Azure caching and entity framework deserialization issue - azure

I have a web project deployed in azure using colocated caching. I have 2 instances of this web role.
I am using Entity framework 5 and upon fetching some entities from the db, I cache them using colocated caching.
My entities are defined in class library called Drt.BusinessLayer.Entities
However when I visit my web app, I get the error:
The deserializer cannot load the type to deserialize because type 'System.Data.Entity.DynamicProxies.Country_4C17F5A60A033813EC420C752F1026C02FA5FC07D491A3190ED09E0B7509DD85' could not be found in assembly 'EntityFrameworkDynamicProxies-Drt.BusinessLayer.Entities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. Check that the type being serialized has the same contract as the type being deserialized and the same assembly is used.
Also sometimes I get this too:
Assembly 'EntityFrameworkDynamicProxies-Drt.BusinessLayer.Entities, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' is not found.
It appears that there is an error getting the entities out/deserialized. Since they are 2 instances of my web role, instance1 might place some entity objects in the cache and instance2 might get them out. I was expecting this to work, but I am unsure why I am getting this error....
Can anyone help/advise?

I ran into the same issue. At least in my case, the problem was the DynamicProxies with which the EF wraps all the model classes. In other words, you might think you're retrieving a Country class, but under the hood, EF is actually dynamically generating a class that's called something like Country_4C17F5A60A033813EC420C752F1026C02FA5FC07D491A3190ED09E0B7509DD85. The last part of the name is obviously generated at run-time, and it can be expected to remain static throughout the life of your application - but (and this is the key) only on the same instance of the app domain. If you've got two machines accessing the same out-of-process cache, one will be storing an object of the type Country_4C17F5A60A033813EC420C752F1026C02FA5FC07D491A3190ED09E0B7509DD85, but that type simply won't exist on the other machine. Its dynamic Country class will be something like Country_JF7ASDF8ASDF8ADSF88989ASDF8778802348JKOJASDLKJQAWPEORIU7879243AS, and so there won't be any type into which it can deserialize the serialized object. The same thing will happen if you restart the app domain your web app is running in.
I'm sure the big brains at MS could come up with a better solution, but the one I've been using is to do a "shallow clone" of my EF objects before I cache them. The C# method I'm using looks like this:
public static class TypeHelper
{
public static T ShallowClone<T>(this T obj) where T : class
{
if (obj == null) return null;
var newObj = Activator.CreateInstance<T>();
var fields = typeof(T).GetFields();
foreach (var field in fields)
{
if (field.IsPublic && (field.FieldType.IsValueType || field.FieldType == typeof(string)))
{
field.SetValue(newObj, field.GetValue(obj));
}
}
var properties = typeof(T).GetProperties();
foreach (var property in properties)
{
if ((property.CanRead && property.CanWrite) &&
(property.PropertyType.IsValueType || property.PropertyType == typeof(string)))
{
property.SetValue(newObj, property.GetValue(obj, null), null);
}
}
return newObj;
}
}
This takes care of two problems at once: (1) It ensures that only the EF object I'm specifically interested in gets cached, and not the entire object graph - sometimes huge - to which it's attached; and (2) The object that it caches is of a common type, and not the dynamically generated type: Country and not Country_4C17F5A60A033813EC420C752F1026C02FA5FC07D491A3190ED09E0B7509DD85.
It's certainly not perfect, but it does seem a reasonable workaround for many scenarios.
It would in fact be nice, though, if the good folks at MS were to come up with a way to cache EF objects without this.

I'm not familiar with azure-caching in particular, but I'm guessing you need to hydrate your entities completely before passing them to anything that does serialization, which is something a distributed or out-of-process cache would do.
So, just do .Include() on all relationships when you're fetching an entity or disable lazy initialization and you should be fine.

Related

How to use ObjectContext with Model Builder?

Is there a way we can use ObjectContext with DbContext's ModelBuilder? We don't want to use POCO because we have customized property code that does not modify entire object in update, but only update modified properties. Also we have lots of serialisation and auditing code that uses EntityObject.
Since poco does create a proxy with EntityObject, we want our classes to be derived from EntityObject. We don't want proxy. We also heavily use CreateSourceQuery. The only problem is EDMX file and its big connection string syntax web.config.
Is there any way I can get rid of EDMX file? It will be useful as we can dynamically compile new class based on reverse engineering database.
I would also like to use DbContext with EntityObject instead of poco.
Internal Logic
Access Modified Properties in Save Changes which is available in ObjectStateEntry and Save them onto Audit with Old and New Values
Most of times we need to only check for Any condition on Navigation Property for example
User.EmailAddresses.CreateSourceQuery()
.Any( x=> x.EmailAddress == givenAddress);
Access Property Attributes, such as XmlIgnore etc, we rely heavily on attributes defined on the properties.
A proxy for a POCO is a dynamically created class which derives from (inherits) a POCO. It adds functionality previously found in EntityObject, namely lazy loading and change tracking, as long as a POCO meets requirements. A POCO or its proxy does not contain an EntityObject as the question suggests, but rather a proxy contains functionality of EntityObject. You cannot (AFAIK) use ModelBuilder with EntityObject derivatives and you cannot get to an underlying EntityObject from a POCO or a proxy, since there isn't one as such.
I don't know what features of ObjectContext does your existing serialisation and auditing code use, but you can get to ObjectContext from a DbContext by casting a DbContext to a IObjectContextAdapter and accessing IObjectContextAdapter.ObjectContext property.
EDIT:
1. Access Modified Properties in Save Changes which is available in ObjectStateEntry and Save them onto Audit with Old and New Values
You can achieve this with POCOs by using DbContext.ChangeTracker. First you call DbContext.ChangeTracker.DetectChanges to detect the changes (if you use proxies this is not needed, but can't hurt) and then you use DbCotnext.Entries.Where(e => e.State != EntityState.Unchanged && e.State != EntityState.Detached) to get DbEntityEntry list of changed entities for auditing. Each DbEntityEntry has OriginalValues and CurrentValues and the actual Entity is in property Entity.
You also have access to ObjectStateEntry, see below.
2. Most of times we need to only check for Any condition on Navigation Property for example:
User.EmailAddresses.CreateSourceQuery().Any( x=> x.EmailAddress == givenAddress);
You can use CreateSourceQuery() with DbContext by utilizing IObjectContextAdapter as described previously. When you have ObjectContext you can get to the source query for a related end like this:
public static class DbContextUtils
{
public static ObjectQuery<TMember> CreateSourceQuery<TEntity, TMember>(this IObjectContextAdapter adapter, TEntity entity, Expression<Func<TEntity, ICollection<TMember>>> memberSelector) where TMember : class
{
var objectStateManager = adapter.ObjectContext.ObjectStateManager;
var objectStateEntry = objectStateManager.GetObjectStateEntry(entity);
var relationshipManager = objectStateManager.GetRelationshipManager(entity);
var entityType = (EntityType)objectStateEntry.EntitySet.ElementType;
var navigationProperty = entityType.NavigationProperties[(memberSelector.Body as MemberExpression).Member.Name];
var relatedEnd = relationshipManager.GetRelatedEnd(navigationProperty.RelationshipType.FullName, navigationProperty.ToEndMember.Name);
return ((EntityCollection<TMember>)relatedEnd).CreateSourceQuery();
}
}
This method uses no dynamic code and is strongly typed since it uses expressions. You use it like this:
myDbContext.CreateSourceQuery(invoice, i => i.details);

ServiceStack: RESTful Resource Versioning

I've taken a read to the Advantages of message based web services article and am wondering if there is there a recommended style/practice to versioning Restful resources in ServiceStack? The different versions could render different responses or have different input parameters in the Request DTO.
I'm leaning toward a URL type versioning (i.e /v1/movies/{Id}), but I have seen other practices that set the version in the HTTP headers (i.e Content-Type: application/vnd.company.myapp-v2).
I'm hoping a way that works with the metadata page but not so much a requirement as I've noticed simply using folder structure/ namespacing works fine when rendering routes.
For example (this doesn't render right in the metadata page but performs properly if you know the direct route/url)
/v1/movies/{id}
/v1.1/movies/{id}
Code
namespace Samples.Movies.Operations.v1_1
{
[Route("/v1.1/Movies", "GET")]
public class Movies
{
...
}
}
namespace Samples.Movies.Operations.v1
{
[Route("/v1/Movies", "GET")]
public class Movies
{
...
}
}
and corresponding services...
public class MovieService: ServiceBase<Samples.Movies.Operations.v1.Movies>
{
protected override object Run(Samples.Movies.Operations.v1.Movies request)
{
...
}
}
public class MovieService: ServiceBase<Samples.Movies.Operations.v1_1.Movies>
{
protected override object Run(Samples.Movies.Operations.v1_1.Movies request)
{
...
}
}
Try to evolve (not re-implement) existing services
For versioning, you are going to be in for a world of hurt if you try to maintain different static types for different version endpoints. We initially started down this route but as soon as you start to support your first version the development effort to maintain multiple versions of the same service explodes as you will need to either maintain manual mapping of different types which easily leaks out into having to maintain multiple parallel implementations, each coupled to a different versions type - a massive violation of DRY. This is less of an issue for dynamic languages where the same models can easily be re-used by different versions.
Take advantage of built-in versioning in serializers
My recommendation is not to explicitly version but take advantage of the versioning capabilities inside the serialization formats.
E.g: you generally don't need to worry about versioning with JSON clients as the versioning capabilities of the JSON and JSV Serializers are much more resilient.
Enhance your existing services defensively
With XML and DataContract's you can freely add and remove fields without making a breaking change. If you add IExtensibleDataObject to your response DTO's you also have a potential to access data that's not defined on the DTO. My approach to versioning is to program defensively so not to introduce a breaking change, you can verify this is the case with Integration tests using old DTOs. Here are some tips I follow:
Never change the type of an existing property - If you need it to be a different type add another property and use the old/existing one to determine the version
Program defensively realize what properties don't exist with older clients so don't make them mandatory.
Keep a single global namespace (only relevant for XML/SOAP endpoints)
I do this by using the [assembly] attribute in the AssemblyInfo.cs of each of your DTO projects:
[assembly: ContractNamespace("http://schemas.servicestack.net/types",
ClrNamespace = "MyServiceModel.DtoTypes")]
The assembly attribute saves you from manually specifying explicit namespaces on each DTO, i.e:
namespace MyServiceModel.DtoTypes {
[DataContract(Namespace="http://schemas.servicestack.net/types")]
public class Foo { .. }
}
If you want to use a different XML namespace than the default above you need to register it with:
SetConfig(new EndpointHostConfig {
WsdlServiceNamespace = "http://schemas.my.org/types"
});
Embedding Versioning in DTOs
Most of the time, if you program defensively and evolve your services gracefully you wont need to know exactly what version a specific client is using as you can infer it from the data that is populated. But in the rare cases your services needs to tweak the behavior based on the specific version of the client, you can embed version information in your DTOs.
With the first release of your DTOs you publish, you can happily create them without any thought of versioning.
class Foo {
string Name;
}
But maybe for some reason the Form/UI was changed and you no longer wanted the Client to use the ambiguous Name variable and you also wanted to track the specific version the client was using:
class Foo {
Foo() {
Version = 1;
}
int Version;
string Name;
string DisplayName;
int Age;
}
Later it was discussed in a Team meeting, DisplayName wasn't good enough and you should split them out into different fields:
class Foo {
Foo() {
Version = 2;
}
int Version;
string Name;
string DisplayName;
string FirstName;
string LastName;
DateTime? DateOfBirth;
}
So the current state is that you have 3 different client versions out, with existing calls that look like:
v1 Release:
client.Post(new Foo { Name = "Foo Bar" });
v2 Release:
client.Post(new Foo { Name="Bar", DisplayName="Foo Bar", Age=18 });
v3 Release:
client.Post(new Foo { FirstName = "Foo", LastName = "Bar",
DateOfBirth = new DateTime(1994, 01, 01) });
You can continue to handle these different versions in the same implementation (which will be using the latest v3 version of the DTOs) e.g:
class FooService : Service {
public object Post(Foo request) {
//v1:
request.Version == 0
request.Name == "Foo"
request.DisplayName == null
request.Age = 0
request.DateOfBirth = null
//v2:
request.Version == 2
request.Name == null
request.DisplayName == "Foo Bar"
request.Age = 18
request.DateOfBirth = null
//v3:
request.Version == 3
request.Name == null
request.DisplayName == null
request.FirstName == "Foo"
request.LastName == "Bar"
request.Age = 0
request.DateOfBirth = new DateTime(1994, 01, 01)
}
}
Framing the Problem
The API is the part of your system that exposes its expression. It defines the concepts and the semantics of communicating in your domain. The problem comes when you want to change what can be expressed or how it can be expressed.
There can be differences in both the method of expression and what is being expressed. The first problem tends to be differences in tokens (first and last name instead of name). The second problem is expressing different things (the ability to rename oneself).
A long-term versioning solution will need to solve both of these challenges.
Evolving an API
Evolving a service by changing the resource types is a type of implicit versioning. It uses the construction of the object to determine behavior. Its works best when there are only minor changes to the method of expression (like the names). It does not work well for more complex changes to the method of expression or changes to the change of expressiveness. Code tends to be scatter throughout.
Specific Versioning
When changes become more complex it is important to keep the logic for each version separate. Even in mythz example, he segregated the code for each version. However, the code is still mixed together in the same methods. It is very easy for code for the different versions to start collapsing on each other and it is likely to spread out. Getting rid of support for a previous version can be difficult.
Additionally, you will need to keep your old code in sync to any changes in its dependencies. If a database changes, the code supporting the old model will also need to change.
A Better Way
The best way I've found is to tackle the expression problem directly. Each time a new version of the API is released, it will be implemented on top of the new layer. This is generally easy because changes are small.
It really shines in two ways: first all the code to handle the mapping is in one spot so it is easy to understand or remove later and second it doesn't require maintenance as new APIs are developed (the Russian doll model).
The problem is when the new API is less expressive than the old API. This is a problem that will need to be solved no matter what the solution is for keeping the old version around. It just becomes clear that there is a problem and what the solution for that problem is.
The example from mythz's example in this style is:
namespace APIv3 {
class FooService : RestServiceBase<Foo> {
public object OnPost(Foo request) {
var data = repository.getData()
request.FirstName == data.firstName
request.LastName == data.lastName
request.DateOfBirth = data.dateOfBirth
}
}
}
namespace APIv2 {
class FooService : RestServiceBase<Foo> {
public object OnPost(Foo request) {
var v3Request = APIv3.FooService.OnPost(request)
request.DisplayName == v3Request.FirstName + " " + v3Request.LastName
request.Age = (new DateTime() - v3Request.DateOfBirth).years
}
}
}
namespace APIv1 {
class FooService : RestServiceBase<Foo> {
public object OnPost(Foo request) {
var v2Request = APIv2.FooService.OnPost(request)
request.Name == v2Request.DisplayName
}
}
}
Each exposed object is clear. The same mapping code still needs to be written in both styles, but in the separated style, only the mapping relevant to a type needs to be written. There is no need to explicitly map code that doesn't apply (which is just another potential source of error). The dependency of previous APIs is static when you add future APIs or change the dependency of the API layer. For example, if the data source changes then only the most recent API (version 3) needs to change in this style. In the combined style, you would need to code the changes for each of the APIs supported.
One concern in the comments was the addition of types to the code base. This is not a problem because these types are exposed externally. Providing the types explicitly in the code base makes them easy to discover and isolate in testing. It is much better for maintainability to be clear. Another benefit is that this method does not produce additional logic, but only adds additional types.
I am also trying to come with a solution for this and was thinking of doing something like the below. (Based on a lot of Googlling and StackOverflow querying so this is built on the shoulders of many others.)
First up, I don’t want to debate if the version should be in the URI or Request Header. There are pros/cons for both approaches so I think each of us need to use what meets our requirements best.
This is about how to design/architecture the Java Message Objects and the Resource Implementation classes.
So let’s get to it.
I would approach this in two steps. Minor Changes (e.g. 1.0 to 1.1) and Major Changes (e.g 1.1 to 2.0)
Approach for minor changes
So let’s say we go by the same example classes used by #mythz
Initially we have
class Foo { string Name; }
We provide access to this resource as /V1.0/fooresource/{id}
In my use case, I use JAX-RS,
#Path("/{versionid}/fooresource")
public class FooResource {
#GET
#Path( "/{id}" )
public Foo getFoo (#PathParam("versionid") String versionid, (#PathParam("id") String fooId)
{
Foo foo = new Foo();
//setters, load data from persistence, handle business logic etc
Return foo;
}
}
Now let’s say we add 2 additional properties to Foo.
class Foo {
string Name;
string DisplayName;
int Age;
}
What I do at this point is annotate the properties with a #Version annotation
class Foo {
#Version(“V1.0")string Name;
#Version(“V1.1")string DisplayName;
#Version(“V1.1")int Age;
}
Then I have a response filter that will based on the requested version, return back to the user only the properties that match that version. Note that for convenience, if there are properties that should be returned for all versions, then you just don’t annotate it and the filter will return it irrespective of the requested version
This is sort of like a mediation layer. What I have explained is a simplistic version and it can get very complicated but hope you get the idea.
Approach for Major Version
Now this can get quite complicated when there is a lot of changes been done from one version to another. That is when we need to move to 2nd option.
Option 2 is essentially to branch off the codebase and then do the changes on that code base and host both versions on different contexts. At this point we might have to refactor the code base a bit to remove version mediation complexity introduced in Approach one (i.e. make the code cleaner) This might mainly be in the filters.
Note that this is just want I am thinking and haven’t implemented it as yet and wonder if this is a good idea.
Also I was wondering if there are good mediation engines/ESB’s that could do this type of transformation without having to use filters but haven’t seen any that is as simple as using a filter. Maybe I haven’t searched enough.
Interested in knowing thoughts of others and if this solution will address the original question.

Code Contracts and Auto Generated Files

When I enabled code contracts on my WPF control project I ran into a problem with an auto generated file which was created at compile time (XamlNamespace.GeneratedInternalTypeHelper). Note, the generated file is called GeneratedInternalTypeHelper.g.cs and is not the same as the GeneratedInternalTypeHelper.g.i.cs which there are several obsolete blog posts about.
I'm not exactly sure what its purpose is, but I am assuming it is important for some internal reflection to resolve XAML. The problem is that it does not have code contracts, nor is the code contract system smart enough to recognize it as an auto generated file. This leads to a bunch of errors from the static checker.
I tried searching for a solution to this problem, but it seems like nobody is developing WPF controls and using code contracts. I did come across an interesting attribute, ContractVerificationAttribute, which takes a boolean value to set whether the assembly or class is to be verified. This allows you to decorate a class as not verified. Sadly the GeneratedInternalTypeHelper is regenerated with every compile, so it is not possible to exclude just this one class. The inverse scenario is possible though, decorate the assembly as not verified and then opt in for every class.
To mitigate the obvious hack I wanted to create a test that would at least verify that the exposed classes have code contract verification with a test like the following to ensure that own classes were at least being verified:
[Fact]
public void AllAssemblyTypesAreDecoratedWithContractVerificationTrue()
{
var assembly = typeof(someType).Assembly;
var exposedTypes = assembly.GetTypes().Where(t=>!string.IsNullOrWhiteSpace(t.Namespace) && t.Namespace.StartsWith("MyNamespace") && !t.Name.StartsWith("<>"));
var areAnyNotContractVerified = exposedTypes.Any(t =>
{
var verificationAttribute = t.GetCustomAttributes(typeof(ContractVerificationAttribute), true).OfType<ContractVerificationAttribute>();
return verificationAttribute.Any() && verificationAttribute.First().Value;
});
Assert.False(areAnyNotContractVerified);
}
As you can see it takes all classes in the controls assembly and finds the one from the company namespace which are not also auto generated anonymous types (<>WeirdClassName).
(I also need to exclude Resources and settings, but I hope you get the idea).
I'm not loving the solution since there are ways of avoiding contract verification, but currently it's the best I can come up with. If anyone has a better solution, please let me know.
So you can treat this class exactly like you would treat any other "3rd party" class or library. I'm sure certain assumptions would hold with the interaction with this generated class so at the interaction points, decorate your own code with Contract.Assume(result != null) or similar.
var result = new GennedClass().GetSomeValue();
Contract.Assume(result != null);
What this does is translate into an assertion that is checked at run time, but it allows the static analyzer to reason about the rest of the code that you do control.

NInject and thread-safety

I am having problems with the following class in a multi-threaded environment:
public class Foo
{
[Inject]
public IBar InjectedBar { get; set; }
public bool NonInjectedProp { get; set; }
public void DoSomething()
{
/* The following line is causing a null-reference exception */
InjectedBar.DoSomething();
}
public Foo(bool nonInjectedProp)
{
/* This line should inject the InjectedBar property */
KernelContainer.Inject(this);
NonInjectedProp = nonInjectedProp;
}
}
This is a legacy class which is why I am using property rather than constructor injection.
Sometime when the DoSomething() is called the InjectedBar property is null. In a single-threaded application, everything runs fine.
How can this be occuring and how can I prevent it?
I am using NInject 2.0 without any extensions, although I have copied the KernelContainer from the NInject.Web project.
I have noticed a similar problem occurring in my web services. This problem is extremely intermittent and difficult to replicate.
First of all, let me say that this is wrong on so many levels; the KernelContainer was an infrastructure class kept specifically to work around certain limitations in the ASP.NET WebForms page lifecycle. It was never meant to be used in application code. Using the Ninject kernel (or any DI container) as a service locator is an anti-pattern.
That being said, Ninject itself is definitely thread-safe because it's used to service parallel requests in ASP.NET all the time. Wherever this NullReferenceException is coming from, it's got little if anything to do with Ninject.
I can think of two possibilities:
You have to initialize KernelContainer.Kernel somewhere, and that code might have a race condition. If something tries to use the KernelContainer before the kernel is fully initialized (possible if you use the IKernel.Bind methods instead of loading modules as per the guidance), you'll get errors like this. Or:
It's your IBar implementation itself that has problems, and the NullReferenceException is happening somewhere inside the DoSomething method. You don't actually specify that InjectedBar is null when you get the exception, so that's a legitimate possibility here.
Just to narrow the field of possibilities, I'd eliminate the KernelContainer first. If you absolutely must use Ninject as a service locator due to a poorly-designed legacy architecture, then at least allow it to create the dependencies instead of relying on Inject(this). That is to say, whichever class or classes need to create your Foo, have that class call kernel.Get<Foo>(), and set up your kernel to Bind<Foo>().ToSelf().

Windows Azure Table Services - Extended Properties and Table Schema

I have an entity that, in addition to a few common properties, contains a list of extended properties stored as (Name, Value) pairs of strings within a collection. I should probably mention that these extended properties widely vary from instance to instance, and that they only need to be listed for each instance (there won't be any queries over the extended properties, for example finding all instances with a particular (Name, Value) pair). I'm exploring how I might persist this entity using Windows Azure Table Services. With the particular approach I'm testing now, I'm concerned that there may be a degradation of performance over time as more distinct extended property names are encountered by the application.
If I were storing this entity in a typical relational database, I'd probably have two tables to support this schema: the first would contain the entity identifier and its common properties, and the second would reference the entity identifier and use EAV style row-modeling to store the extended (Name, Value) pairs, one to each row.
Since tables in Windows Azure already use an EAV model, I'm considering custom serialization of my entity so that the extended properties are stored as though they were declared at compile time for the entity. I can use the Reading- and Writing-Entity events provided by DataServiceContext to accomplish this.
private void OnReadingEntity(object sender, ReadingWritingEntityEventArgs e)
{
MyEntity Entry = e.Entity as MyEntity;
if (Entry != null)
{
XElement Properties = e.Data
.Element(Atom + "content")
.Element(Meta + "properties");
//select metadata from the extended properties
Entry.ExtendedProperties = (from p in Properties.Elements()
where p.Name.Namespace == Data && !IsReservedPropertyName(p.Name.LocalName) && !string.IsNullOrEmpty(p.Value)
select new Property(p.Name.LocalName, p.Value)).ToArray();
}
}
private void OnWritingEntity(object sender, ReadingWritingEntityEventArgs e)
{
MyEntity Entry = e.Entity as MyEntity;
if (Entry != null)
{
XElement Properties = e.Data
.Element(Atom + "content")
.Element(Meta + "properties");
//add extended properties from the metadata
foreach (Property p in (from p in Entry.ExtendedProperties
where !IsReservedPropertyName(p.Name) && !string.IsNullOrEmpty(p.Value)
select p))
{
Properties.Add(new XElement(Data + p.Name, p.Value));
}
}
}
This works, and since I can define requirements for extended property names and values, I can ensure that they conform to all the standard requirements for entity properties within a Windows Azure Table.
So what happens over time as the application encounters thousands of different extended property names?
Here's what I've observed within the development storage environment:
The table container schema grows with each new name. I'm not sure exactly how this schema is used (probably for the next point), but obviously this xml document could grow quite large over time.
Whenever an instance is read, the xml passed to OnReadingEntity contains elements for every property name ever stored for any other instance (not just the ones stored for the particular instance being read). This means that retrieval of an entity will become slower over time.
Should I expect these behaviors in the production storage environment? I can see how these behaviors would be acceptable for most tables, as the schema would be mostly static over time. Perhaps Windows Azure Tables were not designed to be used like this? If so, I will certainly need to change my approach. I'm also open to suggestions on alternate approaches.
Development storage uses SQL Express to simulate cloud table storage. Ignore what you see there... the production storage system doesn't store any schema, so there's no overhead to having lots of unique properties in a table.

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