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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"refactor(http): convert Connection interface to be Observable of Response","articleBody":"(recapping discussion with @blesh, who will probably correct me)\n## Current State\n\nRight now, the [`Connection`](https://github.com/angular/angular/blob/a251df9df4a34592afb4984f7a3e13a186562234/modules/angular2/src/http/interfaces.ts#L22) interface, which is implemented by `XHRConnection`, `JSONPConnection`, and `MockConnection`, has simple interface:\n\n``` typescript\ninterface Connection {\n  readyState: ReadyStates;\n  request: Request;\n  response: Observable\u003cResponse\u003e;\n}\n```\n\nCalls to the [Http](https://github.com/angular/angular/blob/a251df9df4a34592afb4984f7a3e13a186562234/modules/angular2/src/http/http.ts) service return the `connection.response` observable, so end users don't really interact with this interface too much in application code. In tests, however, users will be working with `MockConnection` instances created by [`MockBackend`](https://github.com/angular/angular/blob/a251df9df4a34592afb4984f7a3e13a186562234/modules/angular2/src/http/backends/mock_backend.ts) in order to create mock responses for requests.\n\n``` typescript\nmyService.getUsers().subscribe(users =\u003e {\n  expect(users[0].name).toBe('Rob');\n  async.done();\n});\nmockBackend.connections.subscribe(connection =\u003e {\n  connection.mockRespond(mockUsers);\n});\n```\n\n(Note that the mock responding mechanism should be further improved, but that's outside the scope of this proposal).\n## Proposal\n\nChange `Connection` itself to be an Observable of `Response`, and keep `request` property intact. @blesh says it aint so bad to add properties to Observables (though adding methods is a bad idea because observable methods are expected to be operators).\n\n``` typescript\ninterface Connection extends Observable\u003cResponse\u003e { //Observable interface doesn't actually exist yet\n  readyState: ReadyStates; // I would like to get rid of this property\n  request: Request;\n}\n```\n\n`MockConnection` should extend subject, so that it can be `next`-ed with `Response`s.\n\n``` typescript\nclass MockConnection extends Subject\u003cResponse\u003e implements Connection {\n  readyState: ReadyStates;\n  request: Request;\n}\n```\n\nThis change is actually pretty minor from an end-user perspective, other than the change of calling `next` on the `MockConnection` rather than the current `mockRespond`. But internally, it reduces cruft and simplifies logic.\n\nCC: @robwormald \n","author":{"url":"https://github.com/jeffbcross","@type":"Person","name":"jeffbcross"},"datePublished":"2015-10-02T18:28:04.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":9},"url":"https://github.com/4472/angular/issues/4472"}