Stefan (Stephan) W. Email & Phone Number

Amsterdam, Nl

As part of the Data Solutions team, primary work covers B2B projects but also worked on projects with other teams. Generally, projects are Spark Scala and are 3 weeks to 2 months. Independently hash out vague customer desires into project requirements. Typical requirements end up with a Scala Spark ETL, SQL query or ... The Stellantis mission is to establish data infrastructure, promote engineering best data management practices while keeping the high bar for data quality, design and security, scalability, performance, and robust data services for connected vehicle data. Used distributed data processing platforms (AWS / Databricks) and Big Data technologies such as Spark, Kinesis, AWS / Databricks, Scala ... Mentored and trained co-workers on the work produced (or to help them with their own projects) via presentations or 1-on-1. Efforts produced pipelines for metrics info to EV battery vendors and insurance-based concerns such as stolen vehicles and usage based insurance rates.

Amsterdam, Nl

As part of the Data Solutions team, worked on projects with several other teams. Generally, the projects are Spark Scala and are 3 weeks to 2 months. Independently hash out vague customer desires into project requirements. Typical requirements end up with a Scala Spark ETL, SQL query or ... Acquired and transformed data from SFTP, S3, Databricks tables, Alexa APIs, Salesforce, RDBMS, Kinesis ... The Stellantis mission is to establish data infrastructure, promote engineering best data management practices while keeping the high bar for data quality, design and security, scalability, performance, and robust data services for connected vehicle data. Used distributed data processing platforms (AWS / Databricks) and Big Data technologies such as Spark, Kinesis, AWS / Databricks, Scala ... Mentored and trained co-workers on the work produced (or to help them with their own projects) via presentations or 1-on-1. Efforts produced pipelines for metrics info to EV battery vendors, Alexa in-car usage, customer support case and survey mgmt, used auto sales ... Enhanced other pipelines for stability, changing schemas, memory usage, performance ...

San Francisco, Ca, Us

Within the Engineering Effectiveness organization, the Migration Acceleration Team, works with partner engineering teams at Twitter to help speed up technology migrations via a variety of practices including automation, planning, training, measurement, and outsourcing. The team is a cross-functional team in which my current primary role is to be a defacto-team lead to guide 6 contractor data engineers in migrating applications to be consistent with dataset metadata collection APIs (Metrics collected: segments written/read, consumers, producers, schemas, scrubbing, PII, data formats / compressions ...). In this role, I troubleshoot and resolve complex code issues, provide guidance, review work, reach out to partner to solve ambiguities and other internal teams that developed tooling. Other aspects of this work includes the creation of Dev Guides to specific migrations and aid in the design of the project planning dashboards. I am involved in planning and resolving how upcoming migrations may work - such as technologies that are being migrated to Dataflow. Current efforts are with Scalding, Scala, Dataflow, Big Query and other standard tools such as GIT, code review, build and those which are SQL related.

Kirkland, Washington, Us

Working with the Analytics Data Platform / DAL team at Twitter. DAL is using Scalding / Scala to access the Data Access Layer for data discovery, auditing, abstraction and consumption in conjunction with migrations to GCS. The DAL system allows for personal data identification, retention duration, schemas, identifying up- and down-stream jobs and tracking data creation timestamps. Role required fixing bugs / adding features to DAL and helping other teams use this technology. (The following article describes the overall objective: https://techcrunch.com/2021/02/04/twitter-expands-google-cloud-partnership-to-learn-more-from-data-move-faster/) This role is to terminate 3.18 and it's planned to be FTE at Twitter 3.21.

San Francisco, Ca, Us

Bidding Optimization Pipeline -- Coding & optimizing the bidding data pipeline. On a Cloudera cluster, I use tools & technologies such as Scala, Spark, Java, HDFS, HBase, Phoenix, Oozie, Jupyter Notebook with Toree, IntelliJ, Git, Jenkins, PySpark / Python, Greasemonkey / Tampermonkey (with HTML and Javascript to improve web visualizations & leverage tools) ... Recently, made (1) a custom Hive partitioner to reduce number or output files but keep data evenly distributed among files, (2) a distributed repair system of broken Avro data files with executor locality, (3) contributed to the team efforts to create an Ad Awareness Targeting bid optimization system and (4) Explored and wiki-documented several ways debug Spark apps (either with local debugging and cluster support or within an executor or driver) and remotely deployed services.

San Francisco, Ca, Us

ETL Pipeline -- Coding & optimizing a data pipeline that processes the online advertising dimensions on a Cloudera cluster. I use tools & technologies such as Scala, Spark, Java, HDFS, HBase, JDBC, Phoenix, Presto, Oozie, Jupyter Notebook with Toree (which I built for Cloudera), IntelliJ, Greasemonkey / Tampermonkey (with HTML / Javascript to improve data visualizations), Git, Jenkins, ... Notable works include a Kafka streaming system plying Kafka offsets to resume streaming and an ETL processing system that produced advertising campaign dimensional data. ...

San Francisco, Ca, Us

Lead for Tracker Pipeline -- Same as before with lead accountability ... Coding & optimizing a data pipeline that matches 15 TB of session data to 100-200 million Flume-produced events (daily). To understand and process the online advertising events on this Cloudera cluster, I use tools & technologies such as Scala, Spark, Java, HDFS, HBase, JDBC, Phoenix, Oozie, Jupyter Notebook with Toree (which I built for Cloudera), IntelliJ, Scalatra (for custom monitoring tool), Greasemonkey / Tampermonkey (with HTML / Javascript to improve data visualizations), Git, Jenkins, ...

San Francisco, Ca, Us

Coding & optimizing a data pipeline that matches 15 TB of session data to 100-200 million Flume-produced events (daily). To understand and process the online advertising events on this Cloudera cluster, I use tools & technologies such as Scala, Spark, Java, HDFS, HBase, JDBC, Phoenix, Oozie, Jupyter Notebook with Toree, IntelliJ, Scalatra, Greasemonkey / Tampermonkey (with HTML / Javascript) ...

Consulting Work: May / June - CyberCoders / Butler Shine Stern and Partners: Python REST/JSON ETL pipeline for acquiring Google Analytics and storing in MySQL / MariaDBApril / May - TekPerfect / Hapara: Scala pipeline consuming from Kafka with Spark Streaming and producing enriched data back to Kafka. Technological Exploration: Apache Spark: https://gist.github.com/codeaperature/a91de0360dbac89cbb19Scala JSON to PostgreSQL: https://github.com/codeaperature/LoadFredObservationsKafka Polled Consumer: https://gist.github.com/codeaperature/15088179a11fe13bd61e62fd169de1b4JDBC PostgreSQL ingestion with (1) Spark DataFrames: https://gist.github.com/codeaperature/b3b007da4c5817ec9fa803b973ef1c25 (2) Standalone Scala: https://github.com/codeaperature/LoadFredObservationsGo/Golang DB Implementation Challenge: https://github.com/codeaperature/Thumbtack-Simple-DBSpark ML Clustering with McDonalds: https://github.com/codeaperature/MickeyDzC LevenShtein Challenge: https://github.com/codeaperature/LevenshteinDistanceGo/Golang Web Scraper / Server: https://github.com/codeaperature/JobExtractor

Boulder, Colorado, Us

A four month mission to add big data engineering / distributed systems skills to my repertoire.Coded Java & Scala to develop comprehensive understanding of Big Data technologies such as Hadoop / HDFS, Spark (with Streaming, Machine Learning & SQL), Storm, HBase, Pig, Hive, Flume, Kafka and complementary technologies that included Docker / Vagrant, Solr and AWS. ...Capstone: Instead of searching for that job ... What if you could just supply your resume, press a button and have jobs appear that magically match your skills? The 'What Up Resume?' Capstone project uses over 20 technologies to provide a resume-to-jobs solution that included Hadoop DFS, HBase, Golang, AWS S3, AWS RedHat cluster, Spark, Scala, Spark's Machine Learning Lib, IntelliJ, Ambari, Firebug ... Details:Job descriptions are acquired from RSS feeds, skills are stripped & stored in HBase, job descriptions are data cleansed & stored in AWS S3. Scala Spark MLLib is used to match jobs with the job's skills. A Scalatra-based web UI matches a resume with potential jobs....Present - Seeking Big Data / Back-end employment

San Francisco, California, Us

Debugged other software engineers' application security code and build issues which involved runtime & build logs, traces, dumps, binaries, virtual machines, IDA Pro, ADB, Xcode IDE, various build chain analysis tools, and so forth. Wrote & examined C\C++ and Java code as coding examples and for debugging customer-initiated issues. Wrote scripts & web service clients in Golang, JavaScript & Perl that included activities such as web page scrapers, rest web service calls & SQL calls for licensing reports as well as HTML- & Greasemonkey-borne JavaScript tools. Created log-parsing reports for Sales Engineers and Project Dev Team Leaders. Configured production Apache system to deliver a User's Agreement with embedded JavaScript logic. Copiously documented issues, FAQs, requirements, training slides and in-code comments. identified workaround, fixes, enhancements, etc. & used issue tracking systems (incl. CRM). Contributed efforts to change and improve business processes.

San Francisco, California, Us

Managed Technical Services as two offshore teams (India and Mexico). Scheduled / implemented / planned projects, set team priorities, identified risks, documented solutions / SOWs / CRs, troubleshot and implemented web service (SOAP / B-o-o-m-i PaaS) integrations, Jasper Reports and Single Sign-On (SSO). Developed B-o-o-m-i integration code and Greasemonkey-based JavaScript tools to help analyze middleware processes. Troubleshot and implemented ETL / SOAP Web services using SoapUI with B-o-o-m-i . Planned reporting projects & troubleshot back-end / web server-delivery for Jasper Reports. As the main customer interface, planned & implemented, tested, enhanced Single Sign-on (SSO).Supported internal teams and provided services to Tier 1 customers (such as Accenture & GE) that also included scoping, development, integration and UAT process phases. Efforts improved the Technical Services staff skills, teamwork and maintenance costs.

Sunnyvale, Ca, Us

Led the Sprint OEM-facing Integration Engineering Services program for managing integration support to embed C/C++ diagnostics libraries in variety of Android and other mobile devices.OEM project-centric, routine activities included C++ code-level triaging (ADB, Qualcomm debuggers, TCP/IP traces and other tools), producing technical documents, creating OEM release packages / training materials / best practices, mentoring / training co-workers, tracking schedules, developing tools. Greasemonkey-based JavaScript tools made included (1) code to improve ability for the OEMs to have the latest & most-related self-certification test data, (2) tool to manage 3-way OEM / carrier issue tickets and (3) a fix for an issue with leap year seconds that affected logging and results interpretations. Created a highly configurable server- and client-based PHP / AJAX / JavaScript tool, as part of a 2 month full-time solo effort to craft OEM certification test suites based on the to-be-tested device's specifications. Helped OEMs interpret test results & remediates issue related to metrics collecting. Efforts resulted in better program experiences such as product improvements, process changes, improved security, cleaner integrations and quicker certifications. Also worked closely with Sprint, Cricket, LG, Samsung, Franklin, Kyocera, Novatel and Actscom.

Reston, Virginia (Va), Us

Developed & delivered projects (such as CAPTCHA, Single Sign-On (SSO) & security / user experience features) to enhance Verizon Wireless’s Pix Place online photo album and mobile phone wallpapers sites. Produced clear project scope requirements for new features and enhancements. Documented analytics & system overviews. Reported status and communicated / tracked resolution on a vast number of issues. Enhanced revenues by reducing the outstanding list of projects and closing open Statements Of Work (SOWs). Implemented improved content ingestion capacity multi-fold with the use of an HTML-based analysis executable (C++) to help wallpaper content providers self-certify quality in the providers' submitted wallpaper's compressed file. Repaired and improved tenuous customer relationship to help renew the Service Length Agreement (SLA).

Reston, Virginia (Va), Us

Managed key OEM partner relationships with Samsung, Nokia, Motorola, LGE, Hitachi, Toshiba, SK Teletech, Sanyo and others to support the integration process of a proprietary C/C++ library (used for Sprint’s picture mail communications) into a variety of handset platforms that included Brew, Windows, Palm and other systems. Maintained low headcount requirements by taking on diverse program roles including project / product management, escalation management, application & integration engineering (FAE-like), technical support engineering and software engineering. . By generating Integration-based documentation (FAQs, HowTos, Manual content) and copiously tracking issues, reduced everyone’s time to market, generated increased customer rapport and repeat business.

Us

Created C / C++ white & black box tests. Wrote server software tests in C/C++, Java or with other tools to determine image format quality & properties for a wide variety of devices’ server-delivered image formats generated by an in-house media transformer. Created device C++ white-box test software for a mobile phone clip-on camera. Enhanced product quality by detecting flaws to fix & suggesting improvements in various components from servers to embedded systems

Everett, Wa, Us

Worked in various positions that included software engineer, project manager, engineering liaison, product engineer & product manager. As Product Manager, managed world-wide product marketing for several of Raytek’s product lines. Collaborated with Manufacturing and Engineering to guide development of hardware and software product enhancements, accessories and new products (h/w, f/w & s/w). Supported domestic and overseas subsidiaries in their marketing and sales efforts. Provided advanced technical product support that included software programming samples (in C and BASIC), application adaptation, in-house documentation support, trade show demos and training. Efforts resulted in increased sales and presence in the market.As a Software Engineer, developed several C S/W & H/W embedded system for non-contact temperature measuring products covering a range of hardware component features in RTOS environments. Wrote Pascal software to aid in demonstrations and 3rd party development. Developed world’s #1 infrared pyrometer, a graphical panel-mounted instrument and optimized code within various products. Designed hardware and engineered a simple fix that hugely saved the company quality reputation & service costs.

Santa Cruz, Ca, Us

Wrote C and Pascal Z80-based software for headset testing machines.

Us

Wrote C-based test software for digital keyboards and drums

Wilsonville, Or, Us

Part-time: Wrote BASIC software (pre-dating spreadsheets) that would display bar & pie charts for use in quarterly meetings. Wrote programs to calculate optics & report sales. I started in a role sorting & delivering mail, sorting scrap, cycle-counting inventory, soldering components and working on a variety of other tasks.

B.S.E.E., Computer Systems Engineering

Certificate, Data Engineering

High School, General Education

Education record