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icm-iis-primer
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==============
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The aim of this project is to provide a reusability method for Oozie workflows,
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scripts and other file types by utilising import links.
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The Primer traverses a specified Java package, looking for import links. When
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found, it resolves them by creating new elements in the containing directory,
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in accordance with the import link. The primed package is stored in a new
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directory.
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## Import links ##
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Import links are defined as files following the specified format. They are
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always named `import.txt`.
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### Exemplary import link
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## This is a classpath-based import file (this header is required)
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from_jar classpath pl/edu/icm/coansys
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workflow coansys pl.edu.icm.coansys.citations:inner-workflow:1.2-SNAPSHOT
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The file starts with a compulsory header. Then, every line consists of the
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following fields separated by whitespaces:
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- destination - the name that will be given to the imported element
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- import type - the type of imported element
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- imported element description - additional information indentifying the
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imported element (import type-specific)
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The import file presented above will create a directory `from_jar` and
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copy all the contents of `pl/edu/icm/coansys` into it. Additionally, it will
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unpack `inner-workflow` into `workflow` directory.
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### Supported import types ###
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#### Classpath element ####
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The element will be imported from the classpath (it can be either a file or
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directory).
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- **Import type:** `classpath`
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- **Element description:** fully qualified resource name, using forward slashes
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as separators.
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#### CoAnSys Oozie Workflow Package ####
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A CoAnSys Oozie Workflow Package will be imported and unpacked.
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- **Import type:** `coansys`
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- **Element description:** Maven-style package description, i.e.
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`groupId:artifactId:version`
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## Execution ##
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Primer is executed from a Maven plugin implemented in
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`icm-iis-primer-maven-plugin` project. Plugin usage is presented in
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`icm-iis-primer-example` project.
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## For developer ##
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The main element of Primer is `Loader` class. It is a close relative of
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Java `ClassLoader`. It should be provided with `ClassProviders`, which tell
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where it should look for resources. By default, `JarClassProvider` and
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`FileSystemClassProvider` are supplied. `Loader.prime` method executes the
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priming process.
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Another important class is `Resolver`. It is used when resolving import links.
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It groups various `ResolvingServices`. Each import type should be assigned a
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`ResolvingService`. Currently implemented `ResolvingServices` are
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`ClasspathResolvingService` and `CoansysResolvingService`.
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