Permchecker: a toolchain for debugging memory managers with typestate

Dynamic memory managers are a crucial component of almost every modern software system. In addition to implementing efficient allocation and reclamation, memory managers provide the essential abstraction of memory as distinct objects, which underpins the properties of memory safety and type safety. Bugs in memory managers, while not common, are extremely hard to diagnose and fix. One reason is that their implementations often involve tricky pointer calculations, raw memory manipulation, and complex memory state invariants. While these properties are often documented, they are not specified in any precise, machine-checkable form. A second reason is that memory manager bugs can break the client application in bizarre ways that do not immediately implicate the memory manager at all. A third reason is that existing tools for debugging memory errors, such as Memcheck, cannot help because they rely on correct allocation and deallocation information to work. In this paper we present Permchecker, a tool designed specifically to detect and diagnose bugs in memory managers. The key idea in Permchecker is to make the expected structure of the heap explicit by associating typestates with each piece of memory. Typestate captures elements of both type (e.g., page, block, or cell) and state (e.g., allocated, free, or forwarded). Memory manager developers annotate their implementation with information about the expected typestates of memory and how heap operations change those typestates. At runtime, our system tracks the typestates and ensures that each memory access is consistent with the expected typestates. This technique detects errors quickly, before they corrupt the application or the memory manager itself, and it often provides accurate information about the reason for the error. The implementation of Permchecker uses a combination of compile-time annotation and instrumentation, and dynamic binary instrumentation (DBI). Because the overhead of DBI is fairly high, Permchecker is suitable for a testing and debugging setting and not for deployment. It works on a wide variety of existing systems, including explicit malloc/free memory managers and garbage collectors, such as those found in JikesRVM and OpenJDK. Since bugs in these systems are not numerous, we developed a testing methodology in which we automatically inject bugs into the code using bug patterns derived from real bugs. This technique allows us to test Permchecker on hundreds or thousands of buggy variants of the code. We find that Permchecker effectively detects and localizes errors in the vast majority of cases; without it, these bugs result in strange, incorrect behaviors usually long after the actual error occurs.

An Efficient Method for Automatic Antipatterns Detection of REST Web Services

REST Web Services is a lightweight, maintainable, and scalable service accelerating client application development. The antipatterns of these services are inadequate and counter-productive design solutions. They have caused many qualitative problems in the maintenance and evolution of REST web services. This paper proposes an automated approach toward antipattern detection of the REST web services using Genetic Programming (GP). Three sets of generic, REST-specific and code-level metrics are considered. Twelve types of antipatterns are examined. The results are compared with the manual rule-based approach. The statistical analysis indicates that the proposed method has an average precision and recall scores of 98% (95% CI, 92.8% to 100%) and 82% (95% CI, 79.3% to 84.7%) and effectively detects REST antipatterns.

The autonomous control of landing on mobile platforms

In this paper, we propose a simulation application that allows an aerial vehicle to land autonomously on a moving platform in the presence of uncertainties and disturbances. We have tested our method with various speeds and positions for the landing platform. In the context of this article, the autonomous control of landing on mobile platforms consists in synchronizing the movement of an aerial vehicle with the movement of the mobile platform. As a first step, the Spacelab INCAS laboratory group has developed an offline simulation application that allows an ABB robot to receive information on the movement of a Stewart-type mobile platform in order to conduct a landing process. The application can initiate a landing process on the mobile platform and guide the vehicle for perfect docking on the platform. Offline simulation allows the study of several scenarios of a robot working cell - the mobile platform before setting up the production cell. The offline application has a distributed client-server structure. The client communicates with the server through specific communication protocols. The client and server can reside on the same computer. The client application is developed in the Matlab environment and has as object the simulation and programming of the PS-6TL-1500 platform; the server one simulates and programs an ABB 7600-500/2.55 robot that moves on the track, in the RAPID language under RobotStudio ABB simulator.

REST API performance comparison of web applications based on JavaScript programming frameworks

The aim of the work was to compare two technologies for creating server applications based on the JavaScript programming language. For the purposes of the research, two test applications were created. The first one was built on the basis of the Express programming framework and the second one on the basis of the Hapi framework. The client part of both applications was prepared using the React library. The client and server parts communicated with each other by means of REST API – the universal HTTP interface. The client application sent requests to the server application which then performed basic operations on the MongoDB basis and returned the result. As part of the work, an experiment consisting of four scenarios was developed. In each scenario, a different type of data was taken into consideration: a string of characters, an array, an object and an array of objects. The research focused on the efficiency aspect – measuring the response time of requests during GET, POST, PUT and DELETE operations. The tests were performed on two computers and the measurements were made in two ways: using a single code embedded in test applications and using the Postman tool. The obtained results, after averaging and analyzing them allowed for the conclusion that the Express framework proved to be more efficient than Hapi due to the shorter response time of requests. Only in the scenario where operations with large datasets were performed was the response time of requests at a similar level.

Development of Large-Scale User/Client Application for Automobile Networking Sector

Large Scale User Applications have been prevalent in the 5G era especially in sectors such as automobile, employee tracking features, e-commerce management, etc., especially with services that connect users with their pain points. One of the pain points observed in the subcontinent regarding an overlooked scenario was driving schools and the business of driving services. The current state of driving schools tends to confuse the user base with miscommunications, late service delivery, licensing formalities, and also the payment structure in the absence of a feedback loop. This project attempts to create a full-fledged driving service solution for the 38-lakh user base in the Indian Subcontinent, so as to acquire driving service providers and connect them with the target audience. This would prompt a smoother process of user onboarding as well as improve the service quality with an integrated milestone payment loop. The results observed through the launch of the application on the Play Store were positive and the young generation aged 18-15 were highly enthusiastic about using the service.

Lazy Loading Based with Load On Demand and Currency Support in Web Browser

In this work our goal is to make a Web client application for the Real Estate Business. We already have a Stand-Alone Application for the same, so we are migrating from Online Application to the Web Client. Here for this we are using XPA tool which is a tool to move a project and make changes as per necessity. During this, we designed the editing function size and position adjustment, hiding and displaying, style editing, editing by device type etc. for every device type such that the contents will be dynamically converted according to resolution or screen-size in step with various devices. To be able to answer various devices, storing device information in an exceedingly component is created through editing function. With this, we have worked on Currency Format support in Web Client application and implemented a concept of Lazy Loading. Responsive web functionality improve server throughput that shows the response function of Web Client and therefore the processing speed is improved. All features can operate in real-time manners with our software architecture and loading mechanism, called Lazy Loading.

An approach to information export from database for complex master-detail table hierarchies into a single flat table form

When developing a database client application it is usually required to implement a capability to export information from database tables into some simple data-exchange representations of tables like the CSV (Comma-Separated Values) format. It is very straightforward to implement the export for a single database table. But some information about the records of a master table may be represented by the records from, sometimes, several detail tables, so the resulting CSV table would be incomplete without this information. We develop AIS (automated information systems) using declarative specifications of database applications (SDA). The AIS’es are implemented using general algorithms, which are directed by the specifications. In this article we’ll consider the approach to generation of flat tables from the master-detail groups of tables, which allows users to represent compactly the data from a hierarchy of tables related by the master-detail relationships and to select conveniently which kind of information to include into the resulting table.

Parking Slot Reservation System for Efficient Resource Utilization and Profit

Theparkingspacesavailableindaily moving lifestyle is not considered for parking. This problem causes many people to park their vehicles road side and results traffic violations and many accidents in major cities. These can be avoided when people can find the available parking spaces and reserve them to park their vehicles before reaching to that specific area. The main idea is based on mobile applications where the client and the vendor uses mobile applications for their purposes. The client can viewavailableparkingareasintheirdestination and can book them in advance before reaching them. The vendor application can be used by the parking lot owners to authenticate the incoming vehicles and allocate slots for both the client booked with application and naive users coming without using client application. The main algorithms used provides profit to both the users and the parking lot owners and best slot allocation algorithm. By this way many unused and distance parking lots can be utilisedinordertoreducetheroadsideparkings

TemplateFlow: a community archive of imaging templates and atlases for improved consistency in neuroimaging

Neuroimaging templates and corresponding atlases play a central role in experimental workflows and are the foundation for reporting standardised results. The proliferation of templates and atlases is one relevant source of methodological variability across studies, which has been recently brought to attention as an important challenge to reproducibility in neuroscience. Unclear nomenclature, an overabundance of template variants and options, inadequate provenance tracking and maintenance, and poor concordance between atlases introduce further unreliability into reported results. We introduce TemplateFlow, a cloud-based repository of human and nonhuman imaging templates paired with a client application for programmatically accessing resources. TemplateFlow is designed to be extensible, providing a transparent pathway for researchers to contribute and vet templates and their associated atlases. Following software engineering best practices, TemplateFlow leverages technologies for unambiguous resource identification, data management, versioning and synchronisation, programmatic extensibility, and continuous integration. By equipping researchers with a robust resource for using and evaluating templates, TemplateFlow will contribute to increasing the reliability of neuroimaging results.