Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like BaseService often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use BaseService, and based on these observations, apply Extract Interface, too.
1 | <?php |
||
54 | abstract class BaseService implements IRequestHandler, IService |
||
55 | { |
||
56 | /** |
||
57 | * The wrapper over IQueryProvider and IMetadataProvider implementations. |
||
58 | * |
||
59 | * @var ProvidersWrapper |
||
60 | */ |
||
61 | private $providersWrapper; |
||
62 | |||
63 | /** |
||
64 | * The wrapper over IStreamProvider implementation |
||
65 | * |
||
66 | * @var StreamProviderWrapper |
||
67 | */ |
||
68 | private $_streamProvider; |
||
69 | |||
70 | /** |
||
71 | * Hold reference to the ServiceHost instance created by dispatcher, |
||
72 | * using this library can access headers and body of Http Request |
||
73 | * dispatcher received and the Http Response Dispatcher is going to send. |
||
74 | * |
||
75 | * @var ServiceHost |
||
76 | */ |
||
77 | private $_serviceHost; |
||
78 | |||
79 | |||
80 | /** |
||
81 | * To hold reference to ServiceConfiguration instance where the |
||
82 | * service specific rules (page limit, resource set access rights |
||
83 | * etc...) are defined. |
||
84 | * |
||
85 | * @var ServiceConfiguration |
||
86 | */ |
||
87 | private $config; |
||
88 | |||
89 | /** |
||
90 | * Gets reference to ServiceConfiguration instance so that |
||
91 | * service specific rules defined by the developer can be |
||
92 | * accessed. |
||
93 | * |
||
94 | * @return ServiceConfiguration |
||
95 | */ |
||
96 | public function getConfiguration() |
||
100 | |||
101 | |||
102 | //TODO: shouldn't we hide this from the interface..if we need it at all. |
||
103 | /** |
||
104 | * Get the wrapper over developer's IQueryProvider and IMetadataProvider implementation. |
||
105 | * |
||
106 | * @return ProvidersWrapper |
||
107 | */ |
||
108 | public function getProvidersWrapper() |
||
112 | |||
113 | /** |
||
114 | * Gets reference to wrapper class instance over IDSSP implementation |
||
115 | * |
||
116 | * @return StreamProviderWrapper |
||
117 | */ |
||
118 | public function getStreamProviderWrapper() |
||
122 | |||
123 | /** |
||
124 | * Get reference to the data service host instance. |
||
125 | * |
||
126 | * @return ServiceHost |
||
127 | */ |
||
128 | public function getHost() |
||
132 | |||
133 | /** |
||
134 | * Sets the data service host instance. |
||
135 | * |
||
136 | * @param ServiceHost $serviceHost The data service host instance. |
||
137 | * |
||
138 | * @return void |
||
139 | */ |
||
140 | public function setHost(ServiceHost $serviceHost) |
||
144 | |||
145 | /** |
||
146 | * To get reference to operation context where we have direct access to |
||
147 | * headers and body of Http Request we have received and the Http Response |
||
148 | * We are going to send. |
||
149 | * |
||
150 | * @return IOperationContext |
||
151 | */ |
||
152 | public function getOperationContext() |
||
156 | |||
157 | /** |
||
158 | * Get reference to the wrapper over IStreamProvider or |
||
159 | * IStreamProvider2 implementations. |
||
160 | * |
||
161 | * @return StreamProviderWrapper |
||
162 | */ |
||
163 | public function getStreamProvider() |
||
172 | |||
173 | /** |
||
174 | * Top-level handler invoked by Dispatcher against any request to this |
||
175 | * service. This method will hand over request processing task to other |
||
176 | * functions which process the request, set required headers and Response |
||
177 | * stream (if any in Atom/Json format) in |
||
178 | * WebOperationContext::Current()::OutgoingWebResponseContext. |
||
179 | * Once this function returns, dispatcher uses global WebOperationContext |
||
180 | * to write out the request response to client. |
||
181 | * This function will perform the following operations: |
||
182 | * (1) Check whether the top level service class implements |
||
183 | * IServiceProvider which means the service is a custom service, in |
||
184 | * this case make sure the top level service class implements |
||
185 | * IMetaDataProvider and IQueryProvider. |
||
186 | * These are the minimal interfaces that a custom service to be |
||
187 | * implemented in order to expose its data as OData. Save reference to |
||
188 | * These interface implementations. |
||
189 | * NOTE: Here we will ensure only providers for IDSQP and IDSMP. The |
||
190 | * IDSSP will be ensured only when there is an GET request on MLE/Named |
||
191 | * stream. |
||
192 | * |
||
193 | * (2). Invoke 'Initialize' method of top level service for |
||
194 | * collecting the configuration rules set by the developer for this |
||
195 | * service. |
||
196 | * |
||
197 | * (3). Invoke the Uri processor to process the request URI. The uri |
||
198 | * processor will do the following: |
||
199 | * (a). Validate the request uri syntax using OData uri rules |
||
200 | * (b). Validate the request using metadata of this service |
||
201 | * (c). Parse the request uri and using, IQueryProvider |
||
202 | * implementation, fetches the resources pointed by the uri |
||
203 | * if required |
||
204 | * (d). Build a RequestDescription which encapsulate everything |
||
205 | * related to request uri (e.g. type of resource, result |
||
206 | * etc...) |
||
207 | * (3). Invoke handleRequest2 for further processing |
||
208 | * |
||
209 | * @return void |
||
210 | */ |
||
211 | public function handleRequest() |
||
230 | |||
231 | /** |
||
232 | * @return IQueryProvider |
||
233 | */ |
||
234 | public abstract function getQueryProvider(); |
||
235 | |||
236 | /** |
||
237 | * @return IMetadataProvider |
||
238 | */ |
||
239 | public abstract function getMetadataProvider(); |
||
240 | |||
241 | /** |
||
242 | * @return \POData\Providers\Stream\IStreamProvider |
||
243 | */ |
||
244 | public abstract function getStreamProviderX(); |
||
245 | |||
246 | |||
247 | /** @var ODataWriterRegistry */ |
||
248 | private $writerRegistry; |
||
249 | |||
250 | /** |
||
251 | * Returns the ODataWriterRegistry to use when writing the response to a service document or resource request |
||
252 | * @return ODataWriterRegistry |
||
253 | */ |
||
254 | public function getODataWriterRegistry() |
||
258 | |||
259 | |||
260 | /** |
||
261 | * This method will query and validates for IMetadataProvider and IQueryProvider implementations, invokes |
||
262 | * BaseService::Initialize to initialize service specific policies. |
||
263 | * |
||
264 | * |
||
265 | * @throws ODataException |
||
266 | */ |
||
267 | protected function createProviders() |
||
307 | |||
308 | //TODO: i don't want this to be public..but it's the only way to test it right now... |
||
309 | public function registerWriters() |
||
329 | |||
330 | /** |
||
331 | * Serialize the requested resource. |
||
332 | * |
||
333 | * @param RequestDescription $request The description of the request submitted by the client. |
||
334 | * @param UriProcessor $uriProcessor Reference to the uri processor. |
||
335 | * |
||
336 | * @return void |
||
337 | */ |
||
338 | protected function serializeResult(RequestDescription $request, UriProcessor $uriProcessor) { |
||
494 | |||
495 | /** |
||
496 | * Gets the response format for the requested resource. |
||
497 | * |
||
498 | * @param RequestDescription $request The request submitted by client and it's execution result. |
||
499 | * @param UriProcessor $uriProcessor The reference to the UriProcessor. |
||
500 | * @param IService $service Reference to the service implementation instance |
||
501 | * |
||
502 | * @return string the response content-type, a null value means the requested resource |
||
503 | * is named stream and IDSSP2::getStreamContentType returned null |
||
504 | * |
||
505 | * @throws ODataException, HttpHeaderFailure |
||
506 | */ |
||
507 | public static function getResponseContentType( |
||
654 | |||
655 | |||
656 | |||
657 | /** |
||
658 | * For the given entry object compare it's eTag (if it has eTag properties) |
||
659 | * with current eTag request headers (if it present). |
||
660 | * |
||
661 | * @param mixed &$entryObject entity resource for which etag |
||
662 | * needs to be checked. |
||
663 | * @param ResourceType &$resourceType Resource type of the entry |
||
664 | * object. |
||
665 | * @param boolean &$needToSerializeResponse On return, this will contain |
||
666 | * True if response needs to be |
||
667 | * serialized, False otherwise. |
||
668 | * |
||
669 | * @return string|null The ETag for the entry object if it has eTag properties |
||
670 | * NULL otherwise. |
||
671 | */ |
||
672 | protected function compareETag(&$entryObject, ResourceType &$resourceType, |
||
751 | |||
752 | /** |
||
753 | * Returns the etag for the given resource. |
||
754 | * Note: This function will not add W\" prefix and " suffix, its callers |
||
755 | * repsonsability. |
||
756 | * |
||
757 | * @param mixed &$entryObject Resource for which etag value needs to |
||
758 | * be returned |
||
759 | * @param ResourceType &$resourceType Resource type of the $entryObject |
||
760 | * |
||
761 | * @return string|null ETag value for the given resource (with values encoded |
||
762 | * for use in a URI) there are etag properties, NULL if |
||
763 | * there is no etag property. |
||
764 | */ |
||
765 | protected function getETagForEntry(&$entryObject, ResourceType &$resourceType) |
||
807 | |||
808 | /** |
||
809 | * This function will perform the following operations: |
||
810 | * (1) Invoke delegateRequestProcessing method to process the request based |
||
811 | * on request method (GET, PUT/MERGE, POST, DELETE) |
||
812 | * (3) If the result of processing of request needs to be serialized as HTTP |
||
813 | * response body (e.g. GET request result in single resource or resource |
||
814 | * collection, successful POST operation for an entity need inserted |
||
815 | * entity to be serialized back etc..), Serialize the result by using |
||
816 | * 'serializeReultForResponseBody' method |
||
817 | * Set the serialized result to |
||
818 | * WebOperationContext::Current()::OutgoingWebResponseContext::Stream. |
||
819 | * |
||
820 | * @return void |
||
821 | */ |
||
822 | protected function handleRequest2() |
||
825 | |||
826 | /** |
||
827 | * This method will perform the following operations: |
||
828 | * (1) If request method is GET, then result is already there in the |
||
829 | * RequestDescription so simply return the RequestDescription |
||
830 | * (2). If request method is for CDU |
||
831 | * (Create/Delete/Update - POST/DELETE/PUT-MERGE) hand |
||
832 | * over the responsibility to respective handlers. The handler |
||
833 | * methods are: |
||
834 | * (a) handlePOSTOperation() => POST |
||
835 | * (b) handlePUTOperation() => PUT/MERGE |
||
836 | * (c) handleDELETEOperation() => DELETE |
||
837 | * (3). Check whether its required to write any result to the response |
||
838 | * body |
||
839 | * (a). Request method is GET |
||
840 | * (b). Request is a POST for adding NEW Entry |
||
841 | * (c). Request is a POST for adding Media Resource Stream |
||
842 | * (d). Request is a POST for adding a link |
||
843 | * (e). Request is a DELETE for deleting entry or relationship |
||
844 | * (f). Request is a PUT/MERGE for updating an entry |
||
845 | * (g). Request is a PUT for updating a link |
||
846 | * In case a, b and c we need to write the result to response body, |
||
847 | * for d, e, f and g no body content. |
||
848 | * |
||
849 | * @return RequestDescription|null Instance of RequestDescription with |
||
850 | * result to be write back Null if no result to write. |
||
851 | */ |
||
852 | protected function delegateRequestProcessing() |
||
855 | |||
856 | /** |
||
857 | * Serialize the result in the current request description using |
||
858 | * appropriate odata writer (AtomODataWriter/JSONODataWriter) |
||
859 | * |
||
860 | * @return void |
||
861 | * |
||
862 | */ |
||
863 | protected function serializeReultForResponseBody() |
||
866 | |||
867 | /** |
||
868 | * Handle POST request. |
||
869 | * |
||
870 | * @return void |
||
871 | * |
||
872 | * @throws NotImplementedException |
||
873 | */ |
||
874 | protected function handlePOSTOperation() |
||
877 | |||
878 | /** |
||
879 | * Handle PUT/MERGE request. |
||
880 | * |
||
881 | * @return void |
||
882 | * |
||
883 | * @throws NotImplementedException |
||
884 | */ |
||
885 | protected function handlePUTOperation() |
||
888 | |||
889 | /** |
||
890 | * Handle DELETE request. |
||
891 | * |
||
892 | * @return void |
||
893 | * |
||
894 | * @throws NotImplementedException |
||
895 | */ |
||
896 | protected function handleDELETEOperation() |
||
899 | |||
900 | /** |
||
901 | * Assert that the given condition is true. |
||
902 | * |
||
903 | * @param boolean $condition The condtion to check. |
||
904 | * @param string $conditionAsString Message to show if assertion fails. |
||
905 | * |
||
906 | * @return void |
||
907 | * |
||
908 | * @throws InvalidOperationException |
||
909 | */ |
||
910 | protected static function assert($condition, $conditionAsString) |
||
918 | } |