Domain-Driven Design (DDD) is a great technique bringing designs closer to the domains we are working in, but too often we make early design decisions with a focus on structure, which is not the intention of DDD. Instead, we should start with the events in a domain, Russ Miles recently claimed while describing advantages of going “events-first” when building microservices.
Miles believes that besides focusing on structure, we are also focusing the ubiquitous language too much on things, especially on domain objects. To make things even worse we have also started to create libraries with domain objects for reuse across domain boundaries, effectively preventing different bounded contexts from evolving separately.
In Miles’ experience, this approach has become the default architecture style for enterprise layered architecture, the reason being to make things easier, not simpler or to help in improving a design. This has caused things, like entities, to move from being ubiquitous in one context to being canonical across all contexts, a direct contradiction with the ideas of DDD.
Instead Miles claims that we should start with what happens in a domain- the events. They are better in capturing the ubiquitous language in a domain, and often the easiest way to describe the domain, especially when collaborating with domain experts. He has found that this approach works well both when building a new system and when evolving an existing system.
The first step that Miles favours when working with events is Event storming , a modelling workshop technique created by Alberto Brandolini. The basic idea is to explore a domain by the things happening in it, the domain events, and capturing these events using stickers on a large modelling surface along a timeline. Examples of what can cause an event include a user action, something happening in an external system, and time passing. Events can also help in finding the boundaries within a domain; different interpretations of terms involved may indicate a boundary.
Another cause of complexity for Miles is using the wrong model for the wrong job. DDD has the repository pattern for dealing with persistent state but often uses the same model for read and writes. One advantage this gives is consistency, but if the needs are distinctively different we can gain significant benefits by separating reads from writes with different models.
Command Query Responsibility Segregation (CQRS) is a technique for doing this separation:
Event sourcing is a natural extension to CQRS, where all events emitted by the aggregates are persisted and used to recreate the state of an aggregate, instead of storing the state itself. This ability to recreate state, according to Miles, is a way of reducing the fragility of state.
CQRS together with event sourcing bring other complexities like eventual consistency ; Greg Young , who coined the term CQRS and is behind today’s interest in event sourcing, notes that they are not top-level architectures. According to Young, they should normally be applied selectively just in few places, and he emphasizes that a whole system based on event sourcing is an anti-pattern.

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Dubai-based Aramex , a global provider of logistics and transportation services, has evolved into a global brand in the three decades since it was founded in 1982.
It is a publicly traded company on the Dubai Financial Market and employs more than 17,000 people in 575 locations across 70 countries. The company also leads a network of partners that provides a global presence and brings together 40 independent express companies from around the world.
Its services include logistics, international and domestic express delivery, freight forwarding, secure records and information management. Its e-services include e-business solutions.
In recent years, Aramex has steadily expanded its geographic and business footprint, and each new site has brought familiar challenges: a lengthy network installation and configuration process coupled with a tedious mapping-out of which routes would be best for the new office.
To overcome these challenges and the high volumes of data being transferred and shared across its network, as well as meeting the growing need for increased agility, Aramex chose to optimise its network connectivity, and virtualisation featured heavily on its agenda.
Ramzy Masarweh, corporate IT manager at Aramex , said the company had recently scaled up its branch office performance and connectivity by implementing the Silver Peak SD-WAN, a virtualised environment that was cost-effective for smaller and remote offices.
The high cost and limited capacity of WAN connectivity at some remote sites was restricting the business, said Masarweh. “ Silver Peak’s Unity EdgeConnect SD-WAN has delivered reliable performance and automation at remote sites, freeing us up to open the doors to more locations now and in the future,” he added.
He said the Silver Peak system automated manual and time-consuming processes while delivering greater control. “With our Beirut office, for example, we were experiencing a round trip time of 300 milliseconds for certain applications, which Unity EdgeConnect has brought down to 140 milliseconds,” he added.
Over the years, said Masarweh, Aramex’s IT team had gained the business owners’ trust to proceed with any projects they saw fit, making daily operations run very smoothly. “Our IT team, up to a certain level, adopts the IT-driven business model,” he said. “What this means is that, in most cases, we are able to implement solutions before the business even starts asking for them. I believe getting the business buy-in for any IT project we undertake is critical for the success of the project and the business.”
As corporate IT manager, Masarweh is charged with managing the organisation’s key datacentres across Jordan, the UK, South Africa, the UAE and India, with a new one planned in Singapore.
And although the influence of IT managers, directors and CIOs has been diminishing, Aramex is an example of how corporate IT manager or director roles in the Middle East are changing, transforming expectations of what an IT department can contribute to an organisation’s business goals.
Masarweh said the starting point for any project Aramex undertakes is the proof of concept (PoC), which also involves input from the business owners.
In the case of Silver Peak’s Unity EdgeConnect SD-WAN, Aramex started with the PoC between March and April 2016, and it was quickly accepted. “An order was placed for 20 appliances in May and another 20 in July,” said Masarweh. The appliances are currently being implemented on a needs basis, where the system’s replication and bandwidth compression are required.
“Internally, we are studying the possibility of replacing all VPN concentrators globally in 2017, and we are working closely with our Silver Peak account manager to familiarise him with our needs to help us achieve this with the upcoming new releases from Silver Peak,” said Masarweh.
IT security is another big challenge for the company, he said. “IT security comes at the forefront of every new project we initiate at Aramex. Securing the data, network and the physical premises is always at the top of our list of priorities.
“Our IT security team is extremely aware, and is up to date with new trends. Frequent vulnerability scans are run all over the network, internally and externally, to make sure we are consistently secure and free of threat from potential attacks.”

© Source: http://www.computerweekly.com/news/450410357/Dubai-based-Aramex-optimises-branch-office-connectivity
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