MONITOR BACKEND NAME: back-monitor Backend for monitoring the server's activity. COMPILE AND CONFIGURATION OPTIONS It must be explicitly enabled by configuring with --enable-monitor set; then it must be activated by placing in slapd.conf the database configure directive database monitor The suffix "cn=Monitor" is implicitly activated (it cannot be given as a suffix of the database as usually done for conventional backends). Note that the "cn=Monitor" naming context appears in the rootDSE (FIXME: do we really want this?) A bind operation is provided; at present it allows to bind as the backend rootdn. As a result, the backend supports the rootdn/rootpw directives (only simple bind at present). NAMING CONTEXT AND TREE STRUCTURE The backend naming context is "cn=Monitor"; the first level entries represent the monitored subsystems. It is implemented in a modular way, to ease the addition of new subsystems. SCHEMA All the subsystems get a default "cn" attribute, represented by the subsystem's name, and they all have "top", "monitor" and "extensibleObject" objectclasses. "extensibleObject" is used, and the "description" attribute is used to hold the monitor information of each entry. FUNCTIONALITY Most of the sybsystems contain an additional depth level, represented by detailed item monitoring. All the entries undergo an update operation, if a related method is defined, prior to being returned. Moreover, there's a mechanism to allow volatile entries to be defined, and generated on the fly when requested. As an instance, the connection statistics are updated at each request, while each active connection data is created on the fly. One nice feature of this solution is that granular ACLs can be applied to each entry. OPERATIONS The backend currently supports: bind compare modify search SUBSYSTEMS Currently some subsystems are partially supported. "Partially" means their entries are correctly generated, but sometimes only partially useful information is provided. The subsystems are: Listener Databases Backends Threads SASL TLS Connections Read Waiters Write Waiters Log Operations Statistics Time LISTENER SUBSYSTEM It contains the description of the devices the server is currently listening on DATABASES SUBSYSTEM The main entry contains the naming context of each configured database; the subentries contain, for each database, the type and the naming context. BACKENDS SUBSYSTEMS The main entry contains the type of backends enabled at compile time; the subentries, for each backend, contain the type of the backend. It should also contain the modules that have been loaded if dynamic backends are enabled. THREADS SUBSYSTEM It contains the maximum number of threads enabled at startup and the current backload. SASL Currently empty. TLS Currently empty. CONNECTIONS The main entry is empty; it should contain some statistics on the number of connections. Dynamic subentries are created for each open connection, with stats on the activity on that connection (the format will be detailed later). There are two special subentries that show the number of total and current connections respectively. READ WAITERS SUBSYSTEM It contains the number of current read waiters. WRITE WAITERS SUBSYSTEM It contains the number of current write waiters. LOG SUBSYSTEM It contains the currently active log items. The "Log" subsystem allows user modify operations on the "description" attribute, whose values MUST be in the list of admittable log switches: Trace Packets Args Conns BER Filter Config (useless) ACL Stats Stats2 Shell Parse Cache (deprecated) Index These values can be added, replaced or deleted; they affect what messages are sent to the syslog device. OPERATIONS SUBSYSTEM It shows some statistics on the operations performed by the server: Initiated Completed SENT SUBSYSTEM It shows some statistics on the data sent by the server: Bytes PDU Referrals Entries TIME SUBSISTEM It contains two subentries with the start time and the current time of the server. NOTES This document is in a very early stage of maturity and will probably be rewritten many times before the monitor backend is released. AUTHOR: Pierangelo Masarati