1- # Architectural Decision Record: Rework of Referebce Hints
1+ # Architectural Decision Record: Rework of Reference Hints
22
33### Meaning of Reference Hints
44
55During the transport of software artifacts referenced from external artifact repositories like
66OCI registries, they might be stored as blobs along with the component version (access method
7- ` localBlob ` . If those component versions are transported again into a repository landscape they
7+ ` localBlob ` ) . If those component versions are transported again into a repository landscape they
88might be uploaded again to external repositories.
99
1010To provide useful identities for storing those artifacts hints in external repositories, again,
1111the original identity of the external artifact must be stored along with the local blob.
1212
1313### Current Solution
1414
15- The access method origibally used to refernce the exterbal artfact provides a reference hint,
15+ The access method originally used to reference the external artifact provides a reference hint,
1616which can later be used by the blob uploaders to reconstruct a useful identity.
1717Therefore, the ` localBlob ` access method is able to keep track of this hint value.
18- The hint is just a string, which needs to be intepreted by the uploader.
18+ The hint is just a string, which needs to be interpreted by the uploader.
1919
2020### Problems with Current Solution
2121
22- The assumprion behind the current solution is that the uploader will always upload the
23- artifactinto a similar repository, again. Therefore, there would be a one-to-one relation
22+ The assumption behind the current solution is that the uploader will always upload the
23+ artifact into a similar repository, again. Therefore, there would be a one-to-one relation
2424between access method and uploader.
2525
2626Unfortunately this is not true in all cases:
2727- There are access methods now (like` wget ` ), which are able to handle any kind of artifact blob
28- with different natural repositoty types and identity schemes.
28+ with different natural repository types and identity schemes.
2929- Therefore,
3030 - it can neither provide an implicit reference hint anymore
3131 - nor there is a one-to-one relation to a typed uploader anymore.
3232- artifacts might be uploadable to different repository types using different
3333 identity schemes.
3434
3535This problem is partly covered by allowing to specify a hint along with those access methods
36- similar to the ` localBlob ` access method. But this can only be a workarround , because
37- - the hint is not typed and potential target repositories might use diufferent identity schemes
36+ similar to the ` localBlob ` access method. But this can only be a workaround , because
37+ - the hint is not typed and potential target repositories might use different identity schemes
3838- it is possible to store a single hint, only.
3939
4040### Proposed Solution
4141
42- Hints have to be typed, to allow uploaders to know what identites are provided and how the
42+ Hints have to be typed, to allow uploaders to know what identities are provided and how the
4343hint string has to be interpreted. Additionally, it must be possible to store
44- mulltiple hints for an artifact.
44+ multiple hints for an artifact.
4545
4646To be compatible a serialization format is defined for a list of type hints, which maps such
4747a list to a single string.
@@ -51,33 +51,49 @@ a formal hint, by providing access to a set of string attributes. There are thre
5151attributes:
5252- ` type ` the formal type of the hint (may be empty to cover old component versions)
5353 The types are defined like the resource types. The following types are defined for now:
54- - ` oci ` : OCI identity given by the attribute ` reference ` with the cirrently used format
54+ - ` oci ` : OCI identity given by the attribute ` reference ` with the currently used format
5555 - ` maven ` : Maven identity (GAV) given by the attribute ` reference ` with the currently used format
5656 - ` npm ` : Node package identity given by the attribute ` reference ` with the currently used
5757 format
5858- ` reference ` : the standard attribute to hold a string representation for the identity.
5959- ` implicit ` : Value ` true ` indicated an implicit hint (as used today) provided by an accessmethods.
6060
61- New Hint types my use other attributes.
61+ Typeless former hints are represented by the sole attribute ` reference ` .
62+ New Hint types may use other attributes.
6263
63- An access method can provide (and store) implicit hints as before. THose hints are indicated
64+ #### Access Methods
65+
66+ An access method can provide (and store) implicit hints as before. Those hints are indicated
6467to be implicit. When composing an access method it is only allowed to store implicit hints.
6568This is completely compatible to the current solution.
6669
67- Additionally, multiplehints can be stored abd delivered.
70+ Additionally, multiple hints can be stored abd delivered.
6871
6972To support any kind of hint for any scenario, the artifact metadata (resources and sources)
7073is extended to store explicit hints, which will be part of the normalized form.
7174This is done by an additional attribute ` referenceHints ` . It is a list of string maps
7275holding the hint attributes (including the hint type).
7376
74- Uploaders are called with the aggrgation of explicit (from metadata) and implicit (from
77+ #### Uploaders
78+
79+ Uploaders are called with the aggregation of explicit (from metadata) and implicit (from
7580access methods) hints. Hereby, the explicit hints have precedence.
7681
7782If an uploader creates a local access specification, only implicit hints may be stored, here.
7883
7984There is a new composition option (` --refhint ` ) now for composing resources
80- 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.
85+ 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.
86+
87+ #### Inputs
88+
89+ Inputs may provide explicit or implicit hints, now. All file based inputs now allow to specify implicit hints as used before.
90+ The implicit hints (if not conflicting with explicit hints) are used to be stored in ` localBlob `
91+ access methods. The explicit hints are used to default the explicit artifact hints.
92+
93+ Hints used in a component version must be unique. This check is extended to consider implicit
94+ and explicit hints provided by inputs, access methods and artifact hints.
95+
96+ Hints may either be specified as a list of string maps (canonical form) or as string using the serialized from.
8197
8298### Hint Serialization Format
8399
@@ -86,19 +102,19 @@ In general a hint is serialized to the following string
86102 [<*type*>`::]`<*attribute*>`=`<*value*>{`,`<*attribute*>`=`<*value*>}
87103</center >
88104
89- The type is not serilaized as attribute. The ` implicit ` attribute is never serialized is the string is stored in an access specification.
90- If no type is known the type part is omiited .
105+ 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.
106+ If no type is known the type part is omitted .
91107
92108A list of hints is serialized to
93109
94110<center >
95111 < ; * hint* >{` ; ` < ; * hint* >}
96112</center >
97113
98- * Attributes* names consist of alpha numeric chaŕacters , only.
99- If a * value* may not cotain a ` :: ` . If it contains a ` ; ` , ` , ` or ` " `
114+ * Attributes* names consist of alphanumeric characters , only.
115+ A * value* may not contain a ` :: ` . If it contains a ` ; ` , ` , ` or ` " `
100116character it must be given in double quotes.
101- In the double quote form any ` " ` or ` \ ` character has to be escaped by
117+ In the double-quoted form any ` " ` or ` \ ` character has to be escaped by
102118a preceding ` \ ` character.
103119
104120To be as compatible as possible, a single attribute hint with the attribute
@@ -107,7 +123,7 @@ characters enforcing a quoted form.
107123
108124### Incompatible Changes:
109125
110- #### Componwnt Version Representation
126+ #### Component Version Representation
111127
112128- The new library creates always typed hints for new elements. Old hints are
113129 left as they are. This means, that old versions of the OCM tooling
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