Senior Backend Developer / Architect

Implementation of the operation center core components – Multi-Cloud management and orchestration tools, code generators, development of a VPNaaS solution – kubernetes operators. Evaluation of LXD for the edge, POC for cloud native edge based on metal3. Development of modules for platform provisioning system for bare-metal and hybrid-cloud components based on actor model. Technical solution design. Development of a central edge proxy using REST over Websocket for services running in restricted environment and reverse http proxy over quic protocol. Kotlin, golang, Java, Spring Boot, OpenStack, AWS, Terraform, gitlab, CI/CD pipelines, Kubernetes, k3s, k3d, k9s, docker, helm, helmfile, kubebuilder, postgres, Bolt DB, REST, JWT, WebSockets, gRPC, gin-gonic, microservices, GORM, temporal.io, prometheus, Terraform Plugin Framework, earthly, packer, OpenVPN, RSA, TLS, CRL, Carvel tools, (LXC,LXD, OVN basics), Node.js/Typescript, Jest, GCP K8S Config Connector, Azure Service Operator, Canonical Juju, Hybrid-Cloud, Metal3, Kubernetes ClusterAPI / CAPI, mTLS, L4/L7 load balancing.

Kyma project - development of the Kubernetes service platform. golang, Kubernetes, Istio, Helm, CRD controllers, X.509, mTLS, hyperscalers, GCP, Azure

Development of microservices for secure communication between Mobile App and virtual credit card management system. Java, Spring Boot, Spring Cloud, Microsoft Azure, Azure Kubernetes Service (AKS), Docker, Helm, Jenkins, SQL Server, Apache Kafka, git, Jenkins, PCI compliance, vavr-io, oauth2, OpenID Connect, Keycloak, JOSE, JWT, JWE, RSA, JPA, Hibernate, Swagger/ OpenAPI, Kotlin, microservices

Design and development of a new service platform based on Kubernetes. Migration of existing infrastructure and java services to Kubernetes. Development in area of application security, backend service engineering, proof of concepts, service monitoring and alerting. Design and development of image processing pipeline using TensorFlow GPU, AWS Batch, Step Functions and Lambda. Java, Spring Boot, Spring Cloud, golang, python, WebSockets, AWS, Kubernetes, Docker, Helm, Linkerd2, Chartmuseum, KOPS, EKS, Postgres RDS, RabbitMQ, Terraform, kubebuilder, Packer, Elasticsearch, Kibana, Calico, Fluentd, filebeat, Prometheus, Alertmanager, Grafana, ElastAlert, OpenTracing Zipkin / Jaeger, OAuth2, OIDC, autoscaling based on custom metrics, CI/CD, TeamCity, Kotlin DSL, Argo CD, IntelliJ, GoLand, AppDynamics, DNS, X.509 certificates management, POC, DevOps, ARM, microservices

Development of a basket service used by REWE online-shop delivery service. Software enhancements and migration to support new marketplace architecture. Java 8, Microservices, Docker, Spring Boot, Play 2 for Java, Apache Kafka, Event Sourcing, PostgreSQL, Redis, Liquibase, JUnit, Spock Framework, OAuth2, REST, JSON Jackson, IntelliJ, Immutables, ELK, GIT, Stash, Linux, Bamboo, HipChat, JIRA,Continuous Integration, Load balancing, Blue-Green deployment, Scrum

Development and design of infrastructure and framework components in a multi-datacenter system for HSA4 (Hotel Self Administration) project. Development of inventory, reservation and booking engine services, distributed and off-heap caching solutions, multicast-based service discovery and audit solution. Agile Software Development with Scrum and Kanban, prototyping, performance and last testing, micro-benchmarking, application profiling, GC tuning. Server Side Core Java Development, Technical Architecture, E-Commerce, NoSQL, Apache Cassandra, CQL3, DataStax OpsCenter, Redis / Sentinel, Distributed Caching, Twitter Twemproxy - Nutcracker, Ketama consistent hashing, distributed tracing - Zipkin, sun.misc.Unsafe, Off-Heap Memory, Memory-Mapped Files, SQL, MySQL, Spring, AOP, Hibernate, JPA2, CI / Jenkins, HTTP, Multithreading, Reflection / CGLIB, Java Profiling / Java Mission Control, JProfiler 7, Microbenchmarking – Caliper/ JMH, Azul jHiccup, Guava, JEE, JBoss 7, Linux / CentOS Enterprise, JMeter, JUnit, MBeans, REST, JSON/Jackson, Messaging, JMS / HornetQ, Proxy/ SQUID, Load Balancing, Service Discovery/ Multicast, IGMPv3, Wireshark, Maven, SVN, GIT, Gerrit, Eclipse, IntelliJ IDEA, JIRA Agile, Puppet, Ubuntu Desktop, Vagrant, AMQP / RabbitMQ , ReactiveX / RxJava, AWS cloud computing, Protocol Buffers, Aerospike.

Enhancements of online charging server (backend development in Java, system average/peak load per node – 500/3000 requests per second, availability ~99,999%) to comply with new EU regulations for data roaming overarching spending cap for prepaid and postpaid customers (Opt-In/Opt-Out). Implementation of internal and external rating module (eRAT interface), ARP (automatic repurchase pass) logic and pass logic for business customers. Development of rating functionality for domestic and roaming traffic (allowances, daily usage charges, notifications) replacing Alcatel-Lucent rating enabler legacy platform. Implementation of SOAP server service to receive subscription changes notifications from cNTDB through SOA-Backplane ESB (Enterprise Service Bus), adaptation of Diameter-Gy interface to support IPv6. Development of Wireshark dissectors for ANS.1 based protocols (LUA language) and simulators in Python - socket programming. Development of consistency check, configuration and administration tools. Agile software development using Scrum, integration and performance tests. Production support, PCAP and ticket analysis. RTSP (Real Time Service Platform), Java 5.0/6.0, Python, TCP/IP, SOAP, XSD, Web Services, WSDL, JAX-B, SOAP-UI, HTTP, Diameter, LDAP, CI Hudson/Jenkins, EMMA Coverage, Eclipse, LUA, Oracle 10g, SQL, PL/SQL, SQL Developer, XML, Solaris 10, Linux / Ubunut Desktop, PlantUML, Apache CXF, HTTP 1.0/1.1 Chunking, Ant, JUnit, EasyMock, JSON/Jackson, Wireshark, thark, editcap, capinfos, OTE, IPS, ClearCase.

Implementation of INOX Server (OCS - Online Charging Server) on the NSN RTSP (Real-Time System Platform) based on Diameter protocol, allowing roaming subscribers using vouchers for international data traffic. Integration with Huawei GGSN Diameter Credit Control Interface (Gy Interface), LDAP to CNTDB-HLR, Integration with Landing Page using ESX interface, accounting, charging, ticketing. International Roll-out for T-Mobile Germany, Austria and Netherlands. Diameter RFC 3588, RFC 4006, 3GPP TS 32.299, 3GPP 29.060, 3GPP 29.061. Java 5.0, JUnit, Emma Coverage, EasyMock, Wireshark, Solaris 10, Linux, Oracle 10g.

Design and implementation of MOC, MTC, Web Initiated Calls and USSD IN-Services in project “Office Connect”. Leg management, call forwarding, call deflection, call pickup, A- and B-side call transfer, sequential call hunting, parallel ringing, mid-call features, charging and ticketing, rerouting from VPLMN to HPLMN, User-to-User signalling, service retriggering, ATI (Any Time Interrogation). Coding and decoding of CAMEL structures (ASN.1 BER), integration with Primo MultiSIM, MNP, HomeZone and VDA services, LDAP (CNTDB) and IP Centrex integration. Usage of ITU-T, ETSI and 3GPP standards e.g. 3GPP TS 29.078 v8.0.0, 3GPP TS 29.002 v8.10.0, 3GPP TS 24.008 v8.6.0, ITU-T Q.1218, ITU-T Q.763, ITU-T Q.931, ITU-T Q.716. SCP / NSN IN Advantage 7.5, SLEE, OTE, IPS, SS7 (INAP - SINAP7m+, CAP, MAP), ASN.1, OIF Online Interface, JUnit, EasyMock, SunOS, Oracle, Eclipse, Jbulider, Java 1.2/1.6, JBoss Netty.

Design and implementation of an E-Mail and IP CTI (Core Transfer Interface) in project „Klarios NG” (telecommunication law interception and recording solution). Mass data processing and transfer; back processing, communication with F3S (Flexible Scalable Storage Solution) using Java New I/O, provisioning of the search engine feeder and indexing services. Writing of technical concepts in English; activity, sequence and class diagrams. Conception of a recovery processing, last and performance tests. Java 6, Oracle 11g, Oracle AQ, Derby DB, Magic Draw, Subversion, JPA Java Persistence API, Hibernate, Spring, AOP Aspect Oriented Programming, Eclipse, JUnit 4, XML, JAXB, Ant, Multithreading (Concurrency Framework, Transient Queues, synchronous and asynchronous communication), Connection Pooling, FTP (Jakarta Net), Linux, AIX.

Redesign and refactoring of SPC (Service Provisioning Component) and HCS (Handset Capability Server) interfaces. Usage of Dynamic MBeans for module online administration. Java JDK 5.0, JUnit, Ant, Oracle 10g, JDBC, Hibernate, Spring, Axis.

Design and development of a Java plug-in for a data supply to a VPN (Virtual Private Network) administration system. Sun ONC/RPC (Remote Procedure Call) protocol as a connection between the systems. Usage of multithreading and transient queues. Java JDK 5.0, JUnit, Ant, Concurrency Utilities, ONC/RPC for Java, Oracle 10g.

Porting of C++ XOR-Provisioning module (Xtra Online Rating) to Java. Additional development of test client and mock server. Multithreading, transient queues, queue monitoring, own connection pool implementation, unit and last tests. Java JDK 5.0, JUnit, Ant, Concurrency Utilities.

Enhancements of provisioning system for project "Homezone" (mobile@home). Workflow and models modifications for new IN-Profiles, UCSI-Triggers (USSD CAMEL Subscription Information) provisioning to Subscriber Mediation Device, stored procedures development. C++, STL, Oracle 9i, Power Designer.

Development of a bridge server between CRM and Ericsson MMSC-Proxy. Development of MMSC simulation application. Conception, interface design - IDL,WSDL. Performance and stress tests. Java, CORBA(JacORB), SOAP(AXIS), Multithreading, Ant.

Release Management in Project SMD (Subscriber Mediation Device), Budget approx. 1 million EUR p.a. system release planning, preparation of annual budget, budget forecast, resource planning, budget and cost monitoring, time and man-power estimation, project plan/time scheduling preparation, external work commissioning.

Development of Lock-Server for lock/unlock request processing for GSM-Service SMS-MO (subproject “Warm Billing for Prepaid”). Complete conception, design, data modelling and development of database parts and new workflow. Service development for Customer Care and Customer Billing, data migration, population scripts. SUN Solaris, C++, STL, Oracle, UML, OOA, OOD.

Development and support of online prepaid load system of T-Mobile Germany. Building of database system for persistent storage of online-prepaid business processes. Designing of concept for database migration with warranty of 99% operational availability. Development of database jobs and SAP data transfer. DB-Tuning, DB-Monitoring. Oracle, Shell-Script.

Further development of Swedish ERP System (IFS Applications), Modules: Finance, Distribution, Maintenance, software adjustment to Polish law, enhancements of Data Models and GUI, Performance Tuning. Oracle 8, SUN Solaris, PC-Clients, Centura.