e8de468b0b
* (executor-api) Make executor API talk GRPC The executor's REST API was very fragile and annoying to work with, lacking even basic type safety. Migrate to use GRPC instead. GRPC is a bit of a pain with how verbose it is, but that is probably a lesser evil. This is a fairly straightforward change, but it's also large so a solid round of testing is needed... The change set breaks out the GrpcStubPool previously residing in the QueryService, and makes it available to all clients. ServiceId.name was also renamed to avoid the very dangerous clash with Enum.name(). The boilerplate needed for grpc was also extracted into a common gradle file for inclusion into the appropriate build.gradle-files. |
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| .. | ||
| api | ||
| common | ||
| features-convert | ||
| features-crawl | ||
| features-index | ||
| features-qs | ||
| features-search | ||
| libraries | ||
| process-models | ||
| processes | ||
| services-application | ||
| services-core | ||
| tools | ||
| readme.md | ||
Code
This is a pretty large and diverse project with many moving parts.
You'll find a short description in each module of what it does and how it relates to other modules. The modules each have names like "library" or "process" or "feature". These have specific meanings. See doc/module-taxonomy.md.
Overview
A map of the most important components and how they relate can be found below.
The core part of the search engine is the index service, which is responsible for storing and retrieving the document data. The index serive is partitioned, along with the executor service, which is responsible for executing processes. At least one instance of each service must be run, but more can be run alongside. Multiple partitions is desirable in production to distribute load across multiple physical drives, as well as reducing the impact of downtime.
Search queries are delegated via the query service, which is a proxy that fans out the query to all eligible index services. The control service is responsible for distributing commands to the executor service, and for monitoring the health of the system. It also offers a web interface for operating the system.
Services
- core services Most of these services are stateful, memory hungry, and doing heavy lifting.
- application services Mostly stateless gateways providing access to the core services.
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- api - public API
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- search - marginalia search application
- an internal API
Processes
Processes are batch jobs that deal with data retrieval, processing and loading. These are spawned and orchestrated by the executor service, which is controlled by the control service.
Features
Features are relatively stand-alone components that serve some part of the domain. They aren't domain-independent, but isolated.
Libraries and primitives
Libraries are stand-alone code that is independent of the domain logic.