The document discusses transforming HTML from a third party service without a public API into a REST API. It recommends emulating a browser to issue HTTP requests and parse the resulting HTML. Tools like Wireshark, Chrome Inspector and Gargl can help analyze and record requests. The HTML can then be parsed using a library like JSoup and exposed through a framework to define API endpoints and verbs. Caching is also important to avoid overloading the third party service.

1. Cedric Gatay - c.gatay@code-troopers.com
or HTML to REST API guide
APIs for everyone

2. Cedric Gatay - c.gatay@code-troopers.com
Initial rant
• Want to build an awesome app
• On top of third party service
• No API, only HTML available
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3. Cedric Gatay - c.gatay@code-troopers.com
Basic idea
• Emulate a browser to issue requests
• Parse resulting HTML
• Transform it into a REST API
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4. Cedric Gatay - c.gatay@code-troopers.com
Prerequisites
• Analyze site to find endpoints
• mobile versions are great
• Reverse engineer server requests
• understand parameters might be tricky
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5. Cedric Gatay - c.gatay@code-troopers.com
Tools
• Wireshark to analyze HTTP
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6. Cedric Gatay - c.gatay@code-troopers.com
Tools
• Chrome Inspector to the rescue
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7. Cedric Gatay - c.gatay@code-troopers.com
Tools
• Gargl : https://github.com/jodoglevy/gargl
• Record your requests
• Name them
• Parametrize them
• Generate Java/JavaScript code
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8. Cedric Gatay - c.gatay@code-troopers.com
From HTML to API
• Gargl generates boilerplate for HTTP calls
• Refactor generated code
• Need to parse HTML
• Expose it through API
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9. Cedric Gatay - c.gatay@code-troopers.com
Parse HTML
• JSoup : http://jsoup.org/
• simple parser
• allows to use css selectors
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10. Cedric Gatay - c.gatay@code-troopers.com
Expose API
• Define verbs
• Use your preferred framework here
• restx : http://www.restx.io
• Test extensively
• parsing WILL break
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11. Cedric Gatay - c.gatay@code-troopers.com
Cache API
• Do not spam base server
• Cache external calls as much as possible
• Store constant data
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12. Cedric Gatay - c.gatay@code-troopers.com
Questions ?
Thanks for listening
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