did resolver

打字稿確實是解析器

該庫旨在作為解決JavaScript應用程序解決的簡單常見界面，確實來自分散的標識符（DIDS）的文檔。

這旨在支持W3C憑證社區組的擬議分散標識符規範。

該庫不會實現任何特定的DID方法，但允許DID方法實現者可以釋放應用程序可以添加的NPM軟件包。

配置Resolver對象

現在，您需要在實例化過程中預先配置解決方案。 Resolver構造函數期望映射到解析器函數的方法註冊表。例如：

 {
  ethr : resolve ,
  web : resolve
}

每個方法解析器都應公開一個稱為getResolver函數，該功能將返回包含這些密鑰/值對之一的對象。然後，您可以將它們放入一個對像中以傳遞到Resolver構造函數中。

 import { Resolver } from 'did-resolver'
import ethr from 'ethr-did-resolver'
import web from 'web-did-resolver'
import sov from 'sov-did-resolver'

//returns an object of { methodName: resolveFunction}
ethrResolver = ethr . getResolver ( )
webResolver = web . getResolver ( )

//If you are using multiple methods you need to flatten them into one object
const resolver = new Resolver ( {
  ... ethrResolver ,
  ... webResolver ,
} )

//If you are using one method you can simply pass the result of getResolver( into the constructor
const resolver = new Resolver ( ethrResolver )

使用遺留方法方法解析器

在此庫的3.0.0版本3.0.0之前創建的方法可以用作舊版解析器。

 import { Resolver } from 'did-resolver'
import web from 'web-did-resolver'
import sov from 'sov-did-resolver'

//returns an object of { methodName: resolveFunction}
webResolver = web . getResolver ( )
sovResolver = sov . getResolver ( )

//If you are using multiple methods you need to flatten them into one object
const resolver = new Resolver ( { } , {
  legacyResolvers : {
    ... webResolver ,
    ... sovResolver ,
  }
} )

//If you are using one method you can simply pass the result of getResolver( into the constructor
const resolver = new Resolver ( ethrResolver ) 

解決DID文件

解析器提出了一個簡單的resolve()函數，該函數返回ES6承諾返回DID文檔。

 resolver . resolve ( 'did:ethr:0xF3beAC30C498D9E26865F34fCAa57dBB935b0D74/some/path#fragment=123' ) . then ( doc => console . log )

// You can also use ES7 async/await syntax
const doc = await resolver . resolve ( 'did:ethr:0xF3beAC30C498D9E26865F34fCAa57dBB935b0D74/some/path#fragment=123' ) 

快取

解決DID文件可能很昂貴。在大多數情況下，最好的緩存確實進行了文檔。必須使用cache參數專門啟用緩存

內置的緩存使用地圖，但沒有自動TTL，因此條目不會到期。這在大多數網絡，移動和無服務器上下文中都很好。如果運行長期運行的過程，則可能需要使用現有的可配置緩存系統。

可以通過將true值傳遞給構造函數來啟用內置緩存：

 const resolver = new DIDResolver ( {
  ethr ,
  web
} , {
  cache : true
} )

這是使用尚未測試的js-cache的示例。

 var cache = require ( 'js-cache' )
const customCache : DIDCache = ( parsed , resolve ) => {
  // DID spec requires to not cache if no-cache param is set
  if ( parsed . params && parsed . params [ 'no-cache' ] === 'true' ) return await resolve ( )
  const cached = cache . get ( parsed . didUrl )
  if ( cached !== undefined ) return cached
  const doc = await resolve ( )
  cache . set ( parsed , doc , 60000 )
  return doc
}

const resolver = new DIDResolver ( {
  ethr ,
  web
} , {
  cache : customCache
} ) 

實施DID方法

每個DID方法都將擁有自己的方法，可以在其各自的區塊鍊或其他分散存儲機制上查找標識符。

為了避免進行錯誤的配置，方法實施程序應導出一個getResolver()函數，該函數返回對象將方法名稱映射到resolve(did: string, parsed: ParsedDID, didResolver: DIDResolver, options: DIDResolutionOptions)函數。例如{ ethr: resolve } 。

解析函數應接受DID字符串，並且應該接受ParsedDID類型的對象

 export function getResolver ( ) {
  async function resolve (
    did : string ,
    parsed : ParsedDID ,
    didResolver : Resolver ,
    options : DIDResolutionOptions
  ) : Promise < DIDDocument > {
    console . log ( parsed )
    // {method: 'mymethod', id: 'abcdefg', did: 'did:mymethod:abcdefg/some/path#fragment=123', path: '/some/path', fragment: 'fragment=123'}
    const didDoc = ... // lookup doc
    // If you need to lookup another did as part of resolving this did document, the primary DIDResolver object is passed in as well
    const parentDID = await didResolver . resolve ( ... )
    // Return the DIDResolutionResult object
    return {
      didResolutionMetadata : { contentType : 'application/did+ld+json' } ,
      didDocument : didDoc
      didDocumentMetadata : { ... }
    }
  }

  return { myMethod : resolve }
}

然後可以將myMethod getResolver()結果傳遞到DidResolver構造函數中。請注意，如果也與其他方法一起使用，則應將其扁平化。

 import { DIDResolver } from 'did-resolver'
import MyMethod from 'mymethod-did-resolver'

const myResolver = MyMethod . getResolver ( )
const resolver = new DIDResolver ( myResolver )