July 6, 2014
Here are a few quick tips to examine your existing code to identify reuse candidates:
- Introduce Factory or Builder instead of repetitive boiler-plate code when constructing key objects. Several benefits: makes it easy to refactor and evolve how underlying objects are stitched together, makes it easy to write more intention revealing code, and very relevant / convenient when writing automated tests
- Clarify functional behavior and tease out non-functional logic – look at how functional logic is implemented across your codebase. Do multiple projects share a common set of domain assets – objects, rules, services, and the like? if not, look for areas where functional logic is tightly bound to non-functional aspects like fine-grained metrics capture, exception handling, retry / timeout handling, etc.
- Public API that needs to be accessed across platforms / devices are strong reuse candidates – for instance, are there functional APIs that don’t have a remote interface (e.g. a plain Java implementation without an appropriate REST-ful web service resource)? Do you need functionality to be made available across multiple devices with varying User Interface semantics? If so, look to carve the shared logic out into a service that can be accessed from multiple devices / integration points
July 6, 2014
Resisting the temptation to implement a story is very hard for a dev team – it is all too easy to get carried away in introducing a new idea as a reusable asset. However, these are the moments where you must pause and ask yourself a few basic questions before rushing to write code:
- Is this a one-off requirement or part of a recurring theme? Remember – when in doubt, don’t plan for reuse but continuously align and refactor your codebase. Use before reuse!
- Is there a confirmed consumer of this asset beyond the immediate project? If not, keep it in the originating project and promote it for reuse when you find another team or project that needs the functionality
- What are the likely variations that aren’t captured in the existing implementation? are they all really required for day 1, day N ? Don’t implement anything unless there is a business mandate to do so. It is very easy to add code wishing someone reuses it rather than refactoring a known good piece of functionality
- Do you have the bandwidth to develop unit tests, capture the right domain abstractions, and write developer facing quick start documentation? If not, resist the urge to prematurely introduce new code that ends up being technical debt
November 10, 2013
In an earlier post, I listed reasons why automated tests are foundational for reuse. In this post, want to provide some approaches that will ease automated testing of your components.
- Mock API interactions when using external dependencies. Mocking will reduce runtime dependencies and make your unit tests faster and more robust. Use JUnit with Mockito – mockito has excellent support for a variety of mocking use cases.
- If an external dependency is required from multiple classes, you can define an Adapter that will wrap the external API via an interface. The interface can then be mocked or stubbed and will provide an abstraction layer for your classes. Word of caution: abstractions are leaky and resist the need to wrap every single API provided by the external dependency.
- Use in-memory databases and provide a consistent API for your tests. A common class could initialize and clean up the in-memory db and can be leveraged from tests. Alternatively, it can be provided as an abstract class that your tests can extend. Take the opportunity to standardize location, naming, and directory structure of test resources – if you are using maven for instance, the db related data files can be placed under src/test/resources/db/<db-name>. Finally, this is very useful in ensuring that the database-bound code is indeed testable – forcing the in-memory db test will make technical debt apparent.
- Use db-deploy or some automated database deployment tooling to define and populate databases from tests – these can enable developers to define and execute tests without sharing / corrupting each other’s data. It will also make your database deployment repeatable and well tested eliminating a key deployment risk.
- Provide a common API for routinely used tasks for developers – e.g. APIs that can create test data in in-house / proprietary formats, parse, and populate appropriate data structures will be useful.
- Use JUnit Rule extensions for having a common API for developers – provide a custom rule that will manage the lifecycle of a legacy component or a API that is difficult to use – these are all opportunities to both facilitate testing and add value via reuse.
November 2, 2013
You can wait for that dream initiative or project to build a whole new set of reusable components that will magically make your teams more productive. The only issue is – it is highly likely that it will be just that – a dream. Instead of planning for systematic reuse, start executing on it by taking a few simple steps. Ask yourself the following questions:
1. Are you capitalizing on identifying and sharing common components with your department / team?
2. Is every project encouraged to continuously refactor and harmonize classes for reducing redundancies? If not, why not?
3. Do you have code that caters to common infrastructural concerns – logging, exception management, alerting, monitoring, metrics.? If yes, is their reuse mandated via common framework hooks that your developers are already using? If not, what is preventing adoption of these concerns into your development stack? Ask your developers and listen to their concerns – you will need to unearth and attack the root causes behind reuse barriers.
4. Do you utilize ad-hoc, informal pairing and code review sessions to identify and harmonize similar / duplicate / redundant classes? If you review code the first time before a project go-live, odds are you either will regret missed opportunities or bemoan the lack of time within your development cycle for making improvements. Key is to intervene early and often and front load your investments for systematic reuse
5. How do you ensure reafactoring to reuse opportunities are tracked? do you create improvement tickets and action them on a best-effort basis or are they managed as part of the product backlog of things that have to get done? If its the former, it will be difficult to make much progress. Creating and tracking tickets will will provide visibility – however, for you to make tangible progress in acting on them you need to partner with developers and development managers to action work on an ongoing basis.
These are just example questions to help you get your journey started and it should be abundantly clear that discipline and continuous alignment is key. If you don’t do anything else, just force your team to converge on a common implementation on key functionality. You will be surprised what discipline can deliver.
September 9, 2013
What is the one key aspect of making your APIs reusable? Simply put – reducing the barriers to adoption. It matters because your target audience – architects, developers, and project managers – are all trying to deliver value to their clients. Iteration after iteration. Here are specific strategies to reduce the adoption barriers:
- Make the public API as intention revealing as possible. Looking at the public interface it must be very clear and unambiguous what the purpose and scope is of the reusable capability.
- Provide Builder or abstract factory APIs to stitch together complex object graphs in a simple fashion. Make it very easy to wire up the default behaviour and provide hooks to replace specific bits of behaviour that is varying. For example – if saving to a file is a default, provide alternative implementations or an interface hook for your client to inject a custom one.
- Make it easy to integrate the capability with other complimentary APIs. These could be in-house, open-source, or vendor APIs – key is – if they are likely to co-exist in a solution, make it simple to wire them together. If your developers use Spring for dependency injection, make your components easy to work with when it. Ditto for in-house frameworks that your teams use heavily.
- For reusable assets that perform orchestration logic provide hooks for injecting custom logic before / after your API behaviour This will be useful for initializing / cleanup logic – specially with legacy components that may need a bespoke set of steps to start them or free up resources on shutdown.
- Provide Null and/or mocking friendly implementations for testability. Your clients need to test their code via automated tests and so do you as the provider – both these needs are met via testable providers. Make it easy for developers to use them with JUnit and make it hard for them to bypass the public APIs.
August 31, 2013
Tip #31 – Inject Common Reusable Capabilities via JUnit Rules
JUnit has an extremely useful extension mechanism – Rules. The @Rule annotation can help provide additional capabilities to your test methods. For example, ContiPerf provides annotations for performance testing. Similarly, you can provide reusable framework hooks for developers to use alongside their test methods.
Some examples where this can be applied – capturing test execution metrics and publishing to a API for offline trending/analysis or setting up plumbing components to facilitate in-memory db testing via H2db, or data folders, etc.
Implementing a JUnit rule is quite straight forward – here’s an article from David Gassner that provides a sample rule implementation.
June 16, 2013
It is natural to get comfortable, perhaps too comfortable, with the state of your codebase. After all, it works and is probably meeting tangible business needs. However, if your team has to get the full value out of it – the fair and ongoing return on investment – you have to constantly revisit assumptions about the software design and implementation.
Challenging assumptions has a number of benefits for systematic reuse. It opens up opportunities for refactoring assumptions that are no longer relevant / required (e.g. state information has to be saved for recovery). What if that capability is available in your enterprise through another component? Can you swap your implementation? If not, why not?
Similar opportunities exist on both technical and functional sides – the software is always accessed from the app’s web UI (assumption that might have led to code tightly coupled with presentation logic – business rules implemented alongside HTTP header parsing logic). How about assumptions regarding public APIs, nature/sequence of method invocations, client / calling platform, etc.
These assumptions must have made sense and would have been made for a sound reason at the time the codebase was conceived. Question is – are they still relevant? does the code need refactoring to get rid of native implementations or needs to be decoupled from logic that will make it more reusable? All these questions need careful and thoughtful consideration.
Have this discussion as part of your iteration retrospectives, team discussions, and informal conversations. You’ll be surprised about the quantity and quality of assumptions that are holding the codebase back.