Ricardo A. Baratto

THINC: a virtual display architecture for thin-client computing

Rapid improvements in network bandwidth, cost, and ubiquity combined with the security hazards and high total cost of ownership of personal computers have created a growing market for thin-client computing. We introduce THINC, a virtual display architecture for high-performance thin-client computing in both LAN and WAN environments. THINC virtualizes the display at the device driver interface to transparently intercept application display commands and translate them into a few simple low-level commands that can be easily supported by widely used client hardware. THINCs translation mechanism efficiently leverages display semantic information through novel optimizations such as offscreen drawing awareness, native video support, and server-side screen scaling. This is integrated with an update delivery architecture that uses shortest command first scheduling and non-blocking operation. THINC leverages existing display system functionality and works seamlessly with unmodified applications, window systems, and operating systems.We have implemented THINC in an X/Linux environment and compared its performance against widely used commercial approaches, including Citrix MetaFrame, Microsoft RDP, GoToMyPC, X, NX, VNC, and Sun Ray. Our experimental results on web and audio/video applications demonstrate that THINC can provide up to 4.8 times faster web browsing performance and two orders of magnitude better audio/video performance. THINC is the only thin client capable of transparently playing full-screen video and audio at full frame rate in both LAN and WAN environments. Our results also show for the first time that thin clients can even provide good performance using remote clients located in other countries around the world.

DejaView: a personal virtual computer recorder

As users interact with the world and their peers through their computers, it is becoming important to archive and later search the information that they have viewed. We present DejaView, a personal virtual computer recorder that provides a complete record of a desktop computing experience that a user can playback, browse, search, and revive seamlessly. DejaView records visual output, checkpoints corresponding application and file system state, and captures displayed text with contextual information to index the record. A user can then browse and search the record for any visual information that has been displayed on the desktop, and revive and interact with the desktop computing state corresponding to any point in the record. DejaView combines display, operating system, and file system virtualization to provide its functionality transparently without any modifications to applications, window systems, or operating system kernels. We have implemented DejaView and evaluated its performance on real-world desktop applications. Our results demonstrate that DejaView can provide continuous low-overhead recording without any user noticeable performance degradation, and allows browsing, search and playback of records fast enough for interactive use.

pTHINC: a thin-client architecture for mobile wireless web

Although web applications are gaining popularity on mobile wireless PDAs, web browsers on these systems can be quite slow and often lack adequate functionality to access many web sites. We have developed pTHINC, a PDA thin-client solution that leverages more powerful servers to run full-function web browsers and other application logic, then sends simple screen updates to the PDA for display. pTHINC uses server-side screen scaling to provide high-fidelity display and seamless mobility across a broad range of different clients and screen sizes, including both portrait and landscape viewing modes. pTHINC also leverages existing PDA control buttons to improve system usability and maximize available screen resolution for application display. We have implemented pTHINC on Windows Mobile and evaluated its performance on mobile wireless devices. Our results compared to local PDA web browsers and other thin-client approaches demonstrate that pTHINC provides superior web browsing performance and is the only PDA thin client that effectively supports crucial browser helper applications such as video playback.

THINC: A Remote Display Architecture for Thin-Client Computing

Rapid improvements in network bandwidth, cost, and ubiquity combined with the security hazards and high total cost of ownership of personal computers have created a growing market for thin-client computing. We introduce THINC, a remote display system architecture for high-performance thin-client computing in both LAN and WAN environments. THINC transparently maps high-level application display calls to a few simple low-level commands which can be implemented easily and efficiently. THINC introduces a number of novel latency-sensitive optimization techniques, including offscreen drawing awareness, command buffering and scheduling, nonblocking display operation, native video support, and serverside screen scaling. We have implemented THINC in an XFree86/Linux environment and compared its performance with other popular approaches, including Citrix MetaFrame, Microsoft Terminal Services, SunRay, VNC, and X. Our experimental results on web and video applications demonstrate that THINC can be as much as five times faster than traditional thin-client systems in high latency network environments and is capable of playing full-screen video at full frame rate.

Remotely keyed cryptographics secure remote display access using (mostly) untrusted hardware

Software that covertly monitors user actions, also known as spyware, has become a first-level security threat due to its ubiquity and the difficulty of detecting and removing it. Such software may be inadvertently installed by a user that is casually browsing the web, or may be purposely installed by an attacker or even the owner of a system. This is particularly problematic in the case of utility computing, early manifestations of which are Internet cafes and thin-client computing. Traditional trusted computing approaches offer a partial solution to this by significantly increasing the size of the trusted computing base (TCB) to include the operating system and other software. We examine the problem of protecting a user accessing specific services in such an environment. We focus on secure video broadcasts and remote desktop access when using any convenient, and often untrusted, terminal as two example applications. We posit that, at least for such applications, the TCB can be confined to a suitably modified graphics processing unit (GPU). Specifically, to prevent spyware on untrusted clients from accessing the user’s data, we restrict the boundary of trust to the client’s GPU by moving image decryption into GPUs. This allows us to leverage existing capabilities as opposed to designing a new component from scratch. We discuss the applicability of GPU-based decryption in the two scenarios. We identify limitations due to current GPU capabilities and propose straightforward modifications to GPUs that will allow the realization of our approach.

An Application Streaming Service for Mobile Handheld Devices

Mobile handheld devices such as PDAs and smartphones are increasingly being used by service providers to deliver application functionality similar to that found in traditional desktop computing environments. However, these handheld applications can be quite slow and often lack important functionality compared to their desktop counterparts. We have developed PASSPORT, (PDA application streaming service portal) a thin-client solution that leverages more powerful servers to run full-function desktop applications and then simply stream screen updates to the PDA for display. PASSPORT uses server-side screen scaling to provide high-fidelity display and seamless mobility across a broad range of different clients and screen sizes, including both portrait and landscape viewing modes. PASSPORT also leverages existing PDA control buttons to improve system usability and maximize available screen resolution for application display. We have implemented PASSPORT on Windows PDAs and demonstrate that it can provide superior application performance and functionality compared to the traditional approach of running applications directly on handheld devices

Thinc: a virtual and remote display architecture for desktop computing and mobile devices

THINC is a new virtual and remote display architecture for desktop computing. It has been designed to address the limitations and performance shortcomings of existing remote display technology, and to provide a building block around which novel desktop architectures can be built. THINC is architected around the notion of a virtual display device driver, a software-only component that behaves like a traditional device driver, but instead of managing specific hardware, enables desktop input and output to be intercepted, manipulated, and redirected at will. On top of this architecture, THINC introduces a simple, low-level, device-independent representation of display changes, and a number of novel optimizations and techniques to perform efficient interception and redirection of display output. This dissertation presents the design and implementation of THINC. It also introduces a number of novel systems which build upon THINCs architecture to provide new and improved desktop computing services. The contributions of this dissertation are as follows: (1) A high performance remote display system for LAN and WAN environments. This system differs from existing remote display technologies in that it focuses on the architecture of the system as a mechanism to improve performance, and not just on the remote display protocol and compression techniques. (2) A novel mechanism to natively support multimedia content in a remote display system in a way that is both transparent to applications and format independent. (3) pTHINC, a system to deliver improved remote display support for mobile devices, both in terms of performance and usability, and provide a competitive, and in some cases superior, alternative to native mobile applications. (4) MobiDesk, a desktop utility computing infrastructure that enables service providers to host desktop sessions in fully virtualized environments. Hosted sessions can be remotely accessed using THINC, they can be migrated across computers to provide high-availability, and can be effectively and efficiently protected from denial of service attacks. (5) Moving beyond remote display, we show how THINCs architecture can be used to provide continuous, low overhead recording of a desktop. Alongside, we introduce a novel way to leverage desktop accessibility services to allow users to search their recording based on captured text content. We have implemented prototypes for these systems, and evaluated their performance in a number of scenarios, and compared it to representative alternatives whenever possible. Our results demonstrate that THINC can provide superior remote display performance, and can be successfully used as a fundamental building block for new and improved desktop applications and services.

GamePod: Persistent Gaming Sessions on Pocketable Storage Devices

We present GamePod, a portable system that enables mobile users to use the same persistent, gaming environment on any available computer. No matter what computer is being used, GamePod provides a consistent gaming environment, maintaining all of a users games, including active game state. This is achieved by leveraging rapid improvements in capacity, cost, and size of portable storage devices. GamePod provides a middleware layer that enables virtualization and checkpoint/restart functionality that decouples the gaming environment from a host machine. This enables gaming sessions to be suspended to portable storage, carried around, and resumed from the storage device on another computer. GamePods middleware layer also isolates gaming sessions from the host, protecting the host by preventing malicious executable content from damaging the host. We have implemented a Linux GamePod prototype and demonstrate its ability to quickly suspend and resume gaming sessions, enabling a seamless gaming experience for mobile users as they move among computers.

MediaPod: A Personalized Multimedia Desktop in Your Pocket

We present MediaPod, a portable system that allows mobile users to maintain the same persistent, personalized multimedia desktop environment on any available computer. Regardless of which computer is being used, MediaPod provides a consistent multimedia desktop session, maintaining all of a users applications, documents and configuration settings. This is achieved by leveraging rapid improvements in capacity, cost, and size of portable storage devices. MediaPod provides a virtualization and checkpoint-restart mechanism that decouples a desktop environment and its applications from the host, enabling multimedia desktop sessions to be suspended to portable storage, carried around, and resumed from the storage device on another computer. MediaPod virtualization also isolates desktop sessions from the host, protecting the privacy of the user and preventing malicious applications from damaging the host. We have implemented a Linux MediaPod prototype and demonstrate its ability to quickly suspend and resume multimedia desktop sessions, enabling a seamless computing experience for mobile users as they move among computers.

MEDIAPOD: A POCKET-SIZED AND PERSONALIZED MULTIMEDIA DESKTOP

We present MediaPod, a portable system that allows mobile users to maintain the same persistent, personalized multimedia desktop environment on any available computer. Regardless of which computer is being used, MediaPod provides a consistent multimedia desktop session, maintaining all of a users applications, documents and configuration settings. This is achieved by leveraging rapid improvements in capacity, cost, and size of portable storage devices. MediaPod provides a virtualization and checkpoint-restart mechanism that decouples a desktop environment and its applications from the host, enabling multimedia desktop sessions to be suspended to portable storage, carried around, and resumed from the storage device on another computer. MediaPod virtualization also isolates desktop sessions from the host, protecting the privacy of the user and preventing malicious applications from damaging the host. We have implemented a Linux MediaPod prototype and demonstrate its ability to quickly suspend and resume multimedia desktop sessions, enabling a seamless computing experience for mobile users as they move among computers.