Clustered Serialization with Fuel

International audienceSerializing object graphs is an important activity since objects should be stored and reloaded on different environments. There is a plethora of frameworks to serialize objects based on recursive parsing of the object graphs. However such approaches are often too slow. Most approaches are limited in their provided features. For example, several serializers do not support class shape changes, global references, transient references or hooks to execute something before or after being stored or loaded. Moreover, to be faster, some serializers are not written taking into account the object-oriented paradigm and they are sometimes even implemented in the Virtual Machine hampering code portability. VM-based serializers such as ImageSegment are difficult to understand, maintain, and fix. For the final user, it means a serializer which is difficult to customize, adapt or extend to his own needs. In this paper we present a general purpose object graph serializer based on a pickling format and algorithm. We implement and validate this approach in the Pharo Smalltalk environment. We demonstrate that we can build a really fast serializer without specific VM support, with a clean object-oriented design, and providing most possible required features for a serializer. We show that our approach is faster that traditional serializers and compare favorably with ImageSegment as soon as serialized objects are not in isolation

Fuel: A Fast General Purpose Object Graph Serializer

International audienceSince objects need to be stored and reloaded on different environments, serializing object graphs is a very important activity. There is a plethora of serialization frameworks with different requirements and design trade-offs. Most of them are based on recursive parsing of the object graphs, an approach which often is too slow. In addition, most of them prioritize a language-agnostic format instead of speed and language-specific object serialization. For the same reason, such serializers usually do not support features like class-shape changes, global references or executing pre and post load actions. Looking for speed, some frameworks are partially implemented at Virtual Machine (VM) level, hampering code portability and making them difficult to understand, maintain and extend. In this paper we present Fuel, a general-purpose object serializer based on these principles: (1) speed, through a compact binary format and a pickling algorithm which invests time in serialization for obtaining the best performance on materialization; (2) good object-oriented design, without special help at VM; (3) serialize any object, thus have a full-featured language-specific format. We implement and validate this approach in Pharo, where we demonstrate that Fuel is faster than other serializers, even those with special VM support. The extensibility of Fuel made possible to successfully serialize various objects: classes in Newspeak, debugger stacks, and full CMS object graphs

Object Cloning for Ownership Systems

Modern object-oriented programming languages frequently need the ability to clone, duplicate, and copy objects. The usual approaches taken by languages are rudimentary, primarily because these approaches operate with little understanding of the object being cloned. Deep cloning naively copies every object that has a reachable reference path from the object being cloned, even if the objects being copied have no innate relationship with that object. For more sophisticated cloning operations, languages usually only provide the capacity for programmers to define their own cloning operations for specific objects, and with no help from the type system. Sheep cloning is an automated operation that clones objects by leveraging information about those objects’ structures, which the programmer imparts into their programs with ownership types. Ownership types are a language mechanism that defines an owner for every object in the program. Ownership types create a hierarchical structure for the heap. In this thesis, we construct an extensible formal model for an object-oriented language with ownership types (Core), and use it to explore different formalisms of sheep cloning. We formalise three distinct operational semantics of sheep cloning, and for each approach we include proofs or proof outlines where appropriate, and provide a comparative analysis of each model’s benefits. Our main contribution is the descripSC formal model of sheep cloning and its proof of type soundness. The second contribution of this thesis is the formalism of Mojo-jojo, a multiple ownership system that includes existential quantification over types and context parameters, along with a constraint system for context parameters. We prove type soundness for Mojo-jojo. Multiple ownership is a mechanism which allows objects to have more than one owner. Context parameters in Mojo-jojo can use binary operators such as: intersection, union, and disjointness

Design and implementation of a programmable middleware

This thesis presents a languagebased, safely programmable middleware for the simple, highlevel, and expressive construction of composable open systems. The middleware provides services for pickling, components, and distribution. All are based on a minimal set of primitives and syntax extensions, such that they otherwise can be completely implemented and customized in a highlevel language with automatic memory management, exception handling, higherorder functions, futures, and dynamic types. Using this approach, it becomes possible to describe the complete architecture of the middleware system, and to leverage the language\u27;s safety features in the middleware itself.Die vorliegende Arbeit beschreibt eine Programmiersprachenbasierte programmierbare Middleware, die eine einfache Konstruktion offener Systeme auf hoher Ebene ermöglicht. Die Middleware bietet Dienste für Pickling, Komponenten und Verteilung an, die allesamt auf einem minimalen Satz an Primitiven und Syntaxerweiterungen beruhen. Der Hauptteil der Dienste kann so in einer höheren Programmiersprache mit automatischer Speicherverwaltung, Ausnahmebehandlung, Prozeduren höherer Ordnung, Futures und dynamischen Typen realisiert werden. Dies ermöglicht es, die Architektur der Middleware vollständig zu beschreiben, sowie die Sicherheitsgarantien der höheren Programmiersprache in der Implementierung der Middleware selbst zu nutzen

Proceedings of the 4th International Conference on Principles and Practices of Programming in Java

This book contains the proceedings of the 4th international conference on principles and practices of programming in Java. The conference focuses on the different aspects of the Java programming language and its applications