Senior Systems Engineer (Tandem NonStop) Fiserv IncSenior Systems Engineer (Tandem NonStop)VAPerform daily continuous improvements on all NonStop servers, including off-platform servers, such as Splunk, Prognosis, Moogsoft, ServicePoint, SharePoint and BackPak servers, their databases, user and data security, etc. You'll combine technical proficiency with strong problem-solving skills, attention to detail, and a commitment to ensuring the reliability, performance, and security of our infrastructure.
NewSoftware Engineer 3 - FreeWheel Comcast CorporationSoftware Engineer 3 - FreeWheelReston, VA$120,212.52–$180,318.78 / yearAs part of the Ad Server Tools Team, this role supports the development and maintenance of CI/CD pipelines, regression testing environments, and internal engineering tools that improve developer productivity and software quality. That’s why we provide an array of options, expert guidance and always-on tools, that are personalized to meet the needs of your reality - to help support you physically, financially and emotionally through the big milestones and in your everyday life.
Electrical Engineer - Robotics Hunter Defense Technologies Inc.Electrical Engineer - RoboticsFredericksburg, VAPart timeDesign aspects may range from interfacing with sensors and communication buses, power supplies and power management, brushless motor control electronics as well as microcontrollers, DSPs, and microprocessors for controlling robotic devices. Bachelor’s Degree in Electrical Engineering, Computer Engineering, Computer Science from accredited school or equivalent experience required; Master’s Degree strongly preferred.
NAIS / RF Engineer - Subject Matter Expert (REMOTE) AkimaNAIS / RF Engineer - Subject Matter Expert (REMOTE)Suffolk, VARemote$120,000–$150,000 / yearIf you are an individual with a disability, or have known limitations related to pregnancy, childbirth, or related medical conditions, and would like to request a reasonable accommodation for any part of the employment process, please contact us at job-assist@akima.com or 571-353-7053 (information about job applications status is not available at this contact information). For our government customers, ASE delivers solutions in maritime IT, systems engineering, and integration across the Department of Defense and stands ready to help improve operational performance at a reasonable and sustainable cost.
Lead C++ Software Engineer - (Reston, VA - Hybrid) - FreeWheel Comcast CorporationLead C++ Software Engineer - (Reston, VA - Hybrid) - FreeWheelReston, VA$167,383.91–$251,075.87 / yearIn-depth understanding of cloud, containerization and other related technologies, familiar with distributed architecture and commonly-used middleware such as cache, message queue, Nginx, etc., Experience in large-scale online service design, development and operation and maintenance is preferred. That’s why we provide an array of options, expert guidance and always-on tools, that are personalized to meet the needs of your reality - to help support you physically, financially and emotionally through the big milestones and in your everyday life.
AI/ML Engineer - TS/SCI w/Polygraph FinchAIAI/ML Engineer - TS/SCI w/PolygraphMcLean, Virginia$180,000–$250,000 / yearAI/ML Engineer Clearance: Must hold an existing active TS/SCI with required polygraph (US Citizenship required) Location: McLean, VA Onsite Daily Salary: 180,000-250,000 Commensurate with experience Responsibilities: Implement and maintain RAG pipelines, including document processing, embedding generation, retrieval configuration, and prompt assembly. Preferred Skills: Advanced research experience in machine learning, deep learning, natural language processing, generative AI, reinforcement learning, computer vision, or related disciplines.
NewLead Software Engineer (Data)-7999 ComcastLead Software Engineer (Data)-7999Reston, VirginiaREQUIREMENTS: Bachelor’s degree, or foreign equivalent, in Computer Science, Engineering, or related technical field, and seven (7) years of experience developing data processing software using Apache Flink; of which five (5) years of experience include designing extract transform-load (ETL) data pipelines using Flink, Spark, Kafka, AWS EMR, Azkaban and Airflow; storing structured data using Hbase; and developing business-level online video advertising technologies, including ad serving platforms, ad decisioning systems, and audience targeting; of which three (3) years include developing streaming data pipelines using Apache Kafka; storing data, running services, monitoring logs, and managing permissions using AWS services including S3, EC2, CloudWatch, and IAM; and automating tasks in a Unix environment using Linux Command Line Interface (“CLI”) and Bash scripting. That’s why we provide an array of options, expert guidance and always-on tools, that are personalized to meet the needs of your reality – to help support you physically, financially and emotionally through the big milestones and in your everyday life.
NewSr. Software Engineer (Data)-0336 ComcastSr. Software Engineer (Data)-0336Reston, VirginiaREQUIREMENTS: Bachelor’s degree, or foreign equivalent, in Computer Science, Engineering, or related technical field, and five (5) years of experience developing data products using Python; performing exploratory data analysis using SQL; developing data APIs using Golang; of which three (3) years include performing version control using GitHub; building CI/CD pipelines using Jenkins; operationalizing data products within AWS cloud platform; creating, maintaining and extracting data using Clickhouse; of which one (1) year includes using Snowflake and Databricks. That’s why we provide an array of options, expert guidance and always-on tools, that are personalized to meet the needs of your reality – to help support you physically, financially and emotionally through the big milestones and in your everyday life.
NewSr. Software Engineer (C++ or GoLang or Java) - 2 Days Onsite - Reston, VA - FreeWheel ComcastSr. Software Engineer (C++ or GoLang or Java) - 2 Days Onsite - Reston, VA - FreeWheelReston, VirginiaThat’s why we provide an array of options, expert guidance and always-on tools, that are personalized to meet the needs of your reality – to help support you physically, financially and emotionally through the big milestones and in your everyday life. Be an active part of the Net Promoter System a way of working that brings more employee and customer feedback into the company by joining huddles, making call backs and helping us elevate opportunities to do better for our customers.
NewCloud Security Architect / Systems Engineer Staffed4UCloud Security Architect / Systems EngineerChantilly, VirginiaThis team will provide technical guidance, architecture reviews, cost optimization support, cloud service evaluations, cybersecurity vulnerability coordination, and partner adoption support across secure mission environments. The selected candidate will be part of a group-level security and architecture team responsible for supporting the research, design, development, accreditation, and maintenance of complex systems that protect highly sensitive data.
Mid-Level Systems Engineer NewGen TechnologiesMid-Level Systems EngineerVirginiaOur team of Highly Cleared Specialists have hard-to-find skills and expertise in a wide spectrum of technologies to provide solutions that transform business processes and solve problems of national significance. For more than 20 years, NewGen Technologies has solved our clients’ toughest IT challenges with integrity, security, and outstanding service by delivering both technology and talent.
Engineer/Scientist Intern Ignite DigitalEngineer/Scientist InternChesapeake, VirginiaInterns will work alongside experienced engineers and scientists to assist with research, development, modeling, and systems support tasks that directly contribute to Navy and joint operational capabilities. Nor will Ignite Digital Services require, in a posting or otherwise, U.S. citizenship or lawful permanent residency in the U.S. as a condition of employment except as necessary to comply with law, regulation, executive order, or federal, state, or local government contract.
NewSr. Software Engineer 7947 ComcastSr. Software Engineer 7947Reston, VirginiaREQUIREMENTS: Bachelor’s degree, or foreign equivalent, in Computer Science, Engineering, or related technical field, and five (5) years of experience developing back-end software using Golang, Python, Gin, Go modules, pip, Go testing, and Pytest; performing container orchestration using Kubernetes and Docker; of which three (3) years include developing front-end software using JavaScript, TypeScript, HTML5, CSS, React, Angular, Vue.js, Redux, Vuex, Webpack, and Babel; working with Cloud platforms including AWS; using AWS services including EC2, S3, RDS, Lambda, IAM, and VPC; designing and managing CI/CD pipelines using Jenkins, and Github; and managing large-scale clusters using Ansible and Terraform; of which one (1) year includes monitoring and managing services using Prometheus and Grafana. That’s why we provide an array of options, expert guidance and always-on tools, that are personalized to meet the needs of your reality – to help support you physically, financially and emotionally through the big milestones and in your everyday life.
Information Systems Security Engineer (ISSE) NewGen TechnologiesInformation Systems Security Engineer (ISSE)Chantilly, VirginiaWe have helped secure borders, have used artificial intelligence (AI) to fight terror, aided the identification of criminals, and have helped to prevent crime through the introduction of biometrics. Our team of Highly Cleared Specialists have hard-to-find skills and expertise in a wide spectrum of technologies to provide solutions that transform business processes and solve problems of national significance.
ENGINEER SOFTWARE 2 Huntington Ingalls Industries IncENGINEER SOFTWARE 2Newport News, VA$80,000–$101,000 / yearDetermines computer user needs; analyzes system capabilities to resolve problems on program intent, output requirements, input data acquisition, programming techniques and controls; prepares operating instructions; designs and develops compilers and assemblers, utility programs, and operating systems. Conducts multidisciplinary research and collaborates with equipment designers and/or hardware engineers in the planning, design, development, and utilization of electronic data processing systems for product and commercial software.
ENGINEER ELECTROMECHANICAL 3 Huntington Ingalls Industries IncENGINEER ELECTROMECHANICAL 3Newport News, VA$99,000–$122,000 / yearApplies electrical, electronic and mechanical principles to components and systems, including assembly, analysis, and documentation of results; construction of developmental assemblies, sub-assemblies and components; and quality testing. HII's diverse workforce includes skilled tradespeople; artificial intelligence, machine learning (AI/ML) experts; engineers; technologists; scientists; logistics experts; and business administration professionals.
Entry Level Site/Civil Engineer Dewberry Engineers IncEntry Level Site/Civil EngineerFairfax, VA$82,500–$85,000 / yearDewberry is currently seeking an Entry Level Site/Civil Engineer to join our Site/Civil department in our Fairfax, VA office to work on a variety of projects for clients within the commercial and government sector. Site/civil development including grading design, roadway design, storm water management systems design, and erosion and sediment control design.
ENGINEER PLANNING ANALYST 4 Huntington Ingalls Industries IncENGINEER PLANNING ANALYST 4Newport News, VA$111,000–$139,000 / yearHII's diverse workforce includes skilled tradespeople; artificial intelligence, machine learning (AI/ML) experts; engineers; technologists; scientists; logistics experts; and business administration professionals. Our diverse and innovative team of professionals ranges from skilled trades to project managers, engineers and software developers to solution architects, technical subject matter experts, and system users.
Sr. / Principal Platform Engineer, Planning Yard (Norfolk, VA) General Dynamics CorpSr. / Principal Platform Engineer, Planning Yard (Norfolk, VA)Norfolk, VAQuality Management: Provide technical support to Design for Ship Installation Drawing (SID) package development for Ship Alterations and Post Shakedown Availability (PSA) Work Items tasked to Planning Yard. Team Collaboration and Communication: Interface with NAVSEA, ISEAs, and other contractors as required in seeking engineering solutions.
ENGINEER 5 Huntington Ingalls Industries IncENGINEER 5Newport News, VA$150,000–$185,000 / yearHII's diverse workforce includes skilled tradespeople; artificial intelligence, machine learning (AI/ML) experts; engineers; technologists; scientists; logistics experts; and business administration professionals. With more than 25,000 employees - including third-, fourth- and even fifth-generation shipbuilders - HII's Newport News Shipbuilding (NNS) division is the largest industrial employer in Virginia.
ENGINEER PROJECT 5 Huntington Ingalls Industries IncENGINEER PROJECT 5Newport News, VA$144,000–$181,000 / yearA successful candidate should have experience with evaluating and presenting detailed engineering alternatives to the customer and working to mutually agreeable alternative paths for component and system issues for which the primary or historical source or method is no longer an option. Write, evaluate, and review of: scopes, quality notices, white papers, vendor information requests, departure from specification, design integration memos, design liaison action requests, trouble shooting guides, procedures, and techmanuals.
ENGINEER NUCLEAR 4 Huntington Ingalls Industries IncENGINEER NUCLEAR 4Newport News, VA$124,000–$153,000 / yearHII's diverse workforce includes skilled tradespeople; artificial intelligence, machine learning (AI/ML) experts; engineers; technologists; scientists; logistics experts; and business administration professionals. With more than 25,000 employees - including third-, fourth- and even fifth-generation shipbuilders - HII's Newport News Shipbuilding (NNS) division is the largest industrial employer in Virginia.
MGR WELDING ENGINEER 2 Huntington Ingalls Industries IncMGR WELDING ENGINEER 2Newport News, VATests materials to determine conformance to specifications of mechanical strength, strength-weight ratio, ductility, magnetic and electrical properties, and resistance to abrasion, corrosion, heat/cold and recommends them for reliable performance in various environments. HII's diverse workforce includes skilled tradespeople; artificial intelligence, machine learning (AI/ML) experts; engineers; technologists; scientists; logistics experts; and business administration professionals.
Software Engineer Parsons CorpSoftware EngineerNorfolk, VA$74,800–$130,900 / yearWe have built this cultural legacy by working closely with analysts and operators to understand their needs and delivering meaningful value through innovative, cost effective and intuitive software solutions. Minimum of 3+ years of software development experience with a bachelor's degree in computer science or other technical discipline (additional years of experience may be considered in lieu of degree).
NewIT Engineer (Network Infrastructure) -Vienna, VA, Winchester, VA or Pensacola, FL Georgia Tek SystemsIT Engineer (Network Infrastructure) -Vienna, VA, Winchester, VA or Pensacola, FLVienna, VAAbility and willingness to grow skillset for SD-WAN and related technologies such as Cloud Interconnect and Cloud Security services for deployment and traffic flow engineering. ·Maximizes network performance, troubleshoots network problems and outages, scheduling upgrades and collaborating with network architects on network optimization.
NewNetwork Engineer-Vienna, VA Georgia Tek SystemsNetwork Engineer-Vienna, VAVienna, VAAbility and willingness to grow skillset for SD-WAN and related technologies such as Cloud Interconnect and Cloud Security services for deployment and traffic flow engineering. Maximizes network performance, troubleshoots network problems and outages, scheduling upgrades and collaborating with network architects on network optimization.
Software Security Engineer- Cloud/GovCloud (Top Secret cleared) ICF International IncSoftware Security Engineer- Cloud/GovCloud (Top Secret cleared)Reston, VARemote$81,499–$138,549 / yearPay Range - There are multiple factors that are considered in determining final pay for a position, including, but not limited to, relevant work experience, skills, certifications and competencies that align to the specified role, geographic location, education and certifications as well as contract provisions regarding labor categories that are specific to the position. If you accept this position, you should note that ICF does monitor employee work locations and blocks access from foreign locations/foreign IP addresses and also prohibits personal VPN connections.
Site/Civil Project Engineer Dewberry Engineers IncSite/Civil Project EngineerDanville, VATypical projects involve site/civil design for commercial and industrial site development, higher education, parks & recreation and capital improvement projects, water and wastewater, and roadways. Site/civil development including grading design, utility design, roadway design, storm water management systems design, and erosion and sediment control design.
Staff Engineer La Jolla Logic, IncStaff EngineerVA$130,000–$170,000 / yearCross-Functional Integration: Work actively alongside hardware, firmware, and systems engineering teams to integrate DSP code, debug complex low-level system issues, and validate end-to-end performance on target hardware. Production Implementation: Write, review, and optimize production-ready C/C++ code for embedded processors (DSPs, ARM), focusing on fixed-point arithmetic, latency reduction, and memory footprint.
NewResearch Assistant Virginia Polytechnic Institute and State UniversityResearch AssistantRoanoke, VAThe lab requires the candidate to interact with patients, participants, clinicians and researchers on and off site to maintain operation of lab research activities including collection of human subjects data that includes using electroencephalography (EEG), electromyography (EMG), electrocardiography (ECG), continuous blood-pressure monitoring, application of transcranial magnetic stimulation (TMS) and collection of behavioral data. The university has a significant presence across Virginia, including Blacksburg, the greater Washington, D.C. area, the Health Sciences and Technology Campus in Roanoke, sites in Newport News and Richmond, and numerous Extension offices and research institutes.
NewAdvanced Materials Process Solutions Engineer American WoodmarkAdvanced Materials Process Solutions EngineerWinchester, VAAdvanced Materials Process Solutions Engineer Direct message the job poster from American WoodmarkOverview Talent Acquisition, Recruiting, and On Boarding Professional focused on the Candidate ExperiencePrimary purpose:This professional position continuously supports and Improves AWCs Executive level Vision and Mission through technical discipline education and real-life experiences in advance materials, finishes and systems solutions. Engage in systems engineering and the development of alternate product materials and manufacturing systems designs that meet and exceed customer requirements, as well as lower COGS.Managing and leading multi-disciplinary projects assuring vision statements are met regarding performance, budget and timing.
Systems Engineer Twosix TechnologiesSystems EngineerChantilly, VAMinimum of 10 years of related network engineering experience, or equivalent combination of education, technical certifications/training, and/or work experience. The successful candidate is responsible for effective provisioning, installation/configuration, operation, and maintenance of systems hardware and software and related infrastructure.
Software Test Engineer AERMOR LLCSoftware Test EngineerNorfolk, VAFull timeBachelor’s degree in one of the following areas: Computer Science, Information Science, Information Systems Management, Mathematics, Statistics, Operations Research, Engineering, OR equivalent coursework demonstrating a computer-related background. Professional IT certification(s) in one or more of the following areas: Cloud (AWS, Azure, Google), Virtualization (VMware, Citrix, Microsoft), Systems Administration (Microsoft, Red Hat, Linux), or Software development.
Staff Engineer - Entry Level Priority Wire & Cable IncStaff Engineer - Entry LevelChesapeake, VAPart timePriority Wire and Cable is currently in need of a self-starter who can quickly contribute and complement our team! Bachelor's degree from an accredited college/university majoring in Electrical, Mechanical, or Chemical Engineering.
Entry Level Site/Civil Engineer DewberryEntry Level Site/Civil EngineerFairfax, Virginia$82,500–$85,000 / yearFull timeJob Description: Dewberry is currently seeking an Entry Level Site/Civil Engineer to join our Site/Civil department in our Fairfax, VA office to work on a variety of projects for clients within the commercial and government sector. Responsibilities: Site/civil development including grading design, roadway design, storm water management systems design, and erosion and sediment control design.
Engineer Delphinus EngineeringEngineerNorfolk, VirginiaThis position includes opportunities to participate in shipchecks, shipyard visits, and collaboration with Navy activities, shipyards, and equipment manufacturers. Support drawing submittals and participate in technical reviews with program managers, engineering managers, senior engineers and Planning Yard representatives.
Software Engineer InterImageSoftware EngineerArlington, VirginiaThis position offers the opportunity to work alongside experienced engineers, architects, and mission stakeholders to explore and implement Generative AI capabilities that improve automation, data analysis, decision support, and product innovation. This role is ideal for candidates who are passionate about software engineering, curious about Generative AI, and eager to help modernize how technology supports national security and operational effectiveness.
Mid-Level Systems Engineer AvaloreMid-Level Systems EngineerTysons, VirginiaTechnical Skills: Strong working knowledge of Linux/Unix, version control (Git), and scripting languages (Python, Bash, or similar). System Design & Implementation: Design, install, configure, and test operating systems, application software, and system management tools.
Systems Engineer, Expert (Will Consider Senior) AmentumSystems Engineer, Expert (Will Consider Senior)Chantilly, VirginiaThe ideal candidate lead cross-functional teams to plan, execute, and deliver Amazon Web Services (AWS) initiatives—such as cloud migrations, data center modernizations, and infrastructure deployments. The candidate will use their expert knowledge of AWS Cloud Technology, agile framework, and client software development lifecycle to ensure adherence to project plans, schedules, and security requirements for systems authorization and accreditation.
AV Design Engineer DSI TechAV Design EngineerAshburn, VA$80,000–$120,000 / yearMaintain technical expertise in all areas of AV systems, including network, hardware, software, codecs, audio video switchers, AV control systems, AV devices, including monitors, microphones, cameras, mixers, amplifiers, VTC gateways, VTC bridges, video streamers, etc. Specialize in audio digital signal processors, video over IP, networks, video conferencing, web conferencing, matrix switchers, and complex systems.
Software Engineer Anthem EngineeringSoftware EngineerChantilly, VAUpdate job knowledge by researching new internet/intranet technologies and software products; participating in educational opportunities; reading professional publications; maintaining personal networks; and participating in professional organizations. Experience with tools including git (preferably GitHub), CI/CD (preferably Jenkins), artifact management (preferably Nexus), ticketing (preferably Jira), and knowledge management (preferably Confluence).
Computer Network Engineer Obsidian Solutions Group LLCComputer Network EngineerVAMust have experience in the following: configuring, designing, and maintaining Window servers; designing, configuring, and testing personal computer and network software components in a laboratory environment; programming software and command line interfaces; and setting up patch management software and backup management solutions. A career at Obsidian Solutions Group means you can put your expertise, credentials, and talents to great use working with customers in the DOD and Intelligence Community, while enjoying the excitement of working in a fast-growing organization committed to making a difference for our customers and in our community.
Cloud Engineer/Architect Flowers Foods IncCloud Engineer/ArchitectVA$90,000–$105,000 / yeare • Support development, deployment and adherence of a Power Automate governance plan • Support all 3rd party connectors including any requirements for connections to on-premise or Cloud data sources • Teams / SharePoint Online Development and Administration • Work with users at all levels to develop technical architecture and designs for scalable enterprise SharePoint Online solutions • Monitor / Validate all allowed domains, guest accounts and external sharing links for sites and services • Design solutions based on established patterns and best practices around Content Management, Records Management, User Adoption, Governance, Change Management, external access • Support Integration with 3rd party applications • Develop and maintain a Flowers end user training program for existing and new functionality • Monitor, maintain, and support any Office 365 issues, storages, licenses - including renewal - and administrative tasks. • Support design and implementation of processes and procedures for all Power Automate services • Support and Monitor all Flowers Power Automate services for performance, resource availability and cost, including Power BI, Powerapps, Flow, Premium Capacity and Common Data Services.
Software Engineer II VeriSign IncSoftware Engineer IIReston, VA$89,900–$121,700 / yearEngineers on the team will be called on to research technologies, present their findings, document software design, implement business logic, demonstrate completed work, and collaborate with team members to improve incrementally. Successful engineers will work closely with team members to master our software, one component at a time, and make a positive impact on projects as well as team chemistry.
Geospatial Platform Engineer Maxar Technologies Inc (Inactive)Geospatial Platform EngineerMcLean, VA$182,000–$200,200 / yearThe ideal candidate is a self-directed engineer with demonstrated experience developing and supporting geospatial, imagery, AI/ML, or analytic applications in secure hybrid environments, including cloud, on-premises, virtualized, and classified infrastructure. This role will focus on moving mission capabilities from prototype to production through hands-on software development, data and service integration, Kubernetes-based platforms, containerized architectures, CI/CD automation, observability, and secure DevSecOps practices.
Security Engineer, WWPS Solutions Architecture Amazon.com IncSecurity Engineer, WWPS Solutions ArchitectureHerndon, VAAWS Sales, Marketing, and Global Services (SMGS) is responsible for driving revenue, adoption, and growth from the largest and fastest growing small- and mid-market accounts to enterprise-level customers including public sector. We pioneered cloud computing and never stopped innovating - that's why customers from the most successful startups to Global 500 companies trust our robust suite of products and services to power their businesses.
Security Engineer II, Security Incident Response Team (SIRT) Amazon.com IncSecurity Engineer II, Security Incident Response Team (SIRT)Arlington, VAWe offer talented security professionals the chance to accelerate their careers with opportunities to build experience in a wide variety of areas including cloud, devices, retail, entertainment, healthcare, operations, and physical stores. SIRT Security Engineers respond to security events, conduct analysis of threats such as malware and intrusion attempts, and provide security services to safeguard highly sensitive data.
AIML Engineer Verite Group, Inc.AIML EngineerMcLean, VAAdvanced research experience in machine learning, deep learning, natural language processing, generative AI, reinforcement learning, computer vision, or related disciplines. Work on this program takes place in McLean, VA and in various field offices throughout Northern VA (we cannot support remote work) and requires a TS/SCI + Polygraph clearance (acceptable to this customer).
Ontology Engineer (TS/SCI) Maxar Technologies Inc (Inactive)Ontology Engineer (TS/SCI)Herndon, VA$182,000–$200,200 / yearThis position applies semantic technologies and knowledge representation methodologies to enable data interoperability, advanced analytics, and knowledge integration across diverse data sources and object-management systems. The Lead Ontologist serves as the technical authority for the design, development, and maintenance of domain-specific ontologies and knowledge models that support Object-Based Intelligence (OBI) mission requirements.
System Engineer III-Cyber RadiantHire Solutions Inc.System Engineer III-CyberArlington, VirginiaRequired Education: Bachelor’s degree in Systems Engineering, Computer Engineering, Computer Science, Cybersecurity, or related degree; or 7-9 years of directly relevant work experience and High School Diploma. They are seeking an experienced and technically proficient Cyber Technology Researcher responsible for concurrently tracking, advising, and managing individual cases through their lifecycle – from initial submission to capability delivery and feedback.