I wanted to ask you about microservices in Python. As of writing this, i got pretty good with writing well structured flask-restful APIs and I wanted to go and learn about microservices in python.
Right now I have read up quite a lot of info regarding this and even searched online to find examples for this (1 example here) but I am not really sure exactly where to start as I don't want to invest too much time in a inefficient pattern.
So I wanted to know if anyone know any courses with examples for Python on building high load services. My only hints so far as asyncio and aiohttp for request handling and i'm not sure if using a message broker (such as zeromq or rabbitmq) would be a good idea as from what I read, it adds request lag.
Any advice would be great.
PS: The current pattern I'm stuck on is the API Gateway pattern and I would also want to know if it is a good direction as a start.
There are plenty of microservice frameworks in Python that can handle high load and get you a long way towards following best practices.
Try for example pymacaron (http://pymacaron.com/). Pymacaron is basically a flask app whose endpoints are auto-spawn from a swagger specification. To write a pymacaron microservice, you mostly have to:
(1) write a swagger specification for your api (which is always a good starting point, whatever language you are using). Your swagger file describes the get/post/etc calls of your api and which objects (json dicts) they get and return, but also which python method in your code that implement the endpoint.
(2) and implement your endpoints' methods.
Once you have done that, you get loads of things for free: you can package your code as a docker container, deploy it to amazon beanstalk, start asynchronous tasks from within your api calls, or get the api documentation with no extra work.
Here is an example of an helloworld api implemented with pymacaron: https://github.com/pymacaron/pymacaron-helloworld
Related
Could you give me an idea/concepts (not in code) on how could I link NodeJS and Python?
Let's say,
I have NodeJS up and running in PM2 (assuming I already know REST API) and I have a ton of data sets that I need to be ready to display to client side using socket.io (assumming I already know socket.io) as soon as possible.
I'm thinking to use Python. This is for me to implement the basics of machine learning.
In what concept should I start? I'd really love to hear your ideas.
Well you seem to be assuming way too many things, okay from your description I would suggest you to have a look at concept called microservice architecture.
This is how it will work let us assume you want to build an online shopping application where you have 2 main scenarios first is sell all items on your website and second you want to recommend products to your user(Your ML comes into play over here)
So as you said you already know REST API so what you would do is create a microservice (Consider it as a small nodejs application(Using either express or sails or any other framework) which has APIs exposed for all shopping related business logic) also you end up using fromtend technology viz. angularjs for your client side code. You'll show all this shopping stuff by calling your nodejs REST APIs from your angularjs client code. Node provides socket support via socket.io.
Similarly you write a small microservice in python(using Flask and Python-SocketIO) which takes your huge amount of data from datastore does all ML magic and returns recommended products for the particular user(which you received from your angularjs client application), and return it using Python-SocketIO to angularjs(or node application if you're maintaining your frontend logic there instead of angular).
You have provided very less detail so this is abstract view of what you can look into.
Since you're Python oriented for your ML code I'd suggest you to reduce the list of skills you need to learn and/or improve using Python for everything.
You could use Python-SocketIO and Flask, for example.
Here's the setup: On a single-board computer with a very rudimentary linux I'm running a Django app. This app is, when a button is pressed or as a response to the data described below, supposed to call either a function from a library written in C, or a compiled C program, to write data to system memory at a specified address, poke/peek like. (Python doesn't seem to be able to do that natively).
The Django app should also display data, continuously, which is being read from the memory from the same library / program.
My question now is how to even begin with setting up the scenario described above. Is this even possible with a web app? Is a Django or more fundamentally any web framework even the right approach here? I'm at a bit of a loss here, since I've spent quite a few hours now trying to figure out how to do this while not getting the most basic starting point...
Disclaimer: I'm pretty new to the entire web framework thing, and more importantly web development in general, so sorry if this is a bad question as in, I could have easily found information on this topic online, but I couldn't really find a good starting point on this.
I wanted to add a comment but not enough space... anyway
You can write a native extension in C for Python that could do what you need, check this.
Now for the fact of displaying data continuously this is kind of vague, if this C library is switching this hypothetical address, very often and very fast you have to update a browser client as fast as possible.
I think websockets would do the trick but they are js related, so I think NodeJs would be a better candidate for the server side of your application instead of Django.
If you want to stick to Django you can also expose an URL with the generated address value and have a webpage continuously (with a little Interval) checking that URL using a simple ajax call, kind of ugly and inefficient but would work.
Anyway IMHO your best bet is for websockets because with them you have a fullduplex communication between client and server.
Good Luck with your project.
Info:
Websockets in Django with socket.io
Nodejs socket.io
I have developed a python program that parses a webpage and creates a new text document with the parsed data. I want to deliver this new information to the web. I have no idea where to start with something like this. Are there any free options where I can have a site automatically call this python code upon request and update the new data to its page? Or is the only feasible solution here to have my own website/server that uses my code? I'm honestly pretty overwhelmed with many of the options when I try to begin doing a web-search for a solution like this. I have done a decent amount of application programming before so i'm confident in my ability to learn new things, but web protocols are all new to me so its hard to find a starting point.
Ultimately I want this python code to run automatically, or per request of a user, and deliver to the data to them. It could even be through an email, although that is probably less practical.
I personally have good experience using Google Appengine (and its free for a limited amount of requests). The downside is that it does not allow C-extensions or Python3.
If you want to host your own server, tornado is a good option I think. Tornado supports both Python2 and Python3.
There are a great deal of options available.. from 'traditional' virtual server or website hosts like a2hosting or godaddy to 'Cloud Application Hosts' such as Amazon EC2, Heroku or OpenShift.
For your case, and without knowing more, I would suggest that an application hosting is more appropriate, and that you should take a look at Heroku and Openshift in particular.
Define carefully what you want to achieve (how the users access your application, what they see, how they interact with it... etc..) and then evaluate these options based on those requirements.
Most offer a free trial, or even free services, depending on what you need! Good luck
If you've never worked with web technologies before this will be a overwhelming task, since there's a lot of different technologies involved, and many possible ways to combine them.
You'll probably want to start by familiarizing yourself with the very basics of the HTTP protocol.
Then you should read a bit on CGI server-side programming (the article also has a quick overview on HTTP).
Python can run both on CGI and WSGI (if the server provider allows such access), so you may also want to read about WSGI.
Once you grasp all these concepts, you should check this question for actual python techniques.
Also, since you seem to be under the impression you must pay to have a website/app deployed, you should know there are companies that host python apps for free
I'm working on a tracking proxy (for want of a better term) written in Python. It's a simple http (wsgi) application that will run on one (maybe more) server and accepts event data from a desktop client. This service would then forward the tracking data on to some actual tracking platform (DeskMetrics, MixPanel, Google Analytics) so that we don't have to deal with the slicing and dicing of data.
The reason for this implementation is that it's much easier and faster to make changes to a server process that we control rather than having to ensure every client in the wild gets updated if the tracking backend changes in some way.
I've been looking up info on the various options and I was hoping somebody here would have some good advice from their own experiences. Ideally we'd be able to use Google Analytics as it's free for any amount of usage but paid options are fine.
My only real requirement is either a good Python library or a well documented api that I can write a wrapper for (this seems somewhat lacking in GA when it comes to triggering events through any method other than their js or other provided libs).
N.B. We're not really tracking server code so something like NewRelic isn't appropriate, we're just decoupling a desktop application from the specifics of the tracking backend.
We ran into this same problem a bunch of times, we ended up building a suite of server-side analytics libraries to make this easier.
Segment.io has libraries for Python, Ruby, Java, Node, .NET and PHP that abstract the APIs for Mixpanel, KISSmetrics, Google Analytics and a bunch of other analytics services.
You could integrate the Python library once, and then send your data wherever you want. The data is proxied through Segment.io's hosted service. Hopefully this cleans up the mess of integrating a bunch of libraries, each with slightly different APIs. (The service is free for the first million events.)
Have you tried anything below?
The Google Data APIs Python Client Library has source specific to analytics
http://code.google.com/p/gdata-python-client/
http://code.google.com/p/gdata-python-client/source/browse/#hg%2Fsamples%2Fanalytics
https://developers.google.com/gdata/articles/python_client_lib
You might be able to borrow from these sources as well;
Google has something they are working on for mobile and source is available in PHP, JSP, ASP.net and Perl: https://developers.google.com/analytics/devguides/collection/other/mobileWebsites
I also came accross this in PHP http://code.google.com/p/php-ga/
As for others:
KissMetrics: http://support.kissmetrics.com/apis/python
MixPanel: https://mixpanel.com/docs/integration-libraries/python
DeskMetrics: don't seem to have python, http://docs.deskmetrics.com/index.html
Sorry I cannot provide information based off extensive experience with anything python related other then providing a few of these resources. I would be interested to see what you come up with.
I need to create a project that has a web frontend to manage synchronous task execution (ala fabric), async tasks (AMQP), and long-polling/ajax for tabular viewing of results and queues/large, frequently changing datasets (think tail -f syslog). I have an existing Python codebase for a lot of the implementation-specific stuff.
After looking at a bunch of existing frameworks, the obvious answer appears to be Django+Celery. However, I do not want to "learn Django", nor do I need 95% of it's functionality. I just need simple auth, maybe sqlalchemy, easy ajax, amqp, xmlrpc would be helpful.
I would consider using Mongrel2, but I have a strong preference for RabbitMQ over 0MQ (for a few implementation-specific reasons).
I originally spent a great deal of time learning Twisted, and ended up getting a few hundred useful LOC out of it, but I found that I was twisting (lol) too much of my platform code to fit it's callback model. It actually 'fit the bill' very well (except with it's own amqp implementation), but it was so frustrating, and I went through so many iterations of code (one for each 'twisted ahah moment'), that it's 100% out.
Can somebody please help me wade through the mire? Tornado? Pylons? repoze? Pyramid? Flask? Bottle? CherryPy? Web2py? Paster/Webob? Anything else# http://wiki.python.org/moin/WebFrameworks?
Edit:
To be clear, integration with RabbitMQ (or another amqp provider) is of the utmost importance, and is really the crux of problem.
I don't have a full vision of python web frameworks but just want to share my point of view on 2 of them :
Bottle is light and works fine. If you want something easy to learn and easy to use that may be the right choice. I used it for quite simple front-end apps running locally and i liked it very much.
Tornado seems to me as a very good non-blocking server for real-time web app. Combined with tornadio it makes ajax-long-polling quite easy. However, it may be a little harder to learn than Bottle. I would recommend to have a look to the chat app in the example folder of tornadio.
I hope it helps
If you are going to use AMQP long term then I would steer clear of Celery because they use AMQP in a wierd way that suggests the developers did not understand the AMQP model.
bottle is a nice framework for knocking together RESTful apps (I use it to create mock servers for testing) and if you already have the code that does the real work, you may be surprised at how short a bottle app can be.
I'm currently building Python apps using RabbitMQ and using amqplib by way of kombu. I originally chose kombu in case I wanted to swap libraries and use pika or something else, but now I wish that I had just gone with amqplib and built a proper Pythonic AMQP model on top of that.
Do spend some time on the RabbitMQ site reading some of the blogs and slide presentations on AMQP before you get too deep into coding or you won't really understand the AMQP model and will make things harder for yourself.
Please don't use xmlrpc unless you have to talk to other apps. Bottle makes simple RESTful apps so simple, that XMLRPC is just uneccessary complexity.
A couple of suggestions.
CherryPy is a great low level framework. It doesn't provide a lot of functionality, but it provide a very easy system for mapping http requests to function calls.
web.py is another extremely lightweight and easy to use framework. It is more comprehensive than CherryPy, including templates and other features.
Plain wsgi is not a bad choice if your needs are extremely simple. It is a little more complicated to do simple stuff than CherryPy or Web.py. WSGI is the lowest common denominator, these days most web frameworks are built on top of it.