NewGenLib is based on the so called n-tier architecture with an Application Server that mediates between the client machines and the database server. The diagram below shows the NewGenLib architecture.

Advantages of using this technology

• 5-tier application.
• It is very scalable because each layer can be sized depending on the need
• It is very reliable/robust because specialized components can be used at each layer
• It is better maintainable because problems can be easily identified
• Migration to other layers, e.g., presentation layer is possible very easily.
• It is more efficient because of the middle layer, viz., the application layer. Many tasks are managed via this layer
• XML messaging is used to minimize network traffic.
• The technology also uses many open source components to minimize costs for the user.

NewGenLib Architecture

The concept of Application Servers [3] followed the success of the Java platform known as J2EE (Java-2 Enterprise Edition). The advantages of using a middle tier application server resulted in many enterprise level application servers and among these, IBMs WebSphere, WebLogic, JBoss, JonAs, Glassfish are well known. In an application server, Web modules are servlets and Java Server Pages (JSP), while business logic (processing algorithms specific to the business for which the application is designed) is built into the Enterprise JavaBeans (EJB-3). A Java Server Page executes in a Web container—the Java equivalent of CGI scripts. JSPs create HTML pages by embedding references to the server logic within the page. The Hibernate Project (also used in NewGenLib) provides an EJB container implementation for JBoss. NewGenLib’s OPAC uses JSPs. The JBoss application server (open source from RedHat) embeds the Apache Tomcat web server another open-source offering.

Several advantages of using a middle-tier application server are cited and some of these are:

• The integrity of data and code is better ensured
• Centralized business logic on server machines, updates and upgrades to the application for all users can be guaranteed.
• Configurations within an installation can be centralized.
• Changes to the application configuration, such as a move of database server, or system settings, can be done centrally.
• A central point through which access to data and portions of the application itself can be managed is considered a security benefit
• Connection pooling to ensure that response times are good.
• Better scalability of the application via new versions and/or alternative database servers without too much reprogramming effort as long as the application server conforms to the J2EE specifications.

NewGenLib on the other hand is entirely Java-based and uses the following related software technologies in its presentation, application and database server layers.

• Java Web Start – based Applets. Java web Start (JWS) is a framework developed by Sun Microsystems, and allows users to start application software for the Java Platform directly from the Internet using a web browser. Unlike Java applets, Web Start applications do not run inside the browser, and the sandbox (A tightly controlled set of resources) in which they run need not have as many restrictions, although this can be configured. Web Start has an advantage over applets in that it overcomes many compatibility problems with browsers' Java plugins and different Java Virtual Machine (JVM) versions. NewGenLib’s librarian’s interface is entirely written as JWS applets.

Some of the features associated with Java Web Start [4] include:

• A richer user interface is possible as compared to using a browser-based one.
• Portability: Java Web Start is available on Windows, Solaris, and Linux, and is expected to be ported to other platforms.
• Caching: Applications launched with Java Web Start are cached locally. Thus, an already- downloaded application is launched on par with a traditionally installed application.
• Maintainability: If the remote application is updated, Java Web Start updates the locally cached version at the application's next invocation.
• Easy launching: Java Web Start allows applications to be launched independently of a Web browser. The application can also be launched through desktop shortcuts, making launching the Web-deployed application similar to launching a native application.
• Ability to work offline: An application can be used in situations where launching through the browser is inconvenient or impossible.

Other software technologies used in NewGenLib’s presentation layer are:

• Java SWING based GUI client - SWING provides a sophisticated set of graphical user interface (GUI) tools for Java programs.
• Java Runtime Environment (JRE) (freeware). JRE is the only software required at the client side to run NewGenLib’s java programs downloaded from the server
• JDOM (open source) , a parser for XML documents used as the messaging platform between clients and server in NewGenLib.  In NewGenLib XML messages between clients and server are compressed before transmission over the Internet. This is a feature that reduces network traffic.
• Java Help 2.0 for help (freeware)
• Jasper Reports (open source)
• Hibernate (open source)
• Java Mail (Freeware)
• Jakarta POI (open source)
• openOffice 2.0 – to generate and print form letters and reports (open source).

The use of a distinct software technology for the presentation layer in NewGenLib does make it possible, theoretically at least, of moving the front-end to a richer Internet application using new tools such as Adobe’s Flex-3. A recent example of an application that exposes a rich internet interface is Biblios (http://biblios.org/), an open source cataloguing application. How difficult such a move is for NewGenLib and the extent to which code can be reused or repurposed is an issue that will come into play.

Technologies used by NewGenLib in the Application server layer are:

• Servlets and JSPs
• Tomcat web server embedded in the JBoss application server (both open source)
• Struts, an open source framework that has as its goal the separation of model (business logic) from the view (html pages presented to the user) and the Controller (instance that passes information between model and view). A central configuration file binds the model, view and controller.
• Enterprise Java Beans - JBoss Application Server 3.2.1 (open source)
• JDOM
• XCQL – CQL (common query language version 1.1) parser (open source). CQL (Common Query Language now renamed Contextual Query Language) is a a formal language for representing queries to information retrieval systems such as web indexes, bibliographic catalogs and museum collection information. The design objective is that queries be human readable and writable, and that the language be intuitive while maintaining the expressiveness of more complex languages. (http://www.loc.gov/standards/sru/specs/cql.html). NewGenLib supports only the basic version of CQL and the Bath and Dublin Core profiles. The SRU/W federated search protocol searches use CQL queries.

Given the differences in the technological base of the software, it would appear that NewGenLib, because of its more modular architecture, use of object-oriented analysis and design, its use of middle-tier technologies, XML Streams and EJB containers that encapsulate business logic, is probably better suited to be broken into modules with a service-orientation than Koha. NewGenLib may be in a better position to take advantage of the OLE Project’s findings: for modular components dealing with the core processes and for these to connect to one or more open services based on well defined w3c standards.

A distinction between the terms: service-oriented architectures (SOA) and web services is in order. SOA is an approach [http://www.slideshare.net/bikesandbooks/open-library-environment-samm-08] where:

• software pieces are built independently,
• they can be interchanged or repurposed, and
• can be combined to create new systems and services.

NewGenLib already uses XML streams for exchange of data between clients and servers in its different modules. Conceivably, it should be easy for NewGenLib to expand into using web services protocols both at its client as well as server sides, although it does not use any so far. It is not clear to what extent Koha modules use XML streams to communicate between Koha clients and servers and with other servers. But the fact that Koha modules are all written in Perl and that it already invokes web services means that Koha too should have the capability to expand into being compliant with current and new web service applications and standards.