Parallel Workflows: Concurrent Development Strategies

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Parallel Workflows: Concurrent Development Strategies

Software Engineering · Chapter 2: Iterative, Incremental, and Specialized Process ModelsSection 2.4 · lesson 14 of 1036 min · free with a free account

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In this lesson

The concurrent development model: component states, parallel progress, and coordination.

  • Define the concurrent model, and how it differs from a sequential process
  • Describe the states one component can be in
  • Explain how components can be in different states at once
  • Identify the coordination challenges of parallel work

Transcript

Everything said in the video, section by section (804 words). Read along, or search it.

Iterative, Incremental, and Specialized Process Models

Parallel Workflows

Real systems are not one single thing moving through one phase at a time. This section covers the concurrent development model, where different parts of a system progress in parallel. It covers the states a component moves through, how several components progress together, and the coordination challenges that come with it.

Beyond One Phase at a Time

Components Move at Their Own Pace

A typical system is made of multiple components, such as a user interface, a database layer, and a reporting module. Waiting for the user interface to be entirely finished, before starting the database layer, would waste enormous amounts of time. The concurrent development model addresses this directly. Instead of moving the whole system through one phase at a time, each component, or each significant activity, progresses through its own states, independently and in parallel. At any single moment, one component might be finished and in active use. A second might still be under construction. And a third might be back under revision, after failing a review. All on the same project, at the same time.

Figure 2.4(a)

One Component's States

Here are the states one component moves through. Not started, then in development, then in review. If the review approves it, the component is baselined, and eventually marked done. But if it fails review, it goes to revision, and then back to review. That loop can happen more than once. And the dashed path shows that even a finished component can re-enter development, when new requirements surface. So a component does not necessarily move through its states once, in a straight line.

Tracking State

More Precise Than "In Progress"

Rather than describing a component as simply in progress or done, the concurrent model tracks a more specific state. Not started means no work has begun. In development means it is being built. In review means it is being checked. In revision means it was sent back after failing a review. Baselined means it has been formally reviewed and approved, establishing a fixed reference point for later work. And done means complete.

Figure 2.4(b)

3 Components, 3 Timelines

The real value appears once several components are tracked side by side. Picture a user interface that is already baselined, a database layer still in development, and a reporting module back in revision after a failed review. The reporting module's revision loop delays it slightly. But it does not stall the other two. Setbacks in one component do not automatically stop the others. That independence is also exactly where the model's central risk appears. Components that progress independently usually still have to come back together. The user interface has to work with the database layer it was built alongside. That only works if the pieces are compatible when integration arrives.

Coordination Challenges

What Parallel Work Costs

Running several workstreams at once buys speed, but it creates problems a sequential process never faces. State visibility. When one team depends on another's component, it needs to know that component's current state, not last week's. Otherwise, teams build against assumptions, and integration brings surprises. Dependencies. If the reporting module relies on a database structure that changes mid-development, the reporting module may need rework, even though its own work was never wrong. Synchronization. Components move at different paces, and can reach integration at very different levels of readiness, forcing rushed, late fixes. And communication. The more workstreams run in parallel, the more effort it takes to keep everyone aware of changes elsewhere. That overhead is a genuine cost, traded against the time saved by not making every component wait its turn.

Synchronization Points

Plan When the Pieces Meet

The answer to synchronization is planning when the pieces meet. An integration checkpoint is a planned moment when independently progressing components are checked against each other, and brought together. Without these planned moments, incompatibilities tend to surface late, all at once, and under time pressure. A project with no checkpoints discovers its problems only when everything is supposedly finished. The specific tools teams use to track and merge parallel work, such as version control, are a separate topic, covered later.

Key Terms

The Vocabulary of This Section

Let's lock in the key terms. The concurrent development model lets components or activities progress through their own states, independently and in parallel. A component state is the stage a component currently occupies, such as in development, in review, in revision, baselined, or done. Baselined means formally reviewed and approved, creating a fixed reference point. An integration checkpoint is a planned moment when components are brought together, and checked for compatibility. A dependency is one component relying on another. And a workstream is one independent thread of work, running in parallel with others.

Key Takeaways

What to Carry Forward

To pull this together. The concurrent development model lets components progress through their own states in parallel, rather than moving the whole system one phase at a time. Each component's state can change independently of every other component's state. Components that progress in parallel still usually depend on each other, which is why integration checkpoints matter. And running parallel workstreams brings coordination challenges. State visibility, dependencies, synchronization, and communication overhead.

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Software Engineering carries a NCCRS credit recommendation. These universities work with NCCRS; some are UPI Study's signed partners. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.

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FAQ

Questions students ask us

About Parallel Workflows: Concurrent Development Strategies

What is the concurrent development model?
The concurrent development model lets each component or significant activity of a system progress through its own states independently and in parallel, instead of moving the whole system through one phase at a time. At any moment, one component may be finished and in use, another still under construction and a third back in revision after failing a review, all on the same project.
What states can a component be in under the concurrent model?
A component can be not started, in development, in review, in revision, baselined or done. In revision means it was sent back after failing a review, and it returns to review afterward, sometimes more than once. Baselined means formally reviewed and approved, creating a fixed reference point. Even a finished component can re-enter development when new requirements surface.
What are the challenges of concurrent software development?
Parallel work creates four main challenges. State visibility: teams need each component's current state, not last week's. Dependencies: a change in one component, such as a database structure, can force rework in another. Synchronization: components reach integration at different levels of readiness. Communication: more parallel workstreams mean more effort to keep everyone aware of changes elsewhere.
What is an integration checkpoint?
An integration checkpoint is a planned moment when independently progressing components are checked against each other and brought together. It is the main answer to synchronization problems in parallel development. Without these checkpoints, incompatibilities tend to surface late, all at once and under time pressure, often only when everything is supposedly finished.

About the Software Engineering course

How many college credits is Software Engineering?
Software Engineering (Computer Science 301) carries a NCCRS credit recommendation for 3 semester credits. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities.
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$250, paid once, with lifetime access: all 103 video lessons, a practice quiz after each, the graded work and final exam, and an official transcript when you finish. Students who want several courses choose UPI Study PRO instead.
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UPI Study has signed partner agreements with universities such as Thomas Edison State University, University of the People and Charter Oak State College, and works with universities such as Penn State, SNHU and SUNY. ACE and NCCRS have over 2,100 cooperating colleges that will consider accepting credits; the final decision is with the universities. Use "Find my college" on this page to check yours.
How long does Software Engineering take?
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