Source Code for Module occi.workflow

  1  # coding=utf-8 
  2  # 
  3  # Copyright (C) 2010-2012 Platform Computing 
  4  # 
  5  # This library is free software; you can redistribute it and/or 
  6  # modify it under the terms of the GNU Lesser General Public 
  7  # License as published by the Free Software Foundation; either 
  8  # version 2.1 of the License, or (at your option) any later version. 
  9  # 
 10  # This library is distributed in the hope that it will be useful, 
 11  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
 12  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
 13  # Lesser General Public License for more details. 
 14  # 
 15  # You should have received a copy of the GNU Lesser General Public 
 16  # License along with this library; if not, write to the Free Software 
 17  # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA 
 18  # 
 19  ''' 
 20  Python module holding routines for handling resources and collections. 
 21   
 22  Created on Jun 30, 2011 
 23   
 24  @author: tmetsch 
 25  ''' 
 26   
 27  from occi.backend import UserDefinedMixinBackend 
 28  from occi.core_model import Resource, Link, Mixin 
 29  from occi.exceptions import HTTPError 
 30  import uuid 
 31   
 32  #============================================================================== 
 33  # Handling of Resources & Links 
 34  #============================================================================== 
 35   
 36   
 37 -def create_entity(key, entity, registry, extras): 
 38      ''' 
 39      Handles all the model magic during creation of an entity. 
 40   
 41      If it's an resource it will verify that all links are created. 
 42   
 43      If it's a link it will ensure that source and target are properly set. 
 44   
 45      key -- The key for the entity. 
 46      entity -- The entity itself - either Link or Resource instance. 
 47      registry -- The registry used for this process. 
 48      extras -- Any extra arguments which are defined by the user. 
 49      ''' 
 50      entity.identifier = key 
 51   
 52      # if it is an resource we create make sure we create the links properly 
 53      if isinstance(entity, Resource): 
 54          # if it's a resource - set/create links properly. 
 55          for link in entity.links: 
 56              # FUTURE_IMPROVEMENT: string links 
 57              if link.identifier is None: 
 58                  link.identifier = create_id(link.kind) 
 59              elif link.identifier in registry.get_resource_keys(extras): 
 60                  raise AttributeError('A link with that id is already present') 
 61   
 62              for back in registry.get_all_backends(link, extras): 
 63                  back.create(link, extras) 
 64   
 65              registry.add_resource(link.identifier, link, extras) 
 66      elif isinstance(entity, Link): 
 67          entity.source.links.append(entity) 
 68   
 69      # call all the backends who are associated with this entity.kind... 
 70      backends = registry.get_all_backends(entity, extras) 
 71      for backend in backends: 
 72          backend.create(entity, extras) 
 73   
 74      registry.add_resource(key, entity, extras) 
 75   
 76   
 77 -def delete_entity(entity, registry, extras): 
 78      ''' 
 79      Handles all the model magic during deletion if an entity. 
 80   
 81      If it's a link it will remove the link from the entity source links list. 
 82   
 83      entity -- The entity itself - either Link or Resource instance. 
 84      registry -- The registry used for this process. 
 85      extras -- Any extra arguments which are defined by the user. 
 86      ''' 
 87      if isinstance(entity, Resource): 
 88          # it's an resource - so delete all it's links 
 89          # FUTURE_IMPROVEMENT: string links 
 90          for link in entity.links: 
 91              for back in registry.get_all_backends(link, extras): 
 92                  back.delete(link, extras) 
 93              registry.delete_resource(link.identifier, extras) 
 94      elif isinstance(entity, Link): 
 95          entity.source.links.remove(entity) 
 96   
 97      # call all the backends who are associated with this entity.kind... 
 98      backends = registry.get_all_backends(entity, extras) 
 99   
100      for backend in backends: 
101          backend.delete(entity, extras) 
102   
103      registry.delete_resource(entity.identifier, extras) 
104   
105   
106 -def replace_entity(old, new, registry, extras): 
107      ''' 
108      Replace an entity - backends decide what is done. 
109   
110      If it's a link the entities must be replaced. 
111   
112      old -- The old entity. 
113      new -- The new entity. 
114      registry -- The registry used for this process. 
115      extras -- Any extra arguments which are defined by the user. 
116      ''' 
117      if isinstance(new, Resource) and len(new.links) is not 0: 
118          raise HTTPError(400, 'It is not recommend to have links in a full' + 
119                          ' update request') 
120   
121      if new.kind is not old.kind: 
122          raise AttributeError('It is not possible to change the kind of an' + 
123                               ' entity.') 
124   
125      # call all the backends who are associated with this entity.kind... 
126      backends = registry.get_all_backends(old, extras) 
127      new_backends = registry.get_all_backends(new, extras) 
128      for backend in backends: 
129          backend.replace(old, new, extras) 
130      for backend in unique(new_backends, backends): 
131          backend.create(new, extras) 
132      for backend in unique(backends, new_backends): 
133          backend.delete(old, extras) 
134      del new 
135   
136   
137 -def update_entity(old, new, registry, extras): 
138      ''' 
139      Update an entity - backends decide what is done. 
140   
141      If it's a link the entities must be updated. 
142   
143      old -- The old entity. 
144      new -- The new entity. 
145      registry -- The registry used for this process. 
146      extras -- Any extra arguments which are defined by the user. 
147      ''' 
148      if isinstance(new, Resource) and len(new.links) is not 0: 
149          raise HTTPError(400, 'It is not recommend to have links in a full' + 
150                          ' update request') 
151   
152      # call all the backends who are associated with this entity.kind... 
153      backends = registry.get_all_backends(old, extras) 
154      new_backends = registry.get_all_backends(new, extras) 
155      for backend in backends: 
156          backend.update(old, new, extras) 
157      for backend in unique(new_backends, backends): 
158          # for added mixins called create! 
159          backend.create(old, extras) 
160   
161      del new 
162   
163   
164 -def retrieve_entity(entity, registry, extras): 
165      ''' 
166      Retrieves/refreshed an entity. 
167   
168      If it's a link the entities must be retrieved/refreshed. 
169   
170      entity -- The entity which is to be retrieved. 
171      registry -- The registry used for this process. 
172      extras -- Any extra arguments which are defined by the user. 
173      ''' 
174      if isinstance(entity, Resource): 
175          # if it's a resource - retrieve all links... 
176          for link in entity.links: 
177              # FUTURE_IMPROVEMENT: string links 
178              for back in registry.get_all_backends(link, extras): 
179                  back.retrieve(link, extras) 
180   
181      # call all the backends who are associated with this entity.kind... 
182      backends = registry.get_all_backends(entity, extras) 
183      for backend in backends: 
184          backend.retrieve(entity, extras) 
185   
186   
187 -def action_entity(entity, action, registry, attributes, extras): 
188      ''' 
189      Performs an action on the entity. 
190   
191      entity -- The entity on which to perform the operation. 
192      action -- The action definition. 
193      registry -- The registry used for this process. 
194      attributes -- The attributes fro the operation. 
195      extras -- Any extra arguments which are defined by the user. 
196      ''' 
197      backend = registry.get_backend(action, extras) 
198      backend.action(entity, action, attributes, extras) 
199   
200  #============================================================================== 
201  # Collections 
202  #============================================================================== 
203   
204   
205 -def update_collection(mixin, old_entities, new_entities, registry, extras): 
206      ''' 
207      Updates a Collection of Mixin. If not present in the current collections 
208      entities will be added to the collection (aka. assigned the Mixin). 
209   
210      mixin -- The mixin which defines the collection. 
211      old_entities -- The entities which are in the collection to date. 
212      new_entities -- The entities which should be added to the collection. 
213      registry -- The registry used for this process. 
214      extras -- Any extra arguments which are defined by the user. 
215      ''' 
216      if not isinstance(mixin, Mixin): 
217          raise AttributeError('This operation is only supported on Collections' 
218                               + ' of Mixins.') 
219      for entity in unique(new_entities, old_entities): 
220          entity.mixins.append(mixin) 
221          backend = registry.get_backend(mixin, extras) 
222          backend.create(entity, extras) 
223      del new_entities 
224   
225   
226 -def replace_collection(mixin, old_entities, new_entities, registry, extras): 
227      ''' 
228      Replaces a Collection of Mixin. If not present in the current collections 
229      entities will be added to the collection (aka. assigned the Mixin). If old 
230      entities are not present in the new collection the mixin will be removed 
231      from them. 
232   
233      mixin -- The mixin which defines the collection. 
234      old_entities -- The entities which are in the collection to date. 
235      new_entities -- The new collection of entities. 
236      registry -- The registry used for this process. 
237      extras -- Any extra arguments which are defined by the user. 
238      ''' 
239      if not isinstance(mixin, Mixin): 
240          raise AttributeError('This operation is only supported on Collections' 
241                               + ' of Mixins.') 
242      for entity in unique(new_entities, old_entities): 
243          entity.mixins.append(mixin) 
244          backend = registry.get_backend(mixin, extras) 
245          backend.create(entity, extras) 
246      for entity in unique(old_entities, new_entities): 
247          backend = registry.get_backend(mixin, extras) 
248          backend.delete(entity, extras) 
249          entity.mixins.remove(mixin) 
250      del new_entities 
251   
252   
253 -def delete_from_collection(mixin, entities, registry, extras): 
254      ''' 
255      Removes entities from a collection by removing the mixin from their list. 
256   
257      mixin -- The mixin which defines the collection. 
258      entities -- The entities which are to be removed. 
259      registry -- The registry used for this process. 
260      extras -- Any extra arguments which are defined by the user. 
261      ''' 
262      if not isinstance(mixin, Mixin): 
263          raise AttributeError('This operation is only supported on Collections' 
264                               + ' of Mixins.') 
265   
266      for entity in intersect(entities, registry.get_resources(extras)): 
267          backend = registry.get_backend(mixin, extras) 
268          backend.delete(entity, extras) 
269          entity.mixins.remove(mixin) 
270   
271   
272 -def get_entities_under_path(path, registry, extras): 
273      ''' 
274      Return all entities which fall under a path. 
275   
276      If the path is in locations return all entities of the kind which defines 
277      the location. 
278   
279      If the path is just a path return all children. 
280   
281      path -- The path under which to look... 
282      registry -- The registry used for this process. 
283      extras -- Any extra arguments which are defined by the user. 
284      ''' 
285      result = [] 
286      if registry.get_category(path, extras) is None: 
287          for res in registry.get_resources(extras): 
288              if not res.identifier.find(path): 
289                  result.append(res) 
290          return result 
291      else: 
292          cat = registry.get_category(path, extras) 
293          for res in registry.get_resources(extras): 
294              if cat == res.kind or cat in res.mixins: 
295                  result.append(res) 
296          return result 
297   
298   
299 -def filter_entities(entities, categories, attributes): 
300      ''' 
301      Filters a set of entities and return those who match the given categories 
302      and attributes. 
303   
304      entities -- The entities which are to be filtered. 
305      categories -- Categories which must be present in the entity. 
306      attributes -- Attributes which must match with the entity's attrs. 
307      ''' 
308      result = [] 
309      if len(categories) == 0 and len(attributes.keys()) == 0: 
310          return entities 
311   
312      for entity in entities: 
313          indy = 0 
314          if entity.kind in categories: 
315              indy += 1 
316          if len(intersect(categories, entity.mixins)): 
317              indy += 1 
318          for attr in intersect(attributes.keys(), entity.attributes.keys()): 
319              if entity.attributes[attr] == attributes[attr]: 
320                  indy += 3 
321   
322          if len(categories) > 0 and len(attributes.keys()) == 0 and indy >= 1: 
323              result.append(entity) 
324          elif len(categories) == 0 and len(attributes.keys()) > 0 and indy == 3: 
325              result.append(entity) 
326          elif len(categories) > 0 and len(attributes.keys()) > 0 and indy >= 4: 
327              result.append(entity) 
328   
329      return result 
330   
331  #============================================================================== 
332  # Query Interface 
333  #============================================================================== 
334   
335   
336 -def filter_categories(categories, registry, extras): 
337      ''' 
338      Filter the categories. Only those requested should be added to the 
339      resulting list. 
340   
341      categories -- The list of categories to filter against. 
342      registry -- The registry used for this process. 
343      extras -- Passed on extra object. 
344      ''' 
345      if not len(categories): 
346          return registry.get_categories(extras) 
347   
348      result = [] 
349      for cat in registry.get_categories(extras): 
350          if cat in categories: 
351              result.append(cat) 
352      return result 
353   
354   
355 -def append_mixins(mixins, registry, extras): 
356      ''' 
357      Add a mixin to the service. 
358   
359      mixins -- The mixins which are to be added. 
360      registry -- The registry used for this process. 
361      extras -- Passed on extra object. 
362      ''' 
363      for mixin in mixins: 
364          if not isinstance(mixin, Mixin): 
365              raise AttributeError('Needs to be of type Mixin.') 
366          if registry.get_category(mixin.location, extras): 
367              raise AttributeError('Location overlaps with existing one.') 
368   
369          try: 
370              registry.get_backend(mixin, extras) 
371          except AttributeError: 
372              pass 
373          else: 
374              raise AttributeError('Category with same term, scheme already' + 
375                                   ' exists.') 
376   
377          registry.set_backend(mixin, UserDefinedMixinBackend(), extras) 
378   
379   
380 -def remove_mixins(mixins, registry, extras): 
381      ''' 
382      Remove a mixin from the service. 
383   
384      mixins -- The mixin which are to be removed. 
385      registry -- The registry used for this process. 
386      extras -- Any extra arguments which are defined by the user. 
387      ''' 
388      for mixin in mixins: 
389          if not isinstance(mixin, Mixin): 
390              raise AttributeError('Needs to be of type Mixin.') 
391   
392          try: 
393              backend = registry.get_backend(mixin, extras) 
394          except AttributeError: 
395              raise HTTPError(400, 'This Mixin is not registered!') 
396   
397          if not isinstance(backend, UserDefinedMixinBackend): 
398              raise HTTPError(403, 'This Mixin cannot be deleted!') 
399   
400          entities = get_entities_under_path(mixin.location, registry, extras) 
401          for entity in entities: 
402              entity.mixins.remove(mixin) 
403          registry.delete_mixin(mixin, extras) 
404          del mixin 
405   
406  #============================================================================== 
407  # Convenient stuff 
408  #============================================================================== 
409   
410   
411 -def create_id(kind): 
412      ''' 
413      Create a key with the hierarchy of the entity encapsulated. 
414   
415      kind -- The kind which this id should be created for. 
416      ''' 
417      key = kind.location + str(uuid.uuid4()) 
418      return key 
419   
420   
421 -def intersect(list_a, list_b): 
422      ''' 
423      Returns the intersection of two lists. 
424   
425      list_a -- The first list. 
426      list_b -- Another list. 
427      ''' 
428      if len(list_a) > 0 and len(list_b) > 0: 
429          return list(set(list_a) & set(list_b)) 
430      else: 
431          return list() 
432   
433   
434 -def unique(list_a, list_b): 
435      ''' 
436      Returns a list of elements which are only in list_a. 
437   
438      list_a -- The list to look into for unique elements. 
439      list_b -- Ths list the verify against. 
440      ''' 
441      return [item for item in list_a if item not in list_b] 
442