Andrew Cooke | Contents | Latest | RSS | Previous | Next

C[omp]ute

Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Choochoo Training Diary

Last 100 entries

[Programming] React Leaflet; AliExpress Independent Sellers; Applebaum - Twilight of Democracy; [Politics] Back + US Elections; [Programming,Exercise] Simple Timer Script; [News] 2019: The year revolt went global; [Politics] The world's most-surveilled cities; [Bike] Hope Freehub; [Restaurant] Mama Chau's (Chinese, Providencia); [Politics] Brexit Podcast; [Diary] Pneumonia; [Politics] Britain's Reichstag Fire moment; install cairo; [Programming] GCC Sanitizer Flags; [GPU, Programming] Per-Thread Program Counters; My Bike Accident - Looking Back One Year; [Python] Geographic heights are incredibly easy!; [Cooking] Cookie Recipe; Efficient, Simple, Directed Maximisation of Noisy Function; And for argparse; Bash Completion in Python; [Computing] Configuring Github Jekyll Locally; [Maths, Link] The Napkin Project; You can Masquerade in Firewalld; [Bike] Servicing Budget (Spring) Forks; [Crypto] CIA Internet Comms Failure; [Python] Cute Rate Limiting API; [Causality] Judea Pearl Lecture; [Security, Computing] Chinese Hardware Hack Of Supermicro Boards; SQLAlchemy Joined Table Inheritance and Delete Cascade; [Translation] The Club; [Computing] Super Potato Bruh; [Computing] Extending Jupyter; Further HRM Details; [Computing, Bike] Activities in ch2; [Books, Link] Modern Japanese Lit; What ended up there; [Link, Book] Logic Book; Update - Garmin Express / Connect; Garmin Forerunner 35 v 230; [Link, Politics, Internet] Government Trolls; [Link, Politics] Why identity politics benefits the right more than the left; SSH Forwarding; A Specification For Repeating Events; A Fight for the Soul of Science; [Science, Book, Link] Lost In Math; OpenSuse Leap 15 Network Fixes; Update; [Book] Galileo's Middle Finger; [Bike] Chinese Carbon Rims; [Bike] Servicing Shimano XT Front Hub HB-M8010; [Bike] Aliexpress Cycling Tops; [Computing] Change to ssh handling of multiple identities?; [Bike] Endura Hummvee Lite II; [Computing] Marble Based Logic; [Link, Politics] Sanity Check For Nuclear Launch; [Link, Science] Entropy and Life; [Link, Bike] Cheap Cycling Jerseys; [Link, Music] Music To Steal 2017; [Link, Future] Simulated Brain Drives Robot; [Link, Computing] Learned Index Structures; Solo Air Equalization; Update: Higher Pressures; Psychology; [Bike] Exercise And Fuel; Continental Race King 2.2; Removing Lowers; Mnesiacs; [Maths, Link] Dividing By Zero; [Book, Review] Ray Monk - Ludwig Wittgenstein: The Duty Of Genius; [Link, Bike, Computing] Evolving Lacing Patterns; [Jam] Strawberry and Orange Jam; [Chile, Privacy] Biometric Check During Mail Delivery; [Link, Chile, Spanish] Article on the Chilean Drought; [Bike] Extended Gear Ratios, Shimano XT M8000 (24/36 Chainring); [Link, Politics, USA] The Future Of American Democracy; Mass Hysteria; [Review, Books, Links] Kazuo Ishiguro - Never Let Me Go; [Link, Books] David Mitchell's Favourite Japanese Fiction; [Link, Bike] Rear Suspension Geometry; [Link, Cycling, Art] Strava Artwork; [Link, Computing] Useful gcc flags; [Link] Voynich Manuscript Decoded; [Bike] Notes on Servicing Suspension Forks; [Links, Computing] Snap, Flatpack, Appimage; [Link, Computing] Oracle is leaving Java (to die); [Link, Politics] Cubans + Ultrasonics; [Book, Link] Laurent Binet; VirtualBox; [Book, Link] No One's Ways; [Link] The Biggest Problem For Cyclists Is Bad Driving; [Computing] Doxygen, Sphinx, Breathe; [Admin] Brokw Recent Permalinks; [Bike, Chile] Buying Bearings in Santiago; [Computing, Opensuse] Upgrading to 42.3; [Link, Physics] First Support for a Physics Theory of Life; [Link, Bike] Peruvian Frame Maker; [Link] Awesome Game Theory Tit-For-Tat Thing; [Food, Review] La Fabbrica - Good Italian Food In Santiago; [Link, Programming] MySQL UTF8 Broken; [Link, Books] Latin American Authors

© 2006-2017 Andrew Cooke (site) / post authors (content).

Declarative Validation of XMLRPC Responses in Python

From: "andrew cooke" <andrew@...>

Date: Thu, 23 Oct 2008 09:17:10 -0300 (CLST)

This is a fairly nice bit of code I wrote yesterday.  I wanted to validate
XMLRPC responses against a specification.  What I finally ended up with
was code like:

GET_VALUES = Array(Struct(ObjectName=Type(basestring),
                          ObjectClass=Type(basestring))
                   .either(ParameterList=Array(Struct(
                                ParameterName=Type(basestring),
                                ParameterClass=Type(basestring),
                                ParameterValue=Type(basestring),
                                ParameterTime=Optional(Type(int)))))
                   .or_(ParameterName=Type(basestring),
                        ParameterClass=Type(basestring),
                        ParameterValue=Type(basestring),
                        ParameterTime=Optional(Type(int))))
GET_VALUES.validate(client.GetValues(...))

And this would check the response from the client to make sure that it
matched that give above (it checks that: all fields received are in the
spec; all non-optional fields are present; maps and lists and values have
the correct types; the general nested structure is correct).

Note that "ObjectName" and the like are the names used in the XML
response.  They are specified in the declaration above (and are not
hard-coded below).

For Python's standard XMLRPC libraries, "structs" are returned as dicts
and "arrays" are lists.  The code is below.  Apart from the either/or,
which is a bit specific to this particular application, it should be
useful in general.

Andrew

def limit(obj):
  '''
  Reduce text size.
  '''
  text = str(obj)
  if len(text) > 100:
    text = text[0:100] + '...'
  return text

class Type(object):
  '''
  Specification for a simple value.
  '''

  def __init__(self, type):
    self.__type = type

  def validate(self, value):
    '''
    Check type of value.
    '''
    if not isinstance(value, self.__type):
      raise Exception('%s not of type %s' %
                      (limit(value), self.__type))

class Optional(object):
  '''
  Specification for verifying an optional value - does
  nothing, but is detected by Struct.
  '''

  def __init__(self, delegate):
    self.__delegate = delegate

  def validate(self, value):
    '''
    Pass on to delegate.
    '''
    self.__delegate.validate(value)

class Array(Type):
  '''
  Specification for verifying an array of values.
  '''

  def __init__(self, value):
    super(Array, self).__init__(list)
    self.__value = value

  def validate(self, value):
    '''
    Pass each value to delegate.
    '''
    super(Array, self).validate(value)
    for entry in value:
      self.__value.validate(entry)

class Struct(Type):
  '''
  Specification for verifying a struct of values.
  '''

  def __init__(self, **map):
    super(Struct, self).__init__(dict)
    self.__map = map
    self.__either = {}
    self.__or = {}
    self.__choice = None

  def either(self, **choice):
    '''
    Add first of a choice of two maps (chained)
    '''
    self.__either = choice
    return self

  def or_(self, **choice):
    '''
    Add second a choice of two maps
    '''
    self.__or = choice
    return self

  def validate(self, value):
    '''
    Check all entries.
    '''
    super(Struct, self).validate(value)
    self.__choice = None
    for name in value:
      if not self.__validate_choice(name, value[name]):
        if name not in self.__map:
          raise Exception('%s has unexpected content %s' %
                  (limit(value), name))
        else:
          self.__map[name].validate(value[name])
    for name in self.__map:
      if name not in value and \
          not isinstance(self.__map[name], Optional):
        raise Exception('%s is missing %s' %
                        (limit(value), name))
    if self.__choice is None and \
        (self.__either or self.__or):
      raise Exception('%s did not select either choice %s/%s'
              % (limit(value),
                 self.__either.keys(), self.__or.keys()))
    if self.__choice:
      for name in self.__choice:
        if name not in value and \
            not isinstance(self.__choice[name], Optional):
          raise Exception('%s is missing %s' %
                          (limit(value), name))

  def __validate_choice(self, name, value):
    '''
    Check choices
    '''
    # resolve choice once
    if self.__choice is None:
      if name in self.__either:
        self.__choice = self.__either
      elif name in self.__or:
        self.__choice = self.__or
    # check against resolved choice
    if self.__choice is not None:
      if name in self.__choice:
        self.__choice[name].validate(value)
        return True
    return False

Comment on this post