wlanslovenija/django-datastream

Django HTTP interface to time-series Datastream API.

django-datastream's Issues

Do not transmit all tags when loading just data

Currently we transmit all tags again and again as the user is moving the view around. This is probably unnecessary.

Make all related libraries as git submodules

Or use some other way of dependency management.

Use stream metadata information about last value for HTTP caching headers

Use stream metadata information about last value for HTTP caching headers.

Incorrect display in case there is only one datapoint

When the stream only has one datapoint, the graph is not displayed at all. Some kind of warning or notice overlay should probably be displayed instead.

Incorrect display in case all datapoints have the same value

When all datapoints have the same value (for example 1.0), the displayed graph is missing (no datapoints are displayed and the axes are not visible).

Make all strings translatable

Implement waiting for new data

I was thinking that the best way to implement waiting for new data would be to add new HTTP command, for example FETCH. So when you do a GET request with start time interval parameter, you get all data from that interval to current time. If there is no data it returns you an empty list. But by doing FETCH to same URL, django-datastream would wait until data is available and then return you the data. And after it returns the data, you could open another connection with updated start time interval parameter.

Of course, it is not smart to block Django process while both client and server are waiting for data, so another approach should be used. I see two options:

• implement custom Tornado based web server which handles FETCH requests in a asynchronous manner, similar to how django-pushserver implements it, we can then use this server instead of fast cgi process to interact with Django
• instead of reimplementing Tornado integration, just use django-pushserver directly, redirecting on FETCH request to django-pushserver channel and requesting that new data is send to that channel

The tricky thing here is scalability, when you have multiple instances of this asynchronous server, you want that when data comes, that it is pushed to all clients listening on all instances of an asynchronous server (I am not sure if this is handled correctly in django-pushserver even).

Improve content of exported and printed image

Improve content of exported and printed image. We should decide if we want to make 1:1 copy (with all controls) or without controls. Currently some controls are missing, but on the other hand scrollbar is there. Additionally, size of the image does not match displayed and some datapoints are drawn outside the image.

Add export data link

For now, it can be really something so simple as a link to REST API URL for given displayed datapoints.

Enable graph embedding

Enable users to include the graph in other webpages by preparing an embedding code snippet. Useful for sharing graphs on screens for monitoring and other webpages.