| --- |
| title: Serialize Your Domain Objects with PdxSerializer and PdxWrapper |
| --- |
| |
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| |
| For domain objects that you cannot or do not want to modify, use the `PdxSerializer` and the `PdxWrapper` classes to serialize and deserialize the object's fields. |
| |
| You register a `PdxSerializer` implementation for the entire cache, programming it for all of the domain objects that you handle in this way. This way you do not have to implement the `PdxSerializable` interface for each domain class. |
| |
| The `PdxSerializer` allows domain classes to be serialized and deserialized as PDXs without modification of the domain class. It requires only that the domain class have a constructor accessible to the `PdxSerializer` to create an instance. The domain class will be held in a wrapper class, `PdxWrapper`. |
| |
| `PdxSerializer` has the following methods: |
| |
| - The `toData` method returns true if the PdxSerializer was able to serialize the user object, false if not. |
| - If the PdxSerializer was able to deserialize the object, the `fromData` method returns a void pointer to the user object to be wrapped in a `PdxWrapper`. |
| |
| When you later reference the user object, use the `PdxWrapper` class. `PdxWrapper` holds a shared reference to the object in the local cache and is used during serialization and deserialization. `PdxWrapper` acts as a container for the user domain object and needs to wrap every instance of the object that uses a registered `PdxSerializer`. The object instance will not be modified. In addition, when using `PdxWrapper`, you will need to provide a function pointer to a "deallocator", which will delete the user object when the reference is no longer held. |
| |
| The following code example defines a user object and a `PdxSerializer`. It then registers the new `PdxSerializer` and then uses `PdxWrapper` to put the object in a region and retrieve the object from a region. |
| |
| ``` pre |
| class UserClass |
| { |
| public: |
| |
| int m_int; |
| string m_string; |
| |
| UserClass(int intVal, string stringVal) |
| { |
| m_int = intVal; |
| m_string = stringVal; |
| } |
| |
| static void deallocate(void * object, char * className) |
| { |
| if (strcmp(className, "com.example.UserClass") == 0) { |
| UserClass * userObject = reinterpret_cast<UserClass*>(object); |
| delete userObject; |
| } |
| } |
| }; |
| |
| class UserPdxSerializer : public PdxSerializer |
| { |
| public: |
| |
| void* fromData(char * className, PdxReaderPtr pdxReader) |
| { |
| if (strcmp(className, "com.example.UserClass") != 0) { |
| return NULL; |
| } |
| |
| int intVal = pdxReader->readInt("m_int"); |
| string stringVal = pdxReader->readString("m_string"); |
| |
| UserClass * userObject = new UserClass(intVal, stringVal); |
| |
| return (void*) userObject; |
| } |
| |
| bool toData(void * object, char * className, PdxWriterPtr pdxWriter) |
| { |
| if (strcmp(className, "com.example.UserClass") != 0) { |
| return false; |
| } |
| |
| UserClass * userObject = reinterpret_cast<UserClass*>(object); |
| |
| pdxWriter->writeInt("m_int", userObject->m_int); |
| pdxWriter->writeString("m_string", userObject->m_string); |
| |
| return true; |
| } |
| |
| UserDeallocator getDeallocator(char * className) |
| { |
| if (strcmp(className, "com.example.UserClass") == 0) { |
| return UserClass::deallocate; |
| } else { |
| return NULL; |
| } |
| } |
| }; |
| |
| // Register a user PDX serializer |
| |
| Serializable::registerPdxSerializer(new UserPdxSerializer); |
| |
| // Put a user object into a region. |
| |
| UserClass * userObject = new UserClass(123, "someValue"); |
| PdxWrapperPtr pdxWrapper = new PdxWrapper(userObject, "com.example.UserClass", |
| UserClass::deallocate); |
| region->put("key", pdxWrapper); |
| |
| // Get a user object from a region. |
| |
| pdxWrapper = dynCast<PdxWrapperPtr>(region->get("key")); |
| UserClass * userObject = reinterpret_cast<UserClass*>(pdxWrapper->getObject()); |
| ``` |
| |
| |