Class SparqlDataAccessor

Stores all data and metadata of resources in a SPARQL backend. Communication is done by sending SPARQL queries. Queries are constructed in such a way to keep everything consistent, such as updating containment triples and deleting old data when it is overwritten.

Since metadata is hidden, no containment triples are stored for metadata files.

All input container metadata is stored in its metadata identifier. The containment triples are stored in the graph corresponding to the actual identifier so those don't get overwritten.

Hierarchy

SparqlDataAccessor

Implements

DataAccessor

Constructors

constructor

new SparqlDataAccessor(endpoint, identifierStrategy): SparqlDataAccessor
Parameters
- endpoint: string
- identifierStrategy: IdentifierStrategy
Returns SparqlDataAccessor
- Defined in src/storage/accessors/SparqlDataAccessor.ts:54

Properties

`Private` `Readonly` endpoint

endpoint: string

`Private` `Readonly` fetcher

fetcher: SparqlEndpointFetcher

`Private` `Readonly` generator

generator: SparqlGenerator

`Private` `Readonly` identifierStrategy

identifierStrategy: IdentifierStrategy

`Protected` `Readonly` logger

logger: Logger = ...

Methods

canHandle

canHandle(representation): Promise<void>
Only Quad data streams are supported.
Parameters
- representation: Representation
Returns Promise<void>
Implementation of DataAccessor.canHandle
- Defined in src/storage/accessors/SparqlDataAccessor.ts:64

deleteResource

deleteResource(identifier): Promise<void>
Removes all graph data relevant to the given identifier.
Parameters
- identifier: ResourceIdentifier
Returns Promise<void>
Implementation of DataAccessor.deleteResource
- Defined in src/storage/accessors/SparqlDataAccessor.ts:153

getChildren

getChildren(identifier): AsyncIterableIterator<RepresentationMetadata>
Returns metadata for all resources in the requested container. This should not be all metadata of those resources (but it can be), but instead the main metadata you want to show in situations where all these resources are presented simultaneously. Generally this would be metadata that is present for all of these resources, such as resource type or last modified date.

It can be safely assumed that the incoming identifier will always correspond to a container.
Parameters
- identifier: ResourceIdentifier
  
  Identifier of the parent container.
Returns AsyncIterableIterator<RepresentationMetadata>
Implementation of DataAccessor.getChildren
- Defined in src/storage/accessors/SparqlDataAccessor.ts:101

getData

getData(identifier): Promise<Guarded<Readable>>
Returns all triples stored for the corresponding identifier. Note that this will not throw a 404 if no results were found.
Parameters
- identifier: ResourceIdentifier
Returns Promise<Guarded<Readable>>
Implementation of DataAccessor.getData
- Defined in src/storage/accessors/SparqlDataAccessor.ts:74

getMetadata

getMetadata(identifier): Promise<RepresentationMetadata>
Returns the metadata for the corresponding identifier. Will throw 404 if no metadata was found.
Parameters
- identifier: ResourceIdentifier
Returns Promise<RepresentationMetadata>
Implementation of DataAccessor.getMetadata
- Defined in src/storage/accessors/SparqlDataAccessor.ts:83

`Private` getMetadataNode

getMetadataNode(name): NamedNode<string>
Creates the name for the metadata of a resource.
Parameters
- name: NamedNode<string>
  
  Name of the (non-metadata) resource.
Returns NamedNode<string>
- Defined in src/storage/accessors/SparqlDataAccessor.ts:179

`Private` getRelatedNames

getRelatedNames(identifier): {
name: NamedNode<string>;
parent?: NamedNode<string>;
}
Helper function to get named nodes corresponding to the identifier and its parent container. In case of a root container only the name will be returned.
Parameters
- identifier: ResourceIdentifier
Returns {
name: NamedNode<string>;
parent?: NamedNode<string>;
}
- name: NamedNode<string>
- Optional parent?: NamedNode<string>
- Defined in src/storage/accessors/SparqlDataAccessor.ts:162

`Private` isMetadataIdentifier

isMetadataIdentifier(identifier): boolean
Checks if the given identifier corresponds to the names used for metadata identifiers.
Parameters
- identifier: ResourceIdentifier
Returns boolean
- Defined in src/storage/accessors/SparqlDataAccessor.ts:186

`Private` sendSparqlConstruct

sendSparqlConstruct(sparqlQuery): Promise<Guarded<Readable>>
Sends a SPARQL CONSTRUCT query to the endpoint and returns a stream of quads.
Parameters
- sparqlQuery: ConstructQuery
  
  Query to execute.
Returns Promise<Guarded<Readable>>
- Defined in src/storage/accessors/SparqlDataAccessor.ts:332

`Private` sendSparqlUpdate

sendSparqlUpdate(sparqlQuery): Promise<void>
Sends a SPARQL update query to the stored endpoint.
Parameters
- sparqlQuery: Update
  
  Query to send.
Returns Promise<void>
- Defined in src/storage/accessors/SparqlDataAccessor.ts:347

`Private` sparqlConstruct

sparqlConstruct(name): ConstructQuery
Creates a CONSTRUCT query that returns all quads contained within a single resource.
Parameters
- name: NamedNode<string>
  
  Name of the resource to query.
Returns ConstructQuery
- Defined in src/storage/accessors/SparqlDataAccessor.ts:194

`Private` sparqlDelete

sparqlDelete(name, parent?): Update
Creates a query that deletes everything related to the given name.
Parameters
- name: NamedNode<string>
  
  Name of resource to delete.
- Optional parent: NamedNode<string>
  
  Parent of the resource to delete so the containment triple can be removed (unless root).
Returns Update
- Defined in src/storage/accessors/SparqlDataAccessor.ts:286

`Private` sparqlInsert

sparqlInsert(name, metadata, parent?, triples?): Update
Creates an update query that overwrites the data and metadata of a resource. If there are no triples we assume it's a container (so don't overwrite the main graph with containment triples).
Parameters
- name: NamedNode<string>
  
  Name of the resource to update.
- metadata: RepresentationMetadata
  
  New metadata of the resource.
- Optional parent: NamedNode<string>
  
  Name of the parent to update the containment triples.
- Optional triples: Quad[]
  
  New data of the resource.
Returns Update
- Defined in src/storage/accessors/SparqlDataAccessor.ts:221

`Private` sparqlInsertMetadata

sparqlInsertMetadata(metaName, metadata): Update
Creates an update query that overwrites metadata of a resource.
Parameters
- metaName: NamedNode<string>
  
  Name of the metadata resource to update.
- metadata: RepresentationMetadata
  
  New metadata of the resource.
Returns Update
- Defined in src/storage/accessors/SparqlDataAccessor.ts:261

`Private` sparqlSelectGraph

sparqlSelectGraph(name, triples): GraphPattern
Parameters
- name: NamedNode<string>
- triples: Quad[]
Returns GraphPattern
- Defined in src/storage/accessors/SparqlDataAccessor.ts:205

`Private` sparqlUpdateDeleteAll

sparqlUpdateDeleteAll(name): InsertDeleteOperation
Helper function for creating SPARQL update queries. Creates an operation for deleting all triples in a graph.
Parameters
- name: NamedNode<string>
  
  Name of the graph to delete.
Returns InsertDeleteOperation
- Defined in src/storage/accessors/SparqlDataAccessor.ts:311

`Private` sparqlUpdateGraph

sparqlUpdateGraph(name, triples): GraphQuads
Helper function for creating SPARQL update queries. Creates a Graph selector with the given triples.
Parameters
- name: NamedNode<string>
  
  Name of the graph.
- triples: Quad[]
  
  Triples/triple patterns to select.
Returns GraphQuads
- Defined in src/storage/accessors/SparqlDataAccessor.ts:324

writeContainer

writeContainer(identifier, metadata): Promise<void>
Writes the given metadata for the container.
Parameters
- identifier: ResourceIdentifier
- metadata: RepresentationMetadata
Returns Promise<void>
Implementation of DataAccessor.writeContainer
- Defined in src/storage/accessors/SparqlDataAccessor.ts:113

writeDocument

writeDocument(identifier, data, metadata): Promise<void>
Reads the given data stream and stores it together with the metadata.
Parameters
- identifier: ResourceIdentifier
- data: Guarded<Readable>
- metadata: RepresentationMetadata
Returns Promise<void>
Implementation of DataAccessor.writeDocument
- Defined in src/storage/accessors/SparqlDataAccessor.ts:121

writeMetadata

writeMetadata(identifier, metadata): Promise<void>
Reads the metadata and stores it.
Parameters
- identifier: ResourceIdentifier
- metadata: RepresentationMetadata
Returns Promise<void>
Implementation of DataAccessor.writeMetadata
- Defined in src/storage/accessors/SparqlDataAccessor.ts:143

Class SparqlDataAccessor

Hierarchy

Implements

Index

Constructors

Properties

Methods

Constructors

constructor

Parameters

endpoint: string

identifierStrategy: IdentifierStrategy

Returns SparqlDataAccessor

Properties

Private Readonly endpoint

Private Readonly fetcher

Private Readonly generator

Private Readonly identifierStrategy

Protected Readonly logger

Methods

canHandle

Parameters

representation: Representation

Returns Promise<void>

deleteResource

Parameters

identifier: ResourceIdentifier

Returns Promise<void>

getChildren

Parameters

identifier: ResourceIdentifier

Returns AsyncIterableIterator<RepresentationMetadata>

getData

Parameters

identifier: ResourceIdentifier

Returns Promise<Guarded<Readable>>

getMetadata

Parameters

identifier: ResourceIdentifier

Returns Promise<RepresentationMetadata>

Private getMetadataNode

Parameters

name: NamedNode<string>

Returns NamedNode<string>

Private getRelatedNames

Parameters

identifier: ResourceIdentifier

Returns { name: NamedNode<string>; parent?: NamedNode<string>; }

name: NamedNode<string>

Optional parent?: NamedNode<string>

Private isMetadataIdentifier

Parameters

identifier: ResourceIdentifier

Returns boolean

Private sendSparqlConstruct

Parameters

sparqlQuery: ConstructQuery

Returns Promise<Guarded<Readable>>

Private sendSparqlUpdate

Parameters

sparqlQuery: Update

Returns Promise<void>

Private sparqlConstruct

Parameters

name: NamedNode<string>

Returns ConstructQuery

Private sparqlDelete

Parameters

name: NamedNode<string>

Optional parent: NamedNode<string>

Returns Update

Private sparqlInsert

Parameters

name: NamedNode<string>

metadata: RepresentationMetadata

Optional parent: NamedNode<string>

Optional triples: Quad[]

Returns Update

Private sparqlInsertMetadata

Parameters

`Private` `Readonly` endpoint

`Private` `Readonly` fetcher

`Private` `Readonly` generator

`Private` `Readonly` identifierStrategy

`Protected` `Readonly` logger

`Private` getMetadataNode

`Private` getRelatedNames

Returns {
name: NamedNode<string>;
parent?: NamedNode<string>;
}

`Optional` parent?: NamedNode<string>

`Private` isMetadataIdentifier

`Private` sendSparqlConstruct

`Private` sendSparqlUpdate

`Private` sparqlConstruct

`Private` sparqlDelete

`Optional` parent: NamedNode<string>

`Private` sparqlInsert

`Optional` parent: NamedNode<string>

`Optional` triples: Quad[]

`Private` sparqlInsertMetadata

`Private` sparqlSelectGraph

`Private` sparqlUpdateDeleteAll

`Private` sparqlUpdateGraph