What was traditionally known as just Monitoring has clearly been going through a renaissance over the last few years. The industry as a whole is finally moving away from having Monitoring and Logging silos – something we’ve been doing and “preaching” for years – and the term Observability emerged as the new moniker for everything that encompasses any form of infrastructure and application monitoring. Microservices have been around for a over a decade under one name or another. Now often deployed in separate containers it became obvious we need a way to trace transactions through various microservice layers, from the client all the way down to queues, storage, calls to external services, etc. This created a new interest in Transaction Tracing that, although not new, has now re-emerged as the third pillar of observability….
In a distributed system, a trace encapsulates the transaction’s state as it propagates through the system. During the journey of the transaction, it can create one or multiple spans. A span represents a single unit of work inside a transaction, for example, an RPC client/server call, sending query to the database server, or publishing a message to the message bus. Speaking in terms of OpenTracing data model, the trace can also be seen as a collection of spans structured around the directed acyclic graph (DAG).
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