As LabVIEW developers, we are comfortable developing in LabVIEW. However, sometimes we need to leverage code from other languages. This is where DLLs come in. For those of us that are less than comfortable with coding languages outside of LabVIEW, using DLLs can be daunting and frustrating. The Import Shared Library Wizard can make your life easier, however, it is not very reliable when using custom data types. This forces us to use Call Library Function nodes (CLNs) for DLL calls, which can bring up a whole bunch of problems with no intuitive debug strategy.
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If you attended my presentation at NI Developer Day back in March, you probably recognize the content of this three-part blog series. The premise of my presentation was simple and rather obvious given its title “You Already Know How to Use LabVIEW Classes.” In the end, object-oriented LabVIEW is simply a programming style that encourages software modularity and reuse. The doing is easy because it requires mostly bits and pieces with which we are already familiar.
In my previous post, I introduced the concept of object-oriented inheritance. I also suggested that, as a regular G developer, you already know enough to start writing your own object-oriented code.
Maintaining this same (I hope empowering) perspective, let’s dive into the next foundational principle of object-oriented programming: encapsulation. Look for a post covering the final principle (polymorphism) shortly.
You Already Know Enough to Get Started
If you do not currently leverage object-oriented programming techniques in your LabVIEW code (believe it or not) you likely know more than enough to get started. Object-oriented programming is not magic—it is a programming style built for modularity, and maintainability. As a regular G developer, you probably encounter clusters, libraries, type definitions, property nodes, and polymorphic VIs on a daily basis.
What is an interface?
An interface is the set of methods, messages, or VIs (think connector panes) that we use to pass data in and out of a software module. Simply put, what are the inputs and outputs, and how do they get in and out? A software module could be a class, a library, or simply a repository of VIs (in descending order of author preference).
Why are interfaces useful?
In the previous installment, we built a very simple program which consisted of a single actor and a single message. In this part we will create an application that is a bit more complex. This example consists of two actors: a DAQ actor which can read an analog voltage and a User Interface actor which provides a graphical user interface to display the data. Let’s get started!
Scrum is powerful because it takes a large amount of work--for which estimating the total effort needed for completion is very difficult--and breaks it up into several 2-4 week long well-defined sprints. At the end of each sprint, the team delivers tested, documented, working code that the customer can immediately interact with and use to inject feedback into the next sprint cycle. Before the code is handed off, the team holds two meetings: the sprint review meeting and the sprint retrospective meeting.
Sprint planning meetings are held before the start of each sprint and are attended by product owner, scrum master and the entire development team. During the meeting the product owner describes the goal of the upcoming sprint and prioritizes the backlog of user stories based on that goal. The sprint goal is a concise description of what the sprint team plans to achieve in the upcoming sprint.
Agile software development methodologies are built to account for change. As such, it is not necessary that the customer creates a detailed list of requirements before the start of the project or that the developers perfectly predict how long each requirement will take to implement. Agile solves the problem by helping us make decisions based on the information we currently have. We create user stories for features that we can currently define and epic stories for feature sets that we need later but are not yet able to define in detail.
Effective scrum requires its participants to play certain roles and Bloomy’s scrum process is closely based on industry-standard scrum practices. A Bloomy scrum team consists of two to four Bloomy developers and one member of the customer’s team. The customer’s team member acts as the product owner, while the Bloomy team includes at least one scrum master and one developer. Both Bloomy and customer stakeholders provide support throughout the process but do not play a direct role in the scrum.