Matthew Groves delivered part 2 of his 5-part live webinar series on AOP in .NET recently to support his upcoming book Aspect Oriented Programming in .NET, out from Manning Publications in June. The series covers insights found in his book and a variety of real-world coding examples using PostSharp.
In part 2, Matt demonstrates the method interception aspect, and looks at a real-world application of the aspect that can help with data transactions – followed by a lively Q&A session.
Q: With the use of Aspect Interceptors, does the behavior of stepping through and debugging the code in either the Interceptor or calling code change? If so, how?
A: With PostSharp, debugging works great! When PostSharp rewrites your code with IL manipulation it also makes appropriate changes to the debugging file. Which means, if you set a breakpoint in an aspect or in a method that has an aspect on it, that breakpoint will be hit when expected and you’ll get the full stack with that as well.
Q: Can you put a PostSharp attribute on an aspect’s method?
Q: Can we apply interceptors globally to all the methods in a class?
A: Absolutely. You can apply the attribute to the class and by default it will be applied to every method within that class. There are lots of customization available with PostSharp. You can customize how you want the attributes to be applied – even at assembly level.
Q: Is it possible to apply an aspect to DLL methods to which you don’t have the source?
A: In theory yes, but this scenario is not supported so you will be on your own in case of problem.
Q: Can we apply multiple aspects to a given method, and in what order are they executed?
A: In some situations, for instance if you have caching and authorization, the order in which the aspect is applied is very important. PostSharp gives us a few ways to deal with that. The simplest one is called AspectPriority where you specify a number to indicate the order in which aspects are run, and there are more robust features that PostSharp has as well to manage dependencies between aspects and aspect composition.
Q: What are some other examples of practical uses of aspects?
A: Logging, data transactions, caching, INotifyPropertyChanged, exception handling, authorization, validation, etc. In fact, PostSharp Ultimate comes with a whole suite of aspects that have been written for you. It’s a new feature in PostSharp 3 so you don’t have to spend time writing these aspects and can simply drop them in and start using them right away.
Q: Can you add an Attribute to a parent object and have it apply to all child objects?
A: Yes, using aspect inheritance.
Q: Will you show how to TDD aspects in this series, and do you show it in your book?
A: Not TDD specifically, but I have dedicated an entire chapter of my book to unit testing aspects and episode 5 in the series (May 30th) will focus on that.
Q: Does the aspect class name need to end with Attribute, as per .NET convention?
A: No, it’s not necessary. As long as you inherit from the Attribute base class, .NET will recognize it as an Attribute.
Q: Can you use PostSharp in Windows Phone 7 applications?
Q: What are the best practices for bringing dependencies into aspects?
A: That question will be covered at length during the Unit Testing Aspects episode on May 30th.
Q: When will your book be published?
A: June 14th.
If you want to ask Matt any question you may have about AOP in .NET and/or PostSharp be sure to sign-up for the series and join us every Thursday throughout the month of May.
We’re excited to announce that PostSharp 3 RTM is now available for download from Visual Studio Gallery and NuGet. After a successful RC cycle, PostSharp 3 now enters the stable quality band and replaces PostSharp 2.1 as our featured version.
PostSharp 3 marks a huge evolution from previous versions. Designed to deliver more value with less learning, PostSharp 3 is now much more than an awesome framework: using simple smart tags in the Visual Studio code editor, you can add to your code ready-made implementations of some of the most common design patterns. Other improvements include first-class support for Windows Store, Windows Phone and Silverlight apps.
Improved Visual Studio Integration
The single most striking feature of PostSharp 3 is its deeper integration with Visual Studio.
For instance, move the caret to the name of a class or a method. Visual Studio will display a smart tag proposing actions that make sense in the current context: apply a threading model, add logging, implement INotifyPropertyChanged, …
A wizard then guides you through the configuration of the aspect.
The wizard installs all required NuGet packages and generates the code for you – so you don’t have to study documentation to figure out how it works.
Of course, you can still add aspects to your code the old good way.
Ready-Made Pattern Implementations
While talking to customers, we figured out that the Pareto law also applies to our product: 80% of customers use the same top 20% aspects. We thought we would provide more value to our customers by providing ready-made implementations for the most common patterns. The results are our three first pattern libraries:
Windows Store, Windows Phone and Silverlight
In previous versions of PostSharp, support for alien .NET platforms was quite limited. The raise of Windows Phone and Windows Store stressed the importance of supporting new trends, so we decided to invest in providing first-class support for Windows Store, Windows Store and Silverlight.
I’m very pleased that we could this through Portable Class Libraries.
The first challenge was to develop a portable alternative to the system BinaryFormatter and its [Serializable] attribute. The result is the PortableFormatter class and its [PSerializable] attribute – an interesting piece of software in itself.
Deployment through NuGet and Visual Studio Gallery
When PostSharp 1 was released seven years ago, it seemed mandatory to have a setup program. Over the years, source control and build servers have conquered the world, changing requirements on deployment of development tools.
Despites important limitations, Microsoft’s NuGet and Visual Studio Gallery are becoming the de-facto standards for deployment of development components and their user interface, so we decide to get aligned with Microsoft’s lead.
We are aware of some negative consequences and will be happy to work with customers who may be affected by this choice.
Subscription-Based Maintenance Model
PostSharp 3 marks also the move from a per-version to a per-year maintenance model, as described in a previous blog post. A maintenance subscription is now included as a mandatory part of the product fee. The maintenance subscription not only gives right to major versions, but also to bug fixes.
We believe that part of our failure to deliver support for Visual Studio 2012 in time was due to our per-version revenue model. The new revenue model will allow us to release features as soon as they are needed, irrespective of the current major version number.
For more information regarding licensing and support, please read our FAQ page or contact our sales team.
Tip: Upgrade Before Summer
PostSharp 3 is now stable and it’s a good time to upgrade. During the next 2 months, the team will be ready to answer your questions and address support issues, without any other big project in the pipeline. We may be a bit slower during the vacation period, so it’s a good idea not to delay the upgrade if you can do it now.
PostSharp 3 is a big turn for our company, and so far we are very happy with the feedback and the businesses we received.
It’s official: PostSharp 3 RC was a success and we are scheduling to move PostSharp 3 to the “stable” quality band on May 2nd. That means that, on May 2nd, the stable release of the PostSharp package on NuGet will be version 3.0. Because of the way the NuGet client is implemented and how people usually author their NuGet packages, this day may turn into a little apocalypse for some of you.
Problem 1. NuGet client in Visual Studio
The NuGet user interface in Visual Studio is hardwired to always give you the latest stable version of a Package. There is no way to specify that you want to stay in an old branch. Even if NuGet allegedly supports semantic versioning, NuGet is going to try to upgrade you to a new major version even if it not backward compatible with the old one (semantic versioning says that backward compatibility can be broken when the major version number changes).
However, PostSharp 3 is not fully backward-compatible with PostSharp 2:
- There are very minor API changes, and
- You will need to acquire a new license
Problem 2. Packages with dependencies on PostSharp
NuGet packages that have a dependency on PostSharp 2 may install incorrectly after the PostSharp 3 release because NuGet is going to install PostSharp 3 instead of PostSharp 2.
To prevent NuGet from installing PostSharp 3, you need to edit your .nuspec file and add an upper bound to the PostSharp version:
<dependency id="PostSharp" version="[2.1,3)" />
That’s it. Happy PostSharping!
If there’s one topic that is subject to almost religious observance, this is unit testing.
There has been much hesitation in the community about how PostSharp aspects should be tested and how aspects can consume dependencies from a dependency injection container.
Obviously, we have a lot of experience testing aspects. I finally took the time to write down a set of practices that can be used to create efficient tests of aspects. I also show techniques that allow aspects to consume services from a dependency injection container. Last but not least, I publish and document a test framework for aspect build-time logic, especially logic emitting build-time errors and warnings. The framework is derived from the one we are using internally.
More on our online documentation.
Some of you expressed the wish of to be able to read the PostSharp documentation offline on their tablet or ebook reader, so we did it. Our conceptual documentation is now available as a print-ready PDF document, and looks awesome on screen and paper.
It’s incredible the content renders to 140 pages, and it does not even include the class reference, which is still only available online or for download as a CHM.
But there’s an issue: although it looks like a book, it has been designed as a reference document and is not the best introduction to PostSharp. Online tutorials are still the preferred way to get started, and they are not included in the PDF.
We’re happy to announce that PostSharp 3 has finally reached the RC quality band. This means that it is now sufficiently documented, internal testing is completed, all known bugs (except some minor ones) have been fixed, and the rate of new bug reports has significantly decreased. We plan to move to RTW with two weeks, unless important bugs delay this objective.
It is now a good time for small teams to upgrade to the new versions. The procedure is described in our online documentation. We are planning more articles and webinars regarding upgrades and deployment of PostSharp 3 in the next weeks.
We reached one of the last milestones before the RC: publishing the documentation! You can now browse it online from http://doc.postsharp.net/.
Yet this is not a good time for all of you to rush on PostSharp 3 because I’ll have vacation (till April 7th) before the dead march to RTM. Support will be provided as usually, but we won’t do bug fixing releases until I’m back.
I like to write the documentation myself because it forces me to do a last API review and makes sure all concepts line up. Documenting is a never-ending job, and I hope this first version of the documentation cover the most important questions. Yet, there are still important holes. Let me know if you find one that is specially important to you, so I can prioritize.
This being done, the road is now clear for RC and then RTM. Finally!
We just pushed PostSharp 3.0.13 online, and this is just to inform you of the awful update procedure from previous builds.
Why is the upgrade procedure cumbersome?
PostSharp 3.0.12 included NuGet 2.1 in its payload. Unfortunately, because of limitations of the Visual Studio Extension Installer (VsixInstaller), it was not possible to install PostSharp when NuGet 2.2 was already installed. We had other problems with the way that VsixInstaller handled dependencies (I’m quite confident to say that it is a broken feature), so we decided to handle dependencies manually, without relying on VsixInstaller.
Because of the dependency to NuGet, PostSharp needed to be installed for All Users, requiring elevation during installation. But since we don’t have the dependency to NuGet anymore, PostSharp does not need to be installed with elevated privileges anymore. This is one more situation that VsixInstaller does not handle properly.
What is the proper procedure?
Since Visual Studio Extension Installer is not able to upgrade PostSharp 3.0.12 to 3.0.13, you will have to uninstall PostSharp manually.
- Start Visual Studio with elevated privileges.
- Go to Tools / Extensions and Updates, click on PostSharp, then click Uninstall
- Install the new PostSharp
That’s it. Perhaps that was not so awful.
Remember that this procedure updates only the Visual Studio Extension for PostSharp. You can upgrade the compiler itself using NuGet.
It's been a few days since we released our new website. Although PostSharp 3 is still in preview, we've become confident enough in its quality to start selling licenses – with a 30% discount until we reach RTM. I wanted to quickly tell you about changes made to the PostSharp product lineup, including maintenance, pricing, and upgrade conditions.
New focus on design patterns
In the past years, we've successfully positioned PostSharp as the leading framework for Aspect-Oriented Programming in .NET. With time and customer feedback, we've realized that AOP was only an instrument serving automation and enforcement of design patterns. Unlike AOP, design patterns are readily understood and accepted by the majority. We published our view of Design Pattern Automation in a recent article on InfoQ.
PostSharp is now composed of the following members:
Note that Pattern Libraries were previously incubated as a satellite project of PostSharp 2.1, where they were named toolkits. They are now an integral and supported member of our product line.
We're very proud of our new website, reflects our new vision of PostSharp. There are plenty of tutorials for beginners and intermediate users, and more are coming.
What's New in PostSharp 3?
PostSharp 3 is not just about repackaging old ideas differently. We also added a lot of new features and support for the latest platforms:
- First-class support for Silverlight, Windows Phone, and Windows Store. Not only did we add new platforms, but we also brought all features to most cousins of the .NET Framework. Best of all: these platforms are supported through a single Portable Class Library, so it's now possible to write truly portable aspects. A central component of this feature is the Portable Serializer, similar in function to the BinaryFormatter (just replace [Serializable] by [PSerializable]).
- Pattern Libraries, providing ready-made implementation of some the most common patterns. Improvements over PostSharp 2.1 Toolkits include better management through logging profiles, logging to Enterprise Library, code contracts, and performance enhancements.
- Smart tags in the code editor help you adding ready-made aspects to your application without coding – without even reading our Getting Started. Smart tags are completed with a comprehensive wizard interface coupled with NuGet and a code generator.
- Support for Visual Studio 2012, including the dark theme.
- Transparency to all obfuscators: PostSharp does not rely on any string references that may be broken during serialization.
- Better differentiation of "reference assemblies" and "runtime assemblies".
- New approach to licensing that will allow to install the license key to source control.
- Streamlined deployment through NuGet and Visual Studio Gallery
New Maintenance Model
PostSharp 2 was ruled by a "major-version" maintenance model: all updates (minor versions and bug fixes) within a major version were available for free. We released important improvements as "bug fixes": for instance, support for .NET 4.5 was included into PostSharp 2.1 because PostSharp 3 was not ready. This maintenance model created a conflict of interest between us (we need to be paid for our work) and our customers (you can't wait for a new major version to get new necessary features). It was time to change.
PostSharp now comes with 1-year of maintenance subscription included that gives you access to free updates, bug fixes and premium support. Every license key includes the subscription end date, which is tested against the build date of PostSharp. Importantly, licenses are still perpetual: if you can use a given PostSharp build one day, you can use it forever (except with the trial license).
Please read our Licensing & Maintenance FAQ for details. Note that we have an updated License Agreement that reflects these changes. If you need to continue with the previous license agreement, please contact our sales team.
New Product Line
There are now three distinct editions available.
- PostSharp Express (formerly Starter Edition) – for getting started with simple custom design pattern automation. Free as in beer.
- PostSharp Professional – for automating custom design patterns (aspect framework) and logging (diagnostics pattern library). Price: 449$ or 329€ including maintenance subscription.
- PostSharp Ultimate – for automating custom design patterns (aspect framework) and enforcing design rules (architecture framework), includes all ready-made design pattern libraries. Price: 799$ or 589€ including maintenance subscription.
For more information, see the feature matrix
of all editions. As you can see, we dropped the Personal License. On the other side, we're now offering free licenses to all freelancers and consultants, additionally to students, educational facilities, and influencers of all sorts. We're also offering a one-time 1000$ discount to all businesses enrolled in BizSpark.
We're giving 6 months of maintenance subscription for free to all customers:
- Customers without support subscription fully-featured PostSharp Ultimate for free and get 6-months of maintenance starting from the original date of purchase. Practically, it means that this offer only applies to customers who have purchased PostSharp later than six month ago.
- Customers with a current support subscription get PostSharp Ultimate for free and will receive an additional 6 months of maintenance, at no cost.
- Other customers can benefit from our upgrade price (224$/164€ for PostSharp Professional or 399$/299€ for PostSharp Ultimate).
Technically, we consider PostSharp 3 mature enough for most situations. However, if you cannot afford taking risks right now (tight deadline, large team), we recommend to wait until RTM before doing the upgrade. The principle obstacle on the path to RTM is now the lack of documentation for new features and new deployment options.
We understand that some teams don't want to upgrade to PostSharp 3 now, and may need to acquire new PostSharp 2.1 licenses. When you acquire a PostSharp 3 commercial license, you become eligible for a free PostSharp 2.1 license. To request your license key, please contact our sales team. The offer does not apply to PostSharp Express.
For a limited time, we’re offering a special discount on PostSharp 3 purchases. From now until the RTM announcement, purchase any new PostSharp Professional or PostSharp Ultimate license and save 30% off your order by entering the discount code POSTSHARP3 during checkout. This offer also includes license upgrades and maintenance subscription renewals.
PostSharp 3 is going to change the way software engineers think about design patterns. Happy PostSharping!
Just a very short post to update you on the status on PostSharp 3. We spent the last 2 months stabilizing the new version, polishing new features without adding any new one, adding more tests, and running test suites on all supported platforms. The team is now quite satisfied with the quality, so we decided to move the quality label from Alpha to Beta. It means that we are code complete, that no important refactoring is planned, and that the only changes should be bug fixes and documentation. We have a few minor UI and UX bugs open, but there should be nothing serious.
The main task that separates us from the Release Candidate status is API and reference documentation. That’s what we are going to work on during the next couple of weeks. The API could still change during this process because documenting also works as an excellent review process.
If you are already using PostSharp 2.1, it is now a good time to try to upgrade to the next version and see if anything goes well. We don’t recommend you to “commit” the upgrade to your main development branch yet (and the PostSharp 3 does not come with a go-production license yet), but it would really help us to have feedback from the field. To upgrade to PostSharp 3, just use NuGet package manager at solution-level and add the pre-release PostSharp package to all projects.
We’re looking forward for your feedback.