Engineering Resilient Systems on AWS

Download Engineering Resilient Systems on AWS PDF Online Free

Author :
Publisher : "O'Reilly Media, Inc."
ISBN 13 : 1098162390
Total Pages : 348 pages
Book Rating : 4.0/5 (981 download)

DOWNLOAD NOW!


Book Synopsis Engineering Resilient Systems on AWS by : Kevin Schwarz

Download or read book Engineering Resilient Systems on AWS written by Kevin Schwarz and published by "O'Reilly Media, Inc.". This book was released on 2024-10-11 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: To ensure that applications are reliable and always available, more businesses today are moving applications to AWS. But many companies still struggle to design and build these cloud applications effectively, thinking that because the cloud is resilient, their applications will be too. With this practical guide, software, DevOps, and cloud engineers will learn how to implement resilient designs and configurations in the cloud using hands-on independent labs. Authors Kevin Schwarz, Jennifer Moran, and Dr. Nate Bachmeier from AWS teach you how to build cloud applications that demonstrate resilience with patterns like back off and retry, multi-Region failover, data protection, and circuit breaker with common configuration, tooling, and deployment scenarios. Labs are organized into categories based on complexity and topic, making it easy for you to focus on the most relevant parts of your business. You'll learn how to: Configure and deploy AWS services using resilience patterns Implement stateless microservices for high availability Consider multi-Region designs to meet business requirements Implement backup and restore, pilot light, warm standby, and active-active strategies Build applications that withstand AWS Region and Availability Zone impairments Use chaos engineering experiments for fault injection to test for resilience Assess the trade-offs when building resilient systems, including cost, complexity, and operational burden

Engineering Resilient Systems on AWS

Download Engineering Resilient Systems on AWS PDF Online Free

Author :
Publisher :
ISBN 13 : 9781098162429
Total Pages : 0 pages
Book Rating : 4.1/5 (624 download)

DOWNLOAD NOW!


Book Synopsis Engineering Resilient Systems on AWS by : Kevin Schwarz

Download or read book Engineering Resilient Systems on AWS written by Kevin Schwarz and published by . This book was released on 2024-12-31 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: To ensure that applications are reliable and always available, more businesses today are moving applications to AWS. But many companies still struggle to design and build these cloud applications effectively, thinking that because the cloud is resilient, their applications will be too. With this practical guide, software, DevOps, and cloud engineers will learn how to implement resilient designs and configurations in the cloud using hands-on independent labs. Authors Kevin Schwarz, Jennifer Moran, and Dr. Nate Bachmeier from AWS teach you how to build cloud applications that demonstrate resilience with patterns like back off and retry, multi-Region failover, data protection, and circuit breaker with common configuration, tooling, and deployment scenarios. Labs are organized into categories based on complexity and topic, making it easy for you to focus on the most relevant parts of your business. You'll learn how to: Configure and deploy AWS services using resilience patterns Implement stateless microservices for high availability Consider multi-Region designs to meet business requirements Implement backup and restore, pilot light, warm standby, and active-active strategies Build applications that withstand AWS Region and Availability Zone impairments Use chaos engineering experiments for fault injection to test for resilience Assess the trade-offs when building resilient systems, including cost, complexity, and operational burden

Engineering Resilient Systems on AWS

Download Engineering Resilient Systems on AWS PDF Online Free

Author :
Publisher : "O'Reilly Media, Inc."
ISBN 13 : 1098162390
Total Pages : 348 pages
Book Rating : 4.0/5 (981 download)

DOWNLOAD NOW!


Book Synopsis Engineering Resilient Systems on AWS by : Kevin Schwarz

Download or read book Engineering Resilient Systems on AWS written by Kevin Schwarz and published by "O'Reilly Media, Inc.". This book was released on 2024-10-11 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: To ensure that applications are reliable and always available, more businesses today are moving applications to AWS. But many companies still struggle to design and build these cloud applications effectively, thinking that because the cloud is resilient, their applications will be too. With this practical guide, software, DevOps, and cloud engineers will learn how to implement resilient designs and configurations in the cloud using hands-on independent labs. Authors Kevin Schwarz, Jennifer Moran, and Dr. Nate Bachmeier from AWS teach you how to build cloud applications that demonstrate resilience with patterns like back off and retry, multi-Region failover, data protection, and circuit breaker with common configuration, tooling, and deployment scenarios. Labs are organized into categories based on complexity and topic, making it easy for you to focus on the most relevant parts of your business. You'll learn how to: Configure and deploy AWS services using resilience patterns Implement stateless microservices for high availability Consider multi-Region designs to meet business requirements Implement backup and restore, pilot light, warm standby, and active-active strategies Build applications that withstand AWS Region and Availability Zone impairments Use chaos engineering experiments for fault injection to test for resilience Assess the trade-offs when building resilient systems, including cost, complexity, and operational burden

Software Engineering for Resilient Systems

Download Software Engineering for Resilient Systems PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 3319659480
Total Pages : 208 pages
Book Rating : 4.3/5 (196 download)

DOWNLOAD NOW!


Book Synopsis Software Engineering for Resilient Systems by : Alexander Romanovsky

Download or read book Software Engineering for Resilient Systems written by Alexander Romanovsky and published by Springer. This book was released on 2017-08-18 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the International Workshop on Software Engineering for Resilient Systems, SERENE 2017, held in Geneva; Switzerland, in September 2017. The 11 papers presented together with 2 invited talks were carefully reviewed and selected from 16 submissions. They cover the following areas: modeling and specification; safety and security; fault tolerance, resilience and robustness software.

Software Engineering for Resilient Systems

Download Software Engineering for Resilient Systems PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 3319231294
Total Pages : 154 pages
Book Rating : 4.3/5 (192 download)

DOWNLOAD NOW!


Book Synopsis Software Engineering for Resilient Systems by : Alessandro Fantechi

Download or read book Software Engineering for Resilient Systems written by Alessandro Fantechi and published by Springer. This book was released on 2015-08-27 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 7th International Workshop on Software Engineering for Resilient Systems, SERENE 2015, held in Paris, France, in September 2015. The 10 revised technical papers presented were carefully reviewed and selected from 18 submissions. The papers are organized in topical sections on development of resilient systems, verification, validation and evaluation of resilience, case studies and applications.

Chaos Engineering with Go

Download Chaos Engineering with Go PDF Online Free

Author :
Publisher : BPB Publications
ISBN 13 : 9355519648
Total Pages : 438 pages
Book Rating : 4.3/5 (555 download)

DOWNLOAD NOW!


Book Synopsis Chaos Engineering with Go by : Kapil Kumar Khandelwal

Download or read book Chaos Engineering with Go written by Kapil Kumar Khandelwal and published by BPB Publications. This book was released on 2024-08-20 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: DESCRIPTION Chaos Engineering with Go is your essential guide to building resilient systems. In today's complex distributed environments, ensuring system reliability is paramount. By introducing controlled chaos into your systems, you can identify weaknesses and fortify them before they become critical failures. This book explores chaos engineering, offering a complete guide to building resilient systems. Starting with basic concepts and Go programming, it moves to chaos engineering topics like fault tolerance, fault injection, and chaos testing. Readers will learn to design and run chaos experiments using various tools and techniques. The book highlights the importance of monitoring and observability to understand system behavior. It includes practical case studies and best practices, ending with an in-depth look at security chaos engineering and emerging technologies. This book also emphasizes implementing observability practices within chaos engineering workflows, enhancing your ability to reduce downtime and improve system reliability. With a keen focus on best practices and lessons learned, this book equips readers with the knowledge and tools needed to embrace chaos, ensuring robust and reliable systems in an ever-evolving digital landscape. KEY FEATURES ● Master the core concepts and unique principles of chaos engineering. ● Resilience patterns for unstoppable microservices. ● Hands-on chaos experiments for real-world resilience. WHAT YOU WILL LEARN ● Grasp fundamental concepts and principles of chaos engineering. ● Implement fault tolerance and resilience patterns using Go. ● Design and execute effective chaos experiments to test system resilience. ● Utilize cutting-edge tools for chaos testing and fault injection. ● Integrate observability practices into chaos engineering workflows. ● Apply security chaos engineering and learn from real-world case studies. WHO THIS BOOK IS FOR The book caters to both beginners and experienced professionals interested in enhancing system integrity and reducing downtime. Ideal for site reliability engineers (SREs), DevOps engineers, enterprise architects, tech professionals, and college students. TABLE OF CONTENTS 1. Exploring the Essence of Chaos Engineering 2. Chaos Engineering Concepts 3. Revision with Go 4. Fault Tolerance and Resilience Patterns 5. Chaos Fault Injection Techniques 6. Chaos Testing Tools 7. Chaos Experiment Design 8. Chaos with Emerging Tech Stack 9. Essence of Observability in Distributed System 10. Observability in Chaos Engineering 11. Security Chaos Engineering Overview 12. Case Studies: Chaos Engineering in Action 13. Best Practices and Lessons Learned

Resilience and Reliability on AWS

Download Resilience and Reliability on AWS PDF Online Free

Author :
Publisher : "O'Reilly Media, Inc."
ISBN 13 : 1449339255
Total Pages : 163 pages
Book Rating : 4.4/5 (493 download)

DOWNLOAD NOW!


Book Synopsis Resilience and Reliability on AWS by : Jurg van Vliet

Download or read book Resilience and Reliability on AWS written by Jurg van Vliet and published by "O'Reilly Media, Inc.". This book was released on 2013-01-03 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cloud services are just as susceptible to network outages as any other platform. This concise book shows you how to prepare for potentially devastating interruptions by building your own resilient and reliable applications in the public cloud. Guided by engineers from 9apps—an independent provider of Amazon Web Services and Eucalyptus cloud solutions—you’ll learn how to combine AWS with open source tools such as PostgreSQL, MongoDB, and Redis. This isn’t a book on theory. With detailed examples, sample scripts, and solid advice, software engineers with operations experience will learn specific techniques that 9apps routinely uses in its cloud infrastructures. Build cloud applications with the "rip, mix, and burn" approach Get a crash course on Amazon Web Services Learn the top ten tips for surviving outages in the cloud Use elasticsearch to build a dependable NoSQL data store Combine AWS and PostgreSQL to build an RDBMS that scales well Create a highly available document database with MongoDB Replica Set and SimpleDB Augment Redis with AWS to provide backup/restore, failover, and monitoring capabilities Work with CloudFront and Route 53 to safeguard global content delivery

Learning Chaos Engineering

Download Learning Chaos Engineering PDF Online Free

Author :
Publisher : O'Reilly Media
ISBN 13 : 1492050970
Total Pages : 178 pages
Book Rating : 4.4/5 (92 download)

DOWNLOAD NOW!


Book Synopsis Learning Chaos Engineering by : Russ Miles

Download or read book Learning Chaos Engineering written by Russ Miles and published by O'Reilly Media. This book was released on 2019-07-12 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most companies work hard to avoid costly failures, but in complex systems a better approach is to embrace and learn from them. Through chaos engineering, you can proactively hunt for evidence of system weaknesses before they trigger a crisis. This practical book shows software developers and system administrators how to plan and run successful chaos engineering experiments. System weaknesses go beyond your infrastructure, platforms, and applications to include policies, practices, playbooks, and people. Author Russ Miles explains why, when, and how to test systems, processes, and team responses using simulated failures on Game Days. You’ll also learn how to work toward continuous chaos through automation with features you can share across your team and organization. Learn to think like a chaos engineer Build a hypothesis backlog to determine what could go wrong in your system Develop your hypotheses into chaos engineering experiment Game Days Write, run, and learn from automated chaos experiments using the open source Chaos Toolkit Turn chaos experiments into tests to confirm that you’ve overcome the weaknesses you discovered Observe and control your automated chaos experiments while they are running

Advanced Serverless Architectures with Microsoft Azure

Download Advanced Serverless Architectures with Microsoft Azure PDF Online Free

Author :
Publisher : Packt Publishing Ltd
ISBN 13 : 1788395573
Total Pages : 278 pages
Book Rating : 4.7/5 (883 download)

DOWNLOAD NOW!


Book Synopsis Advanced Serverless Architectures with Microsoft Azure by : Daniel Bass

Download or read book Advanced Serverless Architectures with Microsoft Azure written by Daniel Bass and published by Packt Publishing Ltd. This book was released on 2019-02-28 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Build complex, observable, and fault-tolerant serverless systems easily on Microsoft Azure. Key FeaturesUse serverless systems to help you fulfill complex requirements Develop your knowledge of Azure Microsoft ServerlessUnderstand concepts with a hands-on approach and helpful examplesBook Description Advanced Serverless Architectures with Microsoft Azure redefines your experience of designing serverless systems. It shows you how to tackle challenges of varying levels, not just the straightforward ones. You'll be learning how to deliver features quickly by building systems, which retain the scalability and benefits of serverless. You'll begin your journey by learning how to build a simple, completely serverless application. Then, you'll build a highly scalable solution using a queue, load messages onto the queue, and read them asynchronously. To boost your knowledge further, the book also features durable functions and ways to use them to solve errors in a complex system. You'll then learn about security by building a security solution from serverless components. Next, you’ll gain an understanding of observability and ways to leverage application insights to bring you performance benefits. As you approach the concluding chapters, you’ll explore chaos engineering and the benefits of resilience, by actively switching off a few of the functions within a complex system, submitting a request, and observing the resulting behavior. By the end of this book, you will have developed the skills you need to build and maintain increasingly complex systems that match evolving platform requirements. What you will learnUnderstand what true serverless architecture isStudy how to extend and scale architectures until they become ‘complex'Implement durable functions in your designImprove the observability of your serverless architectureImplement security solutions using serverless servicesLearn how to ‘practise' chaos engineering in productionWho this book is for Advanced Serverless Architectures with Microsoft Azure is is ideal if you want to build serverless systems with fewer outages and high performance using Azure. Familiarity with the C# syntax and Azure Functions and ARM templates will help you to benefit more from this book. Prior knowledge of basic front-end development, HTML JS, and CSS is beneficial but not essential. Some DevOps knowledge is also beneficial but not essential.

Adaptive Instructional Systems

Download Adaptive Instructional Systems PDF Online Free

Author :
Publisher : Springer Nature
ISBN 13 : 3031347358
Total Pages : 365 pages
Book Rating : 4.0/5 (313 download)

DOWNLOAD NOW!


Book Synopsis Adaptive Instructional Systems by : Robert A. Sottilare

Download or read book Adaptive Instructional Systems written by Robert A. Sottilare and published by Springer Nature. This book was released on 2023-07-08 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 5th International Conference, AIS 2023, held as part of the 25th International Conference, HCI International 2023, which was held virtually in Copenhagen, Denmark in July 2023. The total of 1578 papers and 396 posters included in the HCII 2023 proceedings was carefully reviewed and selected from 7472 submissions. The AIS 2023 proceeding helps to understand the theory and enhance the state-of-practice for a set of technologies (tools and methods) called adaptive instructional systems (AIS). AIS are defined as artificially intelligent, computer-based systems that guide learning experiences by tailoring instruction and recommendations based on the goals, needs, preferences, and interests of each individual learner or team in the context of domain learning objectives.

Enabling Microservice Success

Download Enabling Microservice Success PDF Online Free

Author :
Publisher : "O'Reilly Media, Inc."
ISBN 13 : 1098130839
Total Pages : 451 pages
Book Rating : 4.0/5 (981 download)

DOWNLOAD NOW!


Book Synopsis Enabling Microservice Success by : Sarah Wells

Download or read book Enabling Microservice Success written by Sarah Wells and published by "O'Reilly Media, Inc.". This book was released on 2024-03-26 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microservices can be a very effective approach for delivering value to your organization and to your customers. If you get them right, microservices help you to move fast by making changes to small parts of your system hundreds of times a day. But if you get them wrong, microservices will just make everything more complicated. In this book, technical engineering leader Sarah Wells provides practical, in-depth advice for moving to microservices. Having built her first microservice architecture in 2013 for the Financial Times, Sarah discusses the approaches you need to take from the start and explains the potential problems most likely to trip you up. You'll also learn how to maintain the architecture as your systems mature while minimizing the time you spend on support and maintenance. With this book, you will: Learn the impact of microservices on software development patterns and practices Identify the organizational changes you need to make to successfully build and operate this architecture Determine the steps you must take before you move to microservices Understand the traps to avoid when you create a microservices architecture—and learn how to recover if you fall into one

Official Google Cloud Certified Professional Cloud Security Engineer Exam Guide

Download Official Google Cloud Certified Professional Cloud Security Engineer Exam Guide PDF Online Free

Author :
Publisher : Packt Publishing Ltd
ISBN 13 : 1835466966
Total Pages : 496 pages
Book Rating : 4.8/5 (354 download)

DOWNLOAD NOW!


Book Synopsis Official Google Cloud Certified Professional Cloud Security Engineer Exam Guide by : Ankush Chowdhary

Download or read book Official Google Cloud Certified Professional Cloud Security Engineer Exam Guide written by Ankush Chowdhary and published by Packt Publishing Ltd. This book was released on 2023-08-30 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master the art of designing, developing, and operating secure infrastructures on Google Cloud Key Features Prepare for the certification exam with clear explanations, real-world examples, and self-assessment questions Review Google Cloud security best practices for building a secure and compliant cloud environment Explore advanced concepts like Security Command Center, BeyondCorp Zero Trust, and container security Book DescriptionGoogle Cloud security offers powerful controls to assist organizations in establishing secure and compliant cloud environments. With this book, you’ll gain in-depth knowledge of the Professional Cloud Security Engineer certification exam objectives, including Google Cloud security best practices, identity and access management (IAM), network security, data security, and security operations. The chapters go beyond the exam essentials, helping you explore advanced topics such as Google Cloud Security Command Center, the BeyondCorp Zero Trust architecture, and container security. With step-by-step explanations, practical examples, and practice exams to help you improve your skills for the exam, you'll be able to efficiently review and apply key concepts of the shared security responsibility model. Finally, you’ll get to grips with securing access, organizing cloud resources, network and data security, and logging and monitoring. By the end of this book, you'll be proficient in designing, developing, and operating security controls on Google Cloud and gain insights into emerging concepts for future exams.What you will learn Understand how Google secures infrastructure with shared responsibility Use resource hierarchy for access segregation and implementing policies Utilize Google Cloud Identity for authentication and authorizations Build secure networks with advanced network features Encrypt/decrypt data using Cloud KMS and secure sensitive data Gain visibility and extend security with Google's logging and monitoring capabilities Who this book is forThis book is for IT professionals, cybersecurity specialists, system administrators, and tech enthusiasts aspiring to strengthen their understanding of Google Cloud security and elevate their career trajectory. Earning this certification not only validates your expertise but also makes you part of an elite group of GCP security engineers, opening doors to opportunities that can significantly advance your career. Prior knowledge of the foundational concepts of Google Cloud or GCP Associate Engineer Certification is strongly recommended.

Mastering Cloud Storage

Download Mastering Cloud Storage PDF Online Free

Author :
Publisher : BPB Publications
ISBN 13 : 935551753X
Total Pages : 294 pages
Book Rating : 4.3/5 (555 download)

DOWNLOAD NOW!


Book Synopsis Mastering Cloud Storage by : Rahul Miglani

Download or read book Mastering Cloud Storage written by Rahul Miglani and published by BPB Publications. This book was released on 2023-12-29 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unlocking the Cloud's Infinite Possibilities KEY FEATURES ● Design scalable cloud storage solutions and optimize costs. ● Integrate cloud storage seamlessly into your applications. ● Apply theoretical knowledge to real-world scenarios through hands-on case studies. DESCRIPTION In today's data-driven world, cloud storage has emerged as an indispensable tool for businesses and individuals alike. With its ability to store and manage vast amounts of data seamlessly, cloud storage has revolutionized the way we handle information. However, navigating the complexities of cloud storage can be a daunting task. This is where this book steps in. Commence on a comprehensive journey through cloud computing fundamentals, exploring evolution, service models, and deployment strategies. Uncover diverse cloud storage technologies, including object, block, and file storage, and look into Amazon S3, Azure Blob Storage, and Google Cloud Storage. Learn to configure storage effectively, implement scalable solutions, and seamlessly integrate with applications. Master disaster recovery, data migration, and hybrid cloud architectures for optimal resource utilization. Perfect the art of cost optimization and performance monitoring, maximizing your cloud storage investment. Mastering Cloud Storage is your ultimate guide to achieving operational excellence, improving system reliability, and enhancing your career in cloud engineering and DevOps. WHAT YOU WILL LEARN ● Master Amazon S3 and Azure Blob Storage. ● Implement robust data security and encryption. ● Apply DevOps and DevSecOps in cloud storage. ● Optimize for high availability and reliability. ● Navigate industry-specific regulations and compliance. WHO THIS BOOK IS FOR Whether you are a seasoned IT professional, a DevOps engineer, a data scientist, system administrators, or a cloud architect, this systematic guide empowers you to unlock the full potential of cloud storage. TABLE OF CONTENTS 1. Introduction to Cloud Computing 2. Understanding Cloud Storage Technologies 3. Exploring Cloud Storage Providers 4. Data Encryption and Security Best Practices 5. Data Redundancy and High Availability 6. Disaster Recovery in the Cloud 7. Configuring Cloud Storage Services 8. Scalable Cloud Storage Solutions 9. Integrating Cloud Storage into Applications 10. Data Migration Techniques 11. Hybrid Cloud Architectures 12. Cost Optimization and Performance Monitoring 13. Industry Trends and Future of Cloud Storage

International Journal of Computer Systems Science & Engineering

Download International Journal of Computer Systems Science & Engineering PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 508 pages
Book Rating : 4.3/5 (91 download)

DOWNLOAD NOW!


Book Synopsis International Journal of Computer Systems Science & Engineering by :

Download or read book International Journal of Computer Systems Science & Engineering written by and published by . This book was released on 2005 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Directory of Engineering Document Sources

Download Directory of Engineering Document Sources PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 484 pages
Book Rating : 4.3/5 (91 download)

DOWNLOAD NOW!


Book Synopsis Directory of Engineering Document Sources by :

Download or read book Directory of Engineering Document Sources written by and published by . This book was released on 1986 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Resilience and Reliability on AWS

Download Resilience and Reliability on AWS PDF Online Free

Author :
Publisher : "O'Reilly Media, Inc."
ISBN 13 : 1449339190
Total Pages : 163 pages
Book Rating : 4.4/5 (493 download)

DOWNLOAD NOW!


Book Synopsis Resilience and Reliability on AWS by : Jurg van Vliet

Download or read book Resilience and Reliability on AWS written by Jurg van Vliet and published by "O'Reilly Media, Inc.". This book was released on 2013 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cloud has achieved an air of invincibility, and solutions such as Amazon Web Services (AWS) make cloud computing look so appealing. But building a good application on any platform is difficult. There will always be outages, small and large. Are you prepared to handle them? 'Resilience and Reliability on AWS' helps you answer that and many other questions.

Railway Engineer International

Download Railway Engineer International PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 1020 pages
Book Rating : 4.3/5 (91 download)

DOWNLOAD NOW!


Book Synopsis Railway Engineer International by :

Download or read book Railway Engineer International written by and published by . This book was released on 1978 with total page 1020 pages. Available in PDF, EPUB and Kindle. Book excerpt: