Complex processes may require collaboration and coordination of many components. We can model such processes using a Design Structure Matrix to represent information flow among the components, and then optimize the process to avoid rework and downtime. As a simplified example, consider a project with only two tasks: “A” and “B”, and a directed graph representing this system where a vertex represents a task and an edge represents the flow of information between tasks. Depending on the process being modeled, these two vertices can be arranged in one of three different configurations. ...

After graduating from university my (future) wife and I travelled and worked in Kenya as part of the Commonwealth of Learning — an intergovernmental agency dedicated to open learning and distance education. As fortune would have it, my brother had an internship in the neighbouring country of Tanzania during the same time period, and we were able to meet for a few days to enjoy the East African coast in the city of Mombasa. ...

To meet the challenges of scaling systems in size, scope, and complexity, it is useful to look at new approaches and theories to analyze, design, deploy, and manage these systems. A Design Structure Matrix (DSM) is an approach that supports the management of complexity by focusing attention on the elements of complex systems and how they relate to each other. DSM‐based techniques have proven to be very valuable in understanding, designing, and optimizing product, organization, and process architectures. This article explores in more depth how we can use the techniques developed by the design structure matrix community to improve software architecture. ...

A queueing system can be described as the flow of items through a queue. In a queueing system, items arrive at some rate to the system and join one or more queues inside the system. These items receive some kind of service, and when the work is done, they depart the system. A simple queueing system Little’s Law is a pretty simple model of queueing systems. $$ L=\lambda W $$ Little’s Law says that the average number of items in a queueing system, denoted \(L\), equals the average arrival rate of items in the system, \(\lambda\), multiplied by the average waiting time of an item in the system, \(W\). ...

Python 2 will retire in about one month. Given many organizations continued reliance on it, you may be asking “Now What?” What does this change mean for a company that heavily relies on a deprecated language? Many times, the Python 2 deployed in an organization still generates a lot of value. Yet as this code continues to age, you expose ourselves to potential security vulnerabilities with fewer avenues to address them. To continue running Python 2 and safely address this challenge, you have three options: ...

Large organizations have a lot of layers. From the C-Suite that is concerned about strategy and vision, to middle management who are executing on projects and programs, down to individual contributors working on project features. These layers provide a number of advantages, all derived from being able to better manage complexity. For example, layers provide a nice separation of concerns: as a software engineer, I don’t have to worry about tax codes and payroll because the finance department can take care of this. As an intern, I don’t need to worry about the global marketing strategy, I can just take care of implementing the widgets we need delivered to customers. ...

To deliver real-time communication (RTC) from browser to browser requires a lot of technologies that work well together: audio and video processing, application and networking APIs, and additional network protocols that for real-time streaming. The end result is WebRTC — over a dozen different standards for the application protocols and browser APIs that enable real-time communication for the web. ...

There is no one-size-fits-all cellular network used across the world, and trying to understand how cellular technology works across all the different uses cases is difficult, if not impossible, in a short blog post. So, rather than trying to understand every possible standard, this article will focus solely on LTE networks. Fortunately, competing standards and implementations are roughly similar and we can extrapolate any lessons learned about LTE to other cellular networks without much difficulty. ...

WiFi, technically specified in the IEEE 802.11 set of standards, is one of the most widely deployed wireless standards in the world. Chance are the device you are using to read this article has is WiFi enabled. WiFi is a straightforward extension of Ethernet, with some slight adaptations for using radio instead of copper wire as the communication channel. Like Ethernet, WiFi has no central process that controls which device is allowed to transmit data at any point in time. Instead, each device decides on its own, and all devices must work together to guarantee good shared channel performance. With Ethernet, the protocol senses when the communication channel is busy and waits until it is free before sending data (carrier sensing). Ethernet also adds a collision detection protocol as an optimization. If a collision is detected, nodes stop sending data and use a randomized backoff algorithm to decide when to begin sending again. Together, these algorithms form the carrier-sense multiple access with collision detection algorithm (CSMA/CD). WiFi uses a similar strategy to Ethernet, but is restricted by the communication channel — there is no reliable way to detect collisions using radio waves. Therefore, instead of collision detection, WiFi uses a collision avoidance strategy defined by the carrier-sense multiple access with collision avoidance algorithm (CSMA/CA). ...

Ethernet is a technology developed a Xerox PARC in 1973 and 1974 to support local area networking. It has since been expanded to include a whole family of technologies that support various network architectures and topologies as part of the IEEE 802.3 working group dedicated to supporting networking using physical connections and devices (i.e. not wireless). Ethernet was built with the assumption that all computers on a network use a shared communication channel. The primary problem with using a shared connection is creating a sense of orderly traffic when an entire network of computers wants to constantly transmit data over the same channel. The core of that solution is sensing other node’s activity and waiting until the line is free and using collision detection to minimize the amount of traffic on the network. ...