Misc. edits preparing for 0.5a2
PEAK Release 0.5 alpha 2 Copyright (C) 1996-2003 by Phillip J. Eby and Tyler C. Sarna. All rights reserved. This software may be used under the same terms as Zope or Python. THERE ARE ABSOLUTELY NO WARRANTIES OF ANY KIND. Code quality varies between modules, from "beta" to "experimental pre-alpha". :) Package Description PEAK is the "Python Enterprise Application Kit". If you develop "enterprise" applications with Python, or indeed almost any sort of application with Python, PEAK may help you do it faster, easier, on a larger scale, and with fewer defects than ever before. The key is component-based development, on a reliable infrastructure. PEAK is an application kit, and applications are made from components. PEAK provides you with a component architecture, component infrastructure, and various general-purpose components and component frameworks for building applications. As with J2EE, the idea is to let you stop reinventing architectural and infrastructure wheels, so you can put more time into your actual application. But PEAK is different from J2EE: it's a single, free implementation of simpler API's based on an easier-to-use language that can nonetheless scale with better performance than J2EE. PEAK is the successor to TransWarp, an experimental toolkit for software automation in Python. PEAK takes the best of the techniques and ideas from TransWarp, and repackages them as an enterprise software toolkit. Where TransWarp emphasized techniques like generative programming and aspect-oriented programming, PEAK emphasizes enterprise applications, and hides the computer science stuff "under the hood", so you can focus on building your application. PEAK tools can be used with other "Python Enterprise" frameworks such as Zope, Twisted, and the Python DBAPI to construct web-based, GUI, or command-line applications, interacting with any kind of storage, or with no storage at all. Whatever the application type, PEAK can help you put it together. Package Features As of version 0.5a2, PEAK features include: * A component binding framework that makes it easy to parameterize components and thus more easily combine and "wire" them together. Interfaces, adaptation, and "assembly events" (notification when components have been engaged as part of a "complete" application) are all available. * A comprehensive configuration framework that allows accessing "utilities" and "configuration properties" in context. Properties and utilities can be loaded or computed on demand, supplied by rules, defined in configuration files or code, in a supplied or custom format. Properties and utilities are contextual and can be safely acquired from parent/context components automatically. * Naming system/framework that's midway between J2EE's JNDI and CORBA's cosNaming in features, but much easier to use and extend than either of those systems. * A storage management and persistence system, including: - Atomic, multi-database transactions with two-phase commit. - "Data Manager" class framework for persistence management, that allows you to separate business logic from storage implementation. If you can write a few simple methods like "load" and "save" for a given object type and storage approach, you can create your own "DM" components. You can think of a DM as an advanced form of Python "shelve", that supports references to other objects, transactions, arbitrary back-end storages, and caching. - "Stackable" data managers: one DM might serialize a set of objects to XML, which could then be stored in a database record by another DM, and then the database record might be implemented via a DM that writes to disk files! Each DM only needs to know how to manipulate objects offered by the next-level DM, not the details of the next DM's implementation, so all the DM's are potentially replaceable with alternate storage mechanisms. - RDBMS and LDAP connection framework based on the Python DBAPI, that handles data type conversions (via the configuration framework) and seamlessly integrates with the transaction system and naming services framework. DB Connections can be accessed by name or URL, and bound as default collaborators or utilities for access by other application components. * CASE/modelling tools: PEAK includes APIs to read object models created in the XML-based XMI format. Many open-source and commercial modelling tools support XMI, inlcuding Argo/Poseidon and MagicDraw UML. PEAK includes pre-built support for UML versions 1.3 and 1.4, and MOF 1.3.1, using XMI versions 1.0 and 1.1. (UML 1.5, CWM 1.0, CWM 1.1, and XMI 1.2-2.0 are anticipated for version 0.6.) Also included is a MOF->Python code generator, which was used to generate the UML support, and which you can use to generate support for other modelling languages based on the MOF. For the specifications of XMI, MOF, CWM, and UML, visit: http://www.omg.org/technology/documents/modeling_spec_catalog.htm * A domain modelling framework for creating "business object models" with unidirectional and bidirectional associations, generated getters/setters and validators for fields, etc., and all necessary persistence support for use with the PEAK storage framework. Domain types can also define string parsing and formatting syntax, so you can create domain-specific data languages or just string formats for data types (such as specialized date/time or currency types). The business object framework supplies structural metadata about classes built with it, so you can query a class for its fields and links, and their names, types, etc. This can be useful for implementing model-driven storage or user interfaces. And the metadata is aligned with the MOF, so generating MOF, UML, or CWM from PEAK models (and vice versa) is possible (although not yet implemented for anything but MOF->PEAK). * Application Runtime tools, including: - a "command objects" framework for creating command-line applications, including the ability to create "executable configuration files" or "configuration interpreters" that can load a configuration file and run an application instance constructed using the configuration data. Supported formats include an .ini-like PEAK format, and arbitrary schemas defined using ZConfig. - a "periodic tasks" framework for executing tasks that perform "as needed", scheduling themselves in response to their available workloads - a CGI/FastCGI publishing framework that uses 'zope.publisher' to publish a PEAK component tree and its associated transaction service - an event-driven "reactor" framework that seamlessly integrates with Twisted, but can also be used without Twisted for applications that are mostly scheduling-oriented, or which use only third-party protocol implementations such as FAM, FastCGI, ReadyExec, etc. - a robust and flexible logging framework that can integrate with the PEP 282 logging module, or stand alone. It's simpler than the PEP 282 system for simple log configuration, and is configured on demand rather than "up front", and is thus more manageably configurable for large or complex applications consisting of components from diverse providers. * AOP and SOP: PEAK allows you to separate concerns as modules, then combine the modules via a "module inheritance" technique. This lets you define a generated business object model as a "structural" concern, and then combine it with a "behavioral" concern. This is as simple as writing classes that contain only what you want to add, and then telling PEAK that your new module "inherits" from the generated module. This is similar to (but designed independently from) the "MixJuice" tool for AOP in Java. Known Issues and Risks of this Version This is ALPHA software. Although much of the system is extensively tested by a battery of automated tests, it may contain bugs, especially in areas not covered by the test suites. Also, many system interfaces are still subject to change. PEAK includes early copies of Zope X3's 'ZConfig' and 'persistence' packages, which have had - and may continue to have - significant implementation changes. We will be tracking Zope X3 periodically, but can't guarantee compatibility with arbitrary (e.g. CVS) versions of Zope X3. Documentation at present is limited, and scattered. The principal documentation is an API reference generated from the code's lengthy docstrings (which usually contain motivating examples for using that class, method, or function). The mailing list and its archives provide a wealth of information on actual usage scenarios, recommended approaches, etc. There is also the beginnings of a tutorial on using the component binding package. Third-Party Software Included with PEAK All third-party software included with PEAK are understood by PEAK's authors to be distributable under terms comparable to those PEAK is offered under. However, it is up to you to understand any obligations those licenses may impose upon you. For your reference, here are the third-party packages and where to find their license terms: The 'kjbuckets' module is Copyright Aaron Watters and contributors; please see the 'src/kjbuckets/COPYRIGHT.txt' file for details of its license. The 'persistence' and 'ZConfig' packages are Copyright Zope Corporation and contributors; please see the 'LICENSE.txt' files in their directories for details of their licenses. The 'fcgiapp' module is Copyright Digital Creations, LC (now Zope Corp.); see the 'fcgiappmodule.c' for details of its license. In the same directory are distributed portions of the FastCGI Development Kit, which is Copyright Open Market, Inc. See the 'LICENSE.TERMS' file in that directory for details of its license. Installation Instructions Please see the INSTALL.txt file.
Powered by ViewCVS 1.0-dev