Getting Started

Welcome to the Hop project! The size of the codebase can perhaps appear to be a bit daunting at first so remember: Don’t Panic!

When it comes down to it the codebase is fairly simple in structure.

Let’s go over the main modules in the source code:


Like the name suggests this module contains the essentials to bootstrap Hop. It has the following types of things on board:

  • Tools: hop-encrypt

  • The plugin registry which keeps track of all the plugins: PluginRegistry

  • Core data types: IValueMeta, ValueMetaString, …​

  • Rows of data: IRowMeta, RowMeta

  • Logging: HopLogStore, ILogChannel,…​

  • Generic relational database handling: Database, IDatabaseMeta, …​

  • Internationalization a.k.a. i18n to translate stuff: BaseMessages

  • Password obfuscation and encryption: Encr

  • Other utility classes like: Const

  • Plugin types: LoggingPluginType, ValueMetaPluginType, DatabasePluginType, ExtensionPointPluginType, TwoWayPasswordEncoderPluginType

  • Bootstrap everything in core with : HopClientEnvironment.init()


This module contains the actual framework to handle pipelines and workflows.

  • Tools: hop-server, hop-run

  • Pipelines : IPipelineMeta, Pipeline, IPipelineEngine, …​

  • Workflows : IWorkflowMeta, Workflow, …​

  • Web server: HopServer, StartPipelineServlet, …​

  • Auditing: AuditManager, AuditEvent, …​

  • Other stuff worth mentioning: partitioning, lineage, …​

  • Plugin types: RowDistributionPluginType, TransformPluginType, TransformDialogFragmentType, PartitionerPluginType, JobEntryPluginType,JobEntryDialogFragmentType, LogTablePluginType, LifecyclePluginType, HopLifecyclePluginType, HopServerPluginType, CompressionPluginType, AuthenticationProviderPluginType, AuthenticationConsumerPluginType, PipelineEnginePluginType

  • Bootstrap everything in engine with : HopEnvironment.init()


This module obviously contains everything related to the Hop GUI

  • Tools: hop-gui, hop-translate

  • Hop GUI: HopGui, HopDataOrchestrationPerspective, HopPipelineFileType, …​

  • Translator, a tool to help you translate Hop itself: Translator

  • The rest is mostly a collection of re-usable dialogs and widgets


This module contains the core metadata serialization API for every shared object in Hop


The plugins module contains all the functionality in Hop which is not absolutely strictly essential. This means that you will find a lot of transforms and actions in this module. You can use this collection as a series of examples on how to build plugins for Hop.