Graph Databases and Web Frameworks (NodeJS, AngularJS, GridFS, OpenLink Virtuoso)
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The document discusses the limitations of relational databases in modeling complex entities with variable attributes and historical values, while presenting graph databases as a more effective solution for certain problems. It covers various technologies such as Node.js, AngularJS, and SPARQL, along with real-world applications like a file management platform called Dendro. The author concludes that while graph databases offer simpler querying and better modeling capabilities, they are less mature than traditional relational database management systems.
![Relational databases
• Handling historical values = complex SQL
• Hierarchies = Foreign Key loops
• Variable attributes, inheritance = [null + if Hell] or
many JOINs](https://image.slidesharecdn.com/lbawapresconvidadajrs14-05-2014-140516131633-phpapp01/85/Graph-Databases-and-Web-Frameworks-NodeJS-AngularJS-GridFS-OpenLink-Virtuoso-6-320.jpg)
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Graph Databases and Web Frameworks (NodeJS, AngularJS, GridFS, OpenLink Virtuoso)
- 1. Web frameworks and graph databases Overview and code demos João Rocha da Silva May 2014 [email protected]
- 2. Contents • Modeling limits of relational databases • Entities with variable attributes • Time-variant values • Inheritance • Hierarchies (parents of parents of parents…)
- 3. Contents (cont’d) • Modeling problems in a graph • Ontologies and SPARQL • OpenLink Virtuoso • Scalable file storage: GridFS within MongoDB • Scalable document indexing : ElasticSearch
- 4. • NodeJS and asynchronous flow control • AngularJS for dynamic web interfaces • BONUS : Socket.io sneak peek Contents (cont’d)
- 5. Relational databases • Good when you know everything about the problem at the time of modeling • A column can only be of a single type (VARCHAR, int, etc) • Hard to document • Model can become too attached to the code
- 6. Relational databases • Handling historical values = complex SQL • Hierarchies = Foreign Key loops • Variable attributes, inheritance = [null + if Hell] or many JOINs
- 8. (one of 78,826 tables and counting) source : SAP Beautiful, meaningful column names ;-) Even better table names
- 9. ! source MediaWiki “Old Versions” aka “copy everything and add a timestamp”
- 10. ! source MediaWiki now imagine we want to images of different kinds, with different attributes…
- 11. Attribute name Timestamps Value (always varchar) Entity with variable, time-dependent attributes Fixed attrs. ! source CKAN
- 12. Graph models
- 13. Graph databases • Represent entities (Users, Products, Places…) as vertexes (entity types are called classes) • Connections between them are directed graph edges (edge types are called properties) ! • The meaning of these connections is expressed in ontologies that can be shared and reused
- 14. Representing a person using ontologies
- 16. Getting all the students SELECT ?uri ?attribute ?value FROM <http://myorganization.com/data> WHERE { ?uri rdfs:type up:Student. ?uri ?attribute ?value } • Will fetch all the students, regardless of their type • Will also return their attributes (“database columns”) • Different types of students will have different attributes
- 17. Inference • Transitive Properties (subclass of subclass…) • Subclasses • Multiple Inheritance Handling (Student + Researcher + ScholarshipHolder) Saves coding time spent writing complex queries
- 18. Nothing comes for free • Aggregation operators slow • Transactions are not supported in standard SPARQL • (“SPARQL 1.1 Query/Update Services should be atomic but that they are not required to be atomic.”) • Graph DBMS Solutions are in early stages (many bugs, many “beta”s, many mailing lists…)
- 20. Dendro (dendro-dev.fe.up.pt:3001) • Dropbox and File/Folder description platform • Variable descriptions • Time-dependent values • Directory structures (hierarchy) • Need for simple querying…
- 21. nie:isLogicalPartOf Pn Dn 280mm “DCB Base Data” 120 Dn-1 dcb:initialCrackLength dc:title dcb:specimenWidth dc:isReferencedBy Fn 120 dc:title dcb:specimenWidth dc:isVersionOf Added property instance 01/01/2014 ^^xsd:date dc:created 01/01/2014 ^^xsd:date dc:modified Changed modification timestamp Revision creation timestamp Un dc:creator Current dataset version Past Revisions ddr:pertainsTo Change recording C ddr:initial CrackLen gth ddr:changedDescriptor “add” ddr:operation “DCB Base Data”
- 22. Socket.io Real-time events NodeJS Business Logic AngularJS Dynamic interfaces à la Google Docs Files GridFS Database OpenLink Virtuoso Free-text search ElasticSearch
- 23. Code Demos NodeJS (Dendro) http://192.168.5.75:3001 GridFS http://192.168.5.75:27017 OpenLink Virtuoso http://192.168.5.75:8890 ElasticSearch http://192.168.5.75:9200/_plugin/ head/ Socket.io (BattleBits) http://localhost:3000
- 24. Conclusions • JavaScript + JSON = easy parsing, less verbose code • NodeJS = asynchronous everything. Needs precise flow control • ElasticSearch = Scalable indexing, easy to use JSON API • GridFS = Transparent scaling for huge numbers of large files; querying using JSON-based API • Graph Databases = Model certain problems better than their relational counterparts. Simpler queries using SPARQL. Less mature than RDBMs. No transactions. • Socket.io = Real-time library for client-server-client push communication
- 25. João Rocha da Silva is an Informatics Engineering PhD student at the Faculty of Engineering of the University of Porto. He specializes on research data management, applying the latest Semantic Web Technologies to the adequate preservation and discovery of research data assets. ! He is experienced in many programming languages (Javascript-Node, PHP with MVC frameworks, Ruby on Rails, J2EE, etc etc) running on the major operating systems (everyday Mac user). Regardless of language, he is a quick learner that can adapt to any new technology quickly and effectively. ! He is also an experienced freelancer iOS Developer with several Apps published on the App Store, and a self-taught DIY mechanic with a special interest in classic cars, particularly his 1987 Toyota Corolla GT Twin Cam, also known as Hachi-Roku or AE86. ! Research Data Management and Semantic Web Researcher, Web & iPhone Developer João Rocha da Silva! [email protected]