Beyond Well-Formed and Valid

2011

XML databases are commonly used for representing data with more complex structures than traditional relational data. Like in any data model, it is very important to ensure that the contents of the database always valid even after any attempt of updates. XML Updates validation is a process of checking the correctness of XML documents, in terms of satisfying their constraints, after updates operations. The validation can be generally categorized into structural and semantic validation.

Complex applications can benefit greatly from using conceptual models and Model Driven Architecture during development, deployment and runtime. XML applications are not different. In this paper, we examine the possibility of using Object Constraint Language (OCL) for expressing constraints over a conceptual model for XML data. We go through the different classes of OCL expression and show how each class can be translated into XPath constructs. Subsequently we show how the constraints can be checked using Schematron. We introduce a function library OclX, which provides constructs necessary to translate those OCL constructs that have no counterpart in XPath. With our tool, it is possible to check validity of OCL constraints in XML data.

2004

Abstract In the past few years, a number of constraint languages for XML documents has been proposed. They are cumulatively called schema languages or validation languages and they comprise, among others, DTD, XML Schema, RELAX NG, Schematron, DSD, xlinkit. One major point of discrimination among schema languages is the support of co-constraints, or co-occurrence constraints, eg, requiring that attribute A is present if and only if attribute B is (or is not) presentin the same element.

This paper shows how XML metalanguage capabilities and related tools could be used first to model data structures and operations of domain specific languages, and second to facilitate the transformation process from system specifications to software systems. This approach allows to identify the subsystems of a software system using different domain specific languages. Such languages and the language transformer rules are the result of a domain analysis process adequately customized for this propose.

CLEI Electronic …, 2003

After being able to mark-up text and validate its structure according to a document type specification, we may start thinking it would be natural to be able to validate some nonstructural issues in the documents. This paper is to formally discuss semantic-related ...

Proceedings of the 18th ACM/IFIP/USENIX Middleware Conference on Industrial Track - Middleware '17, 2017

Diagnosing misconfiguration across modern software stacks is increasingly difficult. These stacks comprise multiple microservices which are deployed across a combination of containers and hosts (VMs, physical machines) in a cloud or a data center. The existing approaches for detecting misconfiguration, whether rule-based or inference, are highly specialized (e.g., security only), cumbersome to write and maintain, geared towards a host (instead of container images), and can result into false-positives or false-negatives. This paper introduces configuration validation language (CVL), a declarative language for writing rules to detect misconfigurations that can, for instance, impact security, performance, functionality. We have built a system, ConfigValidator, which applies the CVL rules across a multitude of environments such as Docker images, running containers, host, and cloud. The system is running in production and has scanned thousands of Docker images and running containers for identifying misconfigurations.

2000

We present a constraint-based extension of XML for specifying the structure and semantic coherence of websites and their data. This extension is motivated by the fact that many websites, especially organizational websites and corporate intranets, largely contain structured information. Such websites can be regarded as databases. XML can help view, store, manipulate, and transfer semi-structured data that exists in files-often webpages-and facilitates a less ad hoc method of handling data than HTML allows. In support of the view that a website is a database, we introduce CobWeb, a constraint-based extension of XML. CobWeb allows developers to express the concept of the semantic integrity of a database. Constraints may be used in a document type definition (DTD) in order to place restrictions on the values of both elements and attributes in the DTD. These constraints can effectively govern the contents of otherwise disparate webpages in a website, thereby ensuring the both the structured and the semantic integrity of the site as a whole. We provide unary (or domain) constraints, binary constraints (including various comparison operations), as well as aggregation constraints (sum, average, etc.). We also define data types not included in the XML 1.0 specification, so that declaring constraints can be more easily facilitated. By taking advantage of XML's modular design, we can create a parser that works in conjunction with and extends existing XML parsers. This will allow developers to continue using their own parsers and while taking advantage of CobWeb's constraint features.

2011

2004

This paper outlines a methodology for designing information systems based on XML. The methodology uses XML DTDs to define the design standards, and the structure and constraints of the design specifications. The result of the design process is a set of valid XML documents that are the specifications of transaction programs and applications of the information system. At the start of a design process, the methodology uses a CASE tool to map user requirements into initial XML specifications. Final design specifications are produced by a sequence of XSL transformations of the initial XML specifications. A key feature of the methodology is that it produces a platform independent design of an information system. To enable an early feedback from users, the methodology uses further XSL transformations that produce an executable prototype of the information system in the Java programming environment.

Constraints can express important semantic information about the target XML repository. This information is utilised to model, store and process documents appropriately and more efficiently. In practice, it is challenging to single out the conditions that best capture the semantics of the appli cation domain. Consequently, the task of identifying all relevant constraints is both crucial and difficult. We show how sample documents assist participants of the design process in making informed choices about the specification of Boolean constraints on XML documents. Indeed, the decision whether such a constraint should be specified explicitly is reduced to the problem whether there is any document in our XML sample collection that is relevant for the underlying application domain. Furthermore, we establish how off-the-shelf tools for solving problems in propositional logic can be used to generate the collection of our sample documents semi-automatically.