You might be familiar with the theory behind The Innovator's Dilemma by Clayton Christensen. According to Christensen,...
a company with an established product is less likely to innovate and will eventually be displaced by a newcomer. One way to avoid this dilemma is to self-disrupt -- to go against conventional product development wisdom and build new products that compete with your existing products. VMware does this on a small scale with flings.
Flings are software tools built by VMware engineers. Though they are not part of a product, they are useful to VMware users because they generally address gaps within VMware products. Flings are available for download from VMware Labs, where users can go to learn more about individual flings, as well as the team that developed each fling. VMware does not officially support flings, though the development team usually provides some sort of informal support. Some VMware flings grow so popular that they eventually become product features with full support; vSphere 6.5 includes two former HTML5 client flings.
ESXi Embedded Host Client
The first VMware HTML5 client to become a fling was the ESXi Embedded Host Client, which is the first cross-platform vSphere host management tool. This HTML5 interface manages a single ESXi server and helps customers who don't want to use Windows machines to manage their virtualization hosts. The version of Host Client that appeared on the VMware Labs site supported ESXi version 5.0 and above and allowed server configuration with any HTML5 browser. Without this fling, you had to configure ESXi servers with the vSphere Client, which is a Windows application.
The word "client" in the name is a bit misleading. ESXi Embedded Host Client is really a server application that resides on the ESXi host, in place of the vSphere Client. You must install this fling on each ESXi server you want to manage. This browser-based management is something of a throwback to the early days of VMware. If you worked with ESX 10 years ago, you might remember the Multilingual User Interface, a web interface used to manage an ESX 2.x server. Now, 10 years later, we have the same functionality with the Host Client.
VSphere HTML5 Web Client
Another group of VMware engineers also built an HTML5 client that works with vCenter. The vSphere HTML5 Web Client works with vCenter rather than individual ESXi servers. You install this fling alongside your vCenter server to allow browser-based management. Again, the goal is to use an HTML5 browser for management rather than a Windows application or the Adobe Flash plug-in. This client works with vCenter 6 and above.
From fling to feature
VSphere 6.5 includes both of these VMware flings as part of the core product. ESXi 6.5 replaces the Windows vSphere Client with ESXi Embedded Host Client to directly manage ESXi servers. The team that built the Host Client continues to develop and support the client. This continued support is important, as VMware is not adding the Host Client to older versions of ESXi. If you want HTML5 management on ESXi 5.5 or 6.0, you need the fling. If you have ESXi 6.5 or later, browser-based management is built into each host, so you don't need the fling.
The HTML5 client is also built into vCenter 6.5. This client is called the vSphere Client, which you'll note is the same name as the Windows application it replaces. This is a bit confusing because these two vSphere Clients are very different. The vSphere Web Client -- a browser-based interface that uses Adobe Flash as its runtime -- is the primary vCenter 6.5 management interface. You need a web browser and an up-to-date version of Flash to manage vCenter 6.5. The Windows vSphere Client is incompatible with vCenter 6.5, and many find the Web Client unstable and slow. The new HTML5 vSphere Client aims to improve vCenter management but is incomplete: Although it has many capabilities, it also lacks features, especially host cluster management.
VMware flings are a great way to test new features and support capabilities for existing products. These flings allow market testing for new components without the need to commit to commercial support. In the past, VMware might include a new product component and mark it as experimental support. Now, VMware can ship the product with full support and offer flings to customers who want to experiment with new features. There's a strong precedent for popular VMware flings becoming features in the official product. You might want to look at the VMware flings site to find out whether there are features you'd like to see in future product releases.
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