by erikwett·Comments Off on Checking performance with Add Sense Chrome extension
One of the uses for the Add Sense Chrome extension is to check performance in your Qlik Sense app or mashup. To help you with this the info boxes show you a few numbers, collected as you use the extension. When you select to show the boxes, it will start collecting statistics, and you will se something like this:
In this post I am using one of Qliks demo apps (you find it here, try it yourself!), so I don’t really expect to find any performance problems.
The Chrome extension will find all both objects defined in the app and session objects, but only ones that are shown on the page. For all such objects it will start collecting statistics:
number of recalculations made
latest calculation time in milliseconds
maximum calculation time
In the top left corner you will see the handle, that’s a number that the QIX Engine assigns to objects as they are opened. If you want to see the actual messages sent for a specific object in the web socket log you need this number. Since the handles are assigned in sequence, you will also get a grip of how many objects you are using in your solution.
Now to try this lets make some selection. Open the selection tool and click on show in the extension menu (yes the extension works in the selection tool too).Make some selections and you will see something like this (excuse me, it’s in swedish):
Confirm your selections and close the selection tool. When you come back to the sheet probably only the app infobox will be visible. When Qlik Sense removes the objects from the page, the infoboxes disappear too. But the extension will continue to collect statistics, so click on show again in the extension menu, and you will se something like this:
Note that objects have only been recalculated once. That’s because the client only recalculate objects that are visible on the screen. The text object on the left should not be recalculated at all, since it was not affected by our selections.
So that’s what you need to do in a real situation:
enable timing for objects on the screen with the show command
make your selections, the extension wil register recalculations
if objects have been off screen, reenable the infoboxes with the show command
analyze the figures. Look for long calculation times or too many recalculations
Once you have started the timing, the only way to stop it is by refreshing the page, using the show command will not stop the monitoring.
by erikwett·Comments Off on Qlik Sense developer tool for Chrome now available
Some years ago I developed a Qlik Sense developer tool extension, mainly to help mashup developers with the problem of finding object id’s to use in their mashup. Over time we added more features to it, so you could now access script and variables, and use it as a tool (of several) for performance troubleshooting.
But it always had the problem that you needed to add the extension to the Qlik Sense app, something that is not always possible or practical. What if we could do this without needing to add anything to the app?
That’s the reasoning behind the Qlik Sense developer tool now available in the Chrome web store. It’s still an extension, but now a Chrome extension and not a Qlik Sense extension. That means if you install it in your browser, it will always be available.
Another advantage with this approach is that it also works with Qlik Sense mashups, using Qlik Sense Capabilities API.
Still you can find object id’s with the extension, and explore properties for objects, sheets and apps. You can also read the script (provided you have access rights) and the variables. And you can now see what extensions and charts are actually used in an app, something that is not easy with the standard client.
One of the more interesting features of Qlik Sense is the session sharing. When you open a Qlik Sense app on your iPad that you have already open on your laptop your selections are already there. And when you make a change on the iPad, the laptop window updates. It feels a bit like magic!
Of course it isn’t magic. Qlik Sense automatically shares your sessions on different devices and rather than creating a new one when you connect from the iPad, it attaches to the one you already have on your laptop. Sessions are shared between browser tabs, browsers and devices. Sharing is made based on three factors:
the app, of course. Sessions are app-based so the the app has to be the same for the connections to share the same sesion
the authenticated user. sessions are not shared between users
the URL used when connecting to the QIX engine
You might very well be using session sharing without really thinking about it. If you open the same app in more then one tab in the browser each tab has it’s own connection to the engine, and engine will connect them in just the same way as connections from different devices. Not that neither device or browser used affect the sharing, it’s just app, user and URL.
But sometimes you want to separate connections to have separate selection state. The way to do this is to make sure that the URL used to connect to QIX Engine is different. The standard URL used to connect to Engine has the format:
wss for secure websocket (ws for Qlik Sense Desktop)
your server hostname or ip address, optionally with a port number (4848 for desktop)
possibly a proxy if you are on a server
and the app id
But you can add something more at the end, to make sure you separate your connections
The Qlik Sense Client actually allows you to do this. You can add an identity to the end of the URL to separate sessions. Let’s make an experiment:
Open an app (any app) in a browser window using the Qlik Sense client
Open the same app in another browser window using a different device, a different browser or a different tab
Verify that selections made in one of the windows affects the other – you have got one single session
Now in one of the browser windows, modify the browser URL by adding ‘/identity/xxxx’ at the end and refresh
Verify that selections made in one window does not affect the other
You have just managed to separate your connections into two different sessions! While this can be very useful to do with the standard client, for some solutions it is essential. You should really always consider this when you are building a Qlik Sense solution using the APIs.
Using the browsers developer tools you can see how this is done. Open the developer tools for the browser where you added ‘/identity/xxxx’ at the end of the URL.
Click on the network tab, and filter on Web Sockets (WS). Find the connection to QIX Engine. You will see that the client has added ‘/identity/xxxx’ to the end, probably encoded to ‘%2Fidentity%2Fxxxx’.
Check the messages received on the web socket. At the begging you will find:
The extension is now included in the dashboard bundle, available with the Qlik Sense installation, and available in Qlik Open Source repositories. It is also supported by Qlik.
This has been a fun project to work on, the functionality it brings was something many customers wanted, and it quickly became one of the most commonly used extensions. It was first realeased over four years ago, in the first days of 2015.
The fact that Qlik now delivers a set of extensions with the product, and supports them, is of course great for customers. One of the few frustrating periods during the last years was when there was a Qlik Sense version that actually broke the extension. That will not happen again.
Thanks to everybody who has contributed to the project with suggestions and in some cases even some code!
by erikwett·Comments Off on All good things must end
After more than two years at IKEA, my work with them has now ended. It has been a fantastic journey, with the introduction of a global Qlik Sense dashboard with support both for desktop and mobile and a set of Qlik Sense extensions with the IKEA profile and covering their needs (well, perhaps not everything, but quite a lot of them). I am very happy to have been a part of this, I think we have been able to do amazing things.
My work at Qlik continues. The Advanced Authoring project moves forward, hopefully you will see some really interesting stuff in upcoming Qlik Sense releases. Looks like I will continue helping them a few months more. After that I’m not yet book, so if you ahve an interesting project starting after the summer where you need help with Qlik Sense development, please let me know.
Apart from that I’m in some discussions about other work in the Qlik Sense area And of course, I’m preparing for Master Summit in Stockholm!
by erikwett·Comments Off on Masters Summit in Stockholm
I’m really happy to be guest speaker when Masters Summit for Qlik comes to Stockholm in April. For those of you who have not heard about Masters Summit, you should really check it out. I took part in Boston in 2017, and it was truly a great event.
In Stockholm they are adding an API track, for developers working more with build applications, mashups and extension using Qlik Sense API’s and Qlik Core. Great content and led by people that really know what they are talking about. And with me in a short session on Qlik Sense use of web sockets….
I am happy to tell you that with Qlik Sense november 2018 this is now obsolete. In most cases you don’t need to do anything to have alternate state support in november 2018, it will work out of the box. For example the wordcloud extension:
You will get a new section in the property panel where you can set the state to use. The default setting, ‘inherited’ will mean that the chart will inherit its state from it’s parent (currently the sheet), but you can also specify what state you want.
November 2018 also includes support for managing alternate states and the selection toolbar shows selections for all
by erikwett·Comments Off on Qlik Sense november 2018 – with qsVariable
One of the new features of Qlik Sense november 2018 is the bundled extensions. If you install the bundle that’s included with the release (and I think you should) you will get a couple of extensions, one of them based on my qsVariable:
Based on, because Qlik has renamed it and made some modifications. Since it has a new name your existing apps that uses qsVariable will continue to do so, you will need to convert them to use the bundled version: You should probably do so, since Qlik will maintain the new version, and test and possibly fix it for new Qlik Sense versions.
A common mistake when you start with Qlik Sense extensions is to forget about setting Initial data fetch in your extension. Typically you would include something like this in the initialProperties of your extension:
That would work, and make sure your extension gets the 500 first rows of data in the layout provided to your paint method. But sometimes you want the app developer to be able to set the number of rows fetched. In that case you can simply add the qHeight parameter to the property panel like this:
And the result is a new section in the property panel, where the app developer can set the number of rows initially fetched.
by erikwett·Comments Off on My best advice to Qlik Sense extension developers
When you work a lot with something you develop opinions about how things should be done. Here is my list, after two years as an independent contractor, mainly with Qlik Sense extensions and mashup, and of course based on my experience from Qlik.
Git is the industry standard for version control, and it’s free.
1. Use version handling
There is no reason not to use version handling of your code. I use Git for everything, but if you are still using something else, that might be OK too. You probably should consider switching to Git, but as a developer that might be a decision taken over your head.
The benefits of using version control are enourmous. You can easily go back and find the reason behind a bug or the implementation behind that feature the customer now wants in another extension too. Invaluable!
You also should keep a version number in your qext file, and change it every time you deploy a new version. The main benefit of this is that you can see what version of your extension is in use in a Qlik Sense installation. I have described how to do this in a previous post.
2. Always test your extension in a browser
3. Stay in your sandbox
do not inject HTML elements outside of your own element
prefix your CSS rules so that it affects only the extension
avoid html id’s, since they must be unique within the page. If you must use one (really only when you use a library that needs an id) make sure they are unique for each extension instance (test with multiple instances of the same extension)
There are occasions when you need to break theses rules, but only do it when it’s need for your extension functions.
4. Use modern development tools
Pretty soon after you have started with extension development you will grow out of the Qlik Sense dev-hub extension editor. A modern, nodejs-based environment, with a good text editor gives you a lot of benefits, and works well with version handling software. I would recommend the following:
a good editor. I mostly use Visual Studio Code, but there are others that probably are just as good.
a CSS preprocessor like less helps you with prefixing css, add vendor prefixes etc
a lint tool, to find common errors an enforce good programming practices
5. Always keep your extension backwards compatible
After a while your users will most likely want more functionality in your extension. They might want more interactivity, more rendering options, perhaps support for more dimensions and measures. You will probably add new settings giving your extension more flexibility. You might also find that some of the stuff you originalyy programmed was not perfect (that happens to all of us..). But if you have deployed your extension to production, make sure that all your changes are backward compatible. If you don’t you will have huge problems when you deploy the new version, with breaking apps.
If you find it impossible to make your new extension backwards compatible you probably should not be making a new version, but a new extension, with a different name.
6. Base your rendering on only the layout
The model behind Qlik Sense extensions (and the built-in charts too, actually) is that the extension is based on a Generic Object, where you configure the Generic Object in the property panel and use the layout for rendering. Stick to that model, do not break it. If you need more data for your rendering, add it to the properties structure. Avoid:
creating HyperCubes and ListBox objects programatically, add them to initialProperties and the property panel instead
fetching variable values programatically, add expressions to the property structure instead (that also gives the app developers more options, like hard-coding values, or making them change automatically as selection state (or data) changes
It is however OK, even recommended, to call API methods for:
showing lists of available values in the property panel
making selections etc when the users clicks on buttons, menues or other parts of your UI