---
title:  Generic and Custom Serializable Types
---

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All built-in generics are automatically registered at initialization. You have a couple of options for complex key types.

If your application uses more complex key types that you want to make more accessible or easier to handle, you can derive a new class from `IDataSerializable`. Another option is for the application to do its own object serialization using `Byte[]` or a custom type.

## <a id="concept_5D520C87F65B48AFA4240615190B0150__section_DA3BCFFFCB974C65BEE953DF3FAA8442" class="no-quick-link"></a>Blobs

If you have data that is best handled as a blob, such as structs that do not contain pointers, use a `Byte[]` or, if you need something more complex than `Byte[]`, implement a custom type using either `IPdxSerializable` or `IDataSerializable`.

## <a id="concept_5D520C87F65B48AFA4240615190B0150__section_D49865F1CF5F467A9FFAD244D990F3F5" class="no-quick-link"></a>Object Graphs

If you have a graph of objects in which each node can be serializable, the parent node calls `DataOutput.WriteObject` to delegate the serialization responsibility to its child nodes. Similarly, your application calls `DataInput.ReadObject` to deserialize the object graph.

**Note:**
The <%=vars.product_name%> `IDataSerializable` interface does not support object graphs with multiple references to the same object. If your application uses these types of circular graphs, you must address this design concern explicitly.