C H A P T E R 1 |
Introduction |
The Sun Virtual Desktop Connector (VDC) presents users with easy access to their virtual desktops, typically instances of Microsoft Windows XP, from a wide range of devices, such as PCs and Sun Ray DTUs. The effect is to enable access to the same desktop from anywhere.
The Virtual Desktop Connector consists primarily of:
The Sun Virtual Desktop Connector can control both access management and the lifecycle of virtual desktops, creating new virtual desktop instances on demand, provisioning them to users on a temporary or permanent basis, and decommissioning outdated instances. Its functionality encompasses:
By providing a virtual desktop with a choice of operating systems, access methods, and devices, the Virtual Desktop Connector caters to user preferences while leveraging existing investments in desktop devices and network infrastructure and maximizing utilization of existing computing resources.
By moving applications, operating systems, and computing from individual desktops to secure, centralized servers, the Virtual Desktop Connector reduces risks associated with virus attack, intrusion, and loss of data.
The Virtual Desktop Connector also helps system and network administrators to manage large installations of virtual machines with well-designed tools for centralized administration, largely removing the burden of maintaining individual physical desktops.
The Virtual Desktop Connector architecture has three main layers: virtualization, session management, and desktop access. The virtualization layer, where the virtual machines reside, abstracts interaction with the virtualization solution to allow multiple setups. A Virtual Desktop Connector agent installed on each virtualization server manages the interaction with the various elements.
FIGURE 1-1 Virtual Desktop Connector Layers
The session management layer, consisting typically of either a Sun Ray failover group or a Secure Global Desktop array, is where operation of the Virtual Desktop Connector and the virtual desktop lifecycle are managed. You can use the Virtual Desktop Connector’s Admin GUI to manage the product operation parameters and the Virtual Desktop Connector service to handle desktop lifecycles.
The desktop access layer is where the user gets access to the appropriate desktop, based on the Virtual Desktop Connector configuration and the user environment. The appropriate desktop can be delivered via a Sun Ray Kiosk session, an SGD application object accessed through a Web browser, or some other mechanism. The desktop access layer relies on the Virtual Desktop Connector client, which runs on the SRSS or SGD server, to initiate the virtual desktop lookup process on behalf of the user. Once the lookup process is complete, the VDC client returns the IP address of the virtual desktop so that an RDP connection can be established.
Virtual desktops can be provided to users either from statically assigned virtual machines or from pools of identical virtual machines that are dynamically assigned to sessions as needed. A given user session is associated with the virtual machine used as the desktop through a session identifier and, optionally, the name of a pool from which a dynamic machine is retrieved.
FIGURE 1-2 Static vs. Dynamic Assignment of Virtual Machines
Static assignments are useful for users who require a persistent, dedicated desktop session--the same virtual machine every time they log in. As shown in FIGURE 1-2, static assignment ensures that the user is always directed to the same virtual machine, VM 2 in this case.
Dynamic pools are useful for sharing resources when the desktop is standardized and does not need to retain its state between usages. The lower portion of FIGURE 1-2 shows the dynamic use case, in which various users get access to VMs on demand. The VMs are created from a single template and are assigned to users temporarily.
Using the Admin GUI, you can define which virtualization hosts to use for virtual machine management. You then assign session identifiers to specific virtual machines and create pools of dynamic virtual machines. The pools can be populated either manually, in which case you must assign existing virtual machines to their respective pools, or automatically, from a virtual machine template.
A user session that requires a virtual desktop can be started from a Sun Ray Kiosk session or from an SGD application object. It invokes the Virtual Desktop Connector client, and the proper session identifier and pool name are computed based on the user session environment. The client then contacts the Virtual Desktop Connector service, which in turn contacts the defined Virtual Desktop Connector agents to locate a suitable virtual machine for that identifier and pool.
Once a suitable machine is selected, it is started, and connectivity is established over the Remote Desktop Protocol (RDP) port. The virtual desktop’s IP address is then returned to the client, and an RDP client connects to the IP address to provide the user’s desktop session. The RDP client can be the Sun Ray Connector for Windows OS or the Sun Secure Global Desktop client.
Periodically, the Virtual Desktop Connector service ensures that the pools are properly populated according to the parameters you have defined, and clones new virtual machines from the specified template if the need arises. It also checks the state of the dynamically assigned machines in the various pools. Those virtual machines which have not been used for a given period of time are reclaimed, thus removing their association with a session identifier.
Once the Virtual Desktop Connector components are installed and configured, you can use the Admin GUI to set up session provisioning. The first step is to add a VirtualCenter server to the system. You can then browse the associated resources.
In a scenario with two groups of users--salespeople who use their desktops to access a variety of remote resources (with applications such as a Web browser, an email client, and an internal database front-end application), and developers who use their desktops for coding and testing applications--you might assign a specific virtual machine to each developer and create a pool for salespeople, based on a template machine with the appropriate applications installed.
Assume that the virtual machines are configured to go into standby mode and suspend themselves after 30 minutes of inactivity, and that a pool machine remains assigned to an inactive session identifier for up to an hour, after which it can be recycled.
Users insert smart cards into a Sun Ray DTU to access their desktops. The smart cards have been registered in the Sun Ray Server Software data store and thus associated with their owners, and the Sun Ray Server Software has been configured to provide Kiosk sessions for smart card owners.
When a user inserts the smart card, the Kiosk session asks the Virtual Desktop Connector client for the virtual desktop associated with the user’s smart card token. The Kiosk session also specifies the name of the desired pool.
If the user is a developer with static assignment to a specific virtual desktop, the Virtual Desktop Connector client retrieves it. When the user disconnects from the virtual desktop session and later tries to reconnect, the Virtual Desktop Connector client retrieves the same virtual desktop.
If the user is a salesperson, the Virtual Desktop Connector client selects a virtual desktop from the pool of available virtual machines. After the user disconnects from the virtual desktop session, the virtual machine reverts to the pool to be recycled. If the user tries to reconnect before the specified time is up (after about an hour and a half in this scenario), the Virtual Desktop Connector client retrieves the same dynamically assigned machine. If the connection attempt occurs later, the Virtual Desktop Connector client dynamically assigns another virtual machine to that user from the pool.
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