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The server-side framework

The common blueprint of a server-side framework, read on Express and Spring Boot: routes, middleware or filters, controller, injection, data access, convention over configuration, and the path of a request.

  • 25 cards
  • 6 topics
  • Free
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The outline, topic by topic

Each topic is weighted the way the exam weighs it.

  1. Concepts
  2. Questions
  3. Sort and link
  4. On the diagram
  5. Scenarios
  6. Understand

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  • Middleware: what is it?

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    A function placed on a request's path, which reads or changes it then hands over to the next one, or answers itself.

    In Express: (req, res, next). If it neither answers nor calls next(), the request hangs and the client waits until its timeout.

  • In what order do the lines come out for a GET /?

    ```javascript
    app.use((req, res, next) => { console.log("A avant"); next(); console.log("A après"); });
    app.use((req, res, next) => { console.log("B avant"); next(); console.log("B après"); });
    app.get("/", (req, res) => { console.log("route"); res.send("ok"); });
    `

    • A avant, B avant, route, B après, A après
    • A avant, A après, B avant, B après, route
    • A avant, B avant, route, A après, B après
    • route, A avant, B avant, B après, A après
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    A avant, B avant, route, B après, A après

    next() calls the next link and only returns once that link has finished running: the “after” lines therefore come out in the reverse order of the “before” lines, like nested function calls.

  • In Express, a middleware that has finished its job hands over to the next one by calling …; without that call and without a response, the request ….

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    In Express, a middleware that has finished its job hands over to the next one by calling next(); without that call and without a response, the request hangs.

    next() is the function supplied by the framework: it is the one that knows which link of the chain comes next.

  • Route table: what is it?

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    A list of rules associating an HTTP method and a path with the function that must handle the matching request.

    In Express, the rules are tried in the order they are declared and the first match answers: a broad route placed too early hides the ones after it.

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