Tuesday, January 31, 2017

Serverless JoymonOnline.in - Intermediate update & experience

The Serverless is the new buzzword and it is getting really good attention. It is nothing but an architectural style where developers don't need to worry about servers for deployment, scaling etc... Just write and push the code. It will scale automatically.

In the previous article about Serveless, I had mentioned I am in the process of converting my personal site to Serverless. The decision was purely financial. Why should I give money to GoDaddy for hosting some pages which can be served by GitHub pages for free?

This is just an intermediate update about that effort.

Steps

Below are the steps taken during this effort. It may vary from project to project based on complexity. JoymonOnline.in is just a profile site which don't use any custom modules or handlers.
  1. Avoid server side data rendering
    1. Replace .Net third parties with equivalent JavaScript API
    2. Convert each .aspx page to contain its own Angular application.
    3. Avoid ASP.Net specific skin files and use pure CSS
  2. Client side integration
    1. Replace ASP.Net master page with Angular routing.
    2. Bundling, Minification, CI & CD
  3. Backward compatibility
    1. Links
    2. SEO
Please note that these steps are relevant if the decision is 
  • Not to start a fresh app
  • To ensure that the code base is ready to delivery at any point in time.
If business can keep quite during the migration or the development can be done is separate branch ad later merge, these steps are not required. Just start a new app.

Avoid server side HTML rendering

The current www.JoymonOnline.in site uses ASP.Net web forms technology. In other words it uses server side HTML generation and sends it to the browser. There is no rule that Serverless should not use server side rendering. It can use, provided the server side rendering can scale automatically without doing any extra task. For example a WebAPI service end point can return HTML and it can be rendered at browser with the help of JavaScript. That introduce some kind of client side HTML manipulation. Once we take that decision, there is not much differences between rendering full contents at client side v/s rendering some contents at server and inject it to client side views. So in short Serverless goes hand in hand with client side web apps which we generally call SPA (Single Page application). It can't be done in one step. So sub tasks are as follows.

Replace .Net third party with JS API

If we want to replace the third party .Net API with JS equivalent there are 2 options
  1. Use equivalent JS library
    1. Has to make sure the critical API keys are not exposed. Can do client site authentication or be happy with free quota.
  2. Write a FaaS which uses same .Net API and let it return required data to client.
    1. We have to make sure it is secured and key present only at service and service can only be called from our app.
Coming back to JoymonOnline.in, it uses some third party APIs at server side to get data and render  via ASP.Net. GitHub API, Blogger API are the main third parties. So these calls needs to be done from client machine. For GitHub, it was easy as there is straight JS library. But for Blogger it was little difficult as the Google feed API is discontinued. Finally it worked with blogspot feed url.

But for GitHub, there is a limitation due to the quota for unauthenticated API calls. Since the developer key cannot be exposed to client, it allows only 60 requests / hour / IP address. Since JoymonOnline.in is expecting more than 60 calls from single API it is ok to go with quota. 

Convert each .aspx page to contain its own Angular application

Next step is to convert page by page to Angular. This is to make sure that the application is always in functional condition than like a demolished house before renovation. Convert individual pages to its own angular app and render that app inside the ASPX pages. Let that page be just an angular app host. Noting else. 
In this step we have to identify equivalent third party ASP.Net UI controls, if applicable. For example how to replace Telerik web forms controls with KendoUI.

In case the plan is to first get to ng1 and later to ng2, I would strongly recommend to go with components rather than directives. TypeScript is becoming defacto standard for angular. Use that to avoid debugging time. After this step, we will have ASP.Net application but the functionality working from browser via angular.

Avoid ASP.Net specific skin files and use pure CSS

Next thing to tackle are the styles. If the application is using skin files, we have to get equivalent CSS files. Sometimes we may need to do this along with the previous step. Depends on nature of third parties and our code.

Client side integration

The next big step is to integrate things at client side.

Replace ASP.Net master page with Angular routing.

The main pending thing is to have angular master page and routing. We already have separate components in different apps. Just create new app in index.html and have the routing to load proper components. This steps sound simple but it has many things to do.

Bundling, minification, CI, CD etc...

Now its the time to optimize the site and do integration to build pipeline. Till this point, the expectation is that we are able to use existing build system. Recommended is Webpack for client side activities such as compilation and bundling. CD is always confusing with Continuous Delivery and Continuous Deployment. At least make sure it is Continuous Delivery.

Current, JoymonOnline.in using AppVeyor for CI & CD. Though AppVeyor is mainly intended for Windows development, it supports NodeJS as well. So decided to continue in AppVeyor. At this point the build output will be pushed to \docs folder as staging. GitHub pages recently started supporting serving web pages from \docs folder instead of gh-pages branch.

It is not fun to develop JS based client side app using Visual Studio solution file. After this step we don't need .sln file to work with. Node rules the client side web development world. At some point we have to introduce Node. So why not from the start if it is possible to live with only Node? When it is said 'start', it means the starting of the migrated application. If anyone feels they can live with .sln file without Node, let them continue. But better don't use mix. Comparing Node with .sln is not the right comparison. But the intention is to use Node and its ecosystem such as NPM & package,json etc... 

Backward compatibility

These may be optional depends on scenarios.

Links

This will make sure that the bookmarks saved by users are still valid. The old ASP.Net application could have modified to redirect the .aspx pages to new URLs. But for JoymonOnline.in, this is not done.

SEO

The SEO efforts needs to be put if the application is public facing.

These steps itself needs explanations which will be having contents enough for separate post. At this point, the entire application has converted and available at joymon.github.io . The main pending thing is to change settings in GoDaddy to point JoymonOnline.in records to joymon.github.io.

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