The domain model is a familiar concept to most OOP (Object Oriented Programming) developers and architects, and has been used successfully in a variety of systems and projects. But how does this principle apply to SOA-based solutions?
From a software development viewpoint, model-driven architecture (MDA) encourages efficient use of system models. It also encourages reusing best practices as families of systems are produced. One of the main aims of MDA is to separate design from architecture, which places the business analyst in a unique and potentially powerful position within the organization. Learn how you as a business analyst can take an active role in this type of architecture.
Because it takes time and trust to establish agreement, traditional consensus-based architectural styles cannot safely accommodate resources that change faster than it takes to transmit notification of that change, nor resources that must be shared across independent agencies. The alternative is decentralization: permitting independent agencies to make their own decisions. Our definition contrasts with that of distribution, in which several agents share control of a single decision. Ultimately, the physical limits of network latency and the social limits of independent agency call for solutions that can accommodate multiple values for the same variable. Our approach to this challenge is architectural: proposing constraints on the configuration of components and connectors to induce particular desired properties of the whole application. Specifically, we present, implement, and evaluate variations of the World Wide Webýs REpresentational State Transfer (REST) architectural style that support distributed and decentralized systems.
Extreme Programming (XP) is yet another popular idea gaining press. It adapts the best ideas from the past decades of software development. Whether or not you adopt XP, it's worth considering what XP teaches.
This paper proposes a general synchronization grammar which can describe synchronization rule sets. For example, when handling three input files, we show that changes to elements can be described in terms of just seven possible permutations. Similarly, PCDATA and attribute changes can be described in terms of a fixed set of permutations. Using these permutations a grammar is proposed, allowing precise description of synchronization algorithms and rule sets and providing a testable framework for their implementation. The paper applies the resulting grammar to existing synchronization tools and technologies and shows how the grammar can be applied to provide solutions for specific application areas, including document workflow and translation.
This paper is based from a number of real-world XML validation projects, and compares and contrasts the experience 'in the trenches' with the current state of the art in XML validation standards. Validation is a topic of some controversy in the XML community. While there has been movement from the basic validation offered by XML 1.0 DTD's, there is little consensus on whether that movement has been in the right direction.
Python and XML are two very different animals, each with a rich history. Python is a full-scale programming language that has grown from scripting world roots in a very organic way, through the vision and guidance of Python's inventor, Guido van Rossum. Guido continues to take into account the needs of Python developers as Python matures. XML, on the other hand, though strongly impacted by the ideas of a small cadre of visionaries, has grown from standards-committee roots. It has seen both quiet adoption and wrenching battles over its future. Why bother putting the two technologies together?
XML has become the de facto standard format for web publishing and data transportation. Since online information changes frequently, being able to quickly detect changes in XML documents is important to Internet query systems, search engines, and continuous query systems. Previous work in change detection on XML, or other hierarchically structured documents, used an ordered tree model, in which left-to-right order among siblings is important and it can affect the change result. This paper argues that an unordered model (only ancestor relationships are significant) is more suitable for most database applications. Using an unordered model, change detection is substantially harder than using the ordered model, but the change result that it generates is more accurate. This paper proposes X-Diff, an effective algorithm that integrates key XML structure characteristics with standard tree-to-tree correction techniques. The algorithm is analyzed and compared with XyDiff [CAM02], a published XML diff algorithm. An experimental evaluation on both algorithms is provided.