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Revision: 1752 - (download)
Fri Jun 4 22:34:24 2004 UTC (19 years, 9 months ago) by pje
File size: 5604 byte(s)
Massive refactoring of 'peak.web' to remove all Zope dependencies.  See
'CHANGES.txt' for details.  Note that this is only the beginning of the
refactoring, so please promptly report any problems you may find!  That
way, I hopefully won't get too far ahead, building on anything that might
be broken.
Fixes and Enhancements since Version 0.5 alpha 3

 - 'peak.web' no longer uses Zope X3 for HTTP publishing support; it has been
   refactored to use a "simpler, more uniform architecture":http://www.eby-sarna.com/pipermail/peak/2004-May/001462.html
   See also "more on the architecture":http://www.eby-sarna.com/pipermail/peak/2004-June/001482.html
   and subsequent posts in that thread.

   As a consequence, "various features have been removed":http://www.eby-sarna.com/pipermail/peak/2004-June/001500.html
   from 'peak.web', for possible return at a future date.  Here is a rough
   outline of the changes made so far:
   
    * The 'pageProtocol', 'pathProtocol', and 'errorProtocol' machinery are
      gone.  They will be replaced in the future with an explicit "controller"
      wrapping mechanism to allow application-specific renderings of the same
      underlying components.

    * The Zope 'request' and 'response' objects are gone, along with all of
      their special handling for cookies, character sets, form variables,
      automatically marshalling parameters to functions, etc.  These items of
      functionality will be gradually replaced by functions in 'peak.web.api'.

      As a result of this, arbitrary functions and methods can no longer be
      used as web pages; instead, functions and methods to be published must
      use the same inputs and outputs as the 'IHTTPHandler.handle_http()'
      method.

    * The 'IWebPage', 'IWebInteraction', 'ITraversalContext', 'Traversal',
      'TraversalContext', and 'Interaction' interfaces and classes no longer
      exist, as they are unneeded in the new architecture.  Instead of
      having a central 'IWebInteraction' that's referenced by numerous
      'ITraversalContext' objects, the new approach uses an 'environ' mapping
      for most functions.  For access control, a 'security.IInteraction' is
      now used, whose function is limited to security checks.  Most
      functions previously performed by 'IWebInteraction' have moved to
      'IInteractionPolicy' or to 'peak.web.api' functions operating on
      'environ' mappings.

    * Web exceptions can define a 'levelName' attribute that determines the
      severity level with which the exception will be logged.  This allows
      one to e.g. avoid logging tracebacks for 'NotFound' errors.

    * Various interface calling signatures have changed slightly.  For example,
      'IAuthService.getUser()' now accepts an 'environ' mapping instead of
      an interaction.  'IInteractionPolicy.newInteraction()' now takes keyword
      arguments, but not a 'request'.  The 'IWebTraversable' interface no longer
      has a 'getObject()' method, and the 'IWebException.handleException()'
      method signature has changed as well.  Finally, all methods that
      previously accepted 'ITraversalContext' (such as
      'IDOMletState.renderFor()') now expect 'environ' mappings.

    * 'web.TestInteraction' was replaced with 'web.TestPolicy', and
      'web.Interaction' was removed, since 'IWebInteraction' is no longer part
      of the architecture.

 - The 'log()' method of PEAK loggers ('logs.ILogger') now accepts a level name
   *or* a number, for convenient invocation.

 - SQL transaction semantics have changed.  Now, issuing an SQL statement
   *always* causes the connection to join the active PEAK transaction, even if
   you request that the SQL be issued "outside" a transaction.  Such SQL will
   be issued outside of the *database* transaction, but not outside of the
   PEAK transaction.  This simplifies the overall processing model for dealing
   with "untransacted" SQL such as Sybase DDL or read-only Oracle transactions.
   (In particular, the requirement that triggered this change was to allow
   Oracle read-only transactions to be released at the end of the current PEAK
   transaction.)  Also, got rid of the now-meaningless 'begin' command in n2.

 - The 'events.IEventSource' interface now returns a 'canceller' function from
   the 'addCallback()' method, allowing you to cancel a previously-scheduled
   callback.  This fixes a memory leak and performance problem with
   'events.AnyOf()', which previously could accumulate unneeded callbacks on
   the sources it was monitoring.  Note that if you have developed any custom
   event sources with 'addCallback()' methods, you must make sure that they
   return a canceller from now on.

 - Added 'ref:factory@addr1||addr2' URL scheme that maps to a corresponding
   'naming.Reference("factory",["addr1","addr2"])'.  'factory' can be either a
   dotted import string referencing a 'naming.IObjectFactory', or you can
   define a factory in the 'peak.naming.factories' property space.

 - Added a 'zconfig.schema' factory, so that 'ref:zconfig.schema@streamURL'
   will load a schema loader.  Schema loaders are themselves object factories,
   so you can do something like:

     [Named Services]
     peak.naming.factories.myschema = \
         naming.LinkRef('ref:zconfig.schema@pkgfile:mypkg/Schema.xml')

   in order to make URLs like 'ref:myschema@filename' work.  Note, by the way,
   that the above could also read:

     [Named Services]
     peak.naming.factories.myschema = \
         naming.Reference('zconfig.schema',['pkgfile:mypkg/Schema.xml'])

   which runs somewhat faster at lookup time.  Similarly, one can also use
   'naming.Reference("myschema",["somefile"])' in place of a
   'naming.LinkRef("ref:myschema@filename")'.  As well as being faster, for
   some use cases it's easier to 'Reference' directly than to glue together
   a 'ref:' URL string.



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