Reactive NoSql Image Persistence
Have you bought into the whole Reactive Programming bit yet? Well, I have participated in consuming the "Reactive Flavor Aid" and there is one issue at the moment. Currently, there is a supreme lack of helpful documentation to assist in a seamless development experience. Fear not fellow reactive enthusiast, this post should help you save images in MongoDB utilizing reactive streams!
Recently, I wanted to create a project that is a full slice reactive application. Meaning that the code and communication between the Frontend, Backend, and Data Persistence Layers are reactive. When reactive is stated, the following can be assumed:
- All code is no blocking
- Code is processed in an event loop.
- Push based programming.
- Publisher/Subscriber or Observable/Observer pattern.
With all of this criterion set, here is the following application stack that I came up with:
- Angular 5 paired with RxJS
- Spring 5 paired with WebFlux powered by Reactor
- MongoDB which supports reactive streams!
At a high level, the project consists of a Spring Boot server. Which serves static content to the user, and provides a REST API to save, update, retrieve, and delete persisted images.
The images are stored in a Mongo database. The server takes advantage of GridFS which breaks the image binary into chunks which allows for storage of images greater than 16MB.
This all sounds straight forward, right? As it turns out, there is very little documentation and examples on how to do anything reactive!
Look no further said documentation!
Local Deployment (For the ambitious)
To run this project locally you will need the following goodies:
All you have to do is at the root of this repository run:
docker-compose up -d
Boom! You are done.
What this does is starts a Mongo server. In addition to mounting the data location to dataDump in the root of this repository. So that when the Mongo server container gets removed, all of the data is saved.
In addition to the mongo server, it also spins up the Spring boot server, and binds the container port to the host port 80. So that mean you can open
http://localhost/
An get the index.html!
Local Development
If you want to make changes to any of this code, the unpackaged code exists in the web-content directory. Familiarity with Angular 5 is a plus.
There exists a docker compose file that will allow you to install your node modules locally (node_models).
All you have to do is run docker-compose -f docker-compose-build.yml up.
Once that is done, you are free to make changes! To move the changed code into the web server all you have to do is run,
docker-compose -f docker-compose-deploy.yml up and that should transpile all of the typscript, bundle it up, and move it to web-service/src/main/resources
Live action development!
docker-compose -f docker-compose-dev.yml up -d
will run the web server, mongo, and also serve the static web-content from browsersync.
The plus here is that you get live change updates, as the dev server will watch all web-content files for changes.
The dev server runs on http://localhost:3000.
Fun fact, if you make any changes to typscript files, you will have to recompile the code to get the changes to take hold.
You could create a script that has this as the command:
docker run --rm -v /home/alex/workspace/acari-landing/mong-images:/app alexsimons/nodebuild run compile
You will probably want to replace /home/alex/workspace with whatever you put the repository.
(Maybe I should create a compose file that does that....)
Web-Service
This directory contains a Webflux Spring Boot server.
Which is configured to serve static web content, which was generated from the web-content directory.
The Mongo client and GridFS are from the reactive streams library.
Image binary is streamed chunked to the frontend, to avoid needing to keep the entire image in memory.
Form data sent to the server via the REST API is recieved as a Flux<Part>
Web-content
This directory holds all of the fun bits to serve end-user rendered html. It enables you to pick, view, upload, and delete images! GIFs, JPEGS, PNG, WebP, all work. However, SVGs and ICOs do not display.
Webpack 3
Webpack is currently configured with the following goodies:
- Browsersync Server that runs on localhost:3000 (when you run
npm run watch) with a proxy to redirect HTTP request to an intended destination. - It is set to create 3 files on build
- app.[hash].js: which is all of the application code bundled together in a cache-busting hash post-fixed js file.
- vendor.[hash].js: all of the vendor code wrapped up such as: angular5, bootstrap, rxjs, etc.
- polyfills.[hash].js: all of the browser compatability stuff, I think....
- It is set to expose jquery as the global variables $ and jQuery
- It is set to load html templates post-fixed with htm into the javascript files (to avoid browser caching).
- It has a sass build process.
- All of the bundled files will be put into the index.html body when the node task
buildis run.
Bootstrap 4
Typescript Linting
Which is run by the command npm run lint