did resolver

打字稿确实是解析器

该库旨在作为解决JavaScript应用程序解决的简单常见界面，确实来自分散的标识符（DIDS）的文档。

这旨在支持W3C凭证社区组的拟议分散标识符规范。

该库不会实现任何特定的DID方法，但允许DID方法实现者可以释放应用程序可以添加的NPM软件包。

配置Resolver对象

现在，您需要在实例化过程中预先配置解决方案。 Resolver构造函数期望映射到解析器函数的方法注册表。例如：

 {
  ethr : resolve ,
  web : resolve
}

每个方法解析器都应公开一个称为getResolver函数，该功能将返回包含这些密钥/值对之一的对象。然后，您可以将它们放入一个对象中以传递到Resolver构造函数中。

 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 )

使用遗留方法方法解析器

在此库的3.0.0版本3.0.0之前创建的方法可以用作旧版解析器。

 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 ) 

解决DID文件

解析器提出了一个简单的resolve()函数，该函数返回ES6承诺返回DID文档。

 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' ) 

缓存

解决DID文件可能很昂贵。在大多数情况下，最好的缓存确实进行了文档。必须使用cache参数专门启用缓存

内置的缓存使用地图，但没有自动TTL，因此条目不会到期。这在大多数网络，移动和无服务器上下文中都很好。如果运行长期运行的过程，则可能需要使用现有的可配置缓存系统。

可以通过将true值传递给构造函数来启用内置缓存：

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

这是使用尚未测试的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
} ) 

实施DID方法

每个DID方法都将拥有自己的方法，可以在其各自的区块链或其他分散存储机制上查找标识符。

为了避免进行错误的配置，方法实施程序应导出一个getResolver()函数，该函数返回对象将方法名称映射到resolve(did: string, parsed: ParsedDID, didResolver: DIDResolver, options: DIDResolutionOptions)函数。例如{ ethr: resolve } 。

解析函数应接受DID字符串，并且应该接受ParsedDID类型的对象

 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 }
}

然后可以将myMethod getResolver()结果传递到DidResolver构造函数中。请注意，如果也与其他方法一起使用，则应将其扁平化。

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

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