I am downloading some data and internet connection breaks in between,how to resume download from current state in core data model?
The core data model and the download have nothing to do with each other. You would have to distinguish these steps:
Make a download request.
The download ends with success or error.
Handle the data - e.g. store it in core data.
if finished successfully, you are done
if not continue
Notice that you can download again.
Form a new download request, requesting only the missing data from the server
Go to step 2.
Step 1 will be handled with a NSURLRequest.
Step 2 can be caught in the NSURLConnection delegate methods.
Step 3 is should be routine if you were successful. If not, you would have to analyze your data object to see what you can salvage and save.
Step 4 can be accomplished with the Reachability class. Check Apple's sample code.
Step 5 requires that your server can handle the selective data requests.
There are a lot of details to the single steps. Best scavenge on stackoverflow and consult the documentation to code the individual steps. I hope this scheme is helping you to sort things out.
Related
As the title says I am trying to am creating a Dashboard.
The Dashboard should include an option to view Data inserted in a Database, live or at least "live" with minimal delay.
I was thinking about 2 approaches:
When the option is used the Back-End creates a Trigger in the Database(its only certain Data so i would have to change the Trigger according to the Data). Said trigger should then send the new Data via http to the Back-End.
What i see as a problem is that the delay of sending the Data and possible errors could block the whole database.
1.1. Same as 1. but the trigger puts the new Data in a seperate Table where i can then query and delete the Data.
Just query for the newest data every 1-5 sec. or so. This just seems extremly bad and avoidable.
Which of those is the best way to do this? Am i missing something? How is this usually done?
The Database is a pgsql Database,Back and Front-end are in NodeJs.
I am trying to get data from a website into a table in Excel. I am just using the regular button (get data - from web) in Excel (No code) Works fine for two websites but for a different website I am getting the following error:
Details: "The remote server return an HTTP status code '404' when trying to access 'https://smarkets.com/listing/sport/football/premier-league-2017-2018'."
The webpage certainly exists - I am guessing this is a deliberate strategy by the website to prevent data harvesting.
Anyone have any idea how I can get round it either through the get data route or a VBA approach?
Thanks
JL
I inspected traffic with Fiddler and Postman to no avail and in the end contacted the team direct for an answer.
The short answer, from their API team, is no.
Eventually our API, which may be suitable for your needs, will be
available to everyone.
API is in closed alpha stage as I mentioned in comments. More information here: API feed.
API/Odds Feed We're currently working on a new streaming API that is
faster and more scalable. The API is currently in a closed alpha
stage. Unfortunately there is no timeframe on when we'll be able to
release it to the public.
We will prioritise market makers when issuing streaming API accounts.
If you would like to gain alpha access to this service, you can apply
by outlining your proposal here
You can gain access to their XML feed with odds.smarkets.com/oddsfeed.xml .
The feed is updated every few seconds but the information is delayed
by 30 seconds.
We are observing that there are three API calls happening when we execute an offline sync selective pull query
GET domain/tables/Events?$filter=updatedAt%20ge%20datetimeoffset'1969-12-30T22:00:00.000Z'
GET domain/tables/Events?$filter=updatedAt%20ge%20datetimeoffset'2017-06-27T22:00:00.000Z' (current datetime)
GET domain/tables/Events?$filter=updatedAt%20ge%20datetimeoffset'2017-06-27T22:00:00.000Z'&$skip=1
These 3 calls happen every time a pull is done, can anyone explain why this happens? The selective sync query is created in the following format
syncContext
.pull(new WindowsAzure.Query('Events'), 'eventspull')
.then(function() { /* pull complete */ });
We are using latest version of the following javascript offline library. https://zumo.blob.core.windows.net/sdk/azure-mobile-apps-client.js
These 3 calls happen every time a pull is done, can anyone explain why this happens?
This happens because the "pull" function pulls one page from the server table at a time. You can check out the source code here for details.
Let’s say you have thousands of records. If you execute the query without paging, then it is likely you will tie up your client process on the phone for a considerable period of time as you receive and process the data. To alleviate that and allow your mobile application to remain responsive, the client SDK implements paging. By default, 50 records will be requested for each paged operation. In reality, this means that you will see one more request than you expect.
For more info, pelease refer to Understanding offline sync.
We have a WEBAPI service running on a windows asp.net MVC solution. There is a load method that takes about 40 minutes to complete and return status on the called page. During that time the browser window is tied up. What design options do we have if we want the web page to come back with submitted and the process to continue to run and complete. I don't care if page never shows complete, we can pull that from another status page.
I've done something similar in the past, even though in my case the delay was shorter - 40-50 seconds of loading of fresh data from multiple backend servers in a VPN. It was also in ASP.NET back then, but I believe that the approach is still feasible and you can get some ideas if I share my experience. I remember an old thread that I had favourited in the past and used the insight from it. You can check it out.
Here are some tips, but in short, because I don't remember the details anymore (excuse my google-assisted memory!):
You should start the task in a new thread and not wait for it in your main thread.
You should also make sure that the task is started only once and cannot be initiated infinite number of times by the user via refresh or via the UI. So, you better persist the state in the database, so at refresh, the new thread is created only if the database says that it has not been executed recently or it is not in progress.
Your page will be loaded and show its contents and you can display a .gif representing a progress bar, a loading wheel or something similar to the user.
The task you started will continue on the server. When it completes you can push and update the UI via ajax from within the code-behind to make the experience even smoother if you like.
On subsequent requests, you can just retrieve the state of your task from the database in order to display something like update completed at hh:mm:ss.
Hope this helps you and I wish you the best of luck!
I am coding for a Netty based Notifying Server, which takes in Message Buffer many hundreds at a second from a Server(A) through RPC, and then sends it to an Http Real Time Server, after checking for the validity(the validation consists of checking for a tag ID and its value). If the validation is not successful, the System needs to send an error feedback back to the Server(A) with an Error Code.
I intend to write the validation logic inside a handler, but how do we make the handler to send the feedback if message is found to be invalid?
Can we include database code also into a handler, so I can persist the validation specific details to a Database? Will adding this DB code handicap the Netty performance? If Yes, what's the better way of using a Database (insert) code inside a handler?
Please can anyone guide me? Can I write the DB code inside an Executor?
Kindly excuse me if I am asking a too basic questions. I am still on Learning phase.
Let me try to answer the questions.
1) I think it does not not matter if you want to send an ERROR or SUCCESS response. Just use Channel.write(..) to write it and have an encoder that can handle the encoding to a ChannelBuffer. There is not difference here
2) You should add an ExecutionHandler in front to make sure your db calls do not block the IO-Thread. See [1].
[1] http://netty.io/docs/stable/api/org/jboss/netty/handler/execution/ExecutionHandler.html