Autonomic Web Services Based on Different Adaptive Quasi-Asynchronous Checkpointing Techniques

Abstract

Companies, organizations and individuals use Web services to build complex business functionalities. Web services must operate properly in the unreliable Internet infrastructure even in the presence of failures. To increase system dependability, organizations, including service providers, adapt their systems to the autonomic computing paradigm. Strategies can vary from having one to all (S-CHOP, self-configuration, self-healing, self-optimization and self-protection) features. Regarding self-healing, an almost identical tool is communication-induced checkpointing (CiC), a checkpoint contains the state (heap, registers, stack, kernel state) for each process in the system. CiC is based on quasi-synchronous checkpointing where processes take checkpoints relying of control information piggybacked inside application messages; however, avoiding dangerous patterns such as Z-paths and Z-cycles; in such a regard the system takes forced checkpoints and avoids inconsistent states. CiC, unlike other tools, does not incur system performance, our proposal does not incur high overhead (as results show), and it has the advantage of being scalable. As we have shown in a previous work, CiC can be used to address dependability problems when dealing with Web services, as CiC mechanism work in a distributed and efficient manner. Therefore, in this work we propose an adaptable and dynamic generation of checkpoints to support fault tolerance. We present an alternative considering Quality of Service (QoS) criteria, and the different impact applications have on it. We propose taking checkpoints dynamically in case of failure or QoS degradation. Experimental results show that our approach has significantly reduced the generation of checkpoints of various well-known tools in the literature.

Communication-Induced Checkpointing with Message Logging beyond the Piecewise Deterministic (PWD) Model for Distributed Systems

“…The authors of [6] proposed an adaptive checkpoint generation algorithm in order to decrease the frequency of forced checkpointing actions by considering the system's behavior in comparison with the static algorithm, which did not reflect the environmental changes onto web services being operated. The algorithm made decisions on whether forced checkpoints should be taken based on the quality of the service parameters and the policies currently applied to their corresponding web services.…”

“…According to when and how consistent sets of checkpoints are formed, checkpoint-based recovery protocols are categorized into coordinated, independent, and communication-induced checkpointing [5]. In order to balance trade-offs between independent and coordinated checkpointing in an effective manner, communication-induced checkpointing (CIC) is used to preclude any local checkpoint that have already been taken from becoming useless by performing forced checkpointing while attempting to increase the degree of checkpointing independence as much as possible [6][7][8][9][10][11][12][13][14][15]. The CIC protocols include HMNR [8], which uses this feature to enable the number of extra checkpoints to be much lower by effectively using the control information contained in each sent message.…”

“…However, this may greatly degrade the applicability of the CIC. Lastly, several recent works [6,15] exploited one or more protocols mentioned above to raise the dependability of the systems to a higher level in the fields of distributed database management systems and web services.…”

“…However, these protocols cannot be freed from the PWD assumption. For this reason, none of the existing CIC protocols-including a family of HMNR protocols [6,[8][9][10][11][12][13][14][15]-developed so far can utilize the benefits of message logging on real-world distributed systems without assuming the PWD model. Whenever each process receives a message, the protocols cause the process to perform forced checkpointing if they decide that one or more checkpoints that have already been taken may become useless.…”

Enhanced Sender-Based Message Logging for Reducing Forced Checkpointing Overhead in Distributed Systems

“…To harmonize the pros and cons of uncoordinated and coordinated checkpointing, communication-induced checkpointing (CIC) was developed to provide best-effort autonomy with respect to taking local checkpoints while preventing them from being useless for recovery with forced checkpoints [8], [9]. The prior research works on CIC with this feature have pursued a ultimate goal to minimize the number of forced checkpoints [8], [9], [15]. HMNR protocol [9] effectively utilizes some control information vectors contained in each sent message to attempt to decrease the number of worthless forced checkpoints to a maximum.…”