1- # Architectural Decision Record: Rework of Referebce Hints
1+ # ADR-0003 - Rework of Reference Hints
2+
3+ - Status: proposed
4+ - Date: 2024-12-27
5+ - Authors: @mandelsoft
6+ - Deciders: @fabianburth @jakobmoellerdev
7+ - Reference Implementation: #1212
28
39### Meaning of Reference Hints
410
511During the transport of software artifacts referenced from external artifact repositories like
612OCI 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
13+ ` localBlob ` ) . If those component versions are transported again into a repository landscape they
814might be uploaded again to external repositories.
915
1016To provide useful identities for storing those artifacts hints in external repositories, again,
1117the original identity of the external artifact must be stored along with the local blob.
1218
1319### Current Solution
1420
15- The access method origibally used to refernce the exterbal artfact provides a reference hint,
21+ The access method originally used to reference the external artifact provides a reference hint,
1622which can later be used by the blob uploaders to reconstruct a useful identity.
1723Therefore, 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.
24+ The hint is just a string, which needs to be interpreted by the uploader.
1925
2026### Problems with Current Solution
2127
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
28+ The assumption behind the current solution is that the uploader will always upload the
29+ artifact into a similar repository, again. Therefore, there would be a one-to-one relation
2430between access method and uploader.
2531
2632Unfortunately this is not true in all cases:
2733- 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.
34+ with different natural repository types and identity schemes.
2935- Therefore,
3036 - it can neither provide an implicit reference hint anymore
3137 - nor there is a one-to-one relation to a typed uploader anymore.
3238- artifacts might be uploadable to different repository types using different
3339 identity schemes.
3440
3541This 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
42+ similar to the ` localBlob ` access method. But this can only be a workaround , because
43+ - the hint is not typed and potential target repositories might use different identity schemes
3844- it is possible to store a single hint, only.
3945
4046### Proposed Solution
4147
42- Hints have to be typed, to allow uploaders to know what identites are provided and how the
48+ Hints have to be typed, to allow uploaders to know what identities are provided and how the
4349hint string has to be interpreted. Additionally, it must be possible to store
44- mulltiple hints for an artifact.
50+ multiple hints for an artifact.
4551
4652To be compatible a serialization format is defined for a list of type hints, which maps such
4753a list to a single string.
@@ -51,33 +57,49 @@ a formal hint, by providing access to a set of string attributes. There are thre
5157attributes:
5258- ` type ` the formal type of the hint (may be empty to cover old component versions)
5359 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
60+ - ` oci ` : OCI identity given by the attribute ` reference ` with the currently used format
5561 - ` maven ` : Maven identity (GAV) given by the attribute ` reference ` with the currently used format
5662 - ` npm ` : Node package identity given by the attribute ` reference ` with the currently used
5763 format
5864- ` reference ` : the standard attribute to hold a string representation for the identity.
5965- ` implicit ` : Value ` true ` indicated an implicit hint (as used today) provided by an accessmethods.
6066
61- New Hint types my use other attributes.
67+ Typeless former hints are represented by the sole attribute ` reference ` .
68+ New Hint types may use other attributes.
69+
70+ #### Access Methods
6271
63- An access method can provide (and store) implicit hints as before. THose hints are indicated
72+ An access method can provide (and store) implicit hints as before. Those hints are indicated
6473to be implicit. When composing an access method it is only allowed to store implicit hints.
6574This is completely compatible to the current solution.
6675
67- Additionally, multiplehints can be stored abd delivered.
76+ Additionally, multiple hints can be stored abd delivered.
6877
6978To support any kind of hint for any scenario, the artifact metadata (resources and sources)
7079is extended to store explicit hints, which will be part of the normalized form.
7180This is done by an additional attribute ` referenceHints ` . It is a list of string maps
7281holding the hint attributes (including the hint type).
7382
74- Uploaders are called with the aggrgation of explicit (from metadata) and implicit (from
83+ #### Uploaders
84+
85+ Uploaders are called with the aggregation of explicit (from metadata) and implicit (from
7586access methods) hints. Hereby, the explicit hints have precedence.
7687
7788If an uploader creates a local access specification, only implicit hints may be stored, here.
7889
7990There 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.
91+ 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.
92+
93+ #### Inputs
94+
95+ Inputs may provide explicit or implicit hints, now. All file based inputs now allow to specify implicit hints as used before.
96+ The implicit hints (if not conflicting with explicit hints) are used to be stored in ` localBlob `
97+ access methods. The explicit hints are used to default the explicit artifact hints.
98+
99+ Hints used in a component version must be unique. This check is extended to consider implicit
100+ and explicit hints provided by inputs, access methods and artifact hints.
101+
102+ Hints may either be specified as a list of string maps (canonical form) or as string using the serialized from.
81103
82104### Hint Serialization Format
83105
@@ -86,28 +108,28 @@ In general a hint is serialized to the following string
86108 [<*type*>`::]`<*attribute*>`=`<*value*>{`,`<*attribute*>`=`<*value*>}
87109</center >
88110
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 .
111+ 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.
112+ If no type is known the type part is omitted .
91113
92114A list of hints is serialized to
93115
94116<center >
95117 < ; * hint* >{` ; ` < ; * hint* >}
96118</center >
97119
98- * Attributes* names consist of alpha numeric chaŕacters , only.
99- If a * value* may not cotain a ` :: ` . If it contains a ` ; ` , ` , ` or ` " `
120+ * Attributes* names consist of alphanumeric characters , only.
121+ A * value* may not contain a ` :: ` . If it contains a ` ; ` , ` , ` or ` " `
100122character it must be given in double quotes.
101- In the double quote form any ` " ` or ` \ ` character has to be escaped by
123+ In the double-quoted form any ` " ` or ` \ ` character has to be escaped by
102124a preceding ` \ ` character.
103125
104126To be as compatible as possible, a single attribute hint with the attribute
105127` reference ` is serialized as naked value (as before) if there are no special
106128characters enforcing a quoted form.
107129
108- ### Incompatible Changes:
130+ ### Incompatible Changes
109131
110- #### Componwnt Version Representation
132+ #### Component Version Representation
111133
112134- The new library creates always typed hints for new elements. Old hints are
113135 left as they are. This means, that old versions of the OCM tooling
@@ -123,7 +145,7 @@ characters enforcing a quoted form.
123145
124146- Uploaders provided by a plugin now get a serialized hint list
125147 instead of a simple untyped reference format.
126- -
148+
127149- There are new options for creating resource(source access objects.
128150
129151
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