Better Living

108 Pages·2016·22.6 MB·English

THE MICROSOFT JOURNAL FOR DEVELOPERS AUGUST 2016 VOL 31 NO 8
magazine
Better Living
Through DevOps....16, 24, 30
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S R E P O L E V E D R O F L A N R U O J T F O S O R C I M E H T V 6 1 0 2 T S U G U A OL 31 NO 8
magazine
eB et iL r iv ng
gu o r h T eD0 3 h , 4 2 , 6 1 . . . . s p O v
From Code to Customer: COUL M N S
Exploring Mobile DevOps CUT T I N G E D G E
arK igmhcskco rB itd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Beyond CRUD: Commands,
Events and Bus
Dino Esposito, page 6
Applying DevOps to a
A P O T I N T S AD
Software Development Project
EF Core Change-Tracking
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Behavior: Unchanged,
Modifed and Added
Commit to Git: Source Control Julie Lerman, page 10
in Visual Studio 2015
TES T R U N
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Lightweight Random
Number Generation
Write Apps with Visual Studio Code James McCaffrey, page 64
and Entity Framework THE W O R K I N G
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How To Be MEAN:
Real-World ASP.NET Core MVC Filters Exploring ECMAScript
Ted Neward, page 70
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D O N ’ T G E T M A E R T S E T D
Sing a Song of Silicon
David Platt, page 80
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magazine
AUGUST 2016 VOLUME 31 NUMBER 8
ID STATEMENT MSDN Magazine (ISSN 1528-4859) is
published monthly by 1105 Media, Inc., 9201 Oakdale
Avenue, Ste. 101, Chatsworth, CA 91311. Periodicals
General Manager Jef Sandquist postage paid at Chatsworth, CA 91311-9998, and at
additional mailing offces. Annual subscription rates
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payable in US funds are: U.S. $35.00, International
Editorial Director Mohammad Al- Sabt
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Editor’s NotE MICHAEL DESMOND
DevOps Directive
Writing good sofware is hard. Managing the process of writing, How serious is Microsof about DevOps? Based on the company’s
maintaining and delivering good software is even harder— $400 million-plus purchase of Xamarin in March and the acquisition
particularly when you add cross-platform mobile app development of tools-maker HockeyApp at the close of 2014—very. At the Build
to the mix. Which is why Microsoft has been so busy improv- conference in March, Brown demoed the extended DevOps capa-
ing and extending its DevOps solutions, addressing the sofware bilities in the cloud-based Visual Studio Team Services tool. As he
development lifecycle from planning and development, to testing told the audience before showing how the DevOps tool chain can
and build, to deployment and monitoring. improve a mobile app development scenario: “I’m just going to rub
Donovan Brown is a senior DevOps program manager at a little DevOps on it and make it better.”
Microsof. He defnes DevOps as “the union of people, process and Al Hilwa, program director for sofware development research
products to enable continuous delivery of value to our end users.” at IDC, was impressed. “Microsof wants its tools for developers to
Tat focus on value is important, as it goes beyond simple code be what Ofce is for knowledge workers. Tat is, they want to be
metrics to emphasize the tangible impact that delivered sofware the No. 1 toolchain for cross-platform development, mobile, cloud,
has on the business, its workers and customers. everything,” he says. “Tis is a tall order, but they are in fact exe-
cuting on it and building a multi-platform ecosystem. Given their
history with developers, you have to give them good odds on this.”
Every code writing effort, Tis is exciting stuf. Features like Xamarin Test Cloud let developers
test app code against ranks of cloud-hosted smartphones and devices,
from traditional client-server while HockeyApp provides a way to distribute pre-release code to
select groups of testers and receive both user feedback and app telemetry.
applications to Android- and To help get ahead of it all, this month we’re launching the frst in
a series of articles focused on mobile DevOps, starting with Kraig
iPhone-based mobile apps, Brockschmidt’s feature, “From Code to Customer: Exploring Mobile
DevOps.” Also this month, the ALM Rangers team at Microsof
stands to improve within a robust shows how to leverage DevOps to build Visual Studio Team Services
Extensions, while Jonathan Waldman explores the integration of
DevOps environment. Git source code management with Visual Studio 2015.
Te Microsof efort on DevOps is intriguing in that it promises
to lif all boats. Every code writing efort, from traditional client-server
“To continuously deliver value implies that you are able to monitor applications to Android- and iPhone-based mobile apps, stands
and validate that value is actually delivered,” he says. “Just copying to improve within a robust DevOps environment.
fles to a server and hoping that people use them—there is no way What are your thoughts
to quantify or even qualify if I delivered value.” on Microsof’s DevOps push?
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Cutting EdgE DINO ESPOSITO
Beyond CRUD: Commands, Events and Bus
In recent installments of this column, I discussed what it takes to and keywords of today such as CQRS and Event Sourcing. In this
build a Historical create, read, update, delete (H-CRUD). An column, I’ll take the idea of H-CRUD much further to make it merge
H-CRUD is a simple extension to classic CRUD where you use with the core idea of Event Sourcing. You’ll see how H-CRUD can
two conceptually distinct data stores to persist the current state of turn into an implementation made of commands, buses and events
objects and all the events that happened during the lifetime of indi- that at frst might look like an overly complex way to do basic reads
vidual objects. If you simply limit your vision to the data store that and writes to a database.
contains the current state, then all is pretty much the same as with
classic CRUD. You have your customer records, your invoices, orders
and whatever else forms the data model for the business domain. The real cardinality of the event/
Te key thing that’s going on here is that this summary data store
isn’t the primary data store you create, but is derived as a projection aggregate association is written
from the data store of events. In other words, the essence of building
a historical CRUD is to save events as they happen and then infer in the ubiquitous language of the
the current state of the system for whatever UI you need to create.
Designing your solution around business events is a relatively business domain.
new approach that’s gaining momentum, though there’s a long way
ahead for it to become the mainstream paradigm. Centering your
design on events is benefcial because you never miss anything One Event, Many Aggregates
that happens in the system; you can reread and replay events at In my opinion, one of the reasons sofware is sometimes hard to write
any time and build new projections on top of the same core data on time and on budget is the lack of attention to the business language
for, say, business intelligence purposes. Even more interesting, spoken by the domain expert. Most of the time, acknowledging
with events as an architect, you have the greatest chance to design requirements means mapping understood requirements to some
the system around the business-specifc ubiquitous language. Well sort of relational data model. Te business logic is then architected
beyond being a pillar of Domain-Driven Design (DDD), more to tunnel data between persistence and presentation, making any
pragmatically the ubiquitous language is a great help to understand necessary adjustments along the way. While imperfect, this pattern
the surrounding business domain and plan the most effective worked for a long time and the number of cases where monu-
architectural diagram of cooperating parts and internal dynamics mental levels of complexity made it impractical were numerically
of tasks and workfows. irrelevant and, anyway, brought to the formulation of DDD, is still
the most efective way to tackle any sofware projects today.
Events are benefcial here because they force a diferent form of
Most of the time, acknowledging analysis of the domain, much more task-oriented and without the
urgency of working out the perfect relational model in which to save
requirements means mapping data. When you look at events, though, cardinality is key. In H-CRUD
examples I discussed in past columns, I made an assumption that
understood requirements to could be quite dangerous if let go without further considerations
and explanation. In my examples, I used a one-to-one event-to-
some relational data model. aggregate association. In fact, I used the unique identifer of the
aggregate being persisted as the foreign key to link events. To go
with the example of the article, whenever a room was booked, the
Te implementation of events you might have seen in my May system logs a booking-created event that refers to a given booking ID.
(msdn.com/magazine/mt703431) and June 2016 (msdn.com/magazine/mt707524) To retrieve all events for an aggregate (that is, the booking) a query
columns was very simple and to some extent even simplistic. Te on the events data store for the specifed booking ID is sufcient to
main purpose, though, was showing that any CRUD could be get all information. It defnitely works, but it’s a rather simple sce-
turned into an H-CRUD with minimal efort and still gain some nario. Te danger is that when aspects of a simple scenario become
benefts from the introduction of business events. Te H-CRUD a common practice, you typically move from a simple solution to a
approach has some obvious overlapping with popular acronyms simplistic solution. And this isn’t exactly a good thing.
6 msdn magazine
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