XQuery
is the
Plumber's Toolkit!

• Developer / Consultant

  • XQuery / XSLT / Schema / RelaxNG

  • Scala / Java / C++

  • Concurrency and Scalability

• Creator of FusionDB multi-model database (4 yrs.)

• Contributor to Facebook's RocksDB (4 yrs.)

• Core contributor to eXist-db XML Database (14 yrs.)

• Founder of EXQuery, and creator of RESTXQ

• W3C XQuery WG Invited expert

• Me: www.adamretter.org.uk

• Before XProc there was XPL

  • ~2005 - https://www.w3.org/Submission/xpl/

• Before XPL there was XQuery

  • ~2001 - https://www.w3.org/TR/2001/WD-xquery-20010215/

• Before XQuery there was XPath

  • ~1999 - https://www.w3.org/1999/07/WD-xpath-19990709

• Before XPath there was XSLT

  • ~1998 - https://www.w3.org/TR/1998/WD-xsl-19980818

• Back in 2006...

  • XPL looked nice but was Orbeon only

  • Apache Cocoon was ugly... and dying?

  • So... I wrote "pipelines" in XQuery (and XSLT)!

    • Many modules of small functions

    • XQuery -> XQuery -> XSLT -> XQuery -> XSLT -> XHTML / XUpdate

• Now...

  • Anything XProc can do... I can do in XQuery!

    • Maybe I can even do more!

    • Why do I need XProc?

• Is it's simplicity!

• Data Model supports XML/JSON/Text/Binary

• Mixing XML and XQuery in the same file

  • Creates dynamic documents

• Depends on the Implementation!

  • HTTP Server fits well with the Web

    • Can produce XHTML/HTML5 dynamic websites

• Much comes from EXPath/EXQuery/Vendor extensions!

1. Is there a proportionate relationsip between Covid-19 mortalities and Covid-19 relief funding?

2. Is more or less medical research conducted in areas with a higher Covid-19 mortality rate?

Code: https://github.com/adamretter/markupuk2020

• Today we will aggregate data from...

  • Various Web API using HTTP

  • Relational database using SQL

  • Graph (RDF) using SPARQL

  • JSON

  • XML Database

  • Binary files

• We will then produce...

  • An HTML Page using XSLT

  • A PDF Report using XSL:FO

• Medical Research Journal Articles

• Statistics on Covid-19 Deaths

• Statistics on Covid-19 Relief Funding

• Mapping to/from State Abbreviations and State Names

• National Library of Medicine

  • Pubmed dataset - keyword "covid"

  • https://pubmed.ncbi.nlm.nih.gov/?term=covid%2019&sort=date

  • Provides EUtils Web API

  • Available in XML

  • Limited to 10,000 records per-request

• Our XQuery

  • Use XQuery extension module - EXPath HTTP

  • Call Search API

  • Call Fetch API n-times in pages of 10,000 results

  • Use XQuery extension module - XMLDB

  • Store XML documents into XML Database

  • See: download-pubmed-store-xml.xq

• Centers for Disease Control and Prevention

  • Provisional COVID-19 Death Counts by Sex, Age, and State

  • https://data.cdc.gov/NCHS/Provisional-COVID-19-Death-Counts-by-Sex-Age-and-S/9bhg-hcku

  • Available in CSV

• Our XQuery

  • Use XQuery extension module - EXPath HTTP

  • Call Download API

  • Parse the CSV into XDM Array

  • Cleanup CSV

  • Use XQuery extension module - SQL JDBC

  • Create SQL Table and Insert rows (MariaDB)

  • See: download-cdc-upload-sql.xq

• Centers for Disease Control and Prevention

  • HHS (Health and Human Services) Provider Relief Fund

  • https://data.cdc.gov/Administrative/HHS-Provider-Relief-Fund/kh8y-3es6

  • Available in RDF

• Our XQuery

  • Use XQuery extension module - EXPath HTTP

  • Call Download API

  • Use XQuery extension module - XMLDB

  • Store RDF document into XML Database *

  • See: download-hhs-store-rdf.xq

• World Population Review

  • List of State Abbreviations

  • https://worldpopulationreview.com/states/state-abbreviations/

  • Available in JSON

• Our XQuery

  • Use XQuery extension module - EXPath HTTP

  • Call Download API

  • Use XQuery extension module - XMLDB

  • Store JSON document into XML Database

  • See: download-states-store-json.xq

• Data is in SQL (MariaDB - 1,416 rows)

  • 1. Examine the Data

  • 2. Use the XQuery extension module - SQL JDBC

  • 3. Write some XQuery and SQL to get some stats

  • See: query-sql-dsas.xq

  • See: query-sql-deaths-total-percentage.xq

• Data is in RDF (eXist-db/TDB - 1,471,085 triples)

  • 1. Examine the Data

  • 2. Use the XQuery extension module - SPARQL

  • 3. Write some XQuery and SPARQL to get some stats

  • See: query-sparql-all-states.xq

  • See: query-sparql-state-payment-total.xq

• eXist-db's RDF/SPARQL Module is not returning all the data :-(

  • https://github.com/ljo/exist-sparql/issues/8

• SPARQL Protocol to the rescue!

  • Load data into Jena TDB

  • Use XQuery extension module - EXPath HTTP

  • Query Fuseki over HTTP

  • See: query-fuseki-all-states.xq

  • Write our own XQuery Module for Jena Fuseki

    • For replacing sparql:query with fuseki:query

    • See: fuseki.xqm

  • See: query-fuseki-all-states-2.xq

• Death stats have State Names / Funding stats have State Abbrevs.

  • We want to join the datasets by state

  • We will map Abbrevs. to Names

• Data is in JSON (eXist-db - 1 Map with 55 key/value pairs)

  • 1. Examine the Data

  • 2. Use the XQuery function - fn:json-doc

  • 3. Write some XQuery to lookup names from abbreviations

  • See: query-json-state.xq

• Our XQuery

  • Uses all of the components so far

  • Calculates some percentages of total deaths

  • Calculates some percentages of total funding relief

  • Iterates through deaths by state

    • Joins funding relief payments by state ON state name

  • Produces two reports in XML

    • Each ordered differently for side-by-side comparison

  • See: answer1.xq

• Our XQuery

  • Builds on the previous slide

  • We write an XSLT to transform the XML into HTML

    • See: answer1-to-html.xslt

  • Use XQuery extension module - Transform

    • If available, use fn:transform instead!

  • Produces HTML

    • Could be run from the database's Web Server :-)

  • See: answer1-html.xq

• No!

  • We can and have survived without it!

  • XQuery - best to adopt a functional compsosition style

  • Why even use XQuery?

    • I could have written this in: Assembler / Pascal / Java / C++ / blah!

• Yes!

  • Cleaner Separation of Concerns

  • Better Orchestration of Tasks

  • Exploit Parrallelism (one day?)

  • But... I want it to run inside the database!

    • Avoid Serialization between steps

    • Exploit Indexes

    • Resource Scheduling

fusiondb.com