Welcome!

Server Monitoring Authors: Yeshim Deniz, Liz McMillan, Pat Romanski, Carmen Gonzalez, Ken Schwaber

Blog Feed Post

Design Patterns in Java LiveLessons Review

I have spent the past few weeks watching this video series. I started watching it on the treadmill in the morning before work. I did that until I hit lesson 5. It is 4 hours and 20 minutes long. I started watching lesson 5 in front of the computer, not because I didn't want to walk for over four hours, but because I wanted to look at the code you can download with these lessons.

In lesson 5 covers a ton of patterns. The thing I like most about the way the patterns are introduced is that they are introduced working with other patterns. The way patterns should be used, together.

He uses lots of diagrams and walks through the tons of code making sure the patterns are thoroughly cover.

The thing I liked most about the course was that the speaker is not a pattern zealot. He makes sure to tell you when you would not want to use patterns and why. He gives the advantages and disadvantages of each pattern.

The downloadable code is very well organized and usable. It was really nice to just import the project, build it, and run it. No issues at all. I am not usually that lucky with Java samples.

You do not need to know Java to watch this course. I do very very little in Java. I am in Objective-C or C# 90% of the time I am in code. I do have a lot of experience with patterns at all levels (code, integration, architectural, information management, enterprise, etc.). Although you can do without Java, I do recommend you have OOP under your belt. I also felt having the past experience with pattern really helped me keep up.

If you don't have pattern experience, I think you may have to work a little harder to keep up. That is not a bad thing because the material covered is real worth the extra effort to get under your belt. The more you work at understanding the concepts the the speaker cover, the more embedded in your development thought process it will become.

Below is a brief overview of each lesson. They are taken from the publisher's web site.

Lesson 1:
Experts in most domains perform quite differently than beginners. For example, professional athletes, musicians, and dancers move fluidly and effortlessly, without focusing on each individual movement. Likewise, when master software developers write code, they approach it differently than novices, drawing on years of design experience to help guide their solutions.

When watching experts perform, it's often easy to forget how much effort they put into reaching these high levels of achievement. Continuous practice, repetition, and mentoring from other experts are crucial to their success. At the heart of all these activities is knowledge and mastery of patterns, which are reusable solutions to common problems that arise within particular contexts.

In this lesson you learn to recognize the importance of design experience when becoming a master software developer. You also learn what patterns are and how they help codify design experience to improve software quality and developer productivity. In addition, you learn the common characteristics of patterns and pattern descriptions. Finally, you learn about the history of the Gang of Four book and its patterns, as well as learn about key types of relationships among patterns.

Lesson 2:
While it’s certainly possible to discuss patterns in the abstract, good design and programming practices are not best learned through generalities and platitudes. Instead, it’s more effective to see how significant programs can be made easier to write and read, easier to maintain and modify, and more efficient and robust via the application of time-proven software patterns.

This lesson therefore presents an overview of an expression tree processing app that we use as a case study throughout the course. You learn about the goals of this case study, which provides a realistic–yet tractable–context in which to explore the why, the how, and the benefits and limitations of applying many Gang of Four design patterns to an application written in Java. Using the case study as a guide, you also learn how to recognize key structural and behavioral properties in a domain, as well as understand the case study's functional and non-functional requirements.

All the pattern-oriented software presented in the case study is available in open-source form from the course website. You can see throughout the course that applying Gang of Four patterns in the case study not only improves the application’s modularity, extensibility, and quality but also enhances its portability so that it runs on a range of Java platforms, including Android and Eclipse.

Lesson 3:
Algorithmic decomposition is a historically popular software development method that structures software based on the actions performed by algorithms in a program. It decomposes general actions in an algorithm iteratively and recursively into more specific actions. The design components in an algorithmic decomposition typically correspond to processing steps in an execution sequence, which are usually implemented via functions or procedures.

In this lesson you learn how to develop an algorithmic decomposition of the expression tree processing app case study. You also learn how to evaluate the benefits and limitations of algorithmic decomposition. This material provides a baseline for comparison with our pattern- and object-oriented expression tree processing app presented in subsequent lessons.

Lesson 4:
Object-oriented design is a method of planning a system of interacting objects to solve software problems. This design paradigm employs hierarchical data abstraction, where components are structured based on stable class/object roles and relationships, rather than functions corresponding to actions (as is the case with algorithmic decomposition). Moreover, object-oriented design associates actions with classes of objects in a manner that emphasizes high cohesion and low coupling. In many well-designed object-oriented programs, classes and objects are defined and associated in accordance with patterns and combined to form frameworks.

In this lesson you learn how to develop an object-oriented design for the expression tree processing app case study. In addition, you learn how to evaluate the benefits and limitations of object-oriented design relative to the algorithmic decomposition approach presented in Lesson 3.

Lesson 5:
The book Design Patterns: Elements of Reusable Object-Oriented Software (the so-called “Gang of Four” book) presents 23 patterns that document recurring solutions to common problems that arise when developing software in particular contexts. In this lesson you learn how more than a dozen patterns from the Gang of Four book can be applied to the Java-based expression tree processing app case study to resolve key design problems and improve the apps modularity, extensibility, portability, and quality. This lesson forms the bulk of the course and covers the following patterns:

• Composite, which treats individual objects and multiple, recursively-composed objects uniformly.
• Bridge, which separates an abstraction from its implementation(s) so the two can vary independently.
• Interpreter, which when given a language, defines a representation for its grammar.
• Builder, which separates the construction of a complex object from its representation.
• Iterator, which accesses elements of an aggregate without exposing its representation.
• Strategy, which defines a family of algorithms, encapsulates each one, and makes them interchangeable.
• Visitor, which centralizes operations on an object structure so that they can vary independently.
• Command, which encapsulates the request for a service as an object.
• Factory Method, which provides an interface for creating an object, but leaves the choice of the concrete type to a subclass.
• State, which allows an object to alter its behavior when its internal state changes, making object appear to change its class.
• Template Method, which provides a skeleton of an algorithm in a method, deferring some steps to subclasses.
• Singleton, which ensures a class only has one instance and provides a global point of access.

The lesson also touches on several other Gang of Four patterns, including Abstract Factory, Adaptor, Decorator, and Observer.

Lesson 6:
The pattern- and object-oriented version of the expression tree processing app case study presented in Lesson 5 provided many improvements compared with the algorithmic decomposition approach described in Lesson 3. For example, it's much more modular and extensible, its design matches the domain better, and it incurs less space overhead. The design of the expression tree process app also exhibits “high pattern density.” For instance, nearly all its classes play a role in one or more Gang of Four patterns. In addition, patterns help clarify the relationships of the many classes comprising the case study’s design. The same pattern-oriented design can be implemented readily in many popular object-oriented programming languages. For example, the Java and C++ solutions are nearly identical, modulo minor syntactic and semantic differences in these two languages. Although pattern- and object-oriented solutions are powerful, becoming a master software developer requires a balanced and nuanced understanding of the pros and cons of patterns. In this lesson, you learn how to evaluate both the benefits and limitations of patterns.

I highly recommend this video series to anyone working in an object oriented language.

Get the video series here.

If you have no design pattern experience at all, below are a few of the best available on the topic.

           

Read the original blog entry...

More Stories By Tad Anderson

Tad Anderson has been doing Software Architecture for 18 years and Enterprise Architecture for the past few.

IoT & Smart Cities Stories
The challenges of aggregating data from consumer-oriented devices, such as wearable technologies and smart thermostats, are fairly well-understood. However, there are a new set of challenges for IoT devices that generate megabytes or gigabytes of data per second. Certainly, the infrastructure will have to change, as those volumes of data will likely overwhelm the available bandwidth for aggregating the data into a central repository. Ochandarena discusses a whole new way to think about your next...
CloudEXPO | DevOpsSUMMIT | DXWorldEXPO are the world's most influential, independent events where Cloud Computing was coined and where technology buyers and vendors meet to experience and discuss the big picture of Digital Transformation and all of the strategies, tactics, and tools they need to realize their goals. Sponsors of DXWorldEXPO | CloudEXPO benefit from unmatched branding, profile building and lead generation opportunities.
DXWorldEXPO LLC announced today that Big Data Federation to Exhibit at the 22nd International CloudEXPO, colocated with DevOpsSUMMIT and DXWorldEXPO, November 12-13, 2018 in New York City. Big Data Federation, Inc. develops and applies artificial intelligence to predict financial and economic events that matter. The company uncovers patterns and precise drivers of performance and outcomes with the aid of machine-learning algorithms, big data, and fundamental analysis. Their products are deployed...
All in Mobile is a place where we continually maximize their impact by fostering understanding, empathy, insights, creativity and joy. They believe that a truly useful and desirable mobile app doesn't need the brightest idea or the most advanced technology. A great product begins with understanding people. It's easy to think that customers will love your app, but can you justify it? They make sure your final app is something that users truly want and need. The only way to do this is by ...
Digital Transformation and Disruption, Amazon Style - What You Can Learn. Chris Kocher is a co-founder of Grey Heron, a management and strategic marketing consulting firm. He has 25+ years in both strategic and hands-on operating experience helping executives and investors build revenues and shareholder value. He has consulted with over 130 companies on innovating with new business models, product strategies and monetization. Chris has held management positions at HP and Symantec in addition to ...
Dynatrace is an application performance management software company with products for the information technology departments and digital business owners of medium and large businesses. Building the Future of Monitoring with Artificial Intelligence. Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more busine...
Cell networks have the advantage of long-range communications, reaching an estimated 90% of the world. But cell networks such as 2G, 3G and LTE consume lots of power and were designed for connecting people. They are not optimized for low- or battery-powered devices or for IoT applications with infrequently transmitted data. Cell IoT modules that support narrow-band IoT and 4G cell networks will enable cell connectivity, device management, and app enablement for low-power wide-area network IoT. B...
The hierarchical architecture that distributes "compute" within the network specially at the edge can enable new services by harnessing emerging technologies. But Edge-Compute comes at increased cost that needs to be managed and potentially augmented by creative architecture solutions as there will always a catching-up with the capacity demands. Processing power in smartphones has enhanced YoY and there is increasingly spare compute capacity that can be potentially pooled. Uber has successfully ...
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
When talking IoT we often focus on the devices, the sensors, the hardware itself. The new smart appliances, the new smart or self-driving cars (which are amalgamations of many ‘things'). When we are looking at the world of IoT, we should take a step back, look at the big picture. What value are these devices providing. IoT is not about the devices, its about the data consumed and generated. The devices are tools, mechanisms, conduits. This paper discusses the considerations when dealing with the...