I am new to Python's async, so bear with me please...
So, I am trying to extend the functionality of a class, let's say it's defined as such:
class OrigClass:
...
async def another_method(self, *args):
# Some code irrelevant to that I want to do
...
async def a_method(self, *args):
# Some heavyweight logic which I have no desire to copy
...
# After all that logic, it 'passes the torch' to yet another
await self.another_method(*args)
I want to add some checks to a_method through subclassing, like this:
class SubClass(OrigClass):
...
#asyncio.coroutine
def a_method(self, *args):
# Some checking / mangling of args here
...
# No 'heavyweight logic' done here;
# heavyweight logic is done in OrigClass.a_method
yield from super().a_method(*mangled_args)
Is this the proper way to implement what I want to do?
actually I would to retrieve two params from the #ManagedService path, but i get only null value.
The code is something like:
...
import org.atmosphere.config.service.PathParam;
import org.atmosphere.config.service.ManagedService;
import org.atmosphere.config.service.Singleton;
#Singleton
#ManagedService(path = "/chat/{myId}/{destId}")
public class Chat {
#PathParam("myId")
private String mittId;
#PathParam("destId")
private String destId;
#Ready
public void onReady(AtmosphereResource r) {
logger.info("User {} want to chat with {}", mittId,destId);
}
Debugging "mittId" and "destId" are null.
There's some error on the code or something that I forget?
Actually I'm using Atmosphere-runtime 2.3.0.
Thanks to anybody that will help!
The client is correct. I resolve removing #Singleton annotation. Now while I'm debugging I can see the value of the two params.
Either you are not sharing the enough or the original back-end code or your client application is calling the chat resource incorrectly.
I tested your example and both path parameters are populated.
Please have a look at the example in the Atmosphere Github page about the the multichatroom, especially the client implementation.
I might be confused about something, but when I store a custom object from the Java Riak client and then try to read that object using the Python Riak client, I end up with a raw json string instead of a dict.
However, if I store a the object in python, I am able to output a python dictionary when fetching that object.
I could simply use a json library on the python side to resolve this, but the very fact that I am experiencing this discrepancy makes me think that I am doing something wrong.
On the Java side, this is my object:
class DocObject
{
public String status; // FEEDING | PERSISTED | FAILED | DELETING
public List<String> messages = new ArrayList<String>();
}
class PdfObject extends DocObject
{
public String url;
public String base_url;
}
This is how I am storing that object in Riak:
public void feeding(IDocument doc) throws RiakRetryFailedException {
PdfObject pdfObject = new PdfObject();
pdfObject.url = doc.getElement("url").getValue().toString();
pdfObject.base_url = doc.getElement("base_url").getValue().toString();
pdfObject.status = "FEEDING";
String key = hash(pdfObject.url);
pdfBucket.store(key, pdfObject).execute();
}
And this is what I am doing in Python to fetch the data:
# Connect to Riak.
client = riak.RiakClient()
# Choose the bucket to store data in.
bucket = client.bucket('pdfBucket')
doc = bucket.get('7909aa2f84c9e0fded7d1c7bb2526f54')
doc_data = doc.get_data()
print type(doc_data)
The result of the above python is:
<type 'str'>
I am expecting that to be <type 'dict'>, just like how the example here works:
http://basho.github.com/riak-python-client/tutorial.html#getting-single-values-out
I am perplexed as to why when the object is stored from Java it is stored as a JSON string and not as an object.
I would appreciate if anybody could point out an issue with my approach that might be causing this discrepancy.
Thanks!
It would appear you've found a bug in our Python client with the HTTP protocol/transport.
Both the version you're using and the current one in master are not decoding JSON properly. Myself and another dev looked into this this morning and it appears to stem from an issue with charset parameter being returned from Riak with the content-type as Christian noted in his comment ("application/json; charset=UTF-8")
We've opened an issue on github (https://github.com/basho/riak-python-client/issues/227) and will get this corrected.
In the mean time the only suggestion I have is to decode the returned JSON string yourself, or using the 1.5.2 client (latest stable from pypy) and the Protocol Buffers transport:
client = riak.RiakClient(port=8087, transport_class=riak.RiakPbcTransport)
it will return the decoded JSON as a dict as you're expecting.
A Grails controller received is called with the following request parameters:
defaultPrice[0].amount 22
defaultPrice[0].currency 1
defaultPrice[0].id
defaultPrice[1].amount 33
defaultPrice[1].currency 3
defaultPrice[1].id
I've defined the following command class:
class PriceCommand {
BigDecimal amount
Integer currency
Integer id
}
I attempt to bind the request parameters to a `List' in the action
def save = {List<PriceCommand> defaultPrice ->
}
But within the action, defaultPrice is null.
It requires an command with existing list of data, with specified name, that will be filled with data from request.
Try
import org.apache.commons.collections.ListUtils
import org.apache.commons.collections.Factory
class PriceListCommand {
List<PriceCommand> defaultPrice = ListUtils.lazyList([], {new PriceCommand()} as Factory)
}
and use this command inside controller. It should works
I'm not sure if this is what your looking but it may help...
1.) I think indexed params only work if you have a parent-child or one-to-many relationship. For example you might need to introduce a PriceCommandParent which contains a list of PriceCommand. I may be wrong on this and I welcome any corrections.
2.) I've found that indexed params aren't as magically as some of the other areas of Grails/Groovy so sometimes i'd rather deal with the mapping myself. Below is how i've handled it in the past....
def things = []
params.each{name, value->
if (name.matches('^(thing\\[\\d+\\])$')){ //<-- look for 'thing[x]'
things.add(new Thing(params[name]);
}
}
Let me know if any of this is of help
Let's say I have a simple controller like this:
class FooController {
def index = {
someVeryLongCompution() //e.g crawl a set of web pages
render "Long computation was launched."
}
}
When the index action is invoked, I want the method to return immediately to the user while running the long computation asynchronously.
I understand the most robust way to do this would be to use a message broker in the architecture, but I was wondering if there is a simpler way to do it.
I tried the Executor plugin but that blocks the http request from returning until the long computation is done.
I tried the Quartz plugin, but that seems to be good for periodic tasks (unless there is a way to run a job just once?)
How are you guys handling such requests in Grails?
Where do you want to process veryLongComputation(), on the same Grails server, or a different server?
If the same server, you don't need JMS, another option is to just create a new thread and process the computation asynchronously.
def index = {
def asyncProcess = new Thread({
someVeryLongComputation()
} as Runnable )
asyncProcess.start()
render "Long computation was launched."
}
If you use a simple trigger in Grails Quartz and set the repeatCount to 0, the job will only run once. It runs separate from user requests, however, so you'd need to figure out some way to communicate to user when it completed.
I know this is a very old question, just wanted to give an updated answer.
Since grails 2.3, the framework supports async calls using Servlet 3.0 async request handling (of course, a servlet 3.0 container must be used and the servlet version should be 3.0 in the configuration, which it is per default)
It is documented here : http://grails.org/doc/latest/guide/async.html
In general, there are two ways achieving what you asked for:
import static grails.async.Promises.*
def index() {
tasks books: Book.async.list(),
totalBooks: Book.async.count(),
otherValue: {
// do hard work
}
}
or the Servlet Async way:
def index() {
def ctx = startAsync()
ctx.start {
new Book(title:"The Stand").save()
render template:"books", model:[books:Book.list()]
ctx.complete()
}
}
Small note - The grails method is using promises, which is a major (async) leap forward. Any Promise can be chained to further promised, have a callback on success and fail etc'
Have you tried Grails Promisses API? It should be as simple as
import static grails.async.Promise
import static grails.async.Promises
class FooController {
def index = {
Promise p = Promises.task {
someVeryLongCompution() //e.g crawl a set of web pages
}
render "Long computation was launched."
}
}
Try Spring events plugin - It supports asynchronous event listeners.
If you'd like to use the Quartz plugin (as we always do), you can do it like this. It works well for us:
DEFINE A JOB (with no timed triggers)
static triggers = {
simple name:'simpleTrigger', startDelay:0, repeatInterval: 0, repeatCount: 0
}
CALL <job>.triggerNow() to manually execute the job in asynchronous mode.
MyJob.triggerNow([key1:value1, key2: value2]);
Pro Tip #1
To get the named parameters out the other side...
def execute(context) {
def value1 = context.mergedJobDataMap.get('key1');
def value2 = context.mergedJobDataMap.get('key2');
...
if (value1 && value2) {
// This was called by triggerNow(). We know this because we received the parameters.
} else {
// This was called when the application started up. There are no parameters.
}
}
Pro Tip #2
The execute method always gets called just as the application starts up, but the named parameters come through as null.
Documentation: http://grails.org/version/Quartz%20plugin/24#Dynamic%20Jobs%20Scheduling
The best solution for this kind of problem is to use JMS, via the JMS plugin.
For a simpler implementation, that doesn't requires an externel server/service, you can try the Spring Events plugin.
Grails 2.2.1 Solution I had an additional requirement that said the report had to auto pop a window when it was complete. So I chose the servlet way from above with a twist. I replaced the render a view with a json formatted string return it looked like this.
Additionally my client side is not a gsp view, it is ExtJS 4.1.1 (a HTML5 product)
enter code here
def index() {
def ctx = startAsync()
ctx.start ({
Map retVar = [reportId: reportId, success: success];
String jsonString = retVar as JSON;
log.info("generateTwoDateParamReport before the render out String is: " + jsonString);
ctx.getOriginalWebRequest().getCurrentResponse().setContentType("text/html");
ctx.getOriginalWebRequest().getCurrentResponse().setCharacterEncoding("UTF-8");
log.info("current contentType is: "ctx.getOriginalWebRequest().getCurrentResponse().contentType);
try {
ctx.getOriginalWebRequest().getCurrentResponse().getWriter().write(jsonString);
ctx.getOriginalWebRequest().getCurrentResponse().getWriter().flush();
ctx.getOriginalWebRequest().getCurrentResponse().setStatus(HttpServletResponse.SC_OK);
}
catch (IOException ioe)
{
log.error("generateTwoDateParamReport flush data to client failed.");
}
ctx.complete();
log.info("generateNoUserParamsReport after complete");
});
}