Exercise 1 for Cloud Computing

Summer Semester 2025

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Dear students,

Let's embark in this journey exploring the development of a simple, yet very dynamic webpage. During this time, we will combine cloud standard technologies (Golang) and emerging ones (HTMX) to discover what it takes to deploy an application in the Cloud. From a simple binary running to using FaaS for efficiency and cost optimization.

In this first week, we will explore developing certain views using templating and content swap in the browser. All the heavy-lifting is done by HTMX, you just need to adjust the contents and attributes of the HTML tags to signal how it should react.

In this code, there is already quite a bit of examples on how you can do it: from the usage of templates, rendering upon request, to interacting with the database to maintain your data.

In the topic of database: there is a bunch of different databases, as there is database engines. For simplicity, we will use a NoSQL database called MongoDB. Why NoSQL? Well, the name implies Non-relational database, i.e., here we don't care that much about those peski relations between tables, and foreing keys, and all that technical jargon. Basically, MongoDB works like a big storage for "JSON" documents (or more known as Key-value stores a.k.a KV-stores). That means, for this exercise, we want something simple yet standard in Cloud environments, just to get dabble with them and explore what we can do.

What is the task?

As you have seen from the exercise slides or recording, we will be exploring developing a web-front for a Book Store. For this task, you will need to complete:

1. Finish the implementation for the "Authors" view by: implementing the HTML template, and rendering the content upon a request to /authors

2. Finish the implementation for the "Years" view by: implementing the HTML template, and rendering the content upon a request to /years

3. Implement the methods for:

   3.1. GET. The request path should be /api/books, and it should return an array of objects, in the following form:

    response = [{
            id: "asd34343",    // This is not the MongoID
            title: "The book title",
            author: "The book author",
            pages: "1000",
            edition: "1st Edition",
            year: "1900",
    },{...}]
   

   3.2. POST. The request path should be /api/books, and it should return the proper status code upon correct completion. The body of the request looks as follows:

    request.body = {
            id: "asd34343",            // This is not the MongoID
            title: "The book name",
            author: "The book author",
            pages: "1000",             // optional field
            edition: "1st Edition",    // optional field
            year: "1900",              // optional field
    }
   

   3.3 UPDATE. The request path should be /api/books/:id, and it should return the proper status code upon correct completion, where :id is the id given during the GET operation, which is not the MongoID. The body of the request looks as follows:

    request.body = {
            id: "asd34343",  // for updates, this field in the body is optional 
            title: "The book name",
            author: "The book author",
            edition: "1st Edition",
            pages: "1000",
            year: "1900",
    }
   

   3.4 DELETE. The request path should be /api/books/:id, and it should return the status code 200 upon correct deletion of the respective book. In this context, :id is known as a path parameter, and common HTTP server frameworks (like the one we are using), supports parsing such parameter to the point you can easily access it. The value for :id is the key id from previous responsesx, which is not the MongoID.

   3.5 We will make at least 6 different tests to these endpoints with random (but stable data) to make sure the workflow is correct. If everything is correct, together with the rendering functionality, you will achieve 90 points. Remember that you need 70 % to pass each assignment.

Requirements and Test Scenarios

Requirements

1. The database cannot have duplicate entries. This means, a new book that shares the same id, name, author, year, and pages, with an existing entry on the database (excluding the MongoID) must not result on a new addition to the database.
2. The POST request must return congruent status codes. For a creation of a new object on the database upon request, you can return only valid status codes. Please look at the links given in the code.
3. The GET request must return all entries in the database. The GET response must be an array of JSON objects with proper key-value pairs. A GET operation after an update must return the updated values.
4. The UPDATE request must change one or multiple fields of an entry in the database (excluding the ID and MongoID). A subsequent POST with one or more similar fields (but not all, excluding the ID and MongoID) must result on a new entry.
5. The DELETE request must delete only one entry from the database based on the given reference of ID. A subsequent GET must return all entries except those previously deleted.
6. The GET request to /authors and /years must return a valid response from the Rendering Engine.

Tests

1. The grade of the assignment consist of an average of three tests.

2. Two GET operations to fetch the HTML code for the Authors and Years view

What do you need for this assignment?

Basically Golang 1.22. You can download and install it following these instructions.

Once downloaded and installed, under the exercise folder, run the following commands:

go mod tidy // it will automatically download all dependencies specified in go.mod and go.sum

go run cmd/main.go // it will launch the server and let you access it via localhost:3030

To build your binary, you can perform the following command:

go build -o <out_filename>

The other component you need to run your exercise is a database. Since we are using MongoDB, you can installing following the instructions here. I recommend you use MongoDB CE v.7. Moreover, you will also have to change the MongoDB host inside main.go. Remember that you must also specify an username and password when installing MongoDB. In my case, I chose mongodb as user, and testmongo as password. The port in the URI must be also replace to match your system.

Without further ado,

Happy Coding!