Dynamic Software Updating Research Articles

Strategies and Issues for Dynamic Software Updates Exactitude

Programs are allowed by dynamic software updating (DSU) systems a line to be fixed on-the-fly to adjoin features or fix bugs. Approaches for launching their correctness have normal little interest, while dynamic upgrades may be difficult to create. In this document, we here the first strategy for instantly confirming the truth's of energetic improvements. Developers express the preferred qualities of an up-to-date execution via client-oriented specifications (CO-specs), which may exemplify a broad variety of client-visible actions. We authenticate CO-specs mechanically by utilizing off - the - shelf tools to assess a combined program that is a group of the new and old variants of the plan. We check it right and formalize the addition change. We've implemented a program blend for D, and employed it to improvements for the Redis key-value collect and a few artificial programs. Using Thor, a certification device, we could check lots of the programs; using Otter, a representational executor, every program could be evaluated by us, frequently in less than one minute. Both resources managed to detect defective areas and sustained just a factor-of-four slow down, on regular, compared to single conversion applications.

Dynamic software update model for remote entity management of machine‐to‐machine service capability

Daily life applications of machine-to-machine (M2M) communication are constantly increasing. Typically, M2M communication systems comprise numerous small, cheap and autonomous devices that communicate with each other while monitoring environmental conditions. After their deployment, however, remote entity management of a node is still needed for firmware or software updates required for bug fixes, functional changes or other maintenance. Therefore implementing remote entity management for M2M service capability in third generation partnership project machine-type-communication is a major challenge. Previous works have attempted to reduce traffic by updating only the software changes in the M2M device. However, the device must still reboot after a software update. Rebooting the device is costly since the previous runtime states are lost. The devices expend time and bandwidth when synchronising with other nodes and when rebuilding the routing table. Hence, the dynamic software update model (DSUM) proposed in this study is designed to enable remote entity management for M2M. A dynamic software update programming model and a prototype implementation for M2M service capability are also presented. By allowing M2M service capabilities to update the software without rebooting the node, the DSUM preserves precious runtime states. The tests in this study showed that software updating required only 88 clock cycles. This framework not only enables dynamic replacement of remote entity management functionalities at runtime, it also reduces power consumption by avoiding the need to rebuild the network topology for devices in an M2M communication network.

Evaluating Dynamic Software Update Safety Using Systematic Testing

Dynamic software updating (DSU) systems patch programs on the fly without incurring downtime. To avoid failures due to the updating process itself, many DSU systems employ timing restrictions. However, timing restrictions are theoretically imperfect, and their practical effectiveness is an open question. This paper presents the first significant empirical evaluation of three popular timing restrictions: activeness safety (AS), which prevents updates to active functions, con-freeness safety (CFS), which only allows modifications to active functions when doing so is provably type-safe, and manual identification of the event-handling loops during which an update may occur. We evaluated these timing restrictions using a series of DSU patches to three programs: OpenSSH, vsftpd, and ngIRCd. We systematically applied updates at each distinct update point reached during execution of a suite of system tests for these programs to determine which updates pass and which fail. We found that all three timing restrictions prevented most failures, but only manual identification allowed none. Further, although CFS and AS allowed many more update points, manual identification still supported updates with minimal delay. Finally, we found that manual identification required the least developer effort. Overall, we conclude that manual identification is most effective.

Automating object transformations for dynamic software updating

Dynamic software updating (DSU) systems eliminate costly downtime by dynamically fixing bugs and adding features to executing programs. Given a static code patch, most DSU systems construct runtime code changes automatically. However, a dynamic update must also specify how to change the running program's execution state, e.g., the stack and heap, to make it compatible with the new code. Constructing such state transformations correctly and automatically remains an open problem. This paper presents a solution called Targeted Object Synthesis (TOS). TOS first executes the same tests on the old and new program versions separately, observing the program heap state at a few corresponding points. Given two corresponding heap states, TOS matches objects in the two versions using key fields that uniquely identify objects and correlate old and new-version objects. Given example object pairs, TOS then synthesizes the simplest-possible function that transforms an old-version object to its new-version counterpart. We show that TOS is effective on updates to four open-source server programs for which it generates non-trivial transformation functions that use conditionals, operate on collections, and fix memory leaks. These transformations help programmers understand their changes and apply dynamic software updates.

Kitsune

Dynamic software updating (DSU) systems allow programs to be updated while running, thereby permitting developers to add features and fix bugs without downtime. This paper introduces Kitsune, a new DSU system for C whose design has three notable features. First, Kitsune's updating mechanism updates the whole program, not individual functions. This mechanism is more flexible than most prior approaches and places no restrictions on data representations or allowed compiler optimizations. Second, Kitsune makes the important aspects of updating explicit in the program text, making the program's semantics easy to understand while minimizing programmer effort. Finally, the programmer can write simple specifications to direct Kitsune to generate code that traverses and transforms old-version state for use by new code; such state transformation is often necessary, and is significantly more difficult in prior DSU systems. We have used Kitsune to update five popular, open-source, single- and multi-threaded programs, and find that few program changes are required to use Kitsune, and that it incurs essentially no performance overhead.

A survey of dynamic software updating

ABSTRACTApplication update at run‐time remains a challenging issue in software engineering. There are many techniques with different evaluation metrics, resulting in different behaviours in the application being updated. In this paper, we provide an extensive review of research work on dynamic software updating. A framework for the evaluation of dynamic updating features is developed, and the articles are categorized and discussed based on the provided framework. Areas of online software maintenance requiring further research are also identified and highlighted. This information is deemed to not only assist practitioners in selecting appropriate dynamic updating techniques for their systems, but also to facilitate the ongoing and continuous research in the field of dynamic software updating. Copyright © 2012 John Wiley & Sons, Ltd.

JavAdaptor—Flexible runtime updates of Java applications

SUMMARYSoftware is changed frequently during its life cycle. New requirements come, and bugs must be fixed. To update an application, it usually must be stopped, patched, and restarted. This causes time periods of unavailability, which is always a problem for highly available applications. Even for the development of complex applications, restarts to test new program parts can be time consuming and annoying. Thus, we aim at dynamic software updates to update programs at runtime. There is a large body of research on dynamic software updates, but so far, existing approaches have shortcomings either in terms of flexibility or performance. In addition, some of them depend on specific runtime environments and dictate the program's architecture. We present JavAdaptor, the first runtime update approach based on Java that (a) offers flexible dynamic software updates, (b) is platform independent, (c) introduces only minimal performance overhead, and (d) does not dictate the program architecture. JavAdaptor combines schema changing class replacements by class renaming and caller updates with Java HotSwap using containers and proxies. It runs on top of all major standard Java virtual machines. We evaluate our approach's applicability and performance in non‐trivial case studies and compare it with existing dynamic software update approaches. Copyright © 2012 John Wiley & Sons, Ltd.

Dynamic Software Updating Using a Relaxed Consistency Model

Software is inevitably subject to changes. There are patches and upgrades that close vulnerabilities, fix bugs, and evolve software with new features. Unfortunately, most traditional dynamic software updating approaches suffer some level of limitations; few of them can update multithreaded applications when involving data structure changes, while some of them lose binary compatibility or incur nonnegligible performance overhead. This paper presents POLUS, a software maintenance tool capable of iteratively evolving running unmodified multithreaded software into newer versions, yet with very low performance overhead. The main idea in POLUS is a relaxed consistency model that permits the concurrent activity of the old and new code. POLUS borrows the idea of cache-coherence protocol in computer architecture and uses a ”bidirectional write-through” synchronization protocol to ensure system consistency. To demonstrate the applicability of POLUS, we report our experience in using POLUS to dynamically update three prevalent server applications: vsftpd, sshd, and Apache HTTP server. Performance measurements show that POLUS incurs negligible runtime overhead on the three applications-a less than 1 percent performance degradation (but 5 percent for one case). The time to apply an update is also minimal.

Dynamic software updates

Software evolves to fix bugs and add features. Stopping and restarting programs to apply changes is inconvenient and often costly. Dynamic software updating (DSU) addresses this problem by updating programs while they execute, but existing DSU systems for managed languages do not support many updates that occur in practice and are inefficient. This paper presents the design and implementation of J volve , a DSU-enhanced Java VM. Updated programs may add, delete, and replace fields and methods anywhere within the class hierarchy. Jvolve implements these updates by adding to and coordinating VM classloading, just-in-time compilation, scheduling, return barriers, on-stack replacement, and garbage collection. J volve , is safe : its use of bytecode verification and VM thread synchronization ensures that an update will always produce type-correct executions. Jvolve is flexible : it can support 20 of 22 updates to three open-source programs--Jetty web server, JavaEmailServer, and CrossFTP server--based on actual releases occurring over 1 to 2 years. Jvolve is efficient : performance experiments show that incurs no overhead during steady-state execution. These results demonstrate that this work is a significant step towards practical support for dynamic updates in virtual machines for managed languages.

Contextual effects for version-consistent dynamic software updating and safe concurrent programming

This paper presents a generalization of standard effect systems that we call contextual effects . A traditional effect system computes the effect of an expression e . Our system additionally computes the effects of the computational context in which e occurs. More specifically, we computethe effect of the computation that has already occurred(the prior effect ) and the effect of the computation yet to take place (the future effect ). Contextual effects are useful when the past or future computation of the program is relevant at various program points. We present two substantial examples. First, we show how prior and future effects can be used to enforce transactional version consistency (TVC), a novel correctness property for dynamic software updates. TV Censures that programmer-designated transactional code blocks appear to execute entirely at the same code version, even if a dynamic update occurs in the middle of the block. Second, we show how future effects can be used in the analysis of multi-threaded programs to find thread-shared locations. This is an essential step in applications such as data race detection.

Mutatis Mutandis

This article presents Proteus, a core calculus that models dynamic software updating, a service for fixing bugs and adding features to a running program. Proteus permits a program's type structure to change dynamically but guarantees the updated program remains type-correct by ensuring a property we call con-freeness. We show how con-freeness can be enforced dynamically, and how it can be approximated via a novel static analysis. This analysis can be used to assess the implications of a program's structure on future updates in order to make update success more predictable. We have implemented Proteus for C, and briefly discuss our implementation which we have tested on several well-known programs.

Research on dynamic update transaction for Java classes

Dynamic software updating is critical for many systems that must provide continuous service. In addition, the Java language is gaining increasing popularity in developing distributed systems. Most previous works on updating are concerned with safely updating one class every time. It has many limitations on updating classes, such as not allowing deleting methods invoked in other classes. In this paper, the update transaction is purposed to dynamically update the class set, and some of its properties are discussed, such as atomicity, consistency, isolation, and durability (ACID). Then the property of type-safety is proven formally. In order to update without changing the Java Virtual Machine (JVM) and the Java programming language, this paper proposes a new implementation method. The method makes use of the Java class loading mechanism and reflection mechanism. We also present how to design an updatable Java program and a Java updating program. At the end of the paper, an experiment is made for analysis.

Practical dynamic software updating for C

Software updates typically require stopping and restarting an application, but many systems cannot afford to halt service, or would prefer not to. Dynamic software updating (DSU) addresses this difficulty by permitting programs to be updated while they run. DSU is appealing compared to other approaches for on-line upgrades because it is quite general and requires no redundant hardware. The challenge is in making DSU practical : it should be flexible, and yet safe, efficient, and easy to use.In this paper, we present Ginseng, a DSU implementation for C that aims to meet this challenge. We compile programs specially so that they can be dynamically patched, and generate most of a dynamic patch automatically. Ginseng performs a series of analyses that when combined with some simple runtime support ensure that an update will not violate type-safety while guaranteeing that data is kept up-to-date. We have used Ginseng to construct and dynamically apply patches to three substantial open-source server programs--- Very Secure FTP daemon , OpenSSH sshd daemon , and GNU Zebra . In total, we dynamically patched each program with three years' worth of releases. Though the programs changed substantially, the majority of updates were easy to generate. Performance experiments show that all patches could be applied in less than 5 ms , and that the overhead on application throughput due to updating support ranged from 0 to at most 32%.

Mutatis mutandis

Dynamic software updates can be used to fix bugs or add features to a running program without downtime. Essential for some applications and convenient for others, low-level dynamic updating has been used for many years. Perhaps surprisingly, there is little high-level understanding or language support to help programmers write dynamic updates effectively.To bridge this gap, we present Proteus, a core calculus for dynamic software updating in C-like languages that is flexible, safe, and predictable. Proteus supports dynamic updates to functions (even active ones), to named types and to data, allowing on-line evolution to match source-code evolution as we have observed it in practice. We ensure updates are type-safe by checking for a property we call "con-freeness" for updated types t at the point of update. This means that non-updated code will not use t concretely beyond that point (concrete usages are via explicit coercions) and thus t's representation can safely change. We show how con-freeness can be enforced dynamically for a particular program state. We additionally define a novel and efficient static updateability analysis to establish con-freeness statically, and can thus automatically infer program points at which all future (well-formed) updates will be type-safe. We have implemented our analysis for C and tested it on several well-known programs.