|From Getting MEAN, Second Edition by Simon Holmes
This article is a guide to planning a practical application on the MEAN stack.
This article was originally published here: https://www.sitepoint.com/planning-mean-stack-application/
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Planning a real application
For the purposes of this article, let’s imagine that we’re building a working application on the MEAN stack called Loc8r. Loc8r will list nearby places with WiFi where people can go and get some work done. It will also display facilities, opening times, a rating, and a location map for each place.
Planning the application at a high level
The first step is to think about what screens we’ll need in our application. We’ll focus on the separate page views and the user journeys. We can do this at a high level, not concerning ourselves with the details of what’s on each page. It’s a good idea to sketch out this stage on a piece of paper or a whiteboard, as it helps to visualize the application in its entirety. It also helps with organizing the screens into collections and flows, serving as a good reference point when we build it. As there’s no data attached to the pages or application logic behind them, it’s easy to add and remove parts, change what’s displayed and where, and even change how many pages we want. The chances are that we won’t get it right the first time; the key is to start and iterate and improve until we’re happy with the separate pages and overall user flow.
Planning the screens
Let’s think about Loc8r. As stated our aim is as follows:
Loc8r will list nearby places with WiFi where people can go and get some work done. It displays facilities, opening times, a rating, and a location map for each place. Visitors can to submit ratings and reviews.
From this we can get an idea about some of the screens we’re going to need:
- A screen that lists nearby places
- A screen that shows details about an individual place
- A screen for adding a review about a place
We’ll probably also want to tell visitors what Loc8r is for and why it exists, and we should add another screen to the list:
- A screen for “about us” information
Dividing the screens into collections
Next, we want to take the list of screens and collate them where they logically belong together. For example, the first three in the list are all dealing with locations. The About page doesn’t belong anywhere and it can go in a miscellaneous Others collection. Sketching this out brings us something like figure 1.
Figure 1 Collate the separate screens for our application into logical collections.
Having a quick sketch like this is the first stage in planning, and we need to go through this stage before we can start thinking about architecture. This stage gives us a chance to look at the basic pages, and to also think about the flow. Figure 1, for example, shows a basic user journey in the Locations collection, going from the List page, to a Details page, and then onto the form to add a review.
Architecting the application
On the face of it Loc8r is a simple application, with only a few screens. But we still need to think about how to architect it, because we’re going to be transferring data from a database to a browser, letting users interact with the data and allowing data to be sent back to the database.
Starting with the API
Because the application is going to be using a database and passing data around, we’ll start building the architecture with the piece we’re definitely going to need. Figure 2 shows the starting point, a REST API built with Express and Node.js to enable interactions with the MongoDB database.
Figure 2 Start with the standard MEAN REST API, using MongoDB, Express, and Node.js.
Building an API to interface with our data is the base point of the architecture. The more interesting and difficult question is: How do we architect the application?
Application architecture options
At this point, we need to look at the specific requirements of our application and how we can put together the pieces of the MEAN stack to build the best solution. Do we need something special from MongoDB, Express, Angular, or Node.js that’ll swing the decision a certain way? Do we want HTML served directly from the server, or is an SPA the better option?
For Loc8r there are no unusual or specific requirements, and whether it should be easily crawlable by search engines depends on the business growth plan. If the aim is to bring in organic traffic from search engines, then yes, it needs to be crawlable. If the aim is to promote the application as an application and drive use that way, then search engine visibility is a lesser concern.
Thinking back to the blog example, we can immediately envisage three possible application architectures, as shown in figure 3:
- A Node.js and Express application
- A Node.js and Express application with Angular additions for interactivity
- An Angular SPA
With these three options in mind, which is the best for Loc8r?
Figure 3 Three options for building the Loc8r application, ranging from a server-side Express and Node.js application to a full client-side Angular SPA.
Choosing an application architecture
No specific business requirements are pushing us to favor one architecture over another. Building all three of the architectures allows us to explore how each approach works and enables us to look at each of the technologies in turn, building up the application layer by layer.
We’ll be building the architectures in the order they’re shown in figure 3, starting with a Node.js and Express application, then moving on to add some Angular before refactoring to an Angular SPA. Although this isn’t necessarily how you might normally build a site, it gives you a great opportunity for learning all aspects of the MEAN stack.
Wrapping everything in an Express project
The architecture diagrams we’ve been looking at imply that we’ll have separate Express applications for the API and the application logic. This is perfectly possible and a good way to go for a large project. If we’re expecting large amounts of traffic, we might even want our main application and our API on different servers. An additional benefit of this is that we can have more specific settings for each of the servers and applications which are best suited to the individual needs.
Another way is to keep things simple and contained and have everything inside a single Express project. With this approach, we have only one application to worry about hosting and deploying and one set of source code to manage. This is what we’ll be doing with Loc8r, giving us one Express project containing a few sub-applications. Figure 4 illustrates this approach.
Figure 4 The architecture of the application with the API and application logic wrapped inside the same Express project.
When putting together an application in this way, it’s important to organize our code well to allow the distinct parts of the application to be kept separate. As well as making our code easier to maintain, it makes it easier to split it out into separate projects further down the line if we decide it’s the right route. This is a key theme that we’ll keep coming back to throughout the book.
As you can see, we’ll use all layers of the MEAN stack to create Loc8r. We’ll also include Twitter Bootstrap to help us create a responsive layout. Figure 5 shows some screenshots of what can be built.
Figure 5 Loc8r is a sample application. It displays differently on different devices, shows a list of places and details about each place, and enables visitors to log in and leave reviews.
That’s all for this article.