Ebooki
7993
Ebook

Developer Career Masterplan. Build your path to senior level and beyond with practical insights from industry experts

Heather VanCura, Bruno Souza, Ed Burns

Written by industry experts that have spent the last 20+ years helping developers grow their careers, this book offers invaluable insights and guidance tailored to the specific needs of technical professionals. By discovering the secret of continuous learning and adapting in the ever-evolving field of software development, you’ll explore various learning paths with formal and informal methods, as well as gain an understanding of the value of certifications to validate your skills. This book will teach you the significance of building a strong support network, holding crucial conversations, and taking ownership of your career growth. You'll delve into acquiring both soft and hard skills, becoming a well-rounded and sought-after developer. Packed with practical examples, stories of successful developers, and real-world applications, the chapters will equip you with actionable advice on how to push beyond your comfort zone and embracing communities to enhance your teamwork abilities. Additionally, you’ll uncover the benefits of joining open-source projects, speaking at conferences, and building a personal brand to amplify your visibility and reputation. By the end of this book, you'll have a well-laid-out long-term and short-term plan for your career progression, equipping you with advanced technical skills, strategic thinking, and the ability to effectively manage relationships within your organization.

7994
Ebook

Developing AI Applications. An Introduction

Rheinwerk Publishing, Inc, Metin Karatas

This book opens with a clear introduction to AI fundamentals, covering its history and key concepts while guiding readers through installing essential tools like KNIME and AutoKeras. It begins by building a strong foundation in artificial neural networks and decision trees, enabling readers to grasp core AI methods. The journey then advances to convolutional layers for image classification, transfer learning, and anomaly detection, offering practical, beginner-friendly examples.As the reader progresses, the book explores text classification, cluster analysis, and automated AI model creation with AutoKeras. Visual programming with KNIME is introduced to simplify complex AI workflows. Further chapters cover reinforcement learning and genetic algorithms, expanding the reader’s skill set and preparing them for more advanced challenges. Hands-on exercises throughout reinforce concepts and practical application.In its final chapters, the guide dives into cutting-edge AI tools by demonstrating how to leverage ChatGPT and DALL-E APIs, including prompt engineering and API programming. It concludes with an outlook on the future of AI, equipping readers with the knowledge and confidence to build and deploy their own AI-powered applications from start to finish.

7995
Ebook

Developing Blockchain Solutions in the Cloud. Design and develop blockchain-powered Web3 apps on AWS, Azure, and GCP

Stefano Tempesta, Michael John Pena

As Web3 technologies continue to gain momentum across industries, businesses are looking for new ways to leverage the benefits of Web3 and stay at the forefront of technological innovation. This comprehensive guide offers an in-depth exploration of cloud-native blockchain fundamentals, providing valuable insights into the benefits and challenges of deploying these technologies in the cloud. From foundational concepts to advanced techniques, the book covers everything you need to know about developing and deploying secure, scalable blockchain solutions on AWS, Azure, and GCP. Through hands-on tutorials and projects, you’ll explore the latest tools, technologies, real-world use cases, and best practices to expand your understanding of the field’s complexities and opportunities. This book ensures easy comprehension through practical examples and access to source code on GitHub. As you advance, you’ll master platform selection and apply your newfound knowledge to tackle complex problems and deliver innovative cloud-native blockchain solutions tailored for your specific needs. By the end of this book, you’ll have a deep understanding of cloud-native blockchain deployment and implementation, and you’ll be equipped with the skills and knowledge to build secure and scalable solutions.

7996
Ebook

Developing Extensions for Joomla! 5. Extend your sites and build rich customizations with Joomla! plugins, modules, and components

Joomla! 5 is a groundbreaking CMS that helps you take a significant leap into the world of content management systems. Joomla! 5 features a variety of impressive new features that align with current web standards and enable you to experience lightning-fast performance for optimal web page optimization, leverage the new code architecture, and tap into the WebService API, among others.This book takes you on a journey of extending Joomla's capabilities by developing your own extensions. The chapters not only explain the key concepts behind Joomla's architecture but also equip you with the latest techniques for crafting components and plugins. You’ll discover how to leverage existing features within Joomla! to empower your extensions and create tailored solutions. The book takes you from the initial stages of planning your extension development to a fully featured finished product. As you advance, you'll learn invaluable techniques for testing your extension, addressing common issues, and preparing it for publication. The concluding chapters of this comprehensive guide teach you how to test your extension for common issues, along with how to publish the extension for everyone to use.By the end of this book, you’ll have the confidence and skills to complete the cycle of extension development.

7997
Ebook

Developing High-Frequency Trading Systems. Learn how to implement high-frequency trading from scratch with C++ or Java basics

Sebastien Donadio, Sourav Ghosh, Romain Rossier

The world of trading markets is complex, but it can be made easier with technology. Sure, you know how to code, but where do you start? What programming language do you use? How do you solve the problem of latency? This book answers all these questions. It will help you navigate the world of algorithmic trading and show you how to build a high-frequency trading (HFT) system from complex technological components, supported by accurate data.Starting off with an introduction to HFT, exchanges, and the critical components of a trading system, this book quickly moves on to the nitty-gritty of optimizing hardware and your operating system for low-latency trading, such as bypassing the kernel, memory allocation, and the danger of context switching. Monitoring your system’s performance is vital, so you’ll also focus on logging and statistics. As you move beyond the traditional HFT programming languages, such as C++ and Java, you’ll learn how to use Python to achieve high levels of performance. And what book on trading is complete without diving into cryptocurrency? This guide delivers on that front as well, teaching how to perform high-frequency crypto trading with confidence.By the end of this trading book, you’ll be ready to take on the markets with HFT systems.

7998
Ebook

Developing IoT Projects with ESP32. Automate your home or business with inexpensive Wi-Fi devices

Developing IoT Projects with ESP32 provides end-to-end coverage of secure data communication techniques from sensors to cloud platforms that will help you to develop production-grade IoT solutions by using the ESP32 SoC. You'll learn how to employ ESP32 in your IoT projects by interfacing with different sensors and actuators using different types of serial protocols.This book will show you how some projects require immediate output for end-users, and cover different display technologies as well as examples of driving different types of displays. The book features a dedicated chapter on cybersecurity packed with hands-on examples. As you progress, you'll get to grips with BLE technologies and BLE mesh networking and work on a complete smart home project where all nodes communicate over a BLE mesh. Later chapters will show you how IoT requires cloud connectivity most of the time and remote access to smart devices. You'll also see how cloud platforms and third-party integrations enable endless possibilities for your end-users, such as insights with big data analytics and predictive maintenance to minimize costs.By the end of this book, you'll have developed the skills you need to start using ESP32 in your next wireless IoT project and meet the project's requirements by building effective, efficient, and secure solutions.

7999
Ebook

Developing IoT Projects with ESP32. Unlock the full Potential of ESP32 in IoT development to create production-grade smart devices - Second Edition

Vedat Ozan Oner

ESP32, a low-cost and energy-efficient system-on-a-chip microcontroller, has become the backbone of numerous WiFi devices, fueling IoT innovation. This book offers a holistic approach to building an IoT system from the ground up, ensuring secure data communication from sensors to cloud platforms, empowering you to create production-grade IoT solutions using the ESP32 SoC.Starting with IoT essentials supported by real-world use cases, this book takes you through the entire process of constructing an IoT device using ESP32. Each chapter introduces new dimensions to your IoT applications, covering sensor communication, the integration of prominent IoT libraries like LittleFS and LVGL, connectivity options via WiFi, security measures, cloud integration, and the visualization of real-time data using Grafana. Furthermore, a dedicated section explores AI/ML for embedded systems, guiding you through building and running ML applications with tinyML and ESP32-S3 to create state-of-the-art embedded products.This book adopts a hands-on approach, ensuring you can start building IoT solutions right from the beginning. Towards the end of the book, you'll tackle a full-scale Smart Home project, applying all the techniques you've learned in real-time.Embark on your journey to build secure, production-grade IoT systems with ESP32 today!

8000
Ebook

Developing Java Applications with Spring and Spring Boot. Practical Spring and Spring Boot solutions for building effective applications

Claudio Eduardo de Oliveira, Alex Antonov

Spring Framework has become the most popular framework for Java development. It not only simplifies software development but also improves developer productivity. This book covers effective ways to develop robust applications in Java using Spring.The course is up made of three modules, each one having a take-away relating to building end-to-end java applications. The first module takes the approach of learning Spring frameworks by building applications.You will learn to build APIs and integrate them with popular fraemworks suh as AngularJS, Spring WebFlux, and Spring Data. You will also learn to build microservices using Spring's support for Kotlin. You will learn about the Reactive paradigm in the Spring architecture using Project Reactor. In the second module, after getting hands-on with Spring, you will learn about the most popular tool in the Spring ecosystem-Spring Boot. You will learn to build applications with Spring Boot, bundle them, and deploy them on the cloud. After learning to build applications with Spring Boot, you will be able to use various tests that are an important part of application development. We also cover the important developer tools such as AMQP messaging, websockets, security, and more. This will give you a good functional understanding of scalable development in the Spring ecosystem with Spring Boot. In the third and final module, you will tackle the most important challenges in Java application development with Spring Boot using practical recipes. Including recipes for testing, deployment, monitoring, and securing your applications. This module will also address the functional and technical requirements for building enterprise applications.By the end of the course you will be comfortable with using Spring and Spring Boot to develop Java applications and will have mastered the intricacies of production-grade applications.

8001
Ebook

Developing Kaggle Notebooks. Pave your way to becoming a Kaggle Notebooks Grandmaster

Gabriel Preda, D. Sculley, Anthony Goldbloom

Developing Kaggle Notebooks introduces you to data analysis, with a focus on using Kaggle Notebooks to simultaneously achieve mastery in this fi eld and rise to the top of the Kaggle Notebooks tier. The book is structured as a sevenstep data analysis journey, exploring the features available in Kaggle Notebooks alongside various data analysis techniques.For each topic, we provide one or more notebooks, developing reusable analysis components through Kaggle's Utility Scripts feature, introduced progressively, initially as part of a notebook, and later extracted for use across future notebooks to enhance code reusability on Kaggle. It aims to make the notebooks' code more structured, easy to maintain, and readable.Although the focus of this book is on data analytics, some examples will guide you in preparing a complete machine learning pipeline using Kaggle Notebooks. Starting from initial data ingestion and data quality assessment, you'll move on to preliminary data analysis, advanced data exploration, feature qualifi cation to build a model baseline, and feature engineering. You'll also delve into hyperparameter tuning to iteratively refi ne your model and prepare for submission in Kaggle competitions. Additionally, the book touches on developing notebooks that leverage the power of generative AI using Kaggle Models.

8002
Ebook

Developing Microsoft Dynamics GP Business Applications. If you want a thoroughly practical guide to developing business applications with Microsoft Dynamics GP, this is the book for you. Its hands-on approach will have you developing or customizing in no time

Leslie Vail

Microsoft Dynamics GP is a sophisticated Enterprise Resource Planning (ERP) application with a multitude of features and options. Microsoft Dynamics GP can also be used to develop dynamic, mission critical applications.In Developing Microsoft Dynamics GP Business Applications you will learn how to create and customize Dynamics GP Applications. This hands-on guide will take you through the initial steps of setting up a development environment through to customizing and developing an example application using tools such as Dexterity, VSTools and sanScript.Developing Microsoft Dynamics GP Business Applications will take you through the complex steps of creating and customizing Microsoft Dynamics GP applications. Starting with an overview of Microsoft Dynamics GP architecture you'll then move onto setting up your development environment.You will learn how to make your application come to life with Dexterity and sanScript. You will create table operations and ranges as well as object triggers to make powerful and practical business applications. You will deploy your Dexterity solution before moving onto customization with Modifier and VBA.This book will also take you through ways of enhancing and extending your application without code using the SmartList Builder and Excel Report Builder. Using these highly flexible tools you'll be able to create data connections that will increase the usability and functionality of your ERP applications.

8003
Ebook

Developing Middleware in Java EE 8. Build robust middleware solutions using the latest technologies and trends

Abdalla Mahmoud

Middleware is the infrastructure in software based applications that enables businesses to solve problems, operate more efficiently, and make money. As the use of middleware extends beyond a single application, the importance of having it written by experts increases substantially. This book will help you become an expert in developing middleware for a variety of applications. The book starts off by exploring the latest Java EE 8 APIs with newer features and managing dependencies with CDI 2.0. You will learn to implement object-to-relational mapping using JPA 2.1 and validate data using bean validation. You will also work with different types of EJB to develop business logic, and with design RESTful APIs by utilizing different HTTP methods and activating JAX-RS features in enterprise applications. You will learn to secure your middleware with Java Security 1.0 and implement various authentication techniques, such as OAuth authentication. In the concluding chapters, you will use various test technologies, such as JUnit and Mockito, to test applications, and Docker to deploy your enterprise applications. By the end of the book, you will be proficient in developing robust, effective, and distributed middleware for your business.

8004
Ebook
8005
Ebook

Developing Modern Database Applications with PostgreSQL. Use the highly available and object-relational PostgreSQL to build scalable and reliable apps

Dr. Quan Ha Le, Marcelo Diaz

PostgreSQL is an open-source object-relational database management system (DBMS) that provides enterprise-level services, including high performance and scalability. This book is a collection of unique projects providing you with a wealth of information relating to administering, monitoring, and testing PostgreSQL. The focus of each project is on both the development and the administrative aspects of PostgreSQL.Starting by exploring development aspects such as database design and its implementation, you’ll then cover PostgreSQL administration by understanding PostgreSQL architecture, PostgreSQL performance, and high-availability clusters. Various PostgreSQL projects are explained through current technologies such as DevOps and cloud platforms using programming languages like Python and Node.js. Later, you’ll get to grips with the well-known database API tool, PostgREST, before learning how to use popular PostgreSQL database testing frameworks. The book is also packed with essential tips and tricks and common patterns for working seamlessly in a production environment. All the chapters will be explained with the help of a real-world case study on a small banking application for managing ATM locations in a city.By the end of this DBMS book, you’ll be proficient in building reliable database solutions as per your organization's needs.

8006
Ebook

Developing Multi-Platform Apps with Visual Studio Code. Get up and running with VS Code by building multi-platform, cloud-native, and microservices-based apps

Ovais Mehboob Ahmed Khan, Khusro Habib, Chris Dias

Microsoft Visual Studio Code is a powerful, lightweight code editor for modern web and cloud development. It is a source code editor that can be used with a variety of programming languages, which works on multiple platforms such as Linux, Windows, and macOS. This book provides extensive coverage of the tools, functionalities, and extensions available within the VS Code environment that will help you build multi-platform apps with ease.You’ll start with the installation of VS Code and learn about various tools and features that are essential for development. Progressing through the chapters, you'll explore the user interface while understanding tips and tricks for increasing productivity. Next, you’ll delve into VS Code extensions and discover how they can make life easier for developers. Later, the book shows you how to develop a sample application with different programming languages, tools, and runtimes to display how VS code can be used effectively for development, before helping you get to grips with source code version management and deployment on Azure with VS Code. Finally, you’ll build on your skills by focusing on remote development with VS Code.By the end of this book, you’ll have the knowledge you need to use Visual Studio Code as your primary tool for software development.

8007
Ebook

Developing Robust Date and Time Oriented Applications in Oracle Cloud. A comprehensive guide to efficient date and time management in Oracle Cloud

Michal Kvet

Proper date and time management is critical for the development and reliability of Oracle Databases and cloud environments, which are among the most rapidly expanding technologies today. This knowledge can be applied to cloud technology, on premises, application development, and integration to emphasize regional settings, UTC coordination, or different time zones. This practical book focuses on code snippets and discusses the existing functionalities and limitations, along with covering data migration to the cloud by emphasizing the importance of proper date and time management.This book helps you understand the historical background and evolution of ANSI standards. You’ll get to grips with data types, constructor principles, and existing functionalities, and focus on the limitations of regional parameters and time zones, which help in expanding business to other parts of the world. You’ll also explore SQL injection threats, temporal database architecture, using Flashback Technology to reconstruct valid database images from the past, time zone management, and UTC synchronization across regions.By the end of this book, you’ll be able to create and manage temporal systems, prevent SQL injection attacks, use existing functionalities and define your own robust solutions for date management, and apply time zone and region rules.

8008
Ebook

Developing Solutions for Microsoft Azure AZ-204 Exam Guide. A comprehensive guide to passing the AZ-204 exam - Second Edition

Paul Ivey, Alex Ivanov

Get ready to delve into Microsoft Azure and build efficient cloud-based solutions with this updated second edition. Authored by seasoned Microsoft trainers, Paul Ivey and Alex Ivanov, this book offers a structured approach to mastering the AZ-204 exam topics while focusing on the intricacies of Azure development.You’ll familiarize yourself with cloud fundamentals, understanding the core concepts of Azure and various cloud models. Next, you’ll gain insights into Azure App Service web apps, containers and container-related services in Azure, Azure Functions, and solutions using Cosmos DB and Azure Blob Storage. Later, you'll learn how to secure your cloud solutions effectively as well as how to implement message- and event-based solutions and caching. You’ll also explore how to monitor and troubleshoot your solutions effectively. To build on your skills, you’ll get hands-on with monitoring, troubleshooting, and optimizing Azure applications, ensuring peak performance and reliability. Moving ahead, you’ll be able to connect seamlessly to third-party services, harnessing the power of API management, event-based solutions, and message-based solutions.By the end of this MS Azure book, you'll not only be well-prepared to pass the AZ-204 exam but also be equipped with practical skills to excel in Azure development projects.

8009
Ebook

Developing Solutions for Microsoft Azure AZ-204 Exam Guide. Discover the essentials for success when developing and maintaining cloud-based solutions on Azure

Paul Ivey, Alex Ivanov

With the prevalence of cloud technologies and DevOps ways of working, the industry demands developers who can build cloud solutions and monitor them throughout their life cycle. Becoming a Microsoft-certified Azure developer can differentiate developers from the competition, but with such a plethora of information available, it can be difficult to structure learning in an effective way to obtain certification.Through easy-to-understand explanations and exercises, this book will provide a more palatable learning experience than what you may expect from an exam preparation book. You’ll start off with a recap of some important cloud concepts, such as IaaS, PaaS, and SaaS. From there, you’ll learn about each relevant solution area, with use cases. The chapters also cover different implementation methodologies, both manual and programmatic – ranging from compute resources such as App Service and serverless applications to storage, database, security, monitoring solutions, and connecting to third-party services.By the end of this book, you'll have learned everything you need to pass the AZ-204 certification exam and have a handy, on-the-job reference guide.

8010
Ebook

Developing Web Applications with Oracle ADF Essentials. Quickly build attractive, user-friendly web applications using Oracle's free ADF Essentials toolkit

Sten E Vesterli

With ADF, Oracle gives you the chance to use the powerful tool used by Oracle's own developers. Modern enterprise applications must be user-friendly, visually attractive, and fast performing. Oracle Fusion Applications are just that; but to get the desired output you need proven methods to use this powerful and flexible tool to achieve success in developing your enterprise applications.Developing Web Applications with Oracle ADF Essentials explains all you need to know in order to build good-looking, user-friendly applications on a completely free technology stack. It explains the highly productive, declarative development approach that will literally have your application running within a few hours, as well as how to use Java to add business logic.Developing Web Applications with Oracle ADF Essentials tells you how to develop and deploy web application applications based on the highly productive and free Oracle ADF Essentials framework. You will first learn how to build business services on top of database tables, and then how to easily build a web application using these services. You will see how to visually design the flow through your application with ADF task flows, and how to use Java programming to implement business logic. Using this book, you can start building and deploying advanced web applications on a robust, free platform quickly.Towards the end, you will be ready to build real-world ADF Essentials applications and will be able to consider yourself an ADF Essentials journeyman.

8011
Ebook

Developing Windows Store Apps with HTML5 and JavaScript. The Windows store is growing in popularity and with this step-by-step guide it's easy to join the bandwagon using HTML5, CSS3, and JavaScript. From basic development techniques to publishing on the store, it's the complete primer

Rami Sarieddine

Windows 8 has already been launched and been installed on millions of devices while the store is getting populated with apps, and soon enough everyone will want a Windows Store app. So start now and learn how to develop apps for Windows 8 using HTML5, CSS3, and JavaScript and you will be killing two birds with one stone by getting introduced to important features in HTML5 and CSS3 at the same time. You will gain the advantage of utilizing your web development skills to transform your website into an app or the other way round.Developing Windows Store Apps with HTML5 and JavaScript is a practical, hands-on guide that covers the basic and important features of a Windows Store App along with code examples which will show you how to develop these features, all the while learning some of the new features in HTML5 and CSS3 which you can utilize in other areas of development.This book starts with the new features in HTML5 and CSS3 that are incorporated with Windows 8 development, and then moves on to creating a blank Windows Store app and add features to it as we move through the chapters till we package the app and make it ready for publishing. Finally, we will have a look at how similar it is to develop the same app with XAML.You will also learn how to add and use new controls dedicated for Windows 8 and then see how to fetch data for the app and bind it to the controls. We will also take a look at making the app adapt to change in screen sizes and rotation as well as how to make the app live with tiles and allow users to sign in using their email accounts. Also you will learn how to add an app bar, and lastly you learn how to finalize the app and publish it. If you want to leverage your web development skills and utilize it in developing for Windows 8, then you came to the right place. Developing Windows Store Apps with HTML5 and JavaScript is packed with examples and screenshots which will make it easy for you to implement all the things you learned throughout the book.

8012
Ebook

Developing with Docker. Learn to automate your deployments with Docker

Jaroslaw Krochmalski, Jarosław Krochmalski

This fast-paced practical guide will get you up and running with Docker. Using Docker, you will be able to build, ship, and run many distributed applications in real time. You will start with quickly installing Docker and start working with images and containers. We will present different types of containers and their applications, and show you how to find and build images. You will learn how you can contribute to the image repository by publishing different images. This will familiarize you with the image building process and you will be able to successfully run your programs within containers.By finishing this book, you will be well equipped in deploying your applications using Docker and will have a clear understanding of concepts, techniques, and practical methods to get it running in production systems.

8013
Ebook

Developments in Labour Law from a Comparative Perspective

Izabela Florczak, Zbigniew Góral

The need for comparative studies of labour law seems indisputable, inasmuch it arises from the international character of many labour law norms, as well as from the interconnection between working and social relations which are often conditional and international. Thus, it appears that academic research into the field of labour law would be incomplete without its comparative facet. For these reasons, numerous networks of international cooperation between labour law scholars are being established on both formal and informal levels. The underlying idea is to find a common denominator for the discourse concerning the present condition of labour law, and pathways for its further development. The Labour Law Education Society, established in 2012 at the initiative of Prof. Charles F. X. Szymanski, is one of the networks attempting to accomplish this objective. Its early days were crowned with Developments in Labour Law from a Comparative Perspective, a conference held on 23rd–24th of May 2014 at the Allerhand Instituteʼs branch in Cracow, Poland. The present volume, which is an outgrowth of that conference, presents certain current issues frequently discussed in the realm of labour law. Also, it contains chapters considering the most significant developments within the discipline. 

8014
Ebook

Devi. Waleczna Bogini

Kinga Jesman

"Devi, Waleczna Bogini" to historia młodej Hinduski, która manipulacją zostaje zmuszona do ślubu z jak mogłoby się wydawać kandydatem idealnym. Wszystko było w nim perfekcyjne. Niestety jej serce i rozum głośno protestują. Devi nie potrafi zrozumieć, dlaczego bogaty mężczyzna sukcesu miałby zainteresować się ubogą dziewczyną, jaką przecież była. Jednak z braku argumentów, poddaje się woli rodziców i wychodzi za mąż. Pomimo temperamentnego charakteru, prowadzi życie posłusznej małżonki. Pierze, sprząta, gotuje. Jak na dobrą, hinduską żonę przystało. Wszystko komplikuje się, kiedy na jej drodze staje kusząco atrakcyjny Marokańczyk, nachalnie okazując jej zainteresowanie. Devi ulegając jego urokowi, nie potrafi stwierdzić, czy ta relacja okaże się dla niej błogosławieństwem czy jednak przekleństwem. Małżeństwo aranżowane, oszustwo, tajemniczy spadek, hinduscy bogowie oraz zakazana miłość.

8015
Ebook

Devil Ritter

Max Brand

A power more than human, a will to absolute evil such was he. All who had tried to save her from him perished... Must her true love also die? Max Brand, the pen name of Frederick Faust, was an incredibly proficient author who wrote many books, stories, and even poetry. Brand is generally regarded as the author of superior Westerns like his Destry Rides Again, but Brand also wrote the Dr. Kildare series, numerous detective stories and fantastic novels as well. His Westerns were always different, with complex plots and characters, and uncertain endings but his fantastic novels rank among the best stories he ever wrote. Devil Ritter is a tale of horror that demands your attention!

8016
Ebook

Devils Dice

William Le Queux

Let me gaze down the vista of the tristful past. Ah! there are things that cannot be uttered; there are scenes that still entrance me, and incidents so unexpected and terrible that they cause me even now to hold my breath in horror. The prologue of this extraordinary drama of London life was enacted three years ago; its astounding dénouement occurred quite recently.