ReleaseNotes

                             SysDB Release Notes
                            =====================

  The release notes contain noteworthy changes in each System DataBase (SysDB)
  release, with a summary of the most important changes at the top. A complete
  and very detailed list of changes can be obtained from the Git logs for each
  release.

 Compatibility Note:
 ~~~~~~~~~~~~~~~~~~~
  All pre 1.0 development snapshots are not considered stable yet. That is,
  all interfaces, including the plugin API, the network protocol, or the query
  language, may change in an incompatible way at any time. All changes are
  documented here.

 About SysDB:
 ~~~~~~~~~~~~
  “System DataBase” (SysDB) is a multi-backend system management and inventory
  collection service. It stores system and inventory information about
  hardware and software systems. This information is (continuously) collected
  from various configurable backends (inventory services, monitoring services,
  etc.) and stored in a graph-like hierarchy of generic objects. The store may
  be queried through a generic interface independent of the active backends.
  Object names are canonicalized before they are added to the store to ensure
  a consistent view of your infrastructure.

  <https://sysdb.io/>

Version 0.8.0, Release Date: 2016-02-25
---------------------------------------

  This release focuses on a generic and much more powerful store (query)
  interface and modular store implementations via plugins. The in-memory store
  has been moved into a plugin on top of that. Various fixes and improvements,
  mostly related to iterators, have been applied to the parser and query
  language.

   * build system:
     - Fix VPATH (out of tree) builds.
     - Fixed a build issue (configure failure) when using RRDtool 1.5.
     - Enable silent build rules by default (if supported).
     - Fix build issues with GCC 5.
   * parser:
     - Add a new, standalone parser module based on a generic (public) AST
       (abstract syntax tree). This replaces the (internal) parser of the
       frontend module.
     - Improved error reporting for syntactic and semantic errors by
       propagating error messages in the parser and analyzer.
   * core / store:
     - Fully support array access and comparison (all element types).
     - Service/metric parent host names are now available via the "hostname"
       attribute (populated automatically).
     - Rebase the store query interface on top of the new parser: store
       implementations prepare actual queries from an AST, thus, allowing
       multiple implementations of store readers.
     - Querying the store (through the new interface) will emit data to an
       arbitrary writer implementation allowing for more flexible post-
       processing.
     - Fixed a memory leak in the TIMESERIES implementation.
     - data: Added support for boolean values; this is a backward incompatible
       change which breaks the network encoding.
     - Include nano-second fraction of datatime values (if any) in the string
       format (including JSON query results).
     - Add new callback type for store-readers (query plugins) based on the
       new generic query interface.
     - memstore: Refactor the in-memory store implementation into a separate
       data-type. It implements the writer and query/reader APIs.
     - The main, in-memory store is no longer enabled by default (see
       store::memory plugin). Instead, all updates go through the plugin API
       and are distributed to all registered writers.
     - Handle hostname canonicalization in the generic plugin module instead
       of requiring each writer plugin to do so.
     - Do not canonicalize hostnames when fetching time-series.
     - Determine an object's backends and update interval in the generic
       plugin module and pass it on to writer plugins which are expected to
       merge it with existing entries.
     - Let the JSON formatter implement the writer API to make it more
       flexible and uncouple it from the memstore module; let it support
       arbitrary top-level objects (besides hosts).
     - FETCH (in the core) now supports all object types and child objects as
       well as fetching the base object without children / siblings.
   * frontend:
     - Added the SERVER_VERSION command; this allows clients to check for
       supported servers.
     - Fixed a memory leak in failed FETCH commands.
     - Switch to the new, pluggable query interface: use registered plugins to
       write to or query the SysDB store.
     - Move protocol-specific (query) logic out of the core and into the
       frontend (based on the new query API).
     - A generic TIMESERIES implementation based on the query API replaces the
       in-core implementation.
   * query language:
     - Check types of comparison operands and arithmetic expression and treat
       mismatches as errors; previously those comparisons would fail silently.
     - Added the 'NOT IN' operator.
     - Support iterators (ANY/ALL) of arbitrary array expressions.
     - Change child-object iterator syntax to 'ANY/ALL <type>.name', that is,
       require the field name and add support for accessing arbitrary fields.
     - Added new field "value" for attribute values.
     - Added new field "timeseries" (boolean) for metrics indicating whether
       a time-series store is known to SysDB.
     - Support attribute and backend iterators in FILTER expressions.
     - Enforce that TIMESERIES end times are greater than start times.
     - Added unary 'IS TRUE' / 'IS FALSE' operators.
     - Iterator expressions may now reference a chain of sibling objects as
       long as only one such reference is an iterator. For example,
       `LOOKUP services MATCHING ANY host.backend =~ 'foo'`.
   * testing:
     - Use check "loop" tests; this will run all test-cases even if there are
       failures.
     - Create separate binaries for each test; this allows to run more in
       parallel.
     - Make it possible to run unit and integration tests separately; see
       README.

  Stores:
   * store::memory: Added a store-writer/store-reader plugin providing an
     in-memory store replacing the previous, always-enabled store. It is based
     on the 'memstore' module.

Version 0.7.0, Release Date: 2015-02-21
---------------------------------------

  This release introduces various features related to running SysDB as an
  agent. Objects may now also be submitted by arbitrary applications using the
  network protocol. Two new plugins are available to collect local facter fact
  values and to mirror all store operations to another instance. Various fixes
  and improvements have been applied to the client program (sysdb).

   * build system:
     - Added support for C++.
   * sysdb:
     - Fixed terminal resets on exit.
     - Don't exit if the server closed the connection; instead reconnect
       automatically on the next user input.
     - Fixed string parsing: previously, quoted strings were not handled at
       all and might have been terminated by an embedded semicolon.
     - Also store failed commands in the history to enable history editing in
       such cases.
     - Improved program output: don't mix log messages with prompts after
       sending a command; print log messages to the standard error channel.
     - Fixed lookup of the .sysdb_history file for cases where the SysDB user
       does not match the current operating system user.
   * sysdbd:
     - SSL options can be specified inside a <Listen> block.
     - Unload all plugins on exit to ensure a clean shutdown.
   * client:
     - Simplified RPC handling by providing a helper function.
     - Added support for TCP connections using SSL/TLS and supporting, both,
       IPv4 and IPv6. Remote peer verification is required for any such
       connection.
     - New command line flags -K, -C, and -A to specify the SSL private key,
       client certificate, and CA certificates file names.
   * core:
     - Fully support arrays of all types.
     - Fixed (implemented) reloading of time-series fetcher plugins.
     - Added new callback type for "store-writers", making that part of the
       store pluggable (queries are not supported).
   * store:
     - Added support for querying an object's siblings.
     - Send all stored objects to store-writer plugins in addition to storing
       them in the in-memory store.
   * frontend:
     - Fixed parsing of time values.
     - Add support for storing hosts, services, metrics, and attributes using
       the new 'STORE' command.
     - Fixed handling of subsequent requests on the same connection by
       avoiding unnecessary pauses of up to one second, thus, greatly speeding
       up request handling.
     - Added support for TCP connections supporting, both, IPv4 and IPv6.
       SSL/TLS is enforced for any such connection.
     - Added support for and require actual client authentication:
       UNIX socket connections require peer authentication.
       TCP connections require client SSL certificate authentication.
   * query language:
     - Added support for expressions accessing an object's siblings by using
       the '<object_type>.<sibling_type>' syntax.
   * JSON format:
     - Fixed handling of special characters which are now being escaped.
     - Include a flag indicating whether time-series data are available for a
       metric.
   * utils:
     - os: This utility module provides some Operating System related helper
       functions: access user information (current user, homedir), manage
       directories (create, delete, resolve), I/O helpers (select, read,
       write), networking helpers (DNS resolution).
     - proto: Added support for marshaling and unmarshaling messages encoding
       a datum of any type, hosts, services, metrics, and attributes.
     - ssl: This new module provides convenience functions for SSL/TLS
       servers, clients, and sessions using OpenSSL.

  Backends:
   * facter: Added a plugin collecting local facter fact values using
     libcfacter (C++).

  Stores:
   * store::network: Added a store-writer plugin sending all data to another
     SysDB instance using the client library and low-level STORE commands.

  Plugins:
   * syslog: The log-level is now configurable using the "LogLevel" option.

Version 0.6.0, Release Date: 2014-11-17
---------------------------------------

  This release focuses on a clearer query language. The underlying
  architecture has been refactored to allow for more powerful and generic
  expressions.

   * core:
     - Added support for arrays. Elements may be of any other supported
       data-type but only integers, decimals, and strings are fully supported.
   * store:
     - Refactored matchers: all matchers now operate on one or two expressions
       or other matchers, replacing the old and less flexible conditional
       matchers.
     - Attribute values may now be used anywhere in an expression.
     - On data-type mismatch when comparing attribute values, the values will
       be cast to string (previously only done for regex matches).
     - Added support for querying an object's backends (array of strings).
     - Added support for iterating child objects and array values.
     - All matchers now return false if any operand is NULL (except for IS
       NULL).
     - All operations now return NULL if any operand is NULL.
     - Fixed behavior of not-operators (!=, !~) and let them not match if any
       of the operands is NULL.
     - Add support for looking up all object types (hosts, services, metrics).
     - Refactored the JSON formatter to be more flexible and powerful.
     - Record parent objects for each stored object.
   * frontend:
     - Added a separate parser mode for expressions.
     - Added a new queryable field 'name' to be used in place of the rather
       magical keyword 'host' when looking up hosts.
     - Improved error reporting in the parser and the (newly introduced)
       analyzer.
     - Apply filters to hosts in the FETCH command.
   * query language:
     - All operators may now be used in all places if the involved data-types
       support the respective operation. For example, regular expressions may
       be used to match any value. Non-string values are cast to strings for
       that purpose. IS NULL / IS NOT NULL may be applied to arbitrary
       expressions.
     - Introduced the 'IN' operator to check if a value or an array of values
       is included in an array.
     - Added support for arrays: [<elem1>,<elem2>,...]
     - Added support for string and array concatenation using the '||'
       operator.
     - Attribute names have to be strings instead of identifiers now.
     - Access object fields using '<field>' rather than '.<field>'.
     - Let the LOOKUP and FETCH commands support services and metrics.
     - Introduced 'FETCH service|metric <host>.<name' for fetching services
       and metrics.
     - Added support for 'ANY' and 'ALL' operators which apply a matcher to
       each value emitted by an iterator (a host's services and metrics or
       arrays). 'MATCHING ANY service|metric|attribute <cmp> <expr>' replaces
       'MATCHING service|metric|attribute <cmp> <value>' expressions.

Version 0.5.0, Release Date: 2014-10-06
---------------------------------------

  This release focuses on simplifications and more flexibility in the frontend
  and the query language. Most of those changes are not backward-compatible
  but easy client implementations.

   * sysdb:
     - Include priority when printing log messages.
     - Fixed handling of empty queries.
   * store:
     - When serializing the entire store (LIST command), return an array of
       host objects (rather than wrapping it into another object).
     - Fixed JSON format of time-series data.
     - Fixed error checks of invalid compare expressions and reject them.
     - Fixed lookups by back-end name.
     - Added support for comparing attributes with different types by
       comparing their string values.
   * frontend:
     - Clarified details about asynchronous messages and authentication
       options and made client implementation more robust.
     - Introduced a new message type encoding the JSON serialized response of
       a query and its data type.
     - Include the priority in log messages.
     - Include object types in FETCH, LIST, and LOOKUP messages.
     - Added support for including services and metrics in LIST responses and
       skip hosts without the respective children.
   * query language:
     - Added support for services and metrics to LIST command.
     - Changed syntax for attribute lookup to 'attributes[<name>]'.
     - Changed syntax for accessing queryable fields to '.<field>'.
   * utils:
     - strbuf: Improved memory management.

Version 0.4.0, Release Date: 2014-09-01
---------------------------------------

  This release features support for metrics and transparent access to a
  backend's time-series data. Some backward-incompatible changes were applied
  to some query commands for more consistency.

   * build system:
     - Added checks for format strings and arguments.
     - Changed configure option for collectd::unixsock to
       --enable-collectd-unixsock.
   * core:
     - Added support for “metric” objects which may be assigned to a host.
     - Introduced support for handling time-series data: added new data
       structures describing time-series data and a new type of plugins called
       “time-series fetchers” which are used to access time-series
       information.
   * store:
     - Fixed a memory leak.
     - Apply (very) simple optimizations to lookup expressions.
     - Added support for metrics and their “data-stores” (describing how to
       access the actual data referenced by a metric).
     - Added support for querying time-series data through the newly
       introduced “time-series fetcher” plugins.
   * frontend:
     - Fixed a bug that might have caused reading too much data from the
       connection buffer in certain situations.
   * query language:
     - The ‘MATCHING’ clause is now optional in ‘LOOKUP’ queries.
     - The ‘LIST’ and ‘FETCH’ commands support ‘FILTER’ clauses as well.
     - ‘LIST’ / ‘FETCH’ were changed to ‘LIST hosts’ / ‘FETCH host’.
     - Added the ‘TIMESERIES’ command to query arbitrary time-series which
       fetches time-series data from a backend's data-store for a given period
       of time.
     - Added support for date/time values.
     - Added support for single quotes in string values: two adjacent single
       quotes may be used to specify a single quote.
   * documentation:
     - Documented the frontend protocol in frontend/proto.h.
     - Documented changes to the query language and new / updated plugins.
     - Documented all supported data types.

  Backends:
   * collectd::unixsock:
     - The plugin now uses metrics in place of services.
     - New config options ‘TimeseriesBackend’ and ‘TimeseriesBaseURL’ to
       specify access to time-series, currently limited to ‘rrdtool’ and
       ‘rrdcached’ access.

  Plugins:
   * timeseries::rrdtool:
     - New plugin adding support to fetch time-series from local RRD files.
     - Supports flushing of values in RRDCacheD.

Version 0.3.0, Release Date: 2014-08-01
---------------------------------------

  This release includes major enhancements and new features in the SysDB store
  which is the core of the database. Most notably, complex expressions are now
  supported when looking up information and filters may be used to preselect
  the information to be returned. Some backward-incompatible changes were
  introduced in the query language to avoid potentially confusing semantics.

   * sysdb: Fixed non-interactive mode when using libedit.
   * core:
     - Fixed weird behavior when collector callbacks were registered without
       any plugin context information (as it would, e.g., happen when using
       LoadPlugin instead of LoadBackend in sysdbd).
   * store:
     - Introduced service attributes -- similar to host attributes but
       assigned to a service object.
     - Don't log “value too old” messages if an updated object uses the same
       timestamp as the old object.
     - Switched from linked-lists to AVL trees for storing all object types to
       reduce lookup times from O(n) to O(log n).
     - Added infrastructure for handling and evaluating arithmetic
       expressions and filters (see also the changes to the query language
       below).
     - Export various fields describing base attributes of all stored object
       types: last_update, age, interval, and backend. These fields may be
       used when querying the store.
   * frontend: Include new service attributes in JSON output.
   * query language:
     - Added support for ‘IS NULL’ attribute checks matching on non-existent
       attributes.
     - Changed ‘LOOKUP ... WHERE’ queries to ‘LOOKUP ... MATCHING’ to avoid
       confusion with SQL semantics.
     - Switched from ‘<obj>.name’ to ‘<obj>’ in MATCHING clauses, thus, no
       longer shadowing attributes called “name”.
     - Added support for arithmetic expressions in places that used simple
       data values before. Arithmetic expressions support addition,
       subtraction, multiplication, division, modulo, and concatenation
       operations. The expressions may be based on constant values or
       queryable fields of the stored objects (specified as ‘:last_update’,
       ‘:age’, ‘:interval’, and ‘:backend’).
     - Added ‘FILTER’ support to ‘LOOKUP’ queries. Filters are conditional
       expressions which may optionally be used to limit the query and the
       result to object (of any type) matching the filter condition.
     - Added support to specify date and time values.
   * utils:
     - avltree: Added an AVL tree (self-balancing binary tree) implementation.
   * documentation: Added documentation for the new query language features.
   * testing: Run all unit tests through valgrind by default (if available).

  Backends:
   * collectd::unixsock:
     - Added support for spaces in identifiers.
     - Store plugin identifier (host, plugin, plugin_instance, type,
       type_instance) as service attributes.

Version 0.2.0, Release Date: 2014-07-02
---------------------------------------

  This is another development snapshot of SysDB. The main focus of this
  release is on stabilizing existing features and extending the query
  infrastructure to support all attribute types and further operators.

   * build system: Fixed linking of sysdbd to include *all* necessary object
     files. This bug caused some plugins to be un-loadable.
   * sysdbd: Fixed shutdown process in case of errors.
   * sysdb: Fixed a bug causing some server replies to be ignored when exiting
     from the client.
   * core:
     - Always log to the standard output stream if no user-provided logging
       callbacks had been specified. Previously this was disabled after
       enabling logging to clients in the frontend.
     - Simplified plugin naming information and determine configuration
       callback names automatically to ensure better consistency.
   * store:
     - Simplified internal data management.
     - Store the list of backends along with each stored object which provide
       the respective object.
   * frontend:
     - Simplified and improved the internal architecture matching / looking up
       objects.
     - Fixed parser to correctly reject invalid object types.
     - Automatically create the base directory of a listening UNIX socket.
   * query language: Added support for numeric constants and added operators
     for less and greater than or equal attribute comparison.
   * documentation: Added missing files to the distribution tarball.

  Plugins:
   * syslog: Don't log debug messages to syslog.

Version 0.1.0, Release Date: 2014-06-01
---------------------------------------

  This is the initial release of SysDB. It provides the following core
  features:

   * sysdb: A terminal-based, interactive client program. Supports
     line-editing and history based on libreadline or libedit and uses an
     asynchronous, event-driven architecture to handle user input and server
     replies simultaneously.
   * sysdbd: The database backend service configurable through a configuration
     file. The daemon supports online reconfiguration.
   * core: Flexible, multi-threaded core architecture providing a configurable
     plugin infrastructure for querying external data-sources and extending
     core functionality. The following plugin types are supported:
     - data collection
     - hostname canonicalization
     - logging
   * store: Central, in-memory object store managing host and service objects
     and their attributes. Host names may be canonicalized through respective
     plugins. Each object is automatically attributed with last update and
     interval information using nano-seconds resolution. Attributes may have
     various types (integer, decimal, string, date-time, binary).
   * frontend: The frontend handling client connections uses a multi-threaded,
     asynchronous, event-driven architecture capable of handling multiple
     listen addresses.
   * query language: The store may be queried using the ‘LIST’, ‘LOOKUP’, and
     ‘FETCH’ commands returning JSON formatted objects.
   * utils: A rich set of abstract data-types and utility functions for
     internal use:
     - generic channels for asynchronous, multi-threaded I/O
     - DBI wrapper to ease common database access operations
     - thread-aware error handling and reporting
     - doubly linked-lists
     - dynamic sized memory buffers supporting formatted strings and binary
       data
     - UNIX socket client implementation
   * documentation: Full documentation for the tools, all plugins, and the
     query language provided as manpages and HTML pages.
   * testing: Unit and integration tests exist for most parts except plugins
     covering 77% of all functions. Valgrind and Clang's address sanitzer are
     used to detect memory leaks and programming errors.

  The following plugins are shipped with this version of SysDB:

  Backends:
   * collectd::unixsock: Query collectd through its ‘unixsock’ interface
   * mk-livestatus: Query arbitrary (monitoring) systems using the Check_MK
     Livestatus interface.
   * puppet::store-configs: Query Puppet through its “stored configuration”
     database.

  Plugins:
   * cname::dns: Canonicalize hostnames by querying DNS information.
   * syslog: Send log messages to the system log service.