Publication
Software Entropy Explained: Causes, Effects, and Remedies
https://www.toptal.com/developers/software/software-entropy-explained
Adam is currently unavailable
Adam Wasserman
Verified Expert in Engineering
Software Engineer and Developer
Providence, RI, United States
Toptal member since May 25, 2017
Bio
Adam is particularly interested in multithreaded programming and health care; however, any exciting challenge fits the bill. He believes that a successful project often requires a balance between following and breaking conventions. Adam also considers himself personable and an excellent communicator.
Portfolio
Gartman Digital, LLC
Google Calendar, JavaScript, Node.js, User Interface (UI), User Experience (UX)...
Kairos Solutions
Fast Healthcare Interoperability Resources (FHIR), Azure, HL7 FHIR Standard...
Karius Inc.
Node.js, TypeScript, NestJS, MikroORM, Redox Engine, Okta, Jest...
Experience
- Java - 14 years
- HL7 FHIR Standard - 5 years
- Node.js - 5 years
- Spring Boot - 5 years
- Electronic Health Records (EHR) - 4 years
- HIPAA Compliance - 3 years
- SMART on FHIR - 3 years
- Redox Engine - 1 year
Preferred Environment
IntelliJ IDEA, Android Studio, Git, Gradle, Visual Studio
The most amazing...
...thing I've coded is a PGP encryption library for Android, which has been licensed out.
Work Experience
Full-stack Developer
2026 - 2026
Gartman Digital, LLC
- Developed a prototype for real estate photographers to manage their photo shoots.
- Integrated with Google Calendar for obtaining photo shoot information.
- Managed auto-association of photos into brackets and with photo shoots.
Technologies: Google Calendar, JavaScript, Node.js, User Interface (UI), User Experience (UX), Electron, React
FHIR Developer
2025 - 2025
Kairos Solutions
- Created APIs for the management of FHIR R4 resources: Patient, Practitioner, PractitionerRole, Organization, Medication, MedicationStatement, AllergyIntolerance, Consent, Provenance, DocumentReference, InsurancePlan, and Coverage.
- Explored search capabilities of the HAPI FHIR server, and exposed them to the business layer through search APIs.
- Created a Terminology Service for the lookup of concepts in ValueSets bound to resource properties. Created and uploaded custom CodeSystems and ValueSets where necessary.
Technologies: Fast Healthcare Interoperability Resources (FHIR), Azure, HL7 FHIR Standard, SMART on FHIR, HIPAA Compliance, REST APIs, Node.js, HAPI, Git, Agile, Docker, Electronic Health Records (EHR), REST, RESTful Microservices, Jest
Back-end Developer
2024 - 2025
Karius Inc.
- Designed and implemented from scratch EHR integration services that accept lab test orders and deliver reports via FHIR Messaging. Clients are hospital systems. We used FHIR R4 as the data model and Auth0 for identity and access management.
- Created an FHIR endpoint that accepts FHIR Bundles containing a ServiceRequest and supporting resources: patient, practitioner, encounter, observation, organization, and specimen.
- Created an FHIR IG (implementation guide) for these resources as collective input to the endpoint. Clients can specify additional data requirements based on the format of the incoming bundle and its contents.
- Created a second FHIR endpoint for use by the Redox engine, which acts as a "middleman" between Karius and the medical providers. Worked directly on the Redox onboarding and integration process from start to finish.
Technologies: Node.js, TypeScript, NestJS, MikroORM, Redox Engine, Okta, Jest, RESTful Microservices, API Integration, Docker, Back-end, Containers, HL7, Agile Software Development, HL7 FHIR Standard, Fast Healthcare Interoperability Resources (FHIR), HIPAA Electronic Data Interchange (EDI), Microservices, REST APIs, OAuth, OAuth 2, REST, Healthcare EDI, Amazon S3 (AWS S3), JavaScript, Apache Kafka, HIPAA Compliance, Git, Agile, Electronic Health Records (EHR)
Software Architect and Developer
2022 - 2024
Pro Gravur
- Designed and implemented a multi-platform desktop application using Electron and React/Redux to perform highly specialized, industry-specific data transformations.
- Created a REST service in C++ using the C++ REST SDK to provide back-end services to the desktop app.
- Contributed to the application, essentially a data-transformation pipeline based on the input parameters and using the REST service when necessary.
Technologies: C++, React, Electron, JavaScript, Full-stack, React Redux, REST APIs, Microservices, Full-stack Development, Windows Installer, Git
FHIRcast Developer
2023 - 2023
Smart Reporting
- Brought back and upgraded the FHIRcast client, adapter, and hub.
- Implemented the STU3 version of the FHIRcast specification.
- Added TLS support for a series of back-end microservices written in both Java, Spring, and Node.js using Docker.
Technologies: Java, Spring Boot, Gradle, HL7 FHIR Standard, Docker, JavaScript, Back-end, Next.js, Passport.js, API Integration, TypeScript, Reactive Programming, WebSockets, Containers, REST APIs, Spring, Agile Software Development, Express.js, Fast Healthcare Interoperability Resources (FHIR), RESTful Microservices, HIPAA Electronic Data Interchange (EDI), Git, Agile
Back-end Developer
2021 - 2022
International Baccalaureate
- Designed and implemented a microservice using Spring Cloud that maps data from one format to another. The mapper accepts a tree-like JSON structure and uses a state machine to process it. The input can be quite large in terms of gigabytes.
- Configured the states in the state machine to operate on one-to-many nodes in the input and on zero-to-many objects in the serialized output. Each output object is translated into HTTP requests and executed by a second microservice, the publisher.
- Optimized the publisher in terms of mapper and publisher interaction, as well as publisher performance due to the number of requests.
Technologies: Spring Cloud, Microsoft Azure, Back-end, SQL, REST APIs, Microservices, CI/CD Pipelines, Spring, Azure, Agile Software Development
FHIRcast Developer
2020 - 2021
Smart Reporting
- Created and implemented an FHIRcast client. The client implemented the STU2 FHIRcast specification. The architecture provided pluggable extensions to the functionality (client-specific events and extended event handling). We used the WebSockets flow.
- Developed and implemented a FHIRcast hub (STU2 FHIRcast specification). The architecture allows for extensions (extended event handling). The hub is event-agnostic and underlying FHIR resources (R4) validated. We used the WebSockets flow.
- Provided support for a Nuance-specific extension, Powercast, which supported the DiagnosticReport-update event and retained topic state, including versioning.
- Led the development team and ensured full test coverage. Oversaw the project up to acceptance, then completed handover.
- Implemented SMART on FHIR-based authorization when applicable.
- Implemented a patient database with a simple data feed sourced with HL7 messages. Used Spring Boot with JPA/Hibernate.
Technologies: Fast Healthcare Interoperability Resources (FHIR), Docker, Git, Spring Boot, Java, Agile, JPA 2, WebSockets, REST, Asymmetric Encryption, Multithreading, OAuth 2, HL7 FHIR Standard, Back-end, API Integration, Reactive Programming, SQL, Containers, HL7, REST APIs, Microservices, Spring, Agile Software Development, HIPAA Electronic Data Interchange (EDI)
Back-end and Front-end Developer
2018 - 2021
Patient Insight
- Configured and deployed a Vonk FHIR server and a .NET IdentityServer instance to work together for both SMART on FHIR and SMART back-end services (JWT client credentials grant type) authentication.
- Created a blood pressure dashboard using React for doctors to monitor the condition and treatment of hypertension patients. Observation and patient data were obtained from our FHIR server. The environment was a Google Compute Engine instance.
- Developed an inbound data feed for the blood pressure dashboard: received continuity of care document (CCD), extracted and transformed data into FHIR resources, and added to the FHIR server. Worked with R4 and DSTU2 data.
- Created a sample patient population with complete medical histories using Synthea and imported it into our Vonk server for testing purposes.
Technologies: Google Compute Engine (GCE), Fast Healthcare Interoperability Resources (FHIR), Docker, Angular, React, Node.js, Spring Boot, Java, Git, JPA 2, Healthcare EDI, REST, Electronic Health Records (EHR), Asymmetric Encryption, Multithreading, MongoDB, OAuth 2, SMART on FHIR, HL7 FHIR Standard, JavaScript, OAuth, Linux, Full-stack, API Integration, TypeScript, PostgreSQL, React Redux, NoSQL, Containers, REST APIs, Microservices, Full-stack Development, Google Cloud Platform (GCP), Spring, HIPAA Compliance
Front-end Developer
2018 - 2019
PositionTech
- Maintained and expanded an existing Android app using Protobuf to interface with the back end.
- Created several new web-based UIs and web components written in Angular/TypeScript using PrimeNG and NGXS state management. Also refactored and expanded several existing UIs according to new, more modern design.
- Created unit tests for the UI with the goal of achieving 100% code coverage.
Technologies: Protobuf, Android, PrimeNG, Angular, JavaScript, TypeScript, Mobile Apps, REST APIs, Microservices, Full-stack Development, Agile Software Development, Mobile Development
Back-end Developer
2017 - 2018
CircleBlack
- Created a SAML identity provider for single sign-on.
- Overhauled the authentication strategies using Passport.js in Express.js.
- Implemented a message exchange server operating over HTTPS and secure WebSockets.
- Generated use cases for a complex data feed and produced an initial design that was followed up by the team.
Technologies: WebSockets, MySQL, Liquibase, SAML, Angular, Node.js, Git, REST, SAML-auth, Single Sign-on (SSO), Multithreading, OAuth 2, JavaScript, Linux, Back-end, Passport.js, Redis, REST APIs, CI/CD Pipelines, Express.js
Back-end and EDI Developer
2013 - 2016
Lille Group
- Developed a HIPAA-compliant electronic health record (EHR) system written in Java.
- Built a bundle of services that exposed data via traditional web browsers and mobile devices.
- Created and maintained EDI interfaces based on the HL7 standard for updating patient records with lab results, doctor appointments, and demographics.
Technologies: RMI, Amazon S3 (AWS S3), MyBatis, PostgreSQL, Oracle, Apache Tomcat, Java, Git, Spring Boot, JPA 2, Healthcare EDI, REST, Electronic Health Records (EHR), Linux, Back-end, API Integration, Redis, Amazon Web Services (AWS), SQL, HL7, CI/CD Pipelines, Spring, Agile Software Development
Test Infrastructure Engineer
2013 - 2014
SVB | Sociale Verzekeringsbank
- Established the architecture for running automated test scripts. The system, operated by the government of the Netherlands, makes social welfare payments. Based on IBM mainframes written in COBOL, the tests operated directly on the front end.
- Designed and implemented a thin-client tool for the management of test scripts in Eclipse.
- Expanded the core test engine, written in Java and based on the TestFrame framework.
- Implemented "action words" as defined by the test team.
Technologies: Plugin Development, Oracle, WebSphere, MyBatis, Spring Boot, Back-end, Automated Testing
Software Engineer
2012 - 2013
Ministry of Justice, Netherlands
- Optimized a JBoss app based on the ministry's specific application that used FileNet. The application allowed access to documents, some of which were sensitive, based on credentials.
- Implemented emergency bug fixes on existing applications. A new version of the system was about to be released, but there were reliability problems involving the caching mechanism.
- Established proper configuration and use of JBoss Cache.
Technologies: JBoss, Java Message Service (JMS), Java, Java EE (Jakarta EE), JPA 2, Multithreading, Linux, Back-end, SQL
Software Engineer
2008 - 2012
iBanx
- Developed a risk-management tool for operating, repairing, and expanding huge factories such as oil refineries running 24 hours per day.
- Created custom modules for client-specific needs. These modules were written in Java and backed by a Drools rules engine.
- Built an asset management system for factory components, written in Java and backed by Drools.
Technologies: Oracle, WebSphere, Apache Tomcat, JBoss Drools, JBoss, Agile, Linux, Back-end, SQL, Automated Testing, Agile Software Development
Software Engineer
2011 - 2011
Anva
- Solved a bug emergency in an existing application with a hard deadline for Anva: a company that creates customized software for the insurance industry.
- Built the software's components which exchanged messages via an ESB. The problems involved remote access via RMI of the ESB registry.
- Reviewed the message exchange mechanism and made recommendations on improvements.
Technologies: RMI, JBoss, Java, Multithreading, Linux, Back-end, SQL
Software Engineer
2011 - 2011
I Get It!
- Developed a prototype for a menu application intended for restaurant chains.
- Developed the prototype UI that ran on Android. The back-end services were written in Perl and ran in Apache.
- Provided a content management system for updating and adding to menus.
Technologies: Android, Linux, Perl, Apache, Back-end, Mobile Apps
Software Engineer
2010 - 2010
CliqDigital
- Maintained a proprietary premium text messaging platform written in Perl. It was partly based on something I had written for its predecessor, Blinck. My intimate knowledge of its inner workings was a unique qualification for this project.
- Replaced the existing system with one written in Java using Jakarta EE technologies. There was no documentation, but the existing system was the baseline, and the new system had to behave the same.
- Created, with two junior programmers, a suite of E2E tests that functioned as the definitive technical determination of success.
Technologies: MySQL, JBoss, Java Message Service (JMS), Apache, SMS, Linux, Back-end, SQL
Software Engineer
2009 - 2010
Unavalley
- Adapted an existing premium text-messaging platform for a client's specific needs. Users subscribed via rich front-ends written in Flash and the traffic was provided by advertising affiliates.
- Implemented the routing, tracking, and reporting services for advertising affiliates.
- Worked with third parties to create interfaces for data exchange: status reports, subscriber activity, and payment.
Technologies: Multithreading, MySQL, Perl, Apache, SMS, Linux, Back-end, SQL
Software Engineer
2007 - 2008
Compare Group
- Worked for the company Compare Group. Their platform scraped target websites and aggregated the data encountered there (products and attributes). Written in Java and backed by a series of SOAP web services.
- Conducted emergency bug-fixing; the platform was delivered by a third party full of errors and missing major functionality. It had a hard deadline to get it working. Worked closely with a test team in rapid iterations until all tests passed.
- Introduced AOP as a non-intrusive technology to diagnose, supplement, and correct functionality.
Technologies: SOAP, Apache Tomcat, AOP, JAXB, Java, Linux, Back-end, SQL
Software Engineer
2007 - 2007
Venspro
- Worked in a team on a variety of small projects, as needed. Venspro operated the Greetz brand of online cards and flowers.
- Implemented the real-time data transformation as well as credit-card, bank transfer, and mobile billing interfaces.
- Developed a thin HTML client with a Java/Spring back-end.
Technologies: Oracle, Apache Tomcat, Java, Java EE (Jakarta EE), Multithreading, Back-end, SQL
Software Engineer
2006 - 2007
Glomobi
- Swapped-out JBossMQ for the more advanced JBossMessaging in their proprietary premium text-messaging platform. Dealt with a resolution of race conditions exposed by the update.
- Built a freestanding interface to manage (start, stop, reload) endpoints using JMS and EJB. An endpoint is a combination of gateway and mobile shortcode where text messages originate and can be received.
- Created a strategy for running the system in a cluster of JBoss nodes.
- Implemented the strategy and demonstrated its viability in a test environment.
- Deployed code changes to production in a non-clustered environment.
Technologies: JBoss, SOAP, Java Message Service (JMS), Enterprise Java Beans (EJB), Java, Java EE (Jakarta EE), Apache, Linux, SMS, Perl, Back-end, SQL
Software Engineer
2005 - 2006
Philips IP&S
- Developed an online product license verification system where customs agents checking cargo at the border could use the system to request documents confirming that the products were genuine.
- Created a series of SOAP web services for receiving requests. The product universe varied considerably, a fact which had an impact on the schema describing our XML.
- Ensured that the requests could be processed asynchronously. The software was backed by a state machine written in Java. The eventual output was a PDF sent via email.
Technologies: Enterprise Java Beans (EJB), SOAP, Java, Java EE (Jakarta EE), Multithreading, AOP, Back-end, SQL
Architect | Software Engineer
2003 - 2005
Blinck International
- Designed and implemented a platform written in Perl for delivering premium content via SMS/text-messaging to mobile users all over the world.
- Conduced Apache configuration and optimization including Mod_perl.
- Created and implemented modules to interface with gateways (text-messaging providers) for the purposes of sending text-messages, receiving status alerts, and billing.
Technologies: Perl, Apache, Linux, SMS, Back-end, SQL
Software Engineer
2003 - 2003
MarviQ
- Worked on a single sign-on application based on the SAML and Liberty specifications for identity management.
- Created a web-based application to keep track of billable hours (for internal use only).
- Experimented with EJB technology deployed into WebSphere.
Technologies: SAML, SOAP, Apache Struts, Enterprise Java Beans (EJB), WebSphere, Apache Tomcat, JBoss, Java, SAML-auth, Single Sign-on (SSO), Back-end, SQL
Software Engineer
2002 - 2003
Expresso Paper Platform
- Collaborated with a team to build and expand an eCommerce message exchange connecting clients with suppliers in the paper industry. Orders arrived via SMTP (email) and were processed in a queue-like system (ECXpert).
- Worked on this message exchange between stops in the pipeline that occurred via SOAP. ECXpert was cumbersome, CPU-intensive, and no longer being actively supported.
- Replaced the ECXpert proprietary system with a series of JMS components replicating stages in the pipeline and a daemon using JavaMail to retrieve incoming SMTP messages and submit them to the first stage.
Technologies: Oracle, JavaMail, LDAP, Java Message Service (JMS), Java, Back-end, SQL
Software Developer
2002 - 2002
Holland House
- Benchmarked an existing, proprietary printer spooling system and set a baseline for further improvement.
- Designed a new interprocess communication layer for their printer management system based on JMS.
- Worked directly with the architect to create prototypes as proofs-of-concept in migrating architecture from a proprietary system to a J2EE-based system.
Technologies: Java Message Service (JMS), JBoss, Java, Multithreading, Back-end, SQL
Software Engineer
2001 - 2001
KGBE
- Built and implemented a distributed content-management system for streaming video and audio. The content was used in various branded media portals. Metadata about the content was stored in LDAP. Web pages were generated via JSPs with access to LDAP.
- Ensured that the content management tool had to populate LDAP and copy the corresponding media files from the designer's machine to the appropriate locations on the server.
- Worked directly with Flash designers to create a tool to allow them to plan content in time slots, similar to TV programming.
Technologies: JBoss, LDAP, Enterprise Java Beans (EJB), Java, Back-end
Software Developer
2000 - 2001
Anachron
- Worked on an online bill presentation and payment system.
- Created a payment interface for Equens (Interpay).
- Functioned as the team lead.
Technologies: Java, Back-end
Software Developer
1999 - 2000
NedStat
- Worked on a web traffic tracking system written in Perl and Java with both free and paid services.
- Created a JNI component written in C for performing UNIX-specific functions required by the platform.
- Developed an interface in Java between a remote JDEdwards system and NedStat's internal system.
Technologies: Perl, C, JNI, Java, Back-end, SQL
Software Developer
1997 - 1998
Community of Science
- Worked on a system for providing access to paid academic articles online. Clients could subscribe with various levels of access.
- Kept track of user sessions which had to be done manually.
Technologies: Perl, Back-end, SQL
Software Developer
1996 - 1997
Credit Management Solutions
- Created one of the first online tools accepting applications for consumer car loans.
- Developed a Windows DLL for processing loan results and making them available to the online system.
- Worked with the team in charge of the core credit scoring engine to ensure the online system's compliance with various state laws.
Technologies: C, Back-end, SQL
Software Developer
1996 - 1996
Applied Physics Lab
- Helped to develop software that was intended to predict mechanical problems in tank engines before they actually occurred. It involved real-time data acquisition and comparison to previously obtained data profiles.
- Worked closely with a mechanical engineer to make the physical data in the form of electric signals accessible to a computer system programmatically.
Technologies: C, Back-end
Experience
GenerateKeyRingsTask
This task is part of a PGP library that I wrote for Android and cannot be run independently of the larger framework. Tasks in the library are assigned the data that they require and run on a managed thread by another component. At the end of execution, interested components are notified via broadcast.
The GenerateKeyRingsTask generates a public/private key pair with zero or one sub-key pair, collectively referred to as a "key ring." It can also be used to add a sub-key pair to an existing key ring. The master key pair must use the RSA algorithm. Sub-key pairs for master keys using the DSA algorithm will be created using the ElGamal algorithm.
The GenerateKeyRingsTask generates a public/private key pair with zero or one sub-key pair, collectively referred to as a "key ring." It can also be used to add a sub-key pair to an existing key ring. The master key pair must use the RSA algorithm. Sub-key pairs for master keys using the DSA algorithm will be created using the ElGamal algorithm.
Education
1991 - 1995
Bachelor of Science Degree in Computer Science
Johns Hopkins University - Baltimore, MD, USA
Skills
Libraries/APIs
REST APIs, PrimeNG, Node.js, Java Message Service (JMS), MyBatis, Java RMI, JPA 2, React, JAXB, JavaMail, Liquibase, Protobuf, Passport.js, React Redux, Redox Engine
Tools
SMART on FHIR, Git, Apache Tomcat, Apache, Google Compute Engine (GCE), JBoss Drools, Gradle, Windows Installer, Visual Studio
Frameworks
Spring, Spring Boot, Angular, OAuth 2, Jest, Apache Struts, JNI, Electron, Next.js, Express.js, NestJS
Paradigms
HL7 FHIR Standard, REST, Fast Healthcare Interoperability Resources (FHIR), Microservices, Agile Software Development, Agile, Reactive Programming, Mobile Development, HIPAA Compliance, AOP, Automated Testing
Languages
SAML, JavaScript, Java, TypeScript, SQL, C, Perl, C++
Platforms
Android, Java EE (Jakarta EE), JBoss, WebSphere, Oracle, Linux, Docker, Amazon Web Services (AWS), Google Cloud Platform (GCP), Azure, Apache Kafka
Storage
MySQL, PostgreSQL, Amazon S3 (AWS S3), MongoDB, Redis, NoSQL
Other
Back-end, SAML-auth, SMS, Asymmetric Encryption, Electronic Health Records (EHR), Multithreading, Public-key Cryptography, SOAP, Healthcare EDI, Single Sign-on (SSO), OAuth, Full-stack, API Integration, Containers, Full-stack Development, RESTful Microservices, HIPAA Electronic Data Interchange (EDI), LDAP, RMI, Plugin Development, WebSockets, Enterprise Java Beans (EJB), Spring Cloud, Microsoft Azure, PGP, Mobile Apps, HL7, CI/CD Pipelines, MikroORM, Okta, Algorithms, Grammar & Language Creation, Distributed Software, HAPI, Google Calendar, User Interface (UI), User Experience (UX)
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