to leave SLPHandles openfor as long as you will need them (often for the entire life of a process). If you can help it, DO NOT make a habit of opening and closing SLPHandlesfrequently.<h3>Parameters</h3><table BORDER CELLPADDING=5 NOSAVE ><tr VALIGN=TOP NOSAVE><td NOSAVE><a NAME="lang"></a><tt>lang</tt></td><td NOSAVE>A pointer to null terminated array of characters containingthe RFC 1766 Language Tag for the natural language locale of requests andregistrations issued on the handle. Pass in NULL or the empty string,"" to use the local the machine is configured to use.</td></tr><tr VALIGN=TOP NOSAVE><td><a NAME="isasync"></a><tt>isasync</tt></td><td NOSAVE>A <tt>SLPBoolean</tt> value indicating whether the <tt>SLPHandle</tt>should be opened for asynchronous operation or not.</td></tr><tr VALIGN=TOP NOSAVE><td><a NAME="phslp"></a><tt>phslp</tt></td><td NOSAVE>A pointer to an <tt>SLPHandle</tt>, in which the open <tt>SLPHandle</tt>is returned. If an error occurs, the value upon return is NULL.</td></tr></table><h3>Returns</h3><table BORDER NOSAVE ><tr><td>SLP_AUTHENTICATION_FAILED</td><td>If the SLP framework supports authentication, this error arises whena authentication on an SLP message failed.</td></tr><tr><td>SLP_MEMORY_ALLOC_FAILED </td><td>Out of memory error</td></tr><tr><td>SLP_PARAMETER_BAD</td><td>If a parameter passed into a function is bad, this error is returned.</td></tr><tr><td>SLP_INTERNAL_SYSTEM_ERROR</td><td>A basic failure of the API causes this error to be returned. This occurswhen a system call or library fails. The operation could not recover.</td></tr><tr><td>SLP_HANDLE_IN_USE</td><td>Callback functions are not permitted to recursively call into the APIon the same SLPHandle, either directly or indirectly. If an attempt ismade to do so, this error is returned from the called API function.</td></tr></table><p>Be aware, especially if the call is async, of error codes that may bepassed to the SLPRegReport() callback function.<br> <h3>Status</h3><table CELLPADDING=5 NOSAVE ><tr VALIGN=TOP NOSAVE><td NOSAVE>OpenSLP 0.6.0</td><td NOSAVE>Fully implemented as specified by RFC 2614</td></tr></table><h3>See Also</h3><a href="SLPClose.html">SLPClose()</a><br> </body></html>⌨️ 快捷键说明
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