Internet Tool Survey

Context

The Internet Tool Survey is part of a larger project, Scaling Object Services Architectures to the Internet, whose overall goal is to enable the rapid construction of Internet-enabled applications for electronic commerce, command and control, and virtual enterprises. Our thesis is that an extensible architecture is needed that combines the representational power of today's object technology with the scalability and openness of today's Internet tools, including World Wide Web. We are working to extend a class of architectures called object services architectures to be scaleable and Internet-enabled. Visions: Application and Technology Drivers sketches a number of end-user-oriented visions of the future that will be enabled by the type of Internet/Web/Object/Middleware/DBMS integration toward which we are working.

Today, object services architectures (OSAs) are frameworks which consist of a messaging backplane and a collection of orthogonal plug-in object services. The messaging backplane, called an Object Request Broker by the Object Management Group (OMG) and Component Object Model (COM)/Network OLE by Microsoft, supports an object model and distributed message passing communication between the various services. Benefits include a principled architecture and a rich services toolkit which, if adopted widely, would extend the kinds of benefits provided by today's standard GUI components, common look-and-feel, to a much broader domain, that of common semantics, as provided by a common object services toolkit. End-users would benefit from ease of understanding applications built from a common set of services. Developers would benefit from the availability of a library of common, tested parts and could customize only some parts or include some services instead of starting from scratch when building custom systems. Limitations of OSAs at present include lack of maturity, modest adoption rates, and limited architectural provision for federation of services though there is good progress on federation of backplanes.

At the same time, today, a number of widely-used tools are available in the Internet environment. One of them, the World Wide Web (WWW or The Web), is an increasingly pervasive addition on top of basic Internet protocols that makes is possible for people world wide to access and publish globally accessible hypermedia documents. Beyond the clear benefit of providing a platform-independent way to share information, there is still the challenge of extending the reach of the web beyond unstructured and semi-structured to structured information, which object technology handles well.

Today, corporations, as well as the Government, are moving from proprietary internal networks to intranets, using Internet technologies within a corporate firewall or other protection perimeter. And they are adopting object technology. What is needed is a way to improve both web and object technology frameworks and to grow these architectures together so that the advantages of both can be available to next generation application builders.

Steps in our three year project are:

identify today's object and Internet technologies and tools (this Internet tools survey),
extend the architecture of both OSAs and Internet tools toward unification, and
demonstrate a reference implementation of (some of) this unified architecture based wherever possible on existing tools.

Our approach is open. We are working towards this end not only in our project but also through standards groups like OMG (chairing the OMG Internet Special Interest Group), helping to create forums like the Joint W3C-OMG Workshop on Distributed Objects and Mobile Code (June 24-25 1996 in Boston), and working with like-minded industry groups including the National Industrial Information Infrastructure Protocols (NIIIP) consortium (a DARPA Electronics Technology Office Technology Reinvestment Project) and other members of the DARPA Information Technology Office Defense Technology Integration and Infrastructure (see also DTII Workshop Proceedings '96) community and the DARPA Information Systems Office Intelligent Integration of Information Technology for the Dynamic Database (I3) (see also I3 Workshop Proceedings '96) community.

Purpose

In the above context, this Internet Tool Survey has several goals:

Common Architecture -- gain a better understanding of the glue and architectural properties of large scale architectures. For instance, OSAs are based on APIs while many Internet protocols are based on wire protocols. Any unification of OSAs and these Internet protocols must address this fundamental difference. Understanding properties of glue is a key step in understanding how to bind parts together quickly to build new compositions. Accelerating progress toward populating a large scale object services Internet-based architecture will provide a target for a next generation common operating environment.
Standard Parts -- determine what kinds of service types might reasonably be defined in the Internet world. OMG has identified a large number of services, many of which now have specifications. These are not the same services that are found in an Internet or WWW environment. Surveying the kinds of tools already existing in the Internet and WWW is a necessary prerequisite to defining (some of) them as object services. Reviewing several tools in a class helps identify the common services provided by a class. Orthogonalization of services is extremely important, since it facilitates composition of services in unanticipated ways. The greater the orthogonality, the easier composition becomes. Results of identifying potential Internet object services can be inputs to the OMG Internet SIG.
Reference Implementation -- determine which tools might be available for use in our demonstration scenarios. One thesis of our overall project is that most of the functionality that is required to quickly assemble applications is already available in today's tools but better componentization and better component glue is needed to accomplish the goal of rapid application synthesis. The Tools Survey is a step toward determining what components or compositions of functionality are available today in forms that can be deconstructed into object services leading quickly to a reference implementation of some of the Internet services.
Technology Transfer -- provide a forum by which additional information from both our own and others' efforts can continually be collected, organized, and made available to a wide audience. This includes the Government, industry, and academia.

Structure of the Survey

The Tool Survey groups Internet tools into broad categories according to the characteristics of existing tools and the functionalities we believe are needed in order to support a broad class of distributed applications over the Internet. Additional categories and tools will be surveyed throughout the course of this project and some of the current categories will be updated.

Categorizations of this sort are always somewhat arbitrary because a typical tool performs several functions. We tried to categorize tools based on their primary functionality and were influenced by our eventual need to create orthogonal services that can be composed to easily construct virtual enterprises. The categories thus represent a mix of the real and the ideal (from our perspective). Other categorizations are certainly possible.

When selecting tools to survey in each category, we tried to include a representative mix of popular and leading edge systems from both the commercial and research communities. The survey is by no means comprehensive, either in depth or breadth. Given the scope of the Internet and the rapid rate of introduction of new systems, this will necessarily be true of any such survey. Some categories are intentionally shallower than others. This reflects that the purpose of the survey is to support our architectural and prototyping tasks rather than to attempt to create a comprehensive "parts list". This does not imply any judgment about the value or quality of the tools or the category.

If readers spot an inaccuracy, know of a system they think should be included, or want to contribute a section, please let us know at ford@objs.com.

Tool Categories

Virtual Office

Virtual Office Scenarios. This section describes a collection of scenarios (or scenario fragments) from the Virtual Office (VO) application domain. It explores a wide range of VO scenarios in both military and civilian applications, particularly those that considerably extend activities beyond those that might be imagined to take place in a conventional "office" setting. The intent of describing these scenarios is to provide intuition on how VOs might function, and the types of "office" activities that, given the proper technologies, could be performed virtually, that is, in a distributed environment, and to provide the necessary background to identify technologies required to support VOs.
Enabling Technology for Virtual Office Applications. This section provides an initial description of the enabling technology required to support Virtual Office (VO) applications.
Virtual Office White Paper. This section describes our rationale for setting up OBJS as a Virtual Office, and our initial experiences.
Electronic Support for Collaboration & Decision Making in OBJS. This section reports the experiences of the author using electronic support, primarily email, for a recent OBJS virtual brainstorming session.
Initial Use of COTS Tools in the OBJS Virtual Office. This section describes the construction of a working Virtual Office, using a combination of straightforward operational techniques, and readily available COTS personal computer and Internet hardware and software technology, based on our experience in setting up and using the OBJS VO. The section also describes lessons we have learned based on our experience, and further developments we intend to make in refining and extending our VO capabilities. This is the first in a series of scenarios intended to both illustrate VO capabilities and technology, and drive our development of further VO technology. Subsequent scenarios will involve both more refined uses of COTS technology based on our experience, and the use of new technology we develop, in both internal and DoD-related applications.

Managing and Using Information

Hypermedia Systems and WWW Browsers. The term hypermedia refers to compound documents that allow users to traverse a document space in a non-linear order by means of "hyperlinks" between parts of the document space. Hyperlinks are tailored by a document author to provide meaningful paths through the space. This allows progressive disclosure of information, the ability to add new, supporting information, and the ability to annotate. Hypermedia encompasses multimedia by allowing "documents" to contain data types other than text including graphics, image, video, and sound. This survey covers both integrated hypermedia systems and browsers for the World Wide Web (WWW).
HTML Authoring. HTML is the standard interchange format for documents in the WWW. The increasing complexity of HTML, the preference many "content creators" have for WYSIWYG editors, and the existence of many documents without HTML embeddings leads to a desire to simplify the HTML authoring process. The tools in this category either automate or facilitate the process of inserting HTML markup.
Searching and Indexing. Locating information in the WWW by any means other than simple hyperlink traversal requires the use of an index or some sort of query capability. These two topics are closely related, since an index can be thought of as a cached query and many indices are created by using web crawlers that have much in common with query engines. The tools in this category create and maintain indices and/or provide users with search facilities.
Groupware. Groupware is software and hardware for shared interactive environments. Under the most rigorous definition, a complete groupware infrastructure has three dimensions: communication (pushing information out into an organization), collaboration (shared information and building shared understanding), and coordination (delegation of task, sequential sign-offs, etc.,). Also, see our feasibility study on Video Conferencing, a type of groupware of special interest to distributed workgroups.

Security

Authentication. Authentication tools provide the ability to determine the identity of a party to an interaction and to ensure that a message came from who it claims to have come from. Like encryption, authentication is seldom used in isolation. Authentication is used as the basis for authorization (determining whether a privilege will be granted to a particular user or process), privacy (keeping information from becoming known to non-participants), and non-repudiation (not being able to deny having done something that was authorized to be done based on the authentication).
Encryption. Encryption is used to protect the confidentiality of information when it must reside or be transmitted through otherwise unsafe environments. Encryption is also used for digital signatures to authenticate the origin of messages or data. Encryption algorithms themselves are rarely used alone in practice; rather, they are typically embedded into a larger security frameworks to ensure their correct and consistent use.
Virtual Private Networks. This technical memo briefly describes the current state of application-transparent technologies to secure tcp/ip communications between hosts distributed across the Internet (e.g. PPTP, Altavista Tunnel, IPsec).

Objects and the Internet

Componentware Glossary. At present in industry, there is much more talk than understanding about software architecture and componentware concepts like components, component composition, protocols, frameworks and glue. There is not even a good vocabulary for talking about these terms. This document is a start in that direction. The objective of this document is to provide a glossary of terms central to componentware. This terminology may be useful to other groups like the OMG Architecture Board or various DARPA componentware or architecture efforts (NIIIP Consortium, ComponentWare Consortium, I3, JTF/ATD, DoD DII) that have architecture teams working on these concepts.
IETF. This section overviews the Internet Engineering Task Force (IETF) and links to IETF protocols under development.
Object Models. Representing information is facilitated by object models but sharing is more difficult since there are many different modeling representations. This section reviews the features of object models (by reference to the work of X3H7) and provides a number of approaches to object model interoperation.
OMG. Object technology is becoming a pervasive programming style in several key communities: networking, database, programming, and user interface. Object Management Group (OMG) has developed an open architecture for distributed object communication as well as a suite of object services standards to make it easier to build large intra- and inter-enterprise applications.
Requirements for OO + Web Integration. This section is a listing of some of the unmet requirements of OO + Web integration.
Microsoft Technical Briefs. The following sections briefly describe several important elements of Microsoft's interoperability technology.

OLE. This section OLE's (Object Linking and Embedding) object model and features.
OLE DB. This section describes OLE DB, "an open, extensible collection of interfaces that factor and encapsulate orthogonal, reusable portions of DBMS functionality."
OLE IFilter Interface. This section describes OLE's means of providing the text contents of objects to indexing engines.
OLE Registry. This section describe the OLE Registry, which maps between high level service names, their unique identifiers, their attributes and their concrete implementations.
Replication Services. This section describes the various replication services available within Microsoft's operating systems.

Current Web Architecture. This section describes the current architecture of the World Wide Web (WWW): the basic two-tier architecture in which static web pages (documents) are transferred from information servers to browser clients world-wide, extensions that permit three-tiered architectures where content pages can be constructed dynamically and where programs as well as data can be transferred, other information transfer protocols, and related standards.
Quality of Service (QoS). This section describes the quality of service provided by the Internet. Currently the Internet offers a point-to-point delivery service, which is based on the "best effort" delivery model. In this model, data will be delivered to its destination as soon as possible, but with no commitment as to bandwidth or latency. Using protocols such as TCP, the highest guarantee the network provides is reliable data delivery. This is adequate for traditional data applications like FTP and Telnet, but inadequate for applications requiring timeliness. For example, distributed multimedia applications need to communicate in real-time and are sensitive to the quality of service they receive from the network. For these applications to perform adequately and be widely used, QoS must be quantified and managed, and the Internet must be modified to support real-time QoS and controlled end-to-end delays. The notion of QoS must be extended from the communication layer up through the intervening architectural layers to the application level.
Semantic File Systems. Files are a popular form of data storage as they do not impose any formatting and structuring constraints, and the file/directory abstraction is easy to understand. Conversely, the fact that data is stored in files provides no semantic information about them. Tools that manipulate files carry much of the knowledge about file semantics and form the DBMS for the file formats in a sense. By "file semantics" we mean any higher-level definitional (e.g file extension and magic numbers define file type), associative (e.g keywords in file that characterize content), structural (e.g. physical and logical organization of the data, including intra- and inter-file relationships), behavioral (e.g. viewing and modification semantics, change management), environmental (e.g creator, revision history) or other information related to the file. Looking at file data through the eyes of tools limits us to the particular "views" supported by the tools. Conversely, tool-independent views of file data will allow a finer-grained, seamless access to file information. It will also facilitate the potential integration of file information with information stored in more structured repositories such as RDBs and OODBs.
Web + DBMS Integration. The web is connecting together data sources at a fantastic rate. Many data sources including DBMS systems that were formerly inaccessible and write-only are or could soon become accessible. There is increased incentive in enterprises to make more information available not just within the organization but to customers as well. The purpose of this section is to identify software architecture approaches for integration of the Web with DBMS systems.
Web Programming Languages. This document is a survey of current and planned languages and interfaces for developing World Wide Web based applications. The principal goal of creating this document was to identify the various languages currently in use and to provide some insight into the context in which each language is used. Secondarily, the author sought some insight into the directions that web programming was going, especially in the context of the intense publicity surrounding Sun's Java.
Wrappers. Wrappers are a type of software "glueware" that is used to attach together other software components. A wrapper encapsulates a single data source to make it usable in a more convenient fashion than the original unwrapped source. Wrappers are assumed to be "simple". Wrappers can be used to present a simplified interface, to encapsulate diverse sources so that they all present a common interface, to add functionality to the data source, or to expose some of the data source's internal interfaces.

This research is sponsored by the Defense Advanced Research Projects Agency and managed by the U.S. Army Research Laboratory under contract DAAL01-95-C-0112. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied of the Defense Advanced Research Projects Agency, U.S. Army Research Laboratory, or the United States Government.

© Copyright 1996 Object Services and Consulting, Inc. Permission is granted to copy this document provided this copyright statement is retained in all copies. Disclaimer: OBJS does not warrant the accuracy or completeness of the information in this survey.

The Internet Tool Survey was written by (in alphabetical order) Steve Ford, Gil Hansen, Shaun Joseph, Ansu Kurien, Dave Langworthy, Frank Manola, Paul Pazandak, Craig Thompson, Venu Vasudevan, David Wells, and Nancy Wells. Send questions and comments about it to wells@objs.com.

Last updated: 5/15/97 sjf

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