Enterprise Service Bus libraries for .NET – NServiceBus

Tuesday, 14 November 2017

One in a series of posts giving a quick overview of ESB libraries for .NET

Originally an open-source library developed by Udi Dahan, the licensing was changed after version 2 to put it on a more commercial footing, and the software is now developed and supported by Udi’s company – Particular Software. The source code remains on Github.

NServiceBus is a tried and tested library. It has grown a lot since it's humble beginnings and now is once part of a suite of tools and libraries for building distributed applications. It's no surprise that Udi Dahan just happens to be highly regarded as an expert in distributed software architecture.

https://docs.particular.net/nservicebus/messaging/publish-subscribe/publish-handle-event

Messages

Messages need to either implement a marker interface or use defined conventions.
namespace Domain.Messages
{
  public class UserCreatedEvent : IEvent
  {
    public string Name { get; set; }
  }
}
Or
var conventions = endpointConfiguration.Conventions();

conventions.DefiningEventsAs(
 type =>

     {
       return type.Namespace == "MyNamespace.Messages.Events";
 });

Publishing

You can publish an event from within another handler or when you create an endpoint.
This example shows publishing an event from an endpoint:

var endpointInstance = await Endpoint.Start(endpointConfiguration)
    .ConfigureAwait(false);
    await endpointInstance.Publish(new MyEvent())
      .ConfigureAwait(false);

Subscribing

To handle an event, implement IHandleMessages<T>

public class UserCreatedHandler : IHandleMessages<UserCreatedEvent>
{
  public Task Handle(UserCreatedEvent message, IMessageHandlerContext context)
  { … }
}

NServiceBus will automatically locate handlers by looking for implementations of IHandleMessages<T>



Enterprise Service Bus libraries for .NET

Sunday, 5 November 2017

As a software application becomes larger, you may want to break it into separate parts, both to manage complexity but also to aid scalability. But if you break an application apart, how will the separate parts communicate? One approach is to employ messaging using a publish/subscribe (pub/sub) bus.

A few years ago, I worked on an application that used NServiceBus just for this purpose, but I thought it would be useful to survey the .NET landscape to find out what’s available today.

Here’s a summary of the libraries I’ll be looking at over the next few blog posts:

Name URL Transports Minimum Framework License Dependencies
NServiceBus v6 https://docs.particular.net/nservicebus Azure Service Bus, In-memory?, MSMQ, RabbitMQ, SQL Server 4.5.2 Commercial -
MassTransit http://masstransit-project.com/ Azure Service Bus, In-memory, RabbitMQ 4.5(.2?) Apache 2.0 GreenPipes (>= 1.2.0)
NewId (>= 3.0.1)
Newtonsoft.Json (>= 10.0.3)
Newtonsoft.Json.Bson (>= 1.0.1)
NimbusAPI https://github.com/NimbusAPI/Nimbus Azure Service Bus 4.5 MIT Microsoft.WindowsAzure.ConfigurationManager (= 2.0.3)
Nimbus.InfrastructureContracts (>= 2.0.0.98)
Nimbus.MessageContracts (>= 2.0.0.98)
WindowsAzure.ServiceBus (>= 2.1.3 && <= 2.1.4)
Shuttle.Esb http://shuttle.github.io/shuttle-esb/ MSMQ, RabbitMQ, SQL Server 4.0? BSD 3 Shuttle.Core.Infrastructure (>= 8.0.6)
Rebus https://github.com/rebus-org/Rebus Azure Service Bus, MSMQ, RabbitMQ 4.5 MIT Newtonsoft.Json (>= 9.0.1)

These libraries range from the relatively simple and tightly focused to the complete ‘enterprise-level’ configurable, extensible and/or fully supported.

Some of these libraries distinguish between an ‘event’ (notify subscribers that something has happened) and a ‘command’ (tell subscribers that they should perform an action). Some support long-running business processes, often known as ‘sagas’. Some support distributed transactions. Some use dependency injection and can integrate with an inversion-of-control container.

And because the feature sets vary so widely, I’ll just be highlighting how each library implements publishing an ‘event’ message, and how you subscribe to these messages.

Conditionally format rows in Excel depending on date range

Tuesday, 17 October 2017

Sometimes I get asked Excel questions. This is one of those times!

Given a spreadsheet with rows that contain a start and finish date, format the rows in the past, present and future in different colours, so that it looks like this:

Spreadsheet showing rows with different colours

I initially tried using a formula with Excel’s Conditional Formatting feature. Despite this being the recommended solution in some search results, I just found it set the one format for all the rows – not what I wanted. This post by Joseph D’Emanuele put me on the right track.

Here’s what I ended up doing:

  1. Add a new column next to your existing data
    Spreadsheet with extra Status column added
  2. In the first cell of this new column, insert the formula
    =IF(B2 < TODAY(), "Past", IF(A2 > TODAY(), "Future", "Current"))
  3. Copy this formula down to the remaining rows. eg.
    Spreadsheet with Status column populated
  4. Now select all the rows you want to format (for me that’s A2:D5)
  5. On the Home menu tab, select Conditional Formatting, then Manage Rules
  6. You will add 3 rules – one for each status.
  7. Click New Rule
  8. Select Use a formula to determine which cells to format
  9. In Format values where this formula is true, enter =INDIRECT("D" &ROW()) = "Future"
  10. Click Format and choose the desired formatting to apply for Future dates
  11. Click OK and repeat adding new rules for “Current” and “Past”
  12. You should end up with something like this:
    Excel's Conditional Formatting Rules Manager dialog box
  13. Click OK and you should have rows formatted different colours depending on whether the start/finish date is in the past, current or in the future!
  14. You can optionally choose to hide the Status row if you’d rather not see it all the time.

Note that the formula in the conditional formatting (=INDIRECT("D" &ROW()) = "Future") is hard-coded to the column – “D” in my case. If you move data around, you’ll need to update this to refer to the new column letter.

On the NBN

Friday, 1 September 2017

We switched over to the NBN at home a couple of months ago. Unfortunately since the last change of Government in Australia, it appears that all NBN rollouts are getting fibre to the node (FTTN) rather than original plan of fibre to the premises (FTTP). So with the node servicing our neighbourhood being a fair distance from our house, it looks like the best we can expect for the foreseeable future is ~40MB. That is a 4x increase on what we used to get with ADSL2+, but it is a shame we can’t get the full 100MB if we wanted to pay for it.

40MB isn’t too bad – I know of others that are only getting 20 (and there’s stories of some that switch over from ADSL to get a slower speed than what they used to have). Just seems a lost opportunity that if everyone had got fibre, I’m sure that would be capable of being upgraded in the future to even beyond 100MB.

ShaggyMax screen protectors

Wednesday, 30 August 2017

My old laptop ended up getting a really scratched display. The keyboard obviously had been rubbing against the glass for a while, which was a shame. I think this was made worse because the only thing separating them was two rubber feet that had come loose after a few years.

My new laptop has a different design with a small rubber strip that goes all the way around the edge, which seems to do a better job. Nevertheless, I did want to get something that would help protect the display and reduce the chance of scratches.

A bit of Googling came up with a few options. A call out to Twitter ended up with an in-person response from Ryan showing me he’d got a ShaggyMax-brand protector for his brand new 9560 (the newer version of my 9550).

That was good enough for me, so I’ve now got my own!

I bought a 15.4” Laptop Screen Protector. You can buy them through Amazon, or direct from their website. Here’s what it looks like on my laptop:


Laptop with screen protector covering keyboard

It’s a microfibre cloth that is thin enough that it doesn’t interfere with closing the lid, but hopefully will be thick enough to softly cushion and protect the glass. So far, so good.