pmdahelp(3) [centos man page]

PMDAHELP(3)						     Library Functions Manual						       PMDAHELP(3)

NAME

       pmdaOpenHelp, pmdaGetHelp, pmdaGetInDomHelp, pmdaCloseHelp - help text support for a PMDA

C SYNOPSIS

       #include <pcp/pmapi.h>
       #include <pcp/impl.h>
       #include <pcp/pmda.h>

       int pmdaOpenHelp(char *fname);
       char *pmdaGetHelp(int handle, pmID pmid, int type);
       char *pmdaGetInDomHelp(int handle, pmInDom indom, int type);
       void pmdaCloseHelp(int handle);

       cc ... -lpcp_pmda -lpcp

DESCRIPTION

       As  part  of the Performance Metrics Domain Agent (PMDA) API (see PMDA(3)), this group of routines is used to implement the processing of a
       PMDA's metric help information.

       These routines are really intended for internal use, and should not need to be called directly from any PMDA code.

       Briefly, the base name of the help text file (as created by newhelp(1)) is passed in via a -h command line option for a daemon PMDA  or	as
       an  argument  to pmdaDaemon(3) or pmdaDSO(3).  Then pmdaOpenHelp is called from pmdaInit(3) and returns a handle that is used in subsequent
       calls to identify a particular help text collection (each PMDA typically has only one such collection).

       Requests for help text are passed to pmdaText(3) which calls pmdaGetHelp or pmdaGetInDomHelp as required.

       Other than error cases in pmdaOpenHelp, pmdaCloseHelp is not called.

DIAGNOSTICS

       pmdaOpenHelp returns a negative value for failure, suitable for decoding with pmErrStr(3).  pmdaGetHelp and pmdaGetInDomHelp return NULL if
       the corresponding help text does not exist.

CAVEAT

       The PMDA must be using PMDA_PROTOCOL_2 or later, as specified in the call to pmdaDSO(3) or pmdaDaemon(3).

SEE ALSO

       newhelp(1), PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaInit(3), pmdaText(3) and pmErrStr(3).

Performance Co-Pilot							PCP							       PMDAHELP(3)

PMDAATTRIBUTE(3)					     Library Functions Manual						  PMDAATTRIBUTE(3)

NAME

       pmdaAttribute - informs a PMDA about client connection attributes

C SYNOPSIS

       #include <pcp/pmapi.h>
       #include <pcp/impl.h>
       #include <pcp/pmda.h>

       int pmdaAttribute(int context, int key, char *value, int length, pmdaExt *pmda);

       cc ... -lpcp_pmda -lpcp

DESCRIPTION

       As  part  of  the Performance Metrics Domain Agent (PMDA) API (see PMDA(3)), pmdaAttribute is the generic callback for responding to client
       connection attributes.  These attributes include client credential information, such as user ID and group ID.

       A PMDA that supports connection attributes will provide a private pmdaAttribute callback by  assignment	to  version.six.attribute  of  the
       pmdaInterface structure, and implement custom logic for any of the attribute key-value pairs of interest to it.

       All  attributes are associated with a specific client context, and these can be uniquely identified using the ctx first argument.  The PMDA
       should track client connections, and disconnections using the pmdaSetEndContextCallBack(3) interface, as a result.   The  pmdaGetContext(3)
       interface may be particularly helpful also.

       All  attributes	are  passed  as key-value pairs and the value is always passed as a null-terminated string of given length.  This includes
       numeric attributes like the user ID.

       The most commonly used attributes would be PCP_ATTR_USERID and  PCP_ATTR_GROUPID  but  others  may  also  be  optionally  passed  (such	as
       PCP_ATTR_USERNAME)  if  they  are  available.   Some  attributes  will  be  consumed  by  pmcd  and  never through passed to PMDAs, such as
       PCP_ATTR_PASSWORD.  A complete list of all possible attributes can be found in the headers listed above, all are prefixed by PCP_ATTR.

DIAGNOSTICS

       pmdaAttribute should return either zero on success, or a negative return code to indicate an error in handling the attribute.  This  return
       code  cannot  be  used  to indicate a client should be disallowed access - such functionality must be performed by the agent in response to
       callbacks for the client in question (using PM_ERR_PERMISSION for those specific callbacks, for that  specific  client.	 In  other  words,
       errors  will  be  be passed to PMCD but there is no guarantee made that the error will be return to the client and result in termination of
       the client, for example.

CAVEAT

       The PMDA must be using PMDA_PROTOCOL_6 or later, as specified in the call to pmdaDSO(3) or pmdaDaemon(3).

SEE ALSO

       PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaMain(3) and pmdaGetContext(3).

Performance Co-Pilot							PCP							  PMDAATTRIBUTE(3)