使用SignalR构建实时ASP.NET Web应用 - CSDN文库

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"SignalR Blueprints 是PACKT在2015年出版的一本书，它主要面向ASP.NET开发者，教他们如何在应用中利用SignalR实现实时web功能。书中通过清晰的实际案例，深入讲解SignalR的技术细节，以及何时何地应该使用SignalR。内容涵盖了SignalR的需求背景、架构，构建SignalR驱动的论坛，手机前端与SignalR的连接，以及预设的解决方案托管技术等。" SignalR是ASP.NET框架中的一个库，它为Web开发人员提供了实时通信的能力，使得服务器与客户端之间的交互无需刷新页面即可实时更新。在ASP.NET MVC和C#项目中，SignalR能显著提升用户体验，尤其是在需要即时消息、协作或动态数据更新的场景。本书首先解释了为何需要SignalR，强调了在当前Web环境中实时功能的重要性。然后，作者引导读者了解SignalR的架构，包括心跳机制、连接管理、负载均衡等核心概念，这有助于理解SignalR如何在大规模应用中保持稳定性和效率。在实际应用部分，书中通过构建一个论坛项目，展示了SignalR如何用于实时聊天、发帖和通知。这个案例让读者能直观地看到SignalR如何在用户交互中发挥作用。此外，还涉及了如何将手机作为SignalR的前端，使实时应用跨平台，拓宽了SignalR的应用场景。书中的另一个重点是SignalR的托管和扩展性。作者讨论了一些开箱即用的技术，如故障转移、可伸缩性和自定义中间件，这些都是确保解决方案在生产环境中稳定运行的关键因素。这些内容帮助开发者理解如何根据需求来规划和优化SignalR的应用部署。 "SignalR Blueprints"是一本深入浅出的教程，适合有一定ASP.NET基础的开发者学习，通过这本书，他们可以掌握SignalR的原理和实践技巧，从而构建高效、可靠的实时Web应用程序。同时，书中也提醒读者，虽然已尽力提供准确信息，但任何技术书籍都不能完全保证无误，使用时应结合实际情况进行判断和调整。

Preface

The purpose of software is to be a tool for us humans to help us perform tasks. A

lot of software is also a replacement for something physical for which we had an

opportunity to increase productivity by making it digital and also more accessible.

When replacing a paper form with a digital solution, we as developers pretty much

just copied the form eld by eld and never really thought through what we were

trying to solve. This made the improvement all about the data rather than what the

users were really trying to do. One of the benets of having the forms digitally is that

multiple users can see the same data at the same time and even edit it at the same

time. However, since it has all been modeled as data, with often a single, large model

representing it, we introduce new problems we never had in the real world on paper.

Things such as transactions and data staleness make our software more complex and

they never make sense at all for the user. These are technical requirements that we, as

developers, have introduced to make sure the data is correct at all times.

Users are becoming better; they have new requirements based on their experience

with software. Even in the enterprise, users are now demanding more of their IT

systems. With the advent of the real-time Web, driven by services such as Facebook,

Twitter, and other social media, our users are now used to different experiences that

are more responsive and user friendly.

What is the state of the Web?

The Web has changed a lot over the years, but the core protocol, HTTP, has been

pretty consistent since its rst documented version was released in 1991. The

protocol was optimized for the document delivery system that makes up the World

Wide Web. Later, the protocol included information that helped us keep a session

state on the server and be able to link subsequent requests coming into the same

session state. Later with DHTML and AJAX, we didn't have to do full post backs to

get the full document but get parts of the document, or maybe even just get the data

and perform the necessary rendering or manipulation of the document in the client.

www.it-ebooks.info

Preface

[ 2 ]

With the introduction of standards such as WebSockets, server sent events, and the

like, we can go even further. We can now make our web solutions come even more

alive by having persistent connections with a server and get notied from the server

when something happens. This solves some of the problems discussed earlier, such

as transactions and data staleness. By basically getting the changes continuously from

any other users as they are doing them, we don't need to run into any conditions that

put the system in a mode that it can't get out of. This will increase the user experience

and make our job as developers a lot easier.

SignalR Blueprints will allow you to utilize SignalR to its fullest, showing you how

to create different application types on the Web and mobile devices, along with a

few tips and tricks along the way. In addition, this project book aims to show you

the patterns that are not only good for SignalR but generally with cloud scale in

mind. Most signicantly, you will learn to think differently about software for users,

keeping them in focus all the time.

Personal style

Throughout the book, you'll run into things you might disagree with. It could be

things in naming the classes or methods in C#, for instance, at times, I like to drop

camel casing, both upper and lower and just separate the words with an underscore

yielding "some_type_with_spaces". In addition, I don't use modiers, without them

adding any value. You'll see that I completely avoid private as that is the default

modier for elds or properties on types. I'll also avoid things such as read-only,

especially, if it's a private member. Most annoyingly, you might see that I drop

scoping for single line statements following an IF or FOR. Don't worry, this is my

personal style; you can do as you please. All I'm asking is that you don't judge me

by how my code looks. I'm not a huge fan of measuring code quality with tools such

as R# and its default setting for squiggles. In fact, a colleague and I have been toying

with the idea of using the underscore trick for all our code, as it really makes it a lot

easier to read.

You'll notice throughout that I'm using built-in functions in the browser in

JavaScript, where you might expect jQuery. The reason for this is basically that I

try to limit the usage of jQuery, in fact, it's a dependency I'd prefer not to have in

my solutions as it is not adding anything to the way I do things. There is a bit of an

educational, quite intentional reason for me not using jQuery as well; we now have

most of the things we need in the browser already.

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Preface

[ 3 ]

What this book covers

Chapter 1, The Primer, shows us that in order to hit the ground running with SignalR,

it is important to understand why we need SignalR, but even more importantly, the

architectural decisions that lead to the thinking behind SignalR. For the remainder

of this book, there will be patterns and practices applied; this chapter covers that. In

addition, it also covers the libraries being used.

Chapter 2, Overheating the Discussion, starts gradually by getting to know the basics,

without introducing too much technology and patterns and practices. This chapter

goes through the building of a forum that benets from SignalR.

Chapter 3, Extra! Extra! Read All About It!, introduces e-newspapers—a great scenario

for SignalR and a quite common feature found on the Web. Having SignalR at the

core could be the tiny thing that differentiates you from the crowd. You'll learn how

to scale to meet demand when things go viral.

Chapter 4, Can You Measure It?, introduces increasingly popular dashboards that will

give you numbers at a glance. Often, the aim is to have the dashboards as up to date

as possible but without having to do a timer that refreshes. SignalR can help here

and light it all up, and with the right technique, make it visually appealing.

Chapter 5, What Line of Business Are You In?, shows that enterprise line of business

apps are often referred to as where user experiences go to die, leaving users out of

the equation when the software is designed and implemented. There are no reasons

whatsoever for this. This chapter investigates how can we start to think differently

about things and make them twinkle, like the stars discovered by the many voyages

of the Starship Enterprise.

Chapter 6, An Architectural Taste, shows that software architecture is very important

for many reasons, and this chapter looks more closely at a particular avor that lends

itself to the idea of real-time applications.

Chapter 7, The Three Screens – Mobile First, teaches how to connect the phone as a

frontend for what we built in the previous chapter. SignalR is not only for the Web;

it supports a wide variety of platforms, one of them being the Windows Phone.

Chapter 8, Putting the X in .NET – Xamarin, builds a frontend for the forum in Chapter 2,

Overheating the Discussion, for the iPhone.

Chapter 9, Debugging or Troubleshooting, shows a few techniques that you can apply to

nd out why the code gets broken or systems in general don't do what they are told

to. Then, you need to gure out what went wrong.

Chapter 10, Hosting and Deployment, walks through the varieties and particularly

focuses on cloud and Microsoft Azure. An important fact here will be how one scales.

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