Lately I've been reading a lot of information about App Engine; the Google service that looks very promising to me. However, it all seems too good to be true. Call me a negative person, but I would like to know any reasons NOT to use App Engine.
This is programmers related, since I'm asking as in the programmer point of view.
I just want the general "downsides" of App Engine, if any.
No relational database. (No normal ORM ...)
Limits on the number of files. (Can't just upload the 6,000 files in some standard packages...)
Specific VM required. (Depending on your language you may be a non-starter.)
Runtime limits. (Don't get bogged down.)
SSL only through https://your-app-id.appspot.com (Not directly to your domain.)
Root domains via URL redirection only
I am not criticizing GAE, I'm just listing limitations as the OP asked...
You are designing your app to a Google-specified framework. Presently you can ONLY run an app-engine application on Google's infrastructure. That means you are completely dependent on Google (at least for the moment). Whether that's a problem or not is dependent on the project in question, but it's something you had best be aware of. Google has been known to cancel things in the past (though that seems unlikely with App Engine).
Related
We are starting a new project that requires two main components:
Backend for task management, e.g retrieve a task from a queue and according to some specific logic validate it.
Run a real compiler on that specific task and create an executable that an end user should receive.
We love app engine, however the second part will require a concrete instance where an actual compiler will have to be installed, app engine is not capable here. We were thinking to mix both app engine and aws instances to accomplish the task (part 1 will be app engine and part 2 will be aws).
All of our senses say it's a bad idea:
unneeded traffic between the two providers, someone needs to pay for that unfortunately.
We'll have to deal with two systems, two deployments process, each system has its own quirks --> double the work.
But we love app engine.
Does anyone has any experience in combining the two systems? any recommendations ?
There's no reason why what you suggest won't work, especially if you separate your concerns well, by exposing a clean 'compiler' interface on AWS or a similar service. Yes, you will have to pay for traffic between the two services, but this is unlikely to be substantial. If you are serving up the end result to the user, you can link them directly to AWS, rather than fetching it with your app first.
AWS's EC2s are literally just vanilla linux boxes in the sky. I would also throw out the suggestion of just moving to it completely. Porting your system over may be easier than it sounds if you're unix savvy.
It's still unclear to me when I should or should not use Google App Engine to deploy a commercial web application.
It appears Google has "business" level support.
http://code.google.com/appengine/
Can someone bullet list when I should use Google App Engine and when I shouldn't use it for a web application
The question is surprisingly simple to answer after I've had a stab at google engine with my project for a few weeks. You should use it when:
you can't be arsed to set up a server
you want instant for-free nearly infinite scalability
your traffic is spikey and rather unpredictable
you don't feel like taking care of your own server monitoring tools
you need pricing that fits your actual usage and isn't time-slot based
you are able to chunk long tasks into 30 second pieces
you have the skill/will/desire to work with noSQL and deal with the consequences thereof
you are able to work without direct filesystem access
So actually, you can use it pretty much for anything, especially websites. The only thing it very quickly becomes too pricey for is running large background processes. If you're doing some hardcore number crunching 24/7 you're better off using your own server somewhere because no cloud service can really live up to that.
But think of it this way, where else are you going to get an architecture that can swallow 10+ requests per second load for ten dollars a month?
Basically it boils down to this: If you want to focus on developing your code, not your server architecture. GAE is for you. (unlike amazon which behaves more like a fancy VPS)
I can't really tell you whether you should use App Engine without knowing anything about what you need your web app to do, but I will tell you what App Engine can and can't (or won't) do.
App Engine is fantastically good at scaling. It is, in fact, designed to scale web apps to ridiculous lengths first and foremost, with ease of use and number of features being secondary goals.
That's not to say that App Engine doesn't have features, or isn't easy to use, just that if there ever becomes a choice between adding a feature and staying scalable, the App Engine team will choose scalability.
For example, App Engine doesn't have some of the features of a relational database, because those features don't scale to the size of an app that App Engine is designed to support. App Engine doesn't support requests taking more than 30 seconds, because App Engine is designed to serve a web app, not process long-running requests.
In general, when App Engine doesn't support something, it's not because it's impossible -- nothing is impossible -- but rather because it would detract from the scalability of App Engine.
There are workarounds that can be (and have been) implemented to get around this, particularly with things like the task queue, and App Engine is constantly getting new features and new frameworks built on top of it.
App Engine for Business adds SLAs and different pricing, but is otherwise pretty much the same App Engine.
What is the current status of grails and google app engine deployment. I am new to app engine but wonder worth exploring it. Some specific qns are
the latest plugin, which has high user rating, has any restrictions? or it work seamlessly with all gorm features
is there any issue with high startup time for grails application. How is it in real world scenario? (with a typical small and large scale application)
what about other grails plugins (like, shiro, joda time, nimble etc). I guess they wont play well. So using those libraries directly is the better option
If decided to give up goole-app as a deployment option, how easy to switch to a normal environment. The JPA support ensures the compatibility with other traditional DBs?
Not sure what else are major issues.. probably, this is the foundation for a good discussion.
thanks.
I got few good response from grails mailing list, and the conclusion shares the comment by David. see the thread here
Couple of relevant responses:
From Tomas Lin:
I would suggest looking into Gaelyk if you really want to build a
project on the App Engine. It is built from the ground up with the App
Engine as the target engine, so it can bypass problems like long
loadtimes due to Spring and Hibernate. The newly introduced plugin
mechanism guarantees that your Gaelyk applications can be extended in
a way guaranteed to work on GAE.
Gaelyk has it's own native entity persistence DSL, which is a little
cleaner that the JPA/JDO abstractions on top of the App Engine.
I currently see many HardDeadlineExceeded exceptions with the App
Engine and Grails. It is just not designed to work well with Spring
right now. Hopefully this will improve with the later releases of
Groovy, Grails and the Spring / Google partnership for GAE for
business, but I wouldn't consider Grails on GAE production ready.
Even with Gaelyk, there are reports of slow performance. So imagine
the difficulties that arise with the much bigger Grails stack.
The app-engine comes with it's own implementation of a user / security
management system based on GMail accounts. If you just want to provide
an admin / non-admin implementation, this is supported in the
appengine configuration. Cannot comment on Shiro.
Be aware that one of the major restrictions of the App Engine is the
inability to write a file, so even basic file uploading in Spring
becomes problematic since the default mechanism writes to a temporary
file. I would imagine that most of the plugins would not work out of
the box without digging into their code and changing it.
I think the biggest issue here is lack of support for native JDBC. JPA
is not as well supported as plain JDBC GORM, things like named queries
would probably not work out of the box without retrofitting. If you
want to use the latest and greatest parts of Grails, it might be
worthwhile to consider other hosting solutions.
From Aaron Eischeid
1.The GAE plugin and the JPA-GORM plugins combined do not get you all GORM features seamlessly. Though you should get basics like .save(), .delete(), and maybe .list() the dynamic finders etc. are going to be out (at least for now). I could be way off here, but I think most/all Hibernate dependent features are out or replaced by something else (since it relies on SQL under the hood and GAE doesn't currently have SQL based DB...) so for example any criteria builders are a no go. It is unclear to me how much of the dot drilling you can do on objects. For example, not sure if you could do something like:
def b = new Book()
def stores = b.authors.publishers.bookstores
One place I could use some pointers is how to use JPA in the domain classes. I am sure there is good info out there, but I just haven't found it yet.
unsure
grails plugins that include domain classes or manipulate your current domain classes are bound to have issues since you have to construct your domain classes differently to play nice with JPA which is necessary because Googles Datastore isn't quite like a relational DB. On the flip side. you can use Google's built in security so you shouldn't necessarily need plugins like Acegi or Shiro.
This probably boils down to the different levels of GORM that you can use in controllers and services and the different ways you define domain classes. Some refactoring seems inevitable unless JPA plays just as nice with SQL DB's as it does with Googles Datastore. If JPA can move like that then transferring should be easy, but by using JPA-GORM you give up some stuff you would probably want if you weren't benefiting from due to being on GAE.
Eager to hear what others have to say,
Aaron
I am thinking of making an (initially) small Web Application, which would eventually have a potential to grow. All things considered Google App Engine seems like a very attractive option. Say, user base and complexity grows and for one or other reason I needed to leave GAE behind. How difficult would it be to migrate away?
1) Does GAE provide a way to export the database? What format would it be? Would it be difficult to put it under MySQL (or similar)?
2) In which areas (ex. database access, others?) would I have to use GAE API? I.e. which parts of implementation would have to be abstracted away / interfaced?
Edit: 3) Alternatively, is it even worth to abstract away GAE API?
For question #1: I don't know if GAE specifically supports exports of a database but you can always roll your own, worst case scenario. If you are in a position where you need to, you'll probably have the resources to do it, too.
For question #2: You can and should always encapsulate those kinds of outside dependencies anyway. It doesn't matter whether or not they provide interfaces. Coupling to those interfaces should be kept to an absolute minimum.
For question #3: This question is not really super-clear so I cannot answer it.
I'm speaking strictly from a java webapp point of view...
Google App Engine for python has a backup/restore utility:
http://code.google.com/appengine/articles/gae_backup_and_restore.html
There is a huge interested in porting this to the java flavor.
You can use the higher level standard database apis (JDO/JPS) to allow you to move your app away from google's database services. I suggest purchasing the data nucleus tools in order to smooth the transition from big tables to something like mysql or oracle.
The packaged services GAE provides are enumerated at
http://code.google.com/appengine/docs/java/javadoc/
The stock JRE should handle porting of the urlfetch, mail, and memcache api packages.
You'll have to find a substitute technology for the users, blobstore, xmpp, and taskqueue packages.
I am trying to scrape some website and republish the data as a RSS feed. How hard is this to setup with Google App Engine? Disadvantages and Advantages using GAE. Any recommendations and guidelines greatly appreciated!
Google AppEngine offers much more functionality (and complexity) than you will need if truly all you will want to do is republish some structured data as RSS.
Personally, I would use something like Yahoo pipes for a task like this.
That being said... if you want/need to get your feet wet with GAE, go for it!
Working with Google App Engine is pretty straight forward. I would recommend going through the Getting Started guide. It's short and simple and touches on essential GAE topics. There are more pros and cons than I will list here.
Pros:
In general, App Engine is designed for high traffic web applications that need to scale. Furthermore, it is designed from a programmer's perspective. Much of the scalability issues (database optimization, server administration, etc) are dealt with by Google. Having said that, I find it to be a nice platform. It is still being actively developed by Google engineers, and scheduling of tasks (a feature that has been long requested) is in the current road map.
Cons:
Perhaps the biggest downside right now is again the lack of official scheduling support and the quota limits currently set for free accounts. However you can't complain much if its free. Currently it only supports Python as a programming interface (although a new language [Java I predict] is coming soon). Furthermore, Python 2.6 (and 3.0 for that matter) are not yet supported. In addition, Django 1.0 is not officially supported in App Engine (although you can package Django 1.0 with your application).
Harder than it would be in most other technologies.
GAE can sort of do scheduled batch stuff like this now, but it's really not intended for that type of thing. Pick pretty much any other language and platform for this particular task, and you'll make your life a lot easier.
I think BeautifulSoup could run on GAE, so all your scraping needs are handled :D
Also, GAE has a geturl thingy. The only problem I think you might have is not having enough time to get the data (30 secs limitation).
I am working on a same project and I've decided that it's easier to prepare the data on another server and push them to GAE.
You might also want to look into Yahoo! Query Language (YQL)