Learning NServiceBus - Second Edition

Table of Contents

Learning NServiceBus Second Edition

Credits

Foreword

Early influences

Starting with MSMQ

What open source meant in those days

Clouds on the horizon

Unexpected success

Fast-forward to today

Back to David, and this book

About the Author

About the Reviewers

www.PacktPub.com

Support files, eBooks, discount offers, and more

Why subscribe?

Free access for Packt account holders

Instant updates on new Packt books

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Getting on the IBus

Why use NServiceBus?

Getting the code

NServiceBus NuGet packages

Our first example

Creating a message assembly

Creating a service endpoint

Creating a message handler

Sending a message from an MVC application

Creating the MVC website

Running the solution

Summary

2. Messaging Patterns

Commands versus events

Eventual consistency

Achieving consistency with messaging

Events

Publishing an event

Subscribing to an event

Message routing

Summary

3. Preparing for Failure

Fault tolerance and transactional processing

Error queues and replay

Automatic retries

Replaying errors

Second-level retries

RetryDemo

Messages that expire

Auditing messages

Web service integration and idempotence

Summary

4. Hosting

Hosting types

NServiceBus-hosted endpoints

Self-hosted endpoints

Assembly scanning

Choosing an endpoint name

Dependency injection

Message transport

Reasons to use a different transport

MSMQ

RabbitMQ

SQL Server

Windows Azure

Persistence

In-memory persistence

NHibernate

RavenDB

Windows Azure

Polyglot persistence

Message serialization

Transactions

Purging the queue on startup

Installers

Startup

Send-only endpoints

Summary

5. Advanced Messaging

Unobtrusive mode

TimeToBeReceived attribute

Message versioning

Polymorphic dispatch

Events as interfaces

Specifying the handler order

Message actions

Stopping a message

Deferring a message

Forwarding messages

Message headers

Property encryption

Transporting large payloads

Exposing web services

Summary

6. Sagas

Long-running processes

Defining a saga

Finding saga data

Ending a saga

Dealing with time

Design guidelines

Business logic only

Saga lifetime

Saga patterns

Messages that start sagas

Retraining business stakeholders

Persistence concerns

RavenDB

NHibernate

Azure

Unit testing

Testing events as interfaces

Scheduling

Summary

7. Advanced Configuration

Extending NServiceBus

IConfigureThisEndpoint

INeedInitialization

IWantToRunWhenBusStartsAndStops

Dependency injection

Unit of work

Message mutators

The NServiceBus pipeline

Building behaviors

Ordering behaviors

Replacing behaviors

The pipeline context

Outbox

DTC 101

Life without distributed transactions

Outbox configuration

Session sharing

Summary

8. The Service Platform

ServiceControl

ServiceInsight

Endpoint Explorer

Messages

Main view

Flow Diagram

Saga

Sequence Diagram

Other tabs

ServicePulse

Endpoint activity

Failed messages

Custom checks

Getting notified

ServiceMatrix

Summary

9. Administration

Service installation

Infrastructure installers

Side-by-side installation

Profiles

Environmental profiles

Feature profiles

Customizing profiles

Logging profiles

Customizing the log level

Managing configurations

Monitoring performance

Scalability

Scaling up

Scaling out

Decommissioning a MSMQ worker

Extreme scale

Multiple sites

Virtualization

MSMQ message storage

Clustering

Transport administration

Summary

10. Where to Go from Here?

What we've learned

What next?

Index

Learning NServiceBus Second Edition

Learning NServiceBus Second Edition

Copyright © 2015 Packt Publishing

All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.

Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

First published: August 2013

Second edition: January 2015

Production reference: 1250115

Published by Packt Publishing Ltd.

Livery Place

35 Livery Street

Birmingham B3 2PB, UK.

ISBN 978-1-78439-292-5

www.packtpub.com

Credits

Author

David Boike

Reviewers

Prashant Brall

Roy Cornelissen

Hadi Eskandari

Daniel Marbach

Commissioning Editor

Dipika Gaonkar

Acquisition Editor

Larissa Pinto

Content Development Editor

Kirti Patil

Technical Editor

Chinmay S. Puranik

Copy Editors

Dipti Kapadia

Vikrant Phadke

Project Coordinator

Kranti Berde

Proofreaders

Simran Bhogal

Maria Gould

Ameesha Green

Bernadette Watkins

Indexer

Monica Ajmera Mehta

Graphics

Sheetal Aute

Abhinash Sahu

Production Coordinators

Arvindkumar Gupta

Nilesh R. Mohite

Cover Work

Arvindkumar Gupta

Nilesh R. Mohite

Foreword

Unlike many people who write a foreword for a book, I have myself not actually written a book yet, so I am probably going about this the wrong way. Also, of all the books that I have read, I have almost never read the foreword, which makes me wonder who is actually reading this.

That being said, I think that 10 years of blogging has actually prepared me very well to write this foreword, and it will end up being roughly as long as my regular blog posts.

In any case, I am extremely happy to see how well the first edition of this Learning NServiceBus book has done, and when David asked me to write the foreword for this second edition, I was more than willing to oblige.

Now that you've picked up this book, I think it's fair to assume that you have heard something about NServiceBus, maybe even downloaded it, played with it, or used it on a project or two. What you might not know is the story of how it all began and how we ended up where we are today—seeing the second edition of Learning NServiceBus being published.

Early influences

Almost 15 years ago, I was working as a developer on a gigantic command and control system developed in a language called Ada. This is what Wikipedia has to say about Ada:

[Ada] has built-in language support for explicit concurrency, offering tasks, synchronous message passing, protected objects, and non-determinism.

These were very important attributes for a system that needed to be super reliable, highly performant, and very scalable. Little did I realize at that time how profound an effect this relatively unknown programming language would have on the rest of my career.

In my next company, a software development firm—the kind that does turnkey projects for its customers—I continued my focus on command and control systems, this time using the fairly new .NET platform from Microsoft. The thing was that many of the abilities that I'd come to rely on in Ada were (to me) curiously absent from .NET.

Like any good craftsman who has gotten used to a certain tool, I started looking around for a replacement, and when I couldn't find one, I went and made it myself.

Starting with MSMQ

Although the main message from Microsoft at the time was all about XML Web Services and .NET Remoting, I found that there was support for a message passing model in .NET that was actually built on a piece of infrastructure that was considerably older (originally built in the NT 3.5.1 days, but released with NT 4.0 in 1997). At that time, MSMQ had made it to version 3.0 which, later on, I learned was the magic number when it came to stability of software built by Microsoft.

Still, I found the System Messaging API to be a little too close to the metal for me to feel comfortable using it directly from my application logic, so I created a wrapper library, which gave me some much needed abstraction.

As I moved from one project to the next, I found this little library to be more and more useful and kept on extending and refining it. The developers in my teams seemed to like working with it as well.

After the third or fourth project, I decided to approach the company's management, suggesting that we should consider turning this infrastructure into a product. Seeing how useful it was to us on our projects, I figured that it was a no-brainer.

It turned out that this company had gone down the productization path in the past and had gotten badly burned in the process. As a result, they were very hesitant to make the same mistake again. Realizing that it wasn't going to happen, I managed to get permission to release the infrastructure to the world as an open source project, but only after legal confirmation that there would be no support or other liabilities to the company.

Thus, in 2007, NServiceBus was born.

This also happened to be the time when I started transitioning into my own private consulting practice.

What open source meant in those days

As I continued to use NServiceBus in my work projects, I kept tweaking and expanding it. Version numbers didn't mean a whole lot, and through 2008, the version progressed rapidly from 1.6.1 to a release candidate of 1.9. If it worked on my project, I considered it worthy to ship.

Documentation was practically nonexistent and developers leaned pretty heavily on samples to figure out what the software did, asking questions on the discussion group when they ran into cryptic error messages (of which there were many).

In 2008, the 5-day format of my Advanced Distributed Systems Design course was launched, which was an extension of the 2-day workshop on the same topics I had been teaching since 2006. This course was based on many of the learnings from my old Ada days and continues to serve as the architectural underpinning of much of NServiceBus to this day.

April 2009 brought some stability with the final release of version 1.9 but came with a marked increase in the amount of consulting and training I was doing. This was great for me as I could finally afford to turn down work in order to continue the development of NServiceBus. This worked out great and in March 2010, the much-heralded NServiceBus 2.0 was finally released.

Clouds on the horizon

By almost every measure, things were going great. More companies were adopting NServiceBus and bringing me in for consulting. The Advanced Distributed Systems Design course was getting quite popular, and for a while, I was teaching it almost once a month in a different country around the world. Unfortunately, almost 6 months had gone by without any meaningful development on the code base.

Then it hit me that if another year or two would pass by in this manner, NServiceBus would start to get stale and the companies that had used it in their systems would eventually have to replace it with something else (costing them quite a lot of time and money).

I had lived through this story several times as a consumer of open source projects. As long as the project wasn't too intertwined in our system, it wasn't too painful to remove it. The thing was that NServiceBus was a fairly large framework that supported broad cross-sections of both client-side and server-side logic, so there would be no simple way to replace it.

I tried to figure out how I could guarantee that the development of the code base would stay a priority, yet as long as my primary source of revenue was services (consulting and training), I couldn't see how it would work. The only solution seemed to be to start charging money for NServiceBus licenses. Although larger companies were able to keep an open source core and sell other products around it, I hadn't seen or heard of any one-person operations that had been able to bootstrap their way into that.

I had no idea whether this would work, and whether the open source community that had supported me all this time would accept it or turn their backs on me, but I felt that it needed to be done. Unless there was revenue coming in directly from the features of the product, it wouldn't have a future.

Therefore, in late 2010, I founded the NServiceBus company and steeled myself for the worst.

Unexpected success

Seeing the overwhelmingly positive responses from the community was quite a surprise. Sure, there were those that grumbled, but only a handful ultimately decided to switch to something else.

I had made it—living the dream!

However, lest I paint an overly rosy picture, I knew nothing about running a product company. Pricing was harder than I ever imagined it would be. The legal factor was a crazy-complex where, even after the lawyers explained to me all about things such as indemnification, they told me that it was ultimately my decision whether to accept the client's terms or not.

Most importantly though, I felt that I had secured the future of NServiceBus. As long as there was money to be made from it, even if something happened to me, one of the other contributors to the project could afford to take it over.

Fast-forward to today

So much has happened since those early days of 2011 that it could probably fill its own book, and maybe one of these days, I'll put the proverbial pen to paper and make it happen. Anyway, here are the highlights:

March 2012: NServiceBus 3.0 released. This includes official Azure support for the first time.

July 2013: NServiceBus 4.0 released. This includes modeling and debugging tools.

2013: The company begins to rebrand itself as Particular Software.

August 2013: The first edition of the Learning NServiceBus book comes out.

November 2013: Monitoring tools released for NServiceBus.

April 2014: The first release of the integrated Particular Service Platform.

September 2014: NServiceBus 5.0 released, no longer depending on distributed transactions.

Also, I've got to tell you, the quality of each version has gone up dramatically over time. The level of testing that goes into each release is impressive—looping through every permutation of containers, persistence, transport, and even versions of supported operating systems and databases.

Back to David, and this book

When David wrote the first edition of this Learning NServiceBus book, it was something of a defining moment for NServiceBus—there was finally a book. The technology industry is awash in books about almost every piece of software out there, but for most of the time, NServiceBus was absent. Decision makers took us more seriously when we'd bring physical books with us for their teams.

Books matter!

With this latest edition, David goes beyond just covering the changes that happened in NServiceBus version 5.0, and goes even deeper into the reasoning behind those changes and why you'd want to use which features and when.

As one of the most prominent members of the NServiceBus community, David has interacted with the NServiceBus development team on a regular basis, given valuable feedback on our API, and debated with us on our future technology roadmap.

You're in for a treat.

Udi Dahan

Founder and CEO, Particular Software

About the Author

David Boike is a principal consultant with ILM Professional Services, with experience in building and teaching others how to build distributed systems. He is an NServiceBus Champion, official NServiceBus and RavenDB trainer, Xamarin Certified developer, and amateur beer brewer. He lives in the Twin Cities with his wife and two children.

About the Reviewers

Prashant Brall is a principal consultant and senior software architect and developer at Veritec (www.veritec.com.au) in Canberra, Australia. He has over 19 years of experience in application development, which includes 4 years of work in the USA for Fortune 500 companies and major financial corporations. As a software professional, Prashant loves crafting software and enjoys writing about his experiences on his blog at https://prashantbrall.wordpress.com. He has also reviewed Instant AutoMapper published by Packt Publishing.

In his leisure time, he enjoys watching movies with his wife and playing musical instruments such as piano and guitar.

A big thank you to my wife, Jhumur, for her love and support and for being my best friend. I would also like to thank my parents, Mr. Hem Brall and Mrs. Prabha Brall, for encouraging me and showing me the difference between right and wrong throughout my childhood.

Hadi Eskandari, while working on both Java and .NET technologies, has developed enterprise-level applications on both platforms. He is a regular contributor to various open source projects. Currently, he is working as a senior software developer at Readify, which is a leading company on .NET technology in Australia.

I'd like to thank my family for their support. This wouldn't have been possible without your encouragement and help.

Roy Cornelissen works as a software architect in the Netherlands. With over 15 years of experience in IT, he has designed and built many enterprise systems for customers using Microsoft, Particular, and Xamarin technologies.

As a lead consultant at Xpirit, Roy is responsible for the vision and strategy for the Enterprise Mobile Development competence. He specializes in designing and building mobile applications for iOS,