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- # Architectural Decision Record: Rework of Referebce Hints
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+ # Architectural Decision Record: Rework of Reference Hints
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### Meaning of Reference Hints
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During the transport of software artifacts referenced from external artifact repositories like
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OCI registries, they might be stored as blobs along with the component version (access method
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- ` localBlob ` . If those component versions are transported again into a repository landscape they
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+ ` localBlob ` ) . If those component versions are transported again into a repository landscape they
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might be uploaded again to external repositories.
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To provide useful identities for storing those artifacts hints in external repositories, again,
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the original identity of the external artifact must be stored along with the local blob.
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### Current Solution
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- The access method origibally used to refernce the exterbal artfact provides a reference hint,
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+ The access method originally used to reference the external artifact provides a reference hint,
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which can later be used by the blob uploaders to reconstruct a useful identity.
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Therefore, the ` localBlob ` access method is able to keep track of this hint value.
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- The hint is just a string, which needs to be intepreted by the uploader.
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+ The hint is just a string, which needs to be interpreted by the uploader.
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### Problems with Current Solution
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- The assumprion behind the current solution is that the uploader will always upload the
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- artifactinto a similar repository, again. Therefore, there would be a one-to-one relation
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+ The assumption behind the current solution is that the uploader will always upload the
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+ artifact into a similar repository, again. Therefore, there would be a one-to-one relation
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between access method and uploader.
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Unfortunately this is not true in all cases:
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- There are access methods now (like` wget ` ), which are able to handle any kind of artifact blob
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- with different natural repositoty types and identity schemes.
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+ with different natural repository types and identity schemes.
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- Therefore,
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- it can neither provide an implicit reference hint anymore
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- nor there is a one-to-one relation to a typed uploader anymore.
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- artifacts might be uploadable to different repository types using different
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identity schemes.
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This problem is partly covered by allowing to specify a hint along with those access methods
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- similar to the ` localBlob ` access method. But this can only be a workarround , because
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- - the hint is not typed and potential target repositories might use diufferent identity schemes
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+ similar to the ` localBlob ` access method. But this can only be a workaround , because
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+ - the hint is not typed and potential target repositories might use different identity schemes
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- it is possible to store a single hint, only.
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### Proposed Solution
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- Hints have to be typed, to allow uploaders to know what identites are provided and how the
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+ Hints have to be typed, to allow uploaders to know what identities are provided and how the
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hint string has to be interpreted. Additionally, it must be possible to store
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- mulltiple hints for an artifact.
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+ multiple hints for an artifact.
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To be compatible a serialization format is defined for a list of type hints, which maps such
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a list to a single string.
@@ -51,33 +51,49 @@ a formal hint, by providing access to a set of string attributes. There are thre
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attributes:
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- ` type ` the formal type of the hint (may be empty to cover old component versions)
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The types are defined like the resource types. The following types are defined for now:
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- - ` oci ` : OCI identity given by the attribute ` reference ` with the cirrently used format
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+ - ` oci ` : OCI identity given by the attribute ` reference ` with the currently used format
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- ` maven ` : Maven identity (GAV) given by the attribute ` reference ` with the currently used format
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- ` npm ` : Node package identity given by the attribute ` reference ` with the currently used
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format
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- ` reference ` : the standard attribute to hold a string representation for the identity.
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- ` implicit ` : Value ` true ` indicated an implicit hint (as used today) provided by an accessmethods.
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- New Hint types my use other attributes.
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+ Typeless former hints are represented by the sole attribute ` reference ` .
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+ New Hint types may use other attributes.
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- An access method can provide (and store) implicit hints as before. THose hints are indicated
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+ #### Access Methods
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+
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+ An access method can provide (and store) implicit hints as before. Those hints are indicated
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to be implicit. When composing an access method it is only allowed to store implicit hints.
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This is completely compatible to the current solution.
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- Additionally, multiplehints can be stored abd delivered.
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+ Additionally, multiple hints can be stored abd delivered.
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To support any kind of hint for any scenario, the artifact metadata (resources and sources)
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is extended to store explicit hints, which will be part of the normalized form.
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This is done by an additional attribute ` referenceHints ` . It is a list of string maps
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holding the hint attributes (including the hint type).
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- Uploaders are called with the aggrgation of explicit (from metadata) and implicit (from
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+ #### Uploaders
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+
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+ Uploaders are called with the aggregation of explicit (from metadata) and implicit (from
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access methods) hints. Hereby, the explicit hints have precedence.
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If an uploader creates a local access specification, only implicit hints may be stored, here.
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There is a new composition option (` --refhint ` ) now for composing resources
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- and sources for the CLI. It accepts an attribute setting. Multiple such options starting with the ` type ` attribute are used to compose a single hint.
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+ and sources for the CLI. It accepts an attribute setting. Multiple such options starting with the ` type ` attribute are used to compose a single hint.
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+
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+ #### Inputs
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+
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+ Inputs may provide explicit or implicit hints, now. All file based inputs now allow to specify implicit hints as used before.
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+ The implicit hints (if not conflicting with explicit hints) are used to be stored in ` localBlob `
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+ access methods. The explicit hints are used to default the explicit artifact hints.
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+
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+ Hints used in a component version must be unique. This check is extended to consider implicit
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+ and explicit hints provided by inputs, access methods and artifact hints.
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+ Hints may either be specified as a list of string maps (canonical form) or as string using the serialized from.
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### Hint Serialization Format
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@@ -86,19 +102,19 @@ In general a hint is serialized to the following string
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[<*type*>`::]`<*attribute*>`=`<*value*>{`,`<*attribute*>`=`<*value*>}
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</center >
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- The type is not serilaized as attribute. The ` implicit ` attribute is never serialized is the string is stored in an access specification.
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- If no type is known the type part is omiited .
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+ The type is not serialized as attribute, but as prefix separated by a ` :: ` . The ` implicit ` attribute is never serialized if the string is stored in an access specification.
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+ If no type is known the type part is omitted .
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A list of hints is serialized to
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<center >
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< ; * hint* >{` ; ` < ; * hint* >}
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</center >
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- * Attributes* names consist of alpha numeric chaŕacters , only.
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- If a * value* may not cotain a ` :: ` . If it contains a ` ; ` , ` , ` or ` " `
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+ * Attributes* names consist of alphanumeric characters , only.
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+ A * value* may not contain a ` :: ` . If it contains a ` ; ` , ` , ` or ` " `
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character it must be given in double quotes.
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- In the double quote form any ` " ` or ` \ ` character has to be escaped by
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+ In the double-quoted form any ` " ` or ` \ ` character has to be escaped by
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a preceding ` \ ` character.
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To be as compatible as possible, a single attribute hint with the attribute
@@ -107,7 +123,7 @@ characters enforcing a quoted form.
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### Incompatible Changes:
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- #### Componwnt Version Representation
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+ #### Component Version Representation
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- The new library creates always typed hints for new elements. Old hints are
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left as they are. This means, that old versions of the OCM tooling
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