A little backstory
I have to develop a web application for college. This web application has to do with managing different locations using google maps like pinning new locations adding custom descriptions and so on. The login part is done using facebook (login with facebook). The more interesting part would be that the queries (client-server) would have to be done by using REST.
The part that i try to understand
If i use a database to store my user's unique ID, their online status (online/offline) and somehow (didn't settle actually on the idea) to keep a JSON on the server that would contain each user's pinned locations, would all this actually be ok with the REST paradigm ?
I find mixed answers on the internet and i don't know how to think of the statelessness of the application correctly. A session would not be created but the credentials from the database would be necessary for the users to communicate with each other.
The other side of the question
Considering that i'm mistaken and i shouldn't use the database to store the credentials and locations like that, how am i supposed to keep all that data ? I'm thinking something like JSON cached client-side but what if my client changes the computer, wouldn't this mean that he loses all his data? (Also wouldn't this make MVC handicapped by not having a model?) How do i really keep track of all things.
You're making this way too hard on yourself, try to keep it simple since you probably have a deadline. REST is a way of using APIs with HTTP verbs like GET, POST, PUT, and DELETE. It says nothing about how to store the data behind your APIs.
As for storing the data, a database should be fine. Storing it as JSON in the db could work, but in the end you'll have to parse the json every time that you want to use it, so I would suggest that you store it in a DB in such a way that it can be read easily.
For a beginner (especially if you're doing this for a school project), I would definitely suggest that you set up a relational database like Microsoft SQL Database (Microsoft Stack), or a MySQL/PosGres Database (I think this is what they'd use in linux), but if you wanna skip the relational db approach (because it might not be all that "easy" to get going), you can always try a NoSQL database like MongoDB.
Relevant links to help:
http://rest.elkstein.org/ (REST explained)
http://www.restapitutorial.com/lessons/httpmethods.html (REST verbs)
http://en.wikipedia.org/wiki/Relational_database (what is a relational db)
http://en.wikipedia.org/wiki/Database_normalization (Kinda the goal of relational db.. but note you can go too far...http://lemire.me/blog/archives/2010/12/02/over-normalization-is-bad-for-you/)
http://www.mongodb.com/nosql-explained (NoSQL explanation)
Related
We are currently using direct DB connection to query mongodb from our scripts and retrieve the required data.
Is it advisable / best practice to make the data retrieval from DB as a microservice.
It does until it doesn't :)
A service needs to get its data from somewhere and a database is a good start. If you have high loads you may find that you need to add a cache in the middle see this post from Instagram engineering https://instagram-engineering.com/thundering-herds-promises-82191c8af57d
edit (after comment)
generally speaking, a service should own its database and other services shouldn't access another database service directly only via its API. The idea is to keep services autonomous and enable them to evolve independently.
Depending on the size of microservice, that's now always practical since it can make the overhead of having the service be more of the utility it provide (I call this nanoservices). Also, if you have a lot of services you don't want to allow each one to talk to any other (even not via the DB) since you just get a huge mess. The way I see it there should be clear logical boundaries (services or microservices) and then within each such logical services you may find that it makes sense to have more than one "parts" (which I call aspects) e.g. they have different scaling needs or different suitable technologies etc. When you set things this way aspects can access the same database and services shouldn't (and you can still tame the chaos :) )
One last thing to think about - who said API is only a REST API, you can add views on top of the data that belongs to another service and as long as you treat that like an API (security, versioning etc.) you can have other services access that as well
I am trying to shift towards serverless architecture when it comes to building REST API. I came from Ruby on Rails background.
I have successfully understood and adapted services such as Api Gateway, Cognito, RDS and Lambda functions, however I am struggling with putting it all together in optimal way.
My case is the following. I have a simple user based platform when there are multiple resources related to application members say blog application.
I have used Cognito for the sake of authentication and Aurora as the database service for keeping thing like articles and likes..
Since the database and Cognito user pool are decoupled, it is hard for me to do things like:
Fetching users that liked particular article
Fetching users comments
It seems problematic for me because I need to pass some unique Cognito user identifier (retrieved during authorization phase in API gateway) to lambda function which will then save the database record with an external reference to this user. On the other hand, If I were to fetch particular users, firstly I must fetch their identifiers from my relation database and then request users details from Cognito user pool..I lack some standard ways of accessing current user in my lambda functions as well as mechanisms for easily associating databse record with that user..
I have not found some convincing recommended patterns for designing such applications even though it seems like a very common problem and I am having hard time struggling if my approach is correct..
I would appreciate some comments on what are some patterns to consider when designing simple user based platform and what are the pitfalls of my solution. Any articles and examples will also be very helpfull.
Thanks in advance.
These sound like standard problems associated with distributed, indpependent, databases. You can no longer delegate all relationships to the database and get a result aggregating them in some way. You have to do the work yourself by calling one database, then the other.
For a case like this:
Fetching users that liked particular article
You would look up the "likes" database to determine user IDs of those who liked it, then look up the "users" database to determine user details such as name and avatar.
Most patterns follow standard database advice, e.g. in the above example, you could follow the performance-oriented pattern of de-normalising - store user data such as name and avatar against each "like", as long as you feel the extra storage and burden of keeping it consistent is justified by the reduction in queries (probably too many Likes to justify this).
Another important practice is using bulk queries to avoid N+1 queries. This is what Rails does with the includes syntax, but you may have to do it yourself here. In my example, it should only take two queries because the second query should get all required user data in one go, by querying for users matching the list of user IDs.
Finally, I'd suggest you try to abstract things. This kind of code gets messy fast, so be sure to build a well-encapsulated data layer that isolates application code from dealing with the mess of multiple databases.
I have a rather simple idea for an iPhone app. What I need to accomplish:
Allow login of users (which means I'll have to store usernames, passwords, and other account info).
Allow users to submit strings that other users can view.
Attributes attached to each string that must be tracked (i.e. "votes, views, comments, etc.).
As such, I assume I'll need to start learning about databases and working between a server and client. I've gotten my feet wet in OSX/iOS programming (specifically Objective-C) before. I want to learn how one can accomplish a data-based application and the needs I listed above.
I've done some light research and discovered something called SQLite (free and open-source is always good). Is this the right path to achieve what I want to do? I'm a total "noob" when it comes to this field of server/client/data "stuff".
Your help is greatly appreciated.
SQLLite is more like a local database. Really, the database that you will use is unimportant. It sounds like a project with webservices. Inside your webservices, you might connect to a Microsoft SQL Server or anything you want.
I think you should study how to setup a webservice that can be accessed in your code. Webservices is not an Objective-C topic, it applies to any platform. Your project is more like a web development project.
You can save user's credentials in keychain.
#Kinderchocolate is right about introducing database into your project.
It hears about a app which need transmitting data among clients.It means your need server database and local database.
For server database,I recommend you to use Parse.Parse is a platform which provide a convenient way to use their server database with Objective-c in your app.This tool will save many times and energy(it's not necessary to learn PHP,Apache,Mysql).Parse is not free of course,but it has a free period and enough for you to examine your idea.
Here's Parse!.
For local database,I recommend you to use Core Data,Which is provided by XCode.Core data is so strong to meet your need.You can find a way to use Core Data in many books.
Go try Firebase for database in the cloud. (On the server). In Swift 4 there is complete support for Firebase and SQLite
I am new to iPhone app development and have a question about storing data. I've spent quite sometime learning about core data but still confused about the concept of persistence store.
What I understand is that core data is just a way of managing the data you downloaded from an external database. But given that core data is backed by SQLite, does that mean there exists a SQLite db in-memory while running? If so, does that mean when I use core data it will be more effective if I download a huge data set at start? But what about apps such as twitter or Facebook that require constant update of data, is a straight $NSURLConnection$ sufficient in these cases? If core data is used, will the extra overheads (i.e. data objects) be of any burden for such frequent request of update?
I would also like to find out some common ways of setting up an online database for iPhone app? Is it usually MySQL servers with a homemade Python wrapper that translates the data into JSON? Any standard server provider would provide the whole package? Or open source code?
Many many thanks!
I'm going to go through and try to address each of your questions, let me know if I missed one!
Firstly, Core Data can be used to store information generated in your app as well, there is nothing keeping you from using it in one way or another.
The way I understand it working is that the file, or other storage mechanism Core Data uses, exists regardless of whether or not your app is running. For a user to have to wait for a large database to be downloaded and loaded into a local database without being able to interact with your application is not the best way to do it in my opinion, people react negatively unresponsive UI. When a user may run your app for the first time, its possible you may need to get a larger set of data, but if any of it is generic and can be preloaded that is ideal, the rest should be downloaded as the user attempts to access it.
Facebook and Twitter applications work just as you understand in that a connection is established and the information is pulled from the appropriate site, the only thing they store is profile information, as far as I know. I would hesitate to use Core Data to store peoples information as eventually yes, there would be a significant amount of overhead caused by having to store peoples news feed or messages going back months on end.
As for setting up on online database that is something I'm unfamiliar with, so hopefully someone else can provide some insight on that, or if I find something I think may be of use, I will post back here for you. This part may actually merit its own separate question.
Let me know if you need to me elaborate on anything!
I've tried looking around but honestly not finding much help. I am mostly seeking for advice as to how I should approach to develop what I am thinking.
I want to accomplish something like this.
Imagine a website, with a backend database. This database contains information fed by users themselves. The website is fully functional, now I want users to be able to have the same functionality on their iPhones. I don't use a local database because I want all users to be able to have access to the same database, and this changes constantly.
What would be the best approach to:
Allow users to access all the information currently available on the website (database perspective).
Able to edit & add new entries to the database
I don't know if me creating an array to hold all this data would be wise to do. Specially with large amounts of data. I dont know how well it can scale.
Should I create a duplicate SQL lite database on the phone itself duplicating that of that website? What do you guys feel would be a good approach to this?
Comments, links, references would be greatly appreciated.
Thanks!
Sounds like the perfect time to create an API for your website. If the size of you application is not very big, you can use the same database, but would be good to run the API separated from the web server.
Essentially, such an API should allow you to make requests to certain URLs for retrieving, updating and deleting information from the database.
Depending on what server-side platform you are currently using, there are many options.
Client-side, your iPhone app can use http://restkit.org/ or http://allseeing-i.com/ASIHTTPRequest/ if you feel confident.