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First draft of the Release Notes for 1.4. Changed to .md format so th…
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C# Driver Version 1.4 Release Notes | ||
=================================== | ||
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The major feature of this release is support for LINQ queries. Some of the other | ||
changes (e.g. new IBsonSerializer methods) are also in support of the new LINQ | ||
implementation. | ||
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File by file change logs are available at: | ||
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https://github.com/mongodb/mongo-csharp-driver/blob/master/Release%20Notes/Change%20Log%20v1.4-Bson.txt | ||
https://github.com/mongodb/mongo-csharp-driver/blob/master/Release%20Notes/Change%20Log%20v1.4-Driver.txt | ||
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These release notes describe the changes at a higher level, and omit describing | ||
some of the minor changes. | ||
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Breaking changes | ||
---------------- | ||
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There are some breaking changes in this release. Some of them are only breaking | ||
at the binary level and are easily taken care of by simply recompiling your | ||
application. Others require minor changes to your source code. Many of the | ||
breaking changes are in low level classes, and these won't affect most users, | ||
unless for example you are doing things like writing custom serializers. | ||
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Please read these release notes carefully before adopting the new 1.4 release | ||
of the C# driver to determine if any of the breaking changes affect you. | ||
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LINQ query support | ||
------------------ | ||
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As stated previously, the major feature of this release is support for LINQ | ||
queries. These release notes don't describe the new LINQ support, for that | ||
please refer to the online LINQ tutorial at: | ||
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http://www.mongodb.org/display/DOCS/CSharp+Driver+LINQ+Tutorial | ||
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(Please note that the LINQ tutorial won't be available until several weeks | ||
after the 1.4 release has been shipped. Sorry.) | ||
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CLS compliance | ||
-------------- | ||
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Both the MongoDB.Bson.dll and MongoDB.Driver.dll libraries have been marked | ||
as CLS compliant, which should make them more useful from other .NET languages. | ||
Most of the changes required to make the libraries CLS compliant are not even | ||
visible in the public interface. | ||
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Release builds | ||
-------------- | ||
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Starting with the 1.4 version we are shipping Release builds of the DLLs. | ||
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Code formatting changes | ||
----------------------- | ||
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In response to popular demand the code base has been reformatted using the | ||
default Visual Studio C# code formatting settings. We have also adopted | ||
the convention of prefixing instance field names with a single "_" and static | ||
fields names with a double "__" (while this convention for static fields is | ||
not common it is very useful). One of the nice benefits of these conventions | ||
is that the drop down menu in Visual Studio that displays class members ends | ||
up grouping all static fields first, followed by instance fields, followed by | ||
the rest of the properties and methods. | ||
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BSON library changes | ||
==================== | ||
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ArraySerializationOptions | ||
------------------------- | ||
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This new class allows you to specify serialization options for array-like | ||
members. Initially the only option available is to specify serialization | ||
options for the items of the array. When using attributes to specify | ||
serialization options any attributes that don't apply to the collection as a | ||
whole implictly apply to the items of the collection. | ||
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BsonDateTime is now a pure BSON DateTime value | ||
---------------------------------------------- | ||
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In previous versions the BsonDateTime class stored its value twice in two | ||
different private fields: _millisecondsSinceEpoch (a long) and _value (a .NET | ||
DateTime). The idea was that you could store a .NET DateTime without losing any | ||
precision. However, that turns out to be confusing because as soon as you save | ||
the BsonDateTime value to the database and read it back you are going to lose | ||
precision anyway, so you might as well lose it right up front and not make | ||
false promises. | ||
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BsonDateTime also has two new helper methods: ToLocalTime and ToUniversalTime. | ||
These methods convert the BSON DateTime to either local or UTC .NET DateTime | ||
values. There are also new AsLocalTime and AsUniversalTime properties in | ||
BsonValues that can be used to convert BsonValues to .NET DateTime values (like | ||
all AsXyz properties in BsonValue they throw an InvalidCastException if the | ||
BsonValue is not actually a BsonDateTime). | ||
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BsonIgnoreExtraElements attribute | ||
--------------------------------- | ||
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The BsonIgnoreExtraElements attribute has a new property called Inherited. If | ||
this property is set to true then all classes derived from this one will | ||
automatically inherit this setting, which makes it easy to set it for an | ||
entire class hierarchy at once. | ||
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BsonIgnoreIfDefault attribute | ||
----------------------------- | ||
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This new attribute allows you to specify that you want a field to be ignored | ||
during serialization if it has the default value. This replaces the | ||
SerializeDefaultValue parameter of the BsonDefaultValue attribute. By making | ||
this a separate attribute you can specify that you want the default value | ||
ignored without having to specify the default value as well. | ||
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BsonReader: CurrentBsonType vs GetCurrentBsonType | ||
------------------------------------------------- | ||
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In previous versions the CurrentBsonType property had side effects. In general | ||
it is bad form for the get accessor of a property to have side effects, as even | ||
something as simple as looking at the value of the property in a debugger can | ||
have unintended consequences. Therefore, in the 1.4 release the CurrentBsonType | ||
property has no side effects. The previous behavior is now implemented in the | ||
GetCurrentBsonType method. While this is mostly an internal change, *if* you | ||
have written a custom serializer that used the CurrentBsonType property and | ||
were relying on its side effects you will have to change your custom serializer | ||
to call GetCurrentBsonType instead. | ||
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ConventionProfile new conventions | ||
--------------------------------- | ||
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The ConventionProfile class has two new conventions: IgnoreIfDefaultConvention | ||
and SerializationOptionsConvention. Also, the SerializeDefaultValueConvention | ||
has been obsoleted in favor of the new IgnoreIfDefaultConvention. | ||
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DictionarySerializationOptions | ||
------------------------------ | ||
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This class has a new property called ItemSerializationOptions that can be used | ||
to specify the options to use when serializing the value of the items in the | ||
dictionary. When using attributes to specify serialization options, any | ||
attributes that don't apply to the dictionary as a whole implicitly apply to | ||
the value of the items in the dictionary. | ||
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ExtraElements | ||
------------- | ||
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Previous versions of the C# driver allowed you to specify a field of the class | ||
to be used to store any extra elements encountered during deserialization. | ||
However, this field *had* to be of type BsonDocument, which meant introducing | ||
a dependency on the driver into your data model classes (which some developers | ||
don't want to do). You now have the additional option of declaring your | ||
ExtraElements field to be of type IDictionary<string, object> instead. | ||
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IBsonSerializationOptions | ||
------------------------- | ||
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The IBsonSerializationOptions has several new methods. ApplyAttribute is used | ||
during the AutoMap process to apply an attribute to some serialization options | ||
that are being built incrementally (starting from the default serialization | ||
options). This provides an extensible mechanism for applying new attributes to | ||
new serialization options classes. The Clone and Freeze methods are introduced | ||
to allow serialization options to be converted to read-only once initialization | ||
is complete to provide thread safety. | ||
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IBsonSerializer | ||
--------------- | ||
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The IBsonSerializer has several new methods. GetDefaultSerializationOptions | ||
provides an initial set of serialization options that any serialization | ||
attributes found can be applied against. GetItemSerializationInfo provides | ||
serialization info about the items and applies only to serializers for | ||
collection-like classes. GetMemberSerializationInfo provides serialization | ||
info about members of a class. The last two are used in the implementation | ||
of LINQ queries. | ||
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Image/Bitmap serializers | ||
------------------------ | ||
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New serializers have been provided for the Image abstract base class and the | ||
Bitmap class derived from it. | ||
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ISupportInitialize | ||
------------------ | ||
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The ISupportInitialize interface defines two methods: BeginInit and EndInit. | ||
The BsonClassMapSerializer now checks whether the class being deserialized | ||
implements this interface, and if so, calls BeginInit just before it starts | ||
to deserialize a value, and EndInit just after it has finished. You can | ||
use this feature to do any pre- or post-processing. | ||
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ObjectId/BsonObjectId creation | ||
------------------------------ | ||
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ObjectId (and BsonObjectId) have a new constructor that allows you to supply | ||
the timestamp as a .NET DateTime value and it will automatically be converted | ||
to seconds since the Unix Epoch. These new constructors are useful if you want | ||
to create artificial ObjectIds to use in range based ObjectId queries (in | ||
which case you will usually set the machine, pid and increment fields to zero). | ||
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There are also two new overloads of GenerateNewId that allow you to provide | ||
the desired timestamp as either an int or a .NET DateTime. These new overloads | ||
are useful if you need to create backdated ObjectIds. | ||
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TimeSpanSerializationOptions | ||
---------------------------- | ||
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You can now choose any of the following representations for a TimeSpan: string, | ||
double, Int32 or Int64. In addition, when using any of the numeric | ||
representations, you can use the Units property to choose the units that the | ||
numeric value is in (choose from: Ticks, Days, Hours, Minutes, Seconds, | ||
Milliseconds and Nanoseconds). | ||
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Driver changes | ||
============== | ||
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Authentication support improved | ||
------------------------------- | ||
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Operations that require admin credentials previously required you to set the | ||
DefaultCredentials of MongoServerSettting to admin credentials. But that is | ||
undesirable because it provides the client code full access to all databases, | ||
essentially negating the benefit of using authentication in the first place. | ||
In the 1.4 release all operations that require admin credentials have a new | ||
overload where you can provide the needed credentials; you no longer have to | ||
set the DefaultCredentials. Another option is to store credentials for the | ||
admin database in the new MongoCredentialsStore. | ||
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Connection pool defaults changed | ||
-------------------------------- | ||
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The default value of WaitQueueMultiple has been changed from 1.0 to 5.0 and the | ||
default value of WaitQueueTimeout has been changed from 0.5 seconds to 2 | ||
minutes. These new values are taken from the Java driver, where they have | ||
reportedly been working well for users running under heavy loads. These new | ||
values mean that many more threads can be waiting for a lot longer time | ||
before a timeout occurs and an exception is thrown. | ||
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Exceptions are no longer caught and rethrown when possible | ||
---------------------------------------------------------- | ||
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Wherever possible exception handling code that used to use catch exceptions | ||
and rethrow them after processing them has been changed to roughly equivalent | ||
code that uses try/finally to accomplish the same objective. This is specially | ||
helpful if you are running the debugger set to stop whenever an exception is | ||
thrown. | ||
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IBsonSerializable semi-deprecated | ||
--------------------------------- | ||
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The LINQ support relies heavily on the new methods added to IBsonSerializer. | ||
Because of this it is highly encouraged that in the future you always opt to | ||
write an IBsonSerializer for your class instead of having it implement | ||
IBsonSerializable (see the notes for MongoDBRef and SystemProfileInfo for | ||
examples of where the driver itself has switched from IBsonSerializable to | ||
using a IBsonSerializer). IBsonSerializable still has a modest role to play | ||
in classes that just need to be serialized quickly and simply and for which we | ||
won't be writing LINQ queries (for example, the driver's Builders and Wrappers | ||
still use IBsonSerializable). | ||
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LINQ query support | ||
------------------ | ||
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As mentioned earlier in the release notes more information about the new | ||
support for LINQ queries can be found in the forthcoming LINQ tutorial: | ||
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http://www.mongodb.org/display/DOCS/CSharp+Driver+LINQ+Tutorial | ||
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Locking issues | ||
-------------- | ||
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A number of locking issues related to connection pooling have been resolved. | ||
These issues were particularly likely to occur if you had more threads than | ||
the maximum size of the connection pool and were using the connections heavily | ||
enough that the connection pool could be used up. | ||
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MongoCredentialsStore | ||
--------------------- | ||
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You can now create a credentials store which contains credentials for multiple | ||
databases (the name of the database is the key and the credentials are the | ||
value). The credentials store must be set up (in the MongoServerSettings) | ||
before you call MongoServer.Create, so it is only intended for scenarios | ||
where you have a fixed set of credentials that aren't going to change at runtime. | ||
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MongoDBRef no longer implements IBsonSerializable | ||
------------------------------------------------- | ||
|
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MongoDBRef used to handle its own serialization by virtue of implementing | ||
IBsonSerializable. But the IBsonSerializable interface is not helpful when we | ||
try to add support for writing LINQ queries against components of a MongoDBRef. | ||
Instead, there is now a MongoDBRefSerializer which handles serialization of | ||
MongoDBRefs, while at the same time implementing GetMemberSerializationInfo | ||
which enables the LINQ implementation to support LINQ queries against | ||
MongoDBRefs. | ||
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MongoInsertOptions/MongoUpdateOptions constructor changed | ||
--------------------------------------------------------- | ||
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The constructors for MongoInsertOptions and MongoUpdateOptions used to require | ||
that the collection be passed in as a parameter. The purpose was to allow | ||
the constructor to inherit some of the options from the collection settings. | ||
To the developer however, this was awkward, as it required providing the | ||
collection where it seemed to be redundant. By handling default values in a | ||
different way we no longer require the collection to be supplied to the | ||
constructors. The old constructors (that require the collection parameter) are | ||
still temporarily supported but have been marked as deprecated with a warning. | ||
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MongoServer Admin properties and methods removed | ||
------------------------------------------------ | ||
|
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The following Admin properties and methods have been removed from MongoServer: | ||
AdminDatabase, GetAdminDatabase, RunAdminCommand, and RunAdminCommandAs. The | ||
reason for removing them is that many developers would never use them anyway, | ||
and adding new overloads for providing admin credentials would have resulted | ||
in even more of these rarely used properties and methods. If you were using | ||
any of these methods or properties they can easily be replaced with calls to | ||
methods of an instance of MongoDatabase (use one of the overloads of | ||
GetDatabase with "admin" as the database to get a reference to the admin | ||
database). | ||
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RequestStart/RequestDone | ||
------------------------ | ||
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Recall that the purpose of RequestStart is to tell the driver that a series of | ||
operations should all be done using the same connection (which in the case of a | ||
replica set also implies using the same member of the connection set). Which | ||
member of a replica set was chosen depended on the slaveOk parameter: a value | ||
of false meant that the primary had to be used, and a value of true meant that | ||
an arbitrary secondary would be used. A new overload of RequestStart now allows | ||
the caller to specify which member should be used, which can be very useful for | ||
implementing custom query routing algorithms or for querying specific members | ||
of a replica set. In general though, keep in mind that you should *not* be | ||
using RequestStart unless you have an unusual scenario which requires it. | ||
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SocketTimeout default changed | ||
----------------------------- | ||
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The default value for SocketTimeout has been changed from 30 seconds to 0, | ||
which is a special value meaning to use the operating system default value, | ||
which in turn is infinity. If you actually wanted a SocketTimeout you now | ||
have to set it yourself. The SocketTimeout is currently a server setting, but | ||
most likely in a future release it will be possible to set it at the | ||
individual operation level. | ||
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SystemProfileInfo no longer implements IBsonSerializable | ||
-------------------------------------------------------- | ||
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See the notes for MongoDBRef. SystemProfileInfo no longer implements | ||
IBsonSerializable for the same reasons, and there is a new | ||
SystemProfileInfoSerializer instead. |
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