org.apache.ignite.internal.portable.api

Interface IgnitePortables

All Known Implementing Classes:

IgnitePortablesImpl

public interface IgnitePortables

Defines portable objects functionality. With portable objects you are able to:

• Seamlessly interoperate between Java, .NET, and C++.
• Make any object portable with zero code change to your existing code.
• Nest portable objects within each other.
• Automatically handle circular or null references.
• Automatically convert collections and maps between Java, .NET, and C++.
• Optionally avoid deserialization of objects on the server side (objects are stored in PortableObject format).
• Avoid need to have concrete class definitions on the server side.
• Dynamically change structure of the classes without having to restart the cluster.
• Index into portable objects for querying purposes.

Working With Portables Directly

Once an object is defined as portable, Ignite will always store it in memory in the portable (i.e. binary) format. User can choose to work either with the portable format or with the deserialized form (assuming that class definitions are present in the classpath).

To work with the portable format directly, user should create a special cache projection using IgniteCache.withKeepPortable() method and then retrieve individual fields as needed:

 IgniteCache<PortableObject, PortableObject> prj = cache.withKeepPortable();

 // Convert instance of MyKey to portable format.
 // We could also use PortableBuilder to create the key in portable format directly.
 PortableObject key = grid.portables().toPortable(new MyKey());

 PortableObject val = prj.get(key);

 String field = val.field("myFieldName");
 

Alternatively, if we have class definitions in the classpath, we may choose to work with deserialized typed objects at all times. In this case we do incur the deserialization cost. However, if PortableMarshaller.isKeepDeserialized() is true then Ignite will only deserialize on the first access and will cache the deserialized object, so it does not have to be deserialized again:

 IgniteCache<MyKey.class, MyValue.class> cache = grid.cache(null);

 MyValue val = cache.get(new MyKey());

 // Normal java getter.
 String fieldVal = val.getMyFieldName();
 

If we used, for example, one of the automatically handled portable types for a key, like integer, and still wanted to work with binary portable format for values, then we would declare cache projection as follows:

 IgniteCache<Integer.class, PortableObject> prj = cache.withKeepPortable();
 

Automatic Portable Types

Note that only portable classes are converted to PortableObject format. Following classes are never converted (e.g., toPortable(Object) method will return original object, and instances of these classes will be stored in cache without changes):

• All primitives (byte, int, ...) and there boxed versions (Byte, Integer, ...)
• Arrays of primitives (byte[], int[], ...)
• String and array of Strings
• UUID and array of UUIDs
• Date and array of Dates
• Timestamp and array of Timestamps
• Enums and array of enums
• Maps, collections and array of objects (but objects inside them will still be converted if they are portable)

Working With Maps and Collections

All maps and collections in the portable objects are serialized automatically. When working with different platforms, e.g. C++ or .NET, Ignite will automatically pick the most adequate collection or map in either language. For example, ArrayList in Java will become List in C#, LinkedList in Java is LinkedList in C#, HashMap in Java is Dictionary in C#, and TreeMap in Java becomes SortedDictionary in C#, etc.

Building Portable Objects

Ignite comes with PortableBuilder which allows to build portable objects dynamically:

 PortableBuilder builder = Ignition.ignite().portables().builder();

 builder.typeId("MyObject");

 builder.stringField("fieldA", "A");
 build.intField("fieldB", "B");

 PortableObject portableObj = builder.build();
 

For the cases when class definition is present in the class path, it is also possible to populate a standard POJO and then convert it to portable format, like so:

 MyObject obj = new MyObject();

 obj.setFieldA("A");
 obj.setFieldB(123);

 PortableObject portableObj = Ignition.ignite().portables().toPortable(obj);
 

NOTE: you don't need to convert typed objects to portable format before storing them in cache, Ignite will do that automatically.

Portable Metadata

Even though Ignite portable protocol only works with hash codes for type and field names to achieve better performance, Ignite provides metadata for all portable types which can be queried ar runtime via any of the metadata(Class) methods. Having metadata also allows for proper formatting of PortableObject#toString() method, even when portable objects are kept in binary format only, which may be necessary for audit reasons.

Dynamic Structure Changes

Since objects are always cached in the portable binary format, server does not need to be aware of the class definitions. Moreover, if class definitions are not present or not used on the server, then clients can continuously change the structure of the portable objects without having to restart the cluster. For example, if one client stores a certain class with fields A and B, and another client stores the same class with fields B and C, then the server-side portable object will have the fields A, B, and C. As the structure of a portable object changes, the new fields become available for SQL queries automatically.

Configuration

By default all your objects are considered as portables and no specific configuration is needed. However, in some cases, like when an object is used by both Java and .Net, you may need to specify portable objects explicitly by calling PortableMarshaller.setClassNames(Collection). The only requirement Ignite imposes is that your object has an empty constructor. Note, that since server side does not have to know the class definition, you only need to list portable objects in configuration on the client side. However, if you list them on the server side as well, then you get the ability to deserialize portable objects into concrete types on the server as well as on the client.

Here is an example of portable configuration (note that star (*) notation is supported):

 ...
 <!-- Explicit portable objects configuration. -->
 <property name="marshaller">
     <bean class="org.apache.ignite.internal.portable.api.PortableMarshaller">
         <property name="classNames">
             <list>
                 <value>my.package.for.portable.objects.*</value>
                 <value>org.apache.ignite.examples.client.portable.Employee</value>
             </list>
         </property>
     </bean>
 </property>
 ...
 

or from code:

 IgniteConfiguration cfg = new IgniteConfiguration();

 PortableMarshaller marsh = new PortableMarshaller();

 marsh.setClassNames(Arrays.asList(
     Employee.class.getName(),
     Address.class.getName())
 );

 cfg.setMarshaller(marsh);
 

You can also specify class name for a portable object via PortableTypeConfiguration. Do it in case if you need to override other configuration properties on per-type level, like ID-mapper, or serializer.

Custom Affinity Keys

Often you need to specify an alternate key (not the cache key) for affinity routing whenever storing objects in cache. For example, if you are caching Employee object with Organization, and want to colocate employees with organization they work for, so you can process them together, you need to specify an alternate affinity key. With portable objects you would have to do it as following:

 <property name="marshaller">
     <bean class="org.gridgain.grid.marshaller.portable.PortableMarshaller">
         ...
         <property name="typeConfigurations">
             <list>
                 <bean class="org.apache.ignite.internal.portable.api.PortableTypeConfiguration">
                     <property name="className" value="org.apache.ignite.examples.client.portable.EmployeeKey"/>
                     <property name="affinityKeyFieldName" value="organizationId"/>
                 </bean>
             </list>
         </property>
         ...
     </bean>
 </property>
 

Serialization

Serialization and deserialization works out-of-the-box in Ignite. However, you can provide your own custom serialization logic by optionally implementing PortableMarshalAware interface, like so:

 public class Address implements PortableMarshalAware {
     private String street;
     private int zip;

     // Empty constructor required for portable deserialization.
     public Address() {}

     @Override public void writePortable(PortableWriter writer) throws PortableException {
         writer.writeString("street", street);
         writer.writeInt("zip", zip);
     }

     @Override public void readPortable(PortableReader reader) throws PortableException {
         street = reader.readString("street");
         zip = reader.readInt("zip");
     }
 }
 

Alternatively, if you cannot change class definitions, you can provide custom serialization logic in PortableSerializer either globally in PortableMarshaller or for a specific type via PortableTypeConfiguration instance.

Similar to java serialization you can use writeReplace() and readResolve() methods.

• readResolve is defined as follows: ANY-ACCESS-MODIFIER Object readResolve(). It may be used to replace the de-serialized object by another one of your choice.
• writeReplace is defined as follows: ANY-ACCESS-MODIFIER Object writeReplace(). This method allows the developer to provide a replacement object that will be serialized instead of the original one.

Custom ID Mappers

Ignite implementation uses name hash codes to generate IDs for class names or field names internally. However, in cases when you want to provide your own ID mapping schema, you can provide your own PortableIdMapper implementation.

ID-mapper may be provided either globally in PortableMarshaller, or for a specific type via PortableTypeConfiguration instance.

Query Indexing

Portable objects can be indexed for querying by specifying index fields in CacheTypeMetadata inside of specific CacheConfiguration instance, like so:

 ...
 <bean class="org.apache.ignite.cache.CacheConfiguration">
     ...
     <property name="typeMetadata">
         <list>
             <bean class="CacheTypeMetadata">
                 <property name="type" value="Employee"/>

                 <!-- Fields to index in ascending order. -->
                 <property name="ascendingFields">
                     <map>
                     <entry key="name" value="java.lang.String"/>

                         <!-- Nested portable objects can also be indexed. -->
                         <entry key="address.zip" value="java.lang.Integer"/>
                     </map>
                 </property>
             </bean>
         </list>
     </property>
 </bean>
 

Method Summary

Methods

Modifier and Type	Method and Description
PortableBuilder	builder(int typeId) Creates new portable builder.
PortableBuilder	builder(PortableObject portableObj) Creates portable builder initialized by existing portable object.
PortableBuilder	builder(String typeName) Creates new portable builder.
Collection<PortableMetadata>	metadata() Gets metadata for all known types.
PortableMetadata	metadata(Class<?> cls) Gets metadata for provided class.
PortableMetadata	metadata(int typeId) Gets metadata for provided type ID.
PortableMetadata	metadata(String typeName) Gets metadata for provided class name.
<T> T	toPortable(Object obj) Converts provided object to instance of PortableObject.
int	typeId(String typeName) Gets type ID for given type name.

Method Detail

typeId

int typeId(String typeName)

Gets type ID for given type name.

Parameters:

typeName - Type name.

Returns:

Type ID.

toPortable

<T> T toPortable(@Nullable
               Object obj)
             throws PortableException

Converts provided object to instance of PortableObject.

Parameters:

obj - Object to convert.

Returns:

Converted object.

Throws:

PortableException - In case of error.

builder

PortableBuilder builder(int typeId)

Creates new portable builder.

Parameters:

typeId - ID of the type.

Returns:

Newly portable builder.

builder

PortableBuilder builder(String typeName)

Creates new portable builder.

Parameters:

typeName - Type name.

Returns:

Newly portable builder.

builder

PortableBuilder builder(PortableObject portableObj)

Creates portable builder initialized by existing portable object.

Parameters:

portableObj - Portable object to initialize builder.

Returns:

Portable builder.

metadata

@Nullable
PortableMetadata metadata(Class<?> cls)
                          throws PortableException

Gets metadata for provided class.

Parameters:

cls - Class.

Returns:

Metadata.

Throws:

PortableException - In case of error.

metadata

@Nullable
PortableMetadata metadata(String typeName)
                          throws PortableException

Gets metadata for provided class name.

Parameters:

typeName - Type name.

Returns:

Metadata.

Throws:

PortableException - In case of error.

metadata

@Nullable
PortableMetadata metadata(int typeId)
                          throws PortableException

Gets metadata for provided type ID.

Parameters:

typeId - Type ID.

Returns:

Metadata.

Throws:

PortableException - In case of error.

metadata

Collection<PortableMetadata> metadata()
                                      throws PortableException

Gets metadata for all known types.

Returns:

Metadata.

Throws:

PortableException - In case of error.