zodburi
=======

Overview
--------

A library which parses URIs and converts them to ZODB storage objects and
database arguments.

It will run under CPython 3.7+ and pypy3.  It will not run under Jython.  It requires ZODB >= 5.0.0.

Installation
------------

Install using pip, e.g. (within a virtualenv)::

  $ pip install zodburi

Using
-----

``zodburi`` has exactly one api: :func:`zodburi.resolve_uri`.  This API
obtains a ZODB storage factory and a set of keyword arguments suitable for
passing to the ``ZODB.DB.DB`` constructor.  For example:

.. code-block:: python
   :linenos:

   from zodburi import resolve_uri

   storage_factory, dbkw = resolve_uri(
                     'zeo://localhost:9001?connection_cache_size=20000')

   # factory will be an instance of ClientStorageURIResolver
   # dbkw will be {'connection_cache_size':20000, 'pool_size':7,
   #               'database_name':'unnamed'}

   from ZODB.DB import DB
   storage = storage_factory()
   db = DB(storage, **dbkw)

URI Schemes
-----------

The URI schemes currently recognized in the ``zodbconn.uri`` setting
are ``file://``, ``zeo://``, ``zconfig://``, ``memory://`` and ``demo:``.
Documentation for these URI scheme syntaxes are below.

In addition to those schemes, the relstorage_ package adds support for
``postgres://``.

.. _relstorage : https://pypi.org/project/RelStorage/

``file://`` URI scheme
~~~~~~~~~~~~~~~~~~~~~~

The ``file://`` URI scheme can be passed as ``zodbconn.uri`` to create a ZODB
FileStorage database factory.  The path info section of this scheme should
point at a filesystem file path that should contain the filestorage data.
For example::

  file:///my/absolute/path/to/Data.fs

The URI scheme also accepts query string arguments.  The query string
arguments honored by this scheme are as follows.

FileStorage constructor related
+++++++++++++++++++++++++++++++

These arguments generally inform the FileStorage constructor about
values of the same names.

create
  boolean
read_only
  boolean
quota
  bytesize

Database-related
++++++++++++++++

These arguments relate to the database (as opposed to storage)
settings.

database_name
  string

Connection-related
++++++++++++++++++

These arguments relate to connections created from the database.

connection_cache_size
  integer (default 10000) target size, in number of objects, of each
  connection's object cache

connection_cache_size_bytes
  integer (default 0) target estimated size, in bytes, of each
  connection's object cache

  0 means no limit.

  A suffix of KB, MB, or GB may be used to provide units.

connection_historical_cache_size
  integer (default 1000) target size, in number of objects, of each
  historical connection's object cache

connection_historical_cache_size_bytes
  integer (default 0) target estimated size, in bytes, of each
  historical connection's object cache

  0 means no limit.

  A suffix of KB, MB, or GB may be used to provide units.

connection_historical_pool_size
  integer (default 3) expected maximum total number of historical connections
  simultaneously open

connection_historical_timeout
  integer (default 300) maximum age of inactive historical connections

  When a historical connection has remained unused in a historical
  connection pool for more than connection_historical_timeout seconds,
  it will be discarded and its resources released.

connection_large_record_size
  integer (default 16MB) record size limit before suggesting using blobs

  When object records are saved that are larger than this, a warning
  is issued, suggesting that blobs should be used instead.

  A suffix of KB, MB, or GB may be used to provide units.

connection_pool_size
  integer (default 7) expected maximum number of simultaneously open
  connections

  There is no hard limit (as many connections as are requested
  will be opened, until system resources are exhausted).  Exceeding
  pool-size connections causes a warning message to be logged,
  and exceeding twice pool-size connections causes a critical
  message to be logged.

connection_pool_timeout
  integer (default unlimited) maximum age of inactive (non-historical)
  connections

  When a connection has remained unused in a connection pool for more
  than connection_pool_timeout seconds, it will be discarded and its
  resources released.

Blob-related
++++++++++++

If these arguments exist, they control the blob settings for this
storage.

blobstorage_dir
  string
blobstorage_layout
  string

Misc
++++

demostorage (deprecated in favour of ``demo:`` URI scheme)
  boolean (if true, wrap FileStorage in a DemoStorage)

Example
+++++++

An example that combines a path with a query string::

   file:///my/Data.fs?connection_cache_size=100&blobstorage_dir=/foo/bar

``zeo://`` URI scheme
~~~~~~~~~~~~~~~~~~~~~~

The ``zeo://`` URI scheme can be passed as ``zodbconn.uri`` to create a ZODB
ClientStorage database factory. Either the host and port parts of this scheme
should point at a hostname/portnumber combination e.g.::

  zeo://localhost:7899

Or the path part should point at a UNIX socket name::

  zeo:///path/to/zeo.sock

The URI scheme also accepts query string arguments.  The query string
arguments honored by this scheme are as follows.

ClientStorage-constructor related
+++++++++++++++++++++++++++++++++

These arguments generally inform the ClientStorage constructor about
values of the same names.

storage
  string
cache_size
  bytesize
name
  string
client
  string
debug
  boolean
var
  string
min_disconnect_poll
  integer
max_disconnect_poll
  integer
wait_for_server_on_startup (deprecated alias for wait)
  boolean
wait
  boolean
wait_timeout
  integer
read_only
  boolean
read_only_fallback
  boolean
drop_cache_rather_verify
  boolean
username
  string
password
  string
realm
  string
blob_dir
  string
shared_blob_dir
  boolean
blob_cache_size
  bytesize
blob_cache_size_check
  integer
client_label
  string

Misc
++++

demostorage (deprecated in favour of ``demo:`` URI scheme)
  boolean (if true, wrap ClientStorage in a DemoStorage)

Connection-related
++++++++++++++++++

These arguments relate to connections created from the database.

connection_cache_size
  integer (default 10000)
connection_pool_size
  integer (default 7)

Database-related
++++++++++++++++

These arguments relate to the database (as opposed to storage)
settings.

database_name
  string

Example
+++++++

An example that combines a path with a query string::

  zeo://localhost:9001?connection_cache_size=20000

``zconfig://`` URI scheme
~~~~~~~~~~~~~~~~~~~~~~~~~

The ``zconfig://`` URI scheme can be passed as ``zodbconn.uri`` to create any
kind of storage that ZODB can load via ZConfig. The path info section of this
scheme should point at a ZConfig file on the filesystem. Use an optional
fragment identifier to specify which database to open. This URI scheme does
not use query string parameters.

Examples
++++++++

An example ZConfig file::

    <zodb>
      <mappingstorage>
      </mappingstorage>
    </zodb>

If that configuration file is located at /etc/myapp/zodb.conf, use the
following URI to open the database::

    zconfig:///etc/myapp/zodb.conf

A ZConfig file can specify more than one database.  For example::

    <zodb temp1>
      <mappingstorage>
      </mappingstorage>
    </zodb>
    <zodb temp2>
      <mappingstorage>
      </mappingstorage>
    </zodb>

In that case, use a URI with a fragment identifier::

    zconfig:///etc/myapp/zodb.conf#temp1

``memory://`` URI scheme
~~~~~~~~~~~~~~~~~~~~~~~~~

The ``memory://`` URI scheme can be passed as ``zodbconn.uri`` to create a
ZODB MappingStorage (memory-based) database factory.  The path info section
of this scheme should be a storage name.  For example::

  memory://storagename

However, the storage name is usually omitted, and the most common form is::

  memory://

The URI scheme also accepts query string arguments.  The query string
arguments honored by this scheme are as follows.

Database-related
++++++++++++++++

These arguments relate to the database (as opposed to storage)
settings.

database_name
  string

Connection-related
++++++++++++++++++

These arguments relate to connections created from the database.

connection_cache_size
  integer (default 10000)
connection_pool_size
  integer (default 7)

Example
+++++++

An example that combines a dbname with a query string::

   memory://storagename?connection_cache_size=100&database_name=fleeb


``demo:`` URI scheme
~~~~~~~~~~~~~~~~~~~~

The ``demo:`` URI scheme can be passed as ``zodbconn.uri`` to create a
DemoStorage database factory. DemoStorage provides an overlay combining base
and δ ("delta", or in other words, "changes") storages.
The URI scheme contains two parts, base and δ::

    demo:(base_uri)/(δ_uri)

an optional fragment specifies arguments for ``ZODB.DB.DB`` constructor::

    demo:(base_uri)/(δ_uri)#dbkw

Example
+++++++

An example that combines ZEO with local FileStorage for changes::

    demo:(zeo://localhost:9001?storage=abc)/(file:///path/to/Changes.fs)


More Information
----------------

.. toctree::
   :maxdepth: 1

   api.rst

Reporting Bugs / Development Versions
-------------------------------------

Visit https://github.com/Pylons/zodburi to download development or
tagged versions.

Visit https://github.com/Pylons/zodburi/issues to report bugs.


.. include:: ../CHANGES.rst


Indices and tables
------------------

* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`