Unsolvable (as of yet) serialization error

Question

We are currently experiencing the following error (from the logs) when using our Windows Azure App:

System.Runtime.Serialization.SerializationException Assembly 'EntityFrameworkDynamicProxies-Marriott.emergePortal.Common,
Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' is not found.

This error comes and goes we haven't been able to understand exactly what causes it.

We've tried everything! Any help that anyone could provide would be awesome.

The entire error message from the log is:

    System.Web.HttpException (0x80004005): Exception of type 'System.Web.HttpException' was thrown. ---> System.Runtime.Serialization.SerializatioFnException: Assembly 'EntityFrameworkDynamicProxies-Marriott.emergePortal.Common, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' is not found.
   at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserializeInSharedTypeMode(XmlReaderDelegator xmlReader, Int32 declaredTypeID, Type declaredType, String name, String ns)
   at ReadArrayOfPropertyEnrollmentFromXml(XmlReaderDelegator , XmlObjectSerializerReadContext , XmlDictionaryString , XmlDictionaryString , CollectionDataContract )
   at System.Runtime.Serialization.CollectionDataContract.ReadXmlValue(XmlReaderDelegator xmlReader, XmlObjectSerializerReadContext context)
   at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserializeInSharedTypeMode(XmlReaderDelegator xmlReader, Int32 declaredTypeID, Type declaredType, String name, String ns)
   at ReadArrayOfPropertyEnrollmentFromXml(XmlReaderDelegator , XmlObjectSerializerReadContext , XmlDictionaryString[] , XmlDictionaryString[] )
   at System.Runtime.Serialization.ClassDataContract.ReadXmlValue(XmlReaderDelegator xmlReader, XmlObjectSerializerReadContext context)
   at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserializeInSharedTypeMode(XmlReaderDelegator xmlReader, Int32 declaredTypeID, Type declaredType, String name, String ns)
   at ReadArrayOfanyTypeFromXml(XmlReaderDelegator , XmlObjectSerializerReadContext , XmlDictionaryString , XmlDictionaryString , CollectionDataContract )
   at System.Runtime.Serialization.CollectionDataContract.ReadXmlValue(XmlReaderDelegator xmlReader, XmlObjectSerializerReadContext context)
   at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserializeInSharedTypeMode(XmlReaderDelegator xmlReader, Int32 declaredTypeID, Type declaredType, String name, String ns)
   at ReadSerializableSessionStateStoreDataFromXml(XmlReaderDelegator , XmlObjectSerializerReadContext , XmlDictionaryString[] , XmlDictionaryString[] )
   at System.Runtime.Serialization.ClassDataContract.ReadXmlValue(XmlReaderDelegator xmlReader, XmlObjectSerializerReadContext context)
   at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserializeInSharedTypeMode(XmlReaderDelegator xmlReader, Int32 declaredTypeID, Type declaredType, String name, String ns)
   at System.Runtime.Serialization.XmlObjectSerializerReadContextComplex.InternalDeserialize(XmlReaderDelegator xmlReader, Type declaredType, String name, String ns)
   at System.Runtime.Serialization.NetDataContractSerializer.InternalReadObject(XmlReaderDelegator xmlReader, Boolean verifyObjectName)
   at System.Runtime.Serialization.XmlObjectSerializer.ReadObjectHandleExceptions(XmlReaderDelegator reader, Boolean verifyObjectName, DataContractResolver dataContractResolver)
   at System.Runtime.Serialization.XmlObjectSerializer.ReadObject(XmlDictionaryReader reader)
   at Microsoft.ApplicationServer.Caching.NetDataContractCacheObjectSerializer.Deserialize(Stream stream)
   at Microsoft.ApplicationServer.Caching.DataCacheObjectSerializationProvider.DeserializeUserObject(Byte[][] serializedData, ValueFlagsVersion flagsType)
   at Microsoft.ApplicationServer.Caching.SocketClientProtocol.GetAndLock(String key, TimeSpan timeout, DataCacheLockHandle& lockHandle, String region, Boolean lockKey, IMonitoringListener listener)
   at Microsoft.ApplicationServer.Caching.DataCache.<>c__DisplayClass8a.<GetAndLock>b__89()
   at Microsoft.ApplicationServer.Caching.DataCache.GetAndLock(String key, TimeSpan timeout, DataCacheLockHandle& lockHandle)
   at Microsoft.Web.DistributedCache.DataCacheForwarderBase.<>c__DisplayClass31`1.<PerformCacheOperation>b__30()
   at Microsoft.Web.DistributedCache.DataCacheRetryWrapper.PerformCacheOperation(Action action)
   at Microsoft.Web.DistributedCache.DataCacheForwarderBase.GetAndLock(String key, TimeSpan timeout, DataCacheLockHandle& lockHandle)
   at Microsoft.Web.DistributedCache.BlobBasedSessionStoreProvider.GetItem(HttpContextBase context, String id, Boolean acquireWriteLock, Boolean& locked, TimeSpan& lockAge, Object& lockId, SessionStateActions& actions)
   at Microsoft.Web.DistributedCache.DistributedCacheSessionStateStoreProvider.GetItemExclusive(HttpContext context, String id, Boolean& locked, TimeSpan& lockAge, Object& lockId, SessionStateActions& actions)
   at System.Web.SessionState.SessionStateModule.GetSessionStateItem()
   at System.Web.SessionState.SessionStateModule.PollLockedSessionCallback(Object state)
   at System.Web.SessionState.SessionStateModule.EndAcquireState(IAsyncResult ar)
   at System.Web.HttpApplication.AsyncEventExecutionStep.OnAsyncEventCompletion(IAsyncResult ar)

Answer 1

Without seeing any of the code, it's difficult to troubleshoot. However, we had something similar that was caused because the DataContractSerializer expected a specific type (as defined in the service interface), but was instead getting an EntityFramework proxy type.

We decided to use the Data Transfer Object pattern to resolve this. We created base classes that were simple data transfer objects. EF-aware classes inherit from these and add persistence-related logic.

These DTO objects implement ICloneable (or something similar) which allows us to easily create data transfer copies of the Entity Framework proxy classes before sending objects to the serializer at the service level.

It may also be possible to resolve this by creating a custom serializer that has knowledge of Entity Framework proxy classes but that approach seemed more like a hack. The DTO pattern seemed simpler and was very effective.