+ What is domain logic?
+ Domain logic patterns:
* Transaction script
* Domain model
* Table module
* Service layer
+ Conclusion
by Pavlo Livchak, Software Engineer at ElifTech
Managing transactions on Ethereum with Apache AirflowMichael Ghen
Apache Airflow is a Python-based workflow management system that can be used to actively monitor and execute transactions on blockchain networks like Ethereum. This presentation is an introduction to Apache Airflow followed by a demonstration of a production deployment. Apache Airflow is an excellent tool for anyone already familiar with Python. Its ability to process jobs and handle errors makes it a good choice tool for managing activity on blockchain networks. The goal of this talk is to demonstrate how Apache Airflow can be used for environmental scanning and batch processing transactions. The demonstration will cover using Airflow and Python for monitoring and executing ERC20 token transactions on the Ethereum blockchain.
The most common architecture pattern is the layered architecture pattern, otherwise known as the n-tier architecture pattern. This pattern is the de facto standard for most applications and therefore is widely known by most architects, designers, and developers. The layered architecture pattern closely matches the traditional IT communication and organizational structures found in most companies, making it a natural choice for most business application development efforts.
Managing transactions on Ethereum with Apache AirflowMichael Ghen
Apache Airflow is a Python-based workflow management system that can be used to actively monitor and execute transactions on blockchain networks like Ethereum. This presentation is an introduction to Apache Airflow followed by a demonstration of a production deployment. Apache Airflow is an excellent tool for anyone already familiar with Python. Its ability to process jobs and handle errors makes it a good choice tool for managing activity on blockchain networks. The goal of this talk is to demonstrate how Apache Airflow can be used for environmental scanning and batch processing transactions. The demonstration will cover using Airflow and Python for monitoring and executing ERC20 token transactions on the Ethereum blockchain.
The most common architecture pattern is the layered architecture pattern, otherwise known as the n-tier architecture pattern. This pattern is the de facto standard for most applications and therefore is widely known by most architects, designers, and developers. The layered architecture pattern closely matches the traditional IT communication and organizational structures found in most companies, making it a natural choice for most business application development efforts.
Technical Webinar: Patterns for Integrating Your Salesforce App with Off-Plat...CodeScience
Patterns for Integrating Your Salesforce App with Off-Platform Apps
Integrating Salesforce applications with additional off-platform apps can dramatically extend the capability of powerful business apps. From ERP systems to custom apps, integrating with Salesforce can help streamline essential processes, saving your business valuable time and money. In our latest tech webinar, CodeScience Technical Architect Mark Pond dives into Salesforce integration patterns and the positive impacts they can deliver.
In this technical webinar, you will learn:
- Several common Salesforce integration patterns
- Integration pattern pitfalls
- How to leverage a custom queue to automate background work
- Deliverability and reporting advantages of custom queues
Watch today to learn how automated testing can take your enterprise solutions to the next level.
This document is an overview of a Private Cloud Reference Model. For the purposes of this document, a Reference Model is defined as the problem definition, requirements, and scope for a specific domain including the identification of all layers (or subdomains) and any interactions or dependencies between the components.
The business logic of an enterprise application is probably the most confusing part of the application. By layering the application into presentation, domain and data source layers, we can provide a logical place to put what we call domain logic. It may not always be clear where presentation ends and the domain begins, but that is one of the challenges with building software applications.
In this lecture we look at the domain layer and introduce three domain logic design pattern and one to provide API to the domain.
At Softroniics we provide job oriented training for freshers in IT sector. We are providing IEEE project guidance and Final year project guidance. We are Pioneers in all leading technologies like Android, Java, .NET, PHP, Python, Embedded Systems, Matlab, NS2, VLSI, Modelsim, Tanner, Xilinx etc. We are specializiling in technologies like Big Data, Cloud Computing, Internet Of Things (iOT), Data Mining, Networking, Information Security, Image Processing and many other. We are providing long term and short term internship also. We are also providing IEEE project support at Calicut, Thrissur and Palakkad. For more details contact 9037291113, 7907435072
At Softroniics we provide job oriented training for freshers in IT sector. We are providing IEEE project guidance and Final year project guidance. We are Pioneers in all leading technologies like Android, Java, .NET, PHP, Python, Embedded Systems, Matlab, NS2, VLSI, Modelsim, Tanner, Xilinx etc. We are specializiling in technologies like Big Data, Cloud Computing, Internet Of Things (iOT), Data Mining, Networking, Information Security, Image Processing and many other. We are providing long term and short term internship also. We are also providing IEEE project support at Calicut, Thrissur and Palakkad. For more details contact 9037291113, 7907435072
Sennilega er "business logic" sá hluti af enterprise lausnum sem er hvað erfiðast að skilgreina. Á sama tima er þetta mikilvægasti hlutinn. Með því að lagskipta forritum í framsetningu, domain og data source lög fáum við vísa stað til að geymi það sem við köllum domain logic. Domain logic er annað heiti yfir business logic. Það er hins vegar ekki alltaf ljóst hvar framsetning endar og hvar domain byrjar en þetta er eitt af viðfangsefnum sem þarf að leysa.
Í þessum fyrirlestri förum við yfir domain layer og skoðum nokkru munstur sem henta.
Go provides:
+ Concurrent execution
+ Synchronization and messaging
+ Multi-way concurrent control
Go does NOT provide direct thread manipulation
- Go multithreading is fully managed by Go runtime.
- In Go you use goroutines in place of threads
Learn about Goroutines, channels and standard library
Technical Webinar: Patterns for Integrating Your Salesforce App with Off-Plat...CodeScience
Patterns for Integrating Your Salesforce App with Off-Platform Apps
Integrating Salesforce applications with additional off-platform apps can dramatically extend the capability of powerful business apps. From ERP systems to custom apps, integrating with Salesforce can help streamline essential processes, saving your business valuable time and money. In our latest tech webinar, CodeScience Technical Architect Mark Pond dives into Salesforce integration patterns and the positive impacts they can deliver.
In this technical webinar, you will learn:
- Several common Salesforce integration patterns
- Integration pattern pitfalls
- How to leverage a custom queue to automate background work
- Deliverability and reporting advantages of custom queues
Watch today to learn how automated testing can take your enterprise solutions to the next level.
This document is an overview of a Private Cloud Reference Model. For the purposes of this document, a Reference Model is defined as the problem definition, requirements, and scope for a specific domain including the identification of all layers (or subdomains) and any interactions or dependencies between the components.
The business logic of an enterprise application is probably the most confusing part of the application. By layering the application into presentation, domain and data source layers, we can provide a logical place to put what we call domain logic. It may not always be clear where presentation ends and the domain begins, but that is one of the challenges with building software applications.
In this lecture we look at the domain layer and introduce three domain logic design pattern and one to provide API to the domain.
At Softroniics we provide job oriented training for freshers in IT sector. We are providing IEEE project guidance and Final year project guidance. We are Pioneers in all leading technologies like Android, Java, .NET, PHP, Python, Embedded Systems, Matlab, NS2, VLSI, Modelsim, Tanner, Xilinx etc. We are specializiling in technologies like Big Data, Cloud Computing, Internet Of Things (iOT), Data Mining, Networking, Information Security, Image Processing and many other. We are providing long term and short term internship also. We are also providing IEEE project support at Calicut, Thrissur and Palakkad. For more details contact 9037291113, 7907435072
At Softroniics we provide job oriented training for freshers in IT sector. We are providing IEEE project guidance and Final year project guidance. We are Pioneers in all leading technologies like Android, Java, .NET, PHP, Python, Embedded Systems, Matlab, NS2, VLSI, Modelsim, Tanner, Xilinx etc. We are specializiling in technologies like Big Data, Cloud Computing, Internet Of Things (iOT), Data Mining, Networking, Information Security, Image Processing and many other. We are providing long term and short term internship also. We are also providing IEEE project support at Calicut, Thrissur and Palakkad. For more details contact 9037291113, 7907435072
Sennilega er "business logic" sá hluti af enterprise lausnum sem er hvað erfiðast að skilgreina. Á sama tima er þetta mikilvægasti hlutinn. Með því að lagskipta forritum í framsetningu, domain og data source lög fáum við vísa stað til að geymi það sem við köllum domain logic. Domain logic er annað heiti yfir business logic. Það er hins vegar ekki alltaf ljóst hvar framsetning endar og hvar domain byrjar en þetta er eitt af viðfangsefnum sem þarf að leysa.
Í þessum fyrirlestri förum við yfir domain layer og skoðum nokkru munstur sem henta.
Go provides:
+ Concurrent execution
+ Synchronization and messaging
+ Multi-way concurrent control
Go does NOT provide direct thread manipulation
- Go multithreading is fully managed by Go runtime.
- In Go you use goroutines in place of threads
Learn about Goroutines, channels and standard library
1. What laid behind of creation?
2. About .NET Core
3. Everything is a package
4. .NET Framework, .NET Standard and .NET Native: what’s the difference
5 . .NET Core vs.NET Framework for server apps
6 . What's under the hood? Understanding CoreCLR and IL
Fresh ElifTech's Virtual Reality communiqué: updates, news, releases, features, technologies, hardware, etc. Stay updated, check out VR Digest.
Don't forget to subscribe not to miss next month VR digest.
Check our blog for more: https://www.eliftech.com/blog
JavaScript news and tips: browsers, front-end, Node.js, useful libs. Enjoy our latest JS digest!
Don't forget to subscribe not to miss next month JS digest.
Check our blog for more: https://www.eliftech.com/blog
Latest news, updates and releases from Virtual Reality - technology, hardware, games - in the fresh edition of our monthly VR digest
Don't forget to subscribe not to miss next month VR digest.
Check our blog for more: https://www.eliftech.com/blog
Find out what happened on the Internet of Things area recently. Enjoy our newest monthly IoT digest!
Don't forget to subscribe not to miss next month IoT digest.
Check our blog for more: https://www.eliftech.com/blog
What’s the latest news on virtual reality, augmented reality, and human-computer interaction? Let us keep you up to date!
Don't forget to subscribe not to miss next month VR digest.
Check our blog for more: https://www.eliftech.com/blog
The first summer collection of Internet of Things news and updates. Check out the latest ElifTech's IoT digest.
Don't forget to subscribe not to miss next month IoT digest.
Check our blog for more: https://www.eliftech.com/blog
Whats new at Internet of Things area? Take a look at the latest IoT news and updates in our fresh IoT digest.
Don't forget to subscribe not to miss next month IoT digest.
Check our blog for more: https://www.eliftech.com/blog
The newest compilation of Virtual Reality latest news, updates, releases and our short review of VR Expo 2018 in Amsterdam.
Don't forget to subscribe not to miss next month VR digest.
Check our blog for more: https://www.eliftech.com/blog
Polymer is a Google's attempt to introduce principles that were intended to get ahead of their time (HTML templates, custom elements, shadow DOM, HTML imports), but trends went into another direction. Google uses Polymer in its products including (but not limited to) YouTube, Google Music, Google Earth, but there is hardly any interest to Polymer from the community. Thus, you can develop a rich web application with Polymer, but it's hard to find documentation and examples.
Prepared byVitalii Perehonchuk, Software Developer at ElifTech
Explore JavaScript news, updates and releases in the latest edition of ElifTech's JS digest.
Subscribe not to miss next month JS digest.
Check our blog for more: https://www.eliftech.com/blog
A fresh collection of Virtual Reality's latest news, updates and releases: technology, hardware, business.
Don't forget to subscribe not to miss next month VR digest.
Check our blog for more: https://www.eliftech.com/blog
Stay current on Internet of Things, check out the latest IoT news and updates from our IoT digest.
Don't forget to subscribe not to miss next month IoT digest.
Plugged-in to the latest Internet of Things news: hardware, software and industry in general.
Don't forget to subscribe not to miss next month IoT digest.
March edition of the latest news, updates and releases from Virtual Reality: technology, hardware, business.
Don't forget to subscribe not to miss next month VR digest.
ElifTech's first IoT digest. News about Internet of Thing hardware, software and industry in general.
Don't forget to subscribe not to miss next month IoT digest.
Paketo Buildpacks : la meilleure façon de construire des images OCI? DevopsDa...Anthony Dahanne
Les Buildpacks existent depuis plus de 10 ans ! D’abord, ils étaient utilisés pour détecter et construire une application avant de la déployer sur certains PaaS. Ensuite, nous avons pu créer des images Docker (OCI) avec leur dernière génération, les Cloud Native Buildpacks (CNCF en incubation). Sont-ils une bonne alternative au Dockerfile ? Que sont les buildpacks Paketo ? Quelles communautés les soutiennent et comment ?
Venez le découvrir lors de cette session ignite
Enhancing Research Orchestration Capabilities at ORNL.pdfGlobus
Cross-facility research orchestration comes with ever-changing constraints regarding the availability and suitability of various compute and data resources. In short, a flexible data and processing fabric is needed to enable the dynamic redirection of data and compute tasks throughout the lifecycle of an experiment. In this talk, we illustrate how we easily leveraged Globus services to instrument the ACE research testbed at the Oak Ridge Leadership Computing Facility with flexible data and task orchestration capabilities.
TROUBLESHOOTING 9 TYPES OF OUTOFMEMORYERRORTier1 app
Even though at surface level ‘java.lang.OutOfMemoryError’ appears as one single error; underlyingly there are 9 types of OutOfMemoryError. Each type of OutOfMemoryError has different causes, diagnosis approaches and solutions. This session equips you with the knowledge, tools, and techniques needed to troubleshoot and conquer OutOfMemoryError in all its forms, ensuring smoother, more efficient Java applications.
Designing for Privacy in Amazon Web ServicesKrzysztofKkol1
Data privacy is one of the most critical issues that businesses face. This presentation shares insights on the principles and best practices for ensuring the resilience and security of your workload.
Drawing on a real-life project from the HR industry, the various challenges will be demonstrated: data protection, self-healing, business continuity, security, and transparency of data processing. This systematized approach allowed to create a secure AWS cloud infrastructure that not only met strict compliance rules but also exceeded the client's expectations.
Experience our free, in-depth three-part Tendenci Platform Corporate Membership Management workshop series! In Session 1 on May 14th, 2024, we began with an Introduction and Setup, mastering the configuration of your Corporate Membership Module settings to establish membership types, applications, and more. Then, on May 16th, 2024, in Session 2, we focused on binding individual members to a Corporate Membership and Corporate Reps, teaching you how to add individual members and assign Corporate Representatives to manage dues, renewals, and associated members. Finally, on May 28th, 2024, in Session 3, we covered questions and concerns, addressing any queries or issues you may have.
For more Tendenci AMS events, check out www.tendenci.com/events
Check out the webinar slides to learn more about how XfilesPro transforms Salesforce document management by leveraging its world-class applications. For more details, please connect with sales@xfilespro.com
If you want to watch the on-demand webinar, please click here: https://www.xfilespro.com/webinars/salesforce-document-management-2-0-smarter-faster-better/
Globus Connect Server Deep Dive - GlobusWorld 2024Globus
We explore the Globus Connect Server (GCS) architecture and experiment with advanced configuration options and use cases. This content is targeted at system administrators who are familiar with GCS and currently operate—or are planning to operate—broader deployments at their institution.
SOCRadar Research Team: Latest Activities of IntelBrokerSOCRadar
The European Union Agency for Law Enforcement Cooperation (Europol) has suffered an alleged data breach after a notorious threat actor claimed to have exfiltrated data from its systems. Infamous data leaker IntelBroker posted on the even more infamous BreachForums hacking forum, saying that Europol suffered a data breach this month.
The alleged breach affected Europol agencies CCSE, EC3, Europol Platform for Experts, Law Enforcement Forum, and SIRIUS. Infiltration of these entities can disrupt ongoing investigations and compromise sensitive intelligence shared among international law enforcement agencies.
However, this is neither the first nor the last activity of IntekBroker. We have compiled for you what happened in the last few days. To track such hacker activities on dark web sources like hacker forums, private Telegram channels, and other hidden platforms where cyber threats often originate, you can check SOCRadar’s Dark Web News.
Stay Informed on Threat Actors’ Activity on the Dark Web with SOCRadar!
Modern design is crucial in today's digital environment, and this is especially true for SharePoint intranets. The design of these digital hubs is critical to user engagement and productivity enhancement. They are the cornerstone of internal collaboration and interaction within enterprises.
Advanced Flow Concepts Every Developer Should KnowPeter Caitens
Tim Combridge from Sensible Giraffe and Salesforce Ben presents some important tips that all developers should know when dealing with Flows in Salesforce.
Innovating Inference - Remote Triggering of Large Language Models on HPC Clus...Globus
Large Language Models (LLMs) are currently the center of attention in the tech world, particularly for their potential to advance research. In this presentation, we'll explore a straightforward and effective method for quickly initiating inference runs on supercomputers using the vLLM tool with Globus Compute, specifically on the Polaris system at ALCF. We'll begin by briefly discussing the popularity and applications of LLMs in various fields. Following this, we will introduce the vLLM tool, and explain how it integrates with Globus Compute to efficiently manage LLM operations on Polaris. Attendees will learn the practical aspects of setting up and remotely triggering LLMs from local machines, focusing on ease of use and efficiency. This talk is ideal for researchers and practitioners looking to leverage the power of LLMs in their work, offering a clear guide to harnessing supercomputing resources for quick and effective LLM inference.
OpenFOAM solver for Helmholtz equation, helmholtzFoam / helmholtzBubbleFoamtakuyayamamoto1800
In this slide, we show the simulation example and the way to compile this solver.
In this solver, the Helmholtz equation can be solved by helmholtzFoam. Also, the Helmholtz equation with uniformly dispersed bubbles can be simulated by helmholtzBubbleFoam.
Field Employee Tracking System| MiTrack App| Best Employee Tracking Solution|...informapgpstrackings
Keep tabs on your field staff effortlessly with Informap Technology Centre LLC. Real-time tracking, task assignment, and smart features for efficient management. Request a live demo today!
For more details, visit us : https://informapuae.com/field-staff-tracking/
top nidhi software solution freedownloadvrstrong314
This presentation emphasizes the importance of data security and legal compliance for Nidhi companies in India. It highlights how online Nidhi software solutions, like Vector Nidhi Software, offer advanced features tailored to these needs. Key aspects include encryption, access controls, and audit trails to ensure data security. The software complies with regulatory guidelines from the MCA and RBI and adheres to Nidhi Rules, 2014. With customizable, user-friendly interfaces and real-time features, these Nidhi software solutions enhance efficiency, support growth, and provide exceptional member services. The presentation concludes with contact information for further inquiries.
Exploring Innovations in Data Repository Solutions - Insights from the U.S. G...Globus
The U.S. Geological Survey (USGS) has made substantial investments in meeting evolving scientific, technical, and policy driven demands on storing, managing, and delivering data. As these demands continue to grow in complexity and scale, the USGS must continue to explore innovative solutions to improve its management, curation, sharing, delivering, and preservation approaches for large-scale research data. Supporting these needs, the USGS has partnered with the University of Chicago-Globus to research and develop advanced repository components and workflows leveraging its current investment in Globus. The primary outcome of this partnership includes the development of a prototype enterprise repository, driven by USGS Data Release requirements, through exploration and implementation of the entire suite of the Globus platform offerings, including Globus Flow, Globus Auth, Globus Transfer, and Globus Search. This presentation will provide insights into this research partnership, introduce the unique requirements and challenges being addressed and provide relevant project progress.
Gamify Your Mind; The Secret Sauce to Delivering Success, Continuously Improv...Shahin Sheidaei
Games are powerful teaching tools, fostering hands-on engagement and fun. But they require careful consideration to succeed. Join me to explore factors in running and selecting games, ensuring they serve as effective teaching tools. Learn to maintain focus on learning objectives while playing, and how to measure the ROI of gaming in education. Discover strategies for pitching gaming to leadership. This session offers insights, tips, and examples for coaches, team leads, and enterprise leaders seeking to teach from simple to complex concepts.
Code reviews are vital for ensuring good code quality. They serve as one of our last lines of defense against bugs and subpar code reaching production.
Yet, they often turn into annoying tasks riddled with frustration, hostility, unclear feedback and lack of standards. How can we improve this crucial process?
In this session we will cover:
- The Art of Effective Code Reviews
- Streamlining the Review Process
- Elevating Reviews with Automated Tools
By the end of this presentation, you'll have the knowledge on how to organize and improve your code review proces
First Steps with Globus Compute Multi-User EndpointsGlobus
In this presentation we will share our experiences around getting started with the Globus Compute multi-user endpoint. Working with the Pharmacology group at the University of Auckland, we have previously written an application using Globus Compute that can offload computationally expensive steps in the researcher's workflows, which they wish to manage from their familiar Windows environments, onto the NeSI (New Zealand eScience Infrastructure) cluster. Some of the challenges we have encountered were that each researcher had to set up and manage their own single-user globus compute endpoint and that the workloads had varying resource requirements (CPUs, memory and wall time) between different runs. We hope that the multi-user endpoint will help to address these challenges and share an update on our progress here.
Globus Compute wth IRI Workflows - GlobusWorld 2024Globus
As part of the DOE Integrated Research Infrastructure (IRI) program, NERSC at Lawrence Berkeley National Lab and ALCF at Argonne National Lab are working closely with General Atomics on accelerating the computing requirements of the DIII-D experiment. As part of the work the team is investigating ways to speedup the time to solution for many different parts of the DIII-D workflow including how they run jobs on HPC systems. One of these routes is looking at Globus Compute as a way to replace the current method for managing tasks and we describe a brief proof of concept showing how Globus Compute could help to schedule jobs and be a tool to connect compute at different facilities.
2. www.eliftech.com
Contents
1. What is domain logic?
2. Domain logic patterns:
1. Transaction script
2. Domain model
3. Table module
4. Service layer
3. Conclusion
3. www.eliftech.com
What is domain logic?
▪ Domain logic describe the functional algorithms or business logic that handle the information
exchange between a database and a user interface.
▪ The Domain logic patterns examine different ways to implement the logic for your application.
▪ Main concern is the complexity of the application’s logic.
4. www.eliftech.com
Domain logic patterns
● Transaction Script
● Domain Model
● Table Module
● Service Layer
Taken from “Patterns of Enterprise Application Architecture” by Martin
Fowler
5. www.eliftech.com
Transaction script
● Organizes business logic by procedures where each procedure handles a single request
from the presentation
● A Transaction Script organizes all this logic primarily as a single procedure, making calls
directly to the database or through a thin database wrapper.
Transaction script
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Transaction script
Advantages:
● It is independent from other transactions
● Very simple to implement and understand
Disadvantages:
● Code duplication
For more complex domain logic, Domain model pattern should be used instead.
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Types of Domain model
● Simple Domain model
○ Looks very much like the database design with mostly one domain object for each
database table
○ Uses Active record
● Rich Domain model
○ Looks different from the database design, with inheritance, strategies, and other
patterns, and complex webs of small interconnected objects
○ Uses Data mapper
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When to use it?
● In cases, when you have complicated and changing business rules involving additional
operations like validation, calculation.
10. www.eliftech.com
Table module
▪ The Table Module pattern takes the middle road between a Domain Model and
Transaction Script.
▪ Using this approach the logic for the application is implemented as a set of components
called Table Modules.
▪ Your solution would contain a Table Module for each Table in your database. These
Table Modules implement the functionality related to the entity described in the table.
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When to use it?
▪ Table module is very much based on table-oriented data, so we can use it when we
access tabular data using Record Set.
▪ Table module allows you to fit business logic into the application in a well-organized
manner, without losing the way the elements work on the tabular data.
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Service layer
▪ Service Layer defines an application’s boundary with a layer of services that establishes
a set of available operations and coordinates the application’s response in each
operation.
▪ It encapsulates the application’s business logic, controlling transactions and
coordinating responses in the implementation of its operations.
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Service layer
2 Basic Implementation variations are:
● Domain facade approach
○ Service Layer is implemented as a set of thin facades over a Domain model
○ The classes implementing the facades don’t implement any business logic. All logic
is implemented in Domain Model
● Operation script approach
○ Service Layer is implemented as a set of thicker classes that directly implement
application logic but delegate to encapsulated domain object classes for domain
logic.
○ The operations available to clients of a Service Layer are implemented as scripts,
organized several to a class defining a subject area of related logic.
16. www.eliftech.com
When to use it?
▪ The benefit of Service Layer is that it defines a common set of application operations
available to many kinds of clients and it coordinates an application’s response in each
operation.
▪ In an application with more than one kind of client of its business logic, and complex
responses in its use cases involving multiple transactional resources, it makes a lot of
sense to include a Service Layer with container-managed transactions, even in an
undistributed architecture.
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Conclusion
● Transaction Script: This pattern abstracts each business transaction into a Script object. The
transactions are then performed by running the script.
● Domain Model: This pattern manages the application's complexity within an object oriented
model. Using this approach the business functionality is implemented within the model.
● Table Module: Using this pattern, the data related to the business entities is contained within
DataSet, while the logic is maintained with Table Modules. Each Table Module contains
methods that act upon the DataSet.
● Service Layer: This pattern provides a layer through which client applications can access the
services offered by an application (or service).
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Editor's Notes
Отже перший пункт - що таке domain logic. Domain logic - це функціЇ, які виконує дана система. Відповідно бізнес-логіка входить в це визначення.
Таким чином domain logic patterns - це патерни організації логіки системи, що розробляється. Вибір патернів залежить від складності системи, а саме від моделей даних і їх взаємодії між собою.
Тепер перейдемо до самих патернів. Всі вони висвітлені в цій книзі авторства Мартіна Фаулера, одно з основоположників методології Agile.
Отже, ми маємо 4 патерни. Далі поговоримо про них детальніше.
Перший - transaction script. Хочу зразу прояснити один момент. Тут слово transaction немає ніякого відношення до SQL-транзакцій чи чогось подібно
Тут під транзакцією розуміється ширше поняття. Тобто, транзакція - це просто певна група операції. Це, власне, і є визначенням патерна transaction script.Ми маємо певну процедуру, яка виконує всі необхідні дії. Наприклад, ми маємо функцію “придбати товар”, що включає в себе створення об’єкту “замовлення”,
перевірки чи товар в замовленні є доступним і збереження замовлення в базі даних. Для виконання всіх цих дій ми маємо одну функцію де спілкування з БД відбувається напряму без використання посередників типу ORM-ки.
Отже, основною перевагою все ж таки є простота. В нас є одна функція, немає явних моделей даних. Вся робота йде напряму.
Але по мірі ускладнення системи код для спілкування з БД почне повторюватись. Наприклад, в двох різних транзакціях буде виконуватись запит на зчитування інформації про товар з бази.
Зразу виникає думка про те, що цю операцію можна вписати в якийсь клас. І тут виходить на сцену наш наступний паттерн.
Domain model - це модель предметної області. Або більш приземлено, це сукупність моделей даних і їх взаємодія, що описують дану предметну область. Я впевнений, що кожен з присутніх розробників зустрічався або використовував цей патерн, навіть не знаючи про нього. Це ORM (Object-relational mapping). На даній схемі, спрошено показана операція покупка товарів юзером.
Domain model можна поділити на дві категорії. SDM and RDM відповідно. Випадок сімпл, це типова архітектура з використанням ORM - маємо модель і таблицю, що їй відповідає. Робота з базою даних в цьому випадку є дуже простою. Ми просто викликаємо на екземплярі моделі відповідний метод.
У другому випадку, rich - в системі використовуються моделі, які комбінацією інших моделей або результатом виконання певних функцій, що не мають відповідної таблиці в БД. Як наслідок, потрібен Data Mapper для збереження даних з таких моделей, який перепише дані в екземпляри моделей, які мають таблиці.
Такий патерн підходить для систем де є велика кількість різних видів взаємодії між моделями. Такий підхід є найгнучкішим і запобігає дублюванню коду. Але в свою чергу він вимагає попереднього аналізу, щоб якомога точніше змоделювати дану предметну область.
Наступний патерн - Table module. Цей патерн є чимось середнім між transaction scripts i domain model. Специфіка наступна - для кожної таблиці створюється окремий клас Table module.
Далі вся робота з цією таблицею(створення, читання, редагування, видалення) буде проходити через цей клас. Це основною відмінністю між патерном Domain model. У випадку Domain model, всі операції проводяться на екземплярі моделі, а у цьому випадку ми викликаємо відповідну функцію класу Table Module з відповідними параметрами. Тобто екземплярів моделі може бути багато, а table module - один.
Даний алгоритм роботи пояснює дана схема. Зверху ми маємо 4 колонки. 1-й - presentation - є певним класом, що відповідає за презентацію даних,
2-й table data gateway - формує дані у відповідний датасет, 3-тя - це база даних або клас що відповідає за роботу з нею,
І 4-та це власне наш table module. Він приймає в себе датасет. Далі всі операції над даними спочатку виконуються з цим датасетом, де вони валідуються, а вже далі зміни переходять у базу даних.
Коли ж це викорстовувати? Очевидно, коли в нас дані зберігаються в таблицях. Такий підхід зберігає просту і зрозумілу структуру даних. Також ми абстрагуємося від джерела даних.Клієнт не знає чи прийшли дані з бази чи з іншого місця оскільки всі дані читаються з датаСету. З метою тестуванні ми можемо замокати дані напряму в датасет і десь на клієнті або юзерінтерфейсі не буде ніякої різниці.
І останній патерн - Service Layer. Він сильно відрізняється від попередніх. Попередні патерни включали в себе реалізацію бізнес-логіки і роботу з джерелом даних. Патерн Service layer реалізує інтерфейс для роботи з бізнес-логікою. Тобто є чимось зовнішнім по відношенню до того ж Domain model.
Цей момент прекрасно ілюструє цей малюнок. Тут наш Service layer є інтерфейсом Domain model, в я кому вже, в свою чергу, реалізована бізнес-логіка і робота з бд. Тут показані різні види клієнтів. Ці клієнти можуть бути частиною нашої системи або якоїсь іншої, які намагається дістати дані чи виконати якісь дії в нашій програмі.
Існує два варіанти імплементації цього патерну.
Domain facade approach - множина функцій-фасадів, що дають змогу працювати з певними функціями Domain model. Вони в собі не містять бізнес-логіки
І другий, Operation script - тут все цікавіше. Ми вже маємо певні класи, які відповідають за зв’язок з певними частинами Domain model. Мікросервісна архітектура є прикладом реалізації цього варіанту патерна: ми має певний сервіс, що відповідає за роботу з певною частиною Domain model.
Основною перевагою використання цього патерну є те, що він дає нам змогу інкапсулювати в ньому можливість роботи з різними видами клієнтів, не змінюючи при цьому domain model.
В загальному, також спрощується робота з Domain model.
На цьому слайді ми маємо загальний висновок.
Отже, transaction script - маємо одну процедуру, яка виконує всю роботу.
Domain model - ми реалізуємо модель предметної області шляхом створення сутностей і взаємодії між ними
Table module - створюється клас для роботи з таблицею. Всі операції для роботи з цією таблицею виконує тільки цей клас
І Service Layer - визначає інтерфейс для роботи з моделлю предметної області шляхом створення спеціальних фасадів або класів-сервісів.