Note: In practice, most React apps only call ReactDOM.render() once. In the next sections we will learn how such code gets encapsulated into stateful components. We recommend that you don’t skip topics because they build on each other.
Elements are the smallest building blocks of React apps.
An element describes what you want to see on the screen:
Unlike browser DOM elements, React elements are plain objects, and are cheap to create. React DOM takes care of updating the DOM to match the React elements.
One might confuse elements with a more widely known concept of “components”. We will introduce components in the next section. Elements are what components are “made of”, and we encourage you to read this section before jumping ahead.
Rendering an Element into the DOM
Let’s say there is a somewhere in your HTML FinRL 入门指南 file:
We call this a “root” DOM node because everything inside it will be FinRL 入门指南 managed by React DOM.
Applications built with just React usually have a single root DOM node. If you are integrating React into an existing app, you may have as many isolated root DOM nodes as you like.
To render a React element into a root DOM node, pass both to ReactDOM.render() :
It displays “Hello, world” on the FinRL 入门指南 page.
Updating the Rendered Element
React elements are immutable. Once you create an element, you can’t change its children or attributes. An element is like a single frame in a movie: it represents the UI at a certain point in time.
With our knowledge FinRL 入门指南 so far, the only way to update the UI is to create a new element, and pass it to ReactDOM.render() .
Consider this ticking clock example:
It calls ReactDOM.render() every second from a setInterval() callback.
In practice, most React apps only call ReactDOM.render() once. In the next sections we will learn how such code FinRL 入门指南 FinRL 入门指南 gets encapsulated into stateful components.
We recommend that you don’t skip topics because they build on each other.
React Only Updates What’s Necessary
React DOM compares the element and its children to the previous one, and only applies the DOM updates necessary to bring the DOM to the desired state.
You can verify by inspecting the FinRL 入门指南 last example with the browser tools:
Even though we create an element describing the whole UI tree on every tick, only the text node whose contents has changed gets updated by React DOM.
In our experience, thinking about how the UI should look at any given moment rather than how to change it over time eliminates a whole class of bugs.
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Load balancing in Orleans
Load balancing, in a broad FinRL 入门指南 sense, is one of the pillars of the Orleans runtime. Orleans runtime tries to make everything balanced, since balancing allows to maximize resource usage and avoid hotspots, which leads to better performance, as well as helps with elasticity. Load balancing in Orleans applies in multiple places. Below is a non-exhaustive list of places where the runtime performs balancing:
Default actor placement strategy is random - new activations are placed randomly across silos. That results in a balanced placement and prevents hotspots for most scenarios.
A more advanced ActivationCountPlacement tries to equalize the number of activations on all silos, which results in a more even distribution of activations across silos. This is especially important for elasticity.
Grain Directory service is built on top of a Distributed Hash Table, which inherently is balanced. The directory service maps grains to activations, each silo owns part of the global mapping table, and this table is globally partitioned in a balanced way across all silos. We use consistent hashing with virtual buckets for that.
Clients connect to all FinRL 入门指南 gateways and spread their requests across them, in a balanced way.
Reminder service is a distributed partitioned runtime service. The assignment of which silo is responsible to serve which FinRL 入门指南 reminder is balanced across all silos via consistent hashing, just like in grain directory.
Performance critical components within a silo are partitioned, and the work across them is locally balanced. That way the silo runtime can fully utilize all available CPU cores and not create in-silo bottlenecks. This applies to all local resources: allocation of work to threads, sockets, dispatch responsibilities, queues, etc.
StreamQueueBalance balances the responsibility of pulling events from persistence FinRL 入门指南 queues across silos in the cluster.
Also notice that balancing, in a broad sense, does FinRL 入门指南 not necessarily mean loss of locality. One can be balanced and still maintain a good locality. For example, when balancing means sharding/partitioning, you can partition responsibility for a certain logical task, while still maintaining locality within each partition. That applies both for local and distributed balancing.
Refer to this presentation on Balancing Techniques in Orleans for more details.
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PowerShell Client Module
The Orleans PowerShell Client Module is a set of PowerShell Cmdlets that wraps GrainClient in a set of convenient commands making possible to interact with not just ManagementGrain but any IGrain just as a regular Orleans application can by using Powershell scripts.
These FinRL 入门指南 FinRL 入门指南 Cmdlets enable a series of scenarions from start maintenance tasks, tests, monitoring or any other kind of automation by leveraging Powershel scripts.
Here is how to use it:
Installing the module
You can build from source the OrleansPSUtils project and just import it with:
Althought you can do that, there is a much easier and interesting way for FinRL 入门指南 doing that by installing it from PowerShell Galery.
From PowerShell Galery
Powershell modules today are FinRL 入门指南 FinRL 入门指南 easily shared just as Nuget packages but instead of nuget.org, they are hosted on PowerShell Gallery.
- To install it on a specific folder just run:
- To install it on your PowerShell modules path (the recommended way), just run:
Using the module
Regardless of the way you decide to install it, the first thing you need to do in order to actually use it is import the module on the current PowerShell session so the Cmdlets get available by running this:
Note: In case of building FinRL 入门指南 from source, you must import it as suggested on the Install section by using the path to the .psd1 instead of using the module name since it will not be on the $env:PSModulePath PowerShell runtime variable. Again, it is highly recommended that you install from PowerShell Gallery instead.
After the module is imported (which means it FinRL 入门指南 is loaded on PowerShell session), you will have the following Cmdlets available:
This module is a wrapper around GrainClient.Initialize() and its overloads.
Start-GrainClient FinRL 入门指南
- The same as call GrainClient.Initialize() which will look for the known Orleans Client FinRL 入门指南 configuration file names
Start-GrainClient [-ConfigFilePath] [[-Timeout] ]
- Will use the provided file path as in GrainClient.Initialize(filePath)
Start-GrainClient [-ConfigFile] [[-Timeout] ]
- Use an instance of the System.FileInfo class representing the config file just as GrainClient.Initialize(fileInfo)
- Use an instance of a Orleans.Runtime.Configuration.ClientConfiguration like in GrainClient.Initialize(config)FinRL 入门指南 FinRL 入门指南
Start-GrainClient [-GatewayAddress] [[-OverrideConfig] ] [[-Timeout] ]
- Takes a Orleans Cluster Gateway Address Endpoint
Note: FinRL 入门指南 The Timeout parameter is optional and if it is informed and greater than System.TimeSpan.Zero , it will call Orleans.GrainClient.SetResponseTimeout(Timeout) internally.
Takes no parameters and when called, if the GrainClient is initialized will gracefuly uninitialize.
Wrapper around GrainClient.GrainFactory.GetGrain() and its overloads.
The mandatory parameter is -GrainType and the -XXXKey for the current Grain key types supported by Orleans ( string , Guid , long ) and also the -KeyExrension that can be used on Grains with compound keys.
This Cmdlet return a grain reference of the type passed by as parameter on -GrainType .
A simple example on calling MyInterfacesNamespace.FinRL 入门指南 IMyGrain.SayHeloTo grain method:
Thats it for now. We plan to update this page as we introduce more Cmdlets like use Observers, Streams and other Orleans core features more natively on Powershell. We hope that this help people as a starting point for FinRL 入门指南 automation. As always, this is a work-in-progress and we love contributions! :)
Please note that the intent is not to reimplement the whole client on PowerShell but instead, give IT and DevOps teams a way to interact with the Grains without need to implement a .Net application.
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