Overview

This section introduces the Blue Application Platform. A general description is followed by a concise overview of BlueAP functionalities, design considerations and operational procedures.

A BlueAP System is the collection of Business Server applications built using the Blue Application Platform together with the BlueAP kernel processes (that manage the system) running on a network of host machines.

At the end of this document, the reader should be able to

• identify the functionalities and benefits of BlueAP
• recognize the different components of a BlueAP System, and describe their roles
• decide for which Business Service applications BlueAP can best be deployed
• determine how BlueAP can be used to implement successful solutions

In the first section of this chapter, a description is given of the issues that BlueAP is designed to solve. The second section describes the advantages of a BlueAP solution, and the third section gives an overview of BlueAP, its functionalities and its components.

The chapter concludes with a short summary.

The Aims

All contemporary computer system business solutions are intended to satisfy the often-conflicting demands of its business requirements, its operational and management requirements and its design, development, programming and maintenance requirements.

So, imagine that a system is required to satisfy the following business criteria:

• that different types of communication paradigms are needed; including transaction processing, and peer-to-peer messaging.
• that the system is highly performant; including being able to manage high data throughput rates (both during normal and peak periods), that short user response times are guaranteed, and that recovery from hardware, software or network failures is rapid.
• that the system is highly reliable; including the requirement for reliable and guaranteed messaging; for 24/7 operations, for low mean-times between failures and automatic recovery from failures (when they do occur).
• that the system is distributed over a heterogeneous architecture (including different hardware and different operating systems).
• that the system can respond readily to real-time data and updates.
• that the system can manage foreign data sources, including databases, with proprietary protocols and transports.
• that the system can integrate easily with legacy systems and protocols.
• that the system is scalable to meet growing demands.
• that the system is extensible to meet changing demands.

In addition, imagine that a system is also required to satisfy the following management and operations criteria:

• that the system is readily managed and monitored by systems administration staff.
• that the system provides the tools for managing the release and distribution of the application software, with the necessary version control.

Further imagine that a system is also required to satisfy the following programming and development criteria:

• that application development is rapid and customisable.
• that both internal company and international standards, practises and procedures are comprehensively incorporated into the system.
• that the system integrates seamlessly with other system tools, that offer, for example, user-interface design, database access, internet access, system management and project management.
• that the system is easily comprehended and learnt by analysts and application development staff.
• that the system provides state-of-the-art tracing and debugging facilities for use during the development and testing phases of a project.
• that the application development cycle can be easily integrated into production, either by the incremental or big-bang approach.
• that the alpha, and beta versions of a system (for use during development and testing) can closely match the topography and characteristics of the production system, even to the extent of sharing the same physical network but inhabiting different logical environments.

These, then, are the criteria against which the effectiveness of business solutions is measured.

BlueAP is designed to enable and prescribe the building of applications that meet, and often surpass, these demands.

The remaining chapters of this document describe how the distinctive attributes of the Blue Application Platform achieve this.

The Architecture

The major components of a BlueAP System can be summarised as follows:

hosts, on an inter-connected network

the hosts in a BlueAP System may be spread over Client Networks or various Data-Centres, and be interconnected via bridges, hubs and routers. The topology of the network is of no consequence to the applications and clients, for example, need never know the physical whereabouts of the servers they require.

kernel processes

to manage the BlueAP System, several types of BlueAP Kernel processes are required. These are completely transparent to applications but are necessary to maintain the integrity of the system. These processes provide the necessary management on each host of the system, provide for the supervision of the system (so that its behaviour automatically observes the assertions of the BlueAP Configuration File), and allow the manual monitoring and control of the system by Systems Management Staff.

business services applications [servers]

those applications that manage large amounts of information for many clients, either by caching them for on-demand queries, and/or by adding value to data by cross-referencing data from several sources. Typically, these servers retrieve their real-time information from databases, from gateway servers, or from other BlueAP servers.

business clients applications [workstation clients]

those application running on a workstation to serve the needs of an individual user. They typically provide the user-interface for entering information into the system, for monitoring the arrival of real-time information, and for providing the tools to aid in decision making. These applications typically connect to databases, servers and gateways that supply the user with the information required.

external business services applications  [gateway]

those applications that connect to business services outside the BlueAP System. Typically, these are systems that use proprietary protocols and transports. However, the details of these, often legacy systems, is completely transparent to BlueAP applications.

databases

the repositories of mass information in the system. Typically, this includes information for:

• describing the requirements and permissions relating to applications and users
• for future use; such as data-mining, or historical analysis.
• for the purposes of recovering from failures.
• for the retrieval by other applications – usually those who do not require real-time data.
• for information stored for legal and contractual reasons.

The Paradigms

These paradigms ensure that the components of the BlueAP System architecture work together efficiently to provide the services at the performance required:

Event/State Driven Applications

All BlueAP applications are designed using the event/state paradigm. Their behaviour, is therefore fully described by tables that define the actions an application should take upon receiving a certain event when in a particular state. This means that:

• the behaviour of an application is fully deterministic
• the design of the application is easily documented from the tables
• that the behaviour of applications can easily be traced and logged during the development and testing cycles
• that the tables can easily be modified to incorporate new events, without impacting any other applications
• that the arrival of unknown events (or events arriving whilst in a state not designed to process them) are always logged and therefore easily identifiable

Layered Architecture

The strictly layered design of the Blue Application Platform ensures that application designers have a clear and concise API with which to build solutions.

Such a methodology also means that these designers can concentrate on the functional and business requirements of the solution in the knowledge that many of the complex solutions normally associated with distributed client/server systems are shrink-wrapped within the Blue Application Platform.

Communications Protocol Transparency

A common communications protocol is used whether the interface is to servers, clients, databases or gateway servers. Any foreign protocols (from gateways or legacy systems) are automatically translated into a consistent BlueAP protocol. This is realised through a variety of codec, protocol and transport handlers (including gpb). Standard APIs to these handlers allow for the fast integration of new gateway services.

Name Based Services

The network location of a communicating partner is transparent; processes either communicate by server name or by service name, depending on the application design.

The Advantages

The BlueAP solution brings to the market-place the experience of many years of expertise in the field of high-performance, time-critical and profit generating systems.

Over the past decade the swiftly changing world of international finance has seen the integration of several generations of computing paradigms into high-performance systems. BlueAP has incorporated many of these in a way that has encapsulated the best attributes, without falling victim to the passing whims of fashion.

These ideas have been severely explored and tested during the evolution of BlueAP in such a way that only the most useful and robust features remain.

For example, an earlier generation of BlueAP incorporated the facilities for designing and building graphical user-interfaces. These requirements are now deemed to be better served by more specialised tools, and instead BlueAP provides the capability of integrating with such tools. Moreover, such integration allows a system designer to more easily adhere to GUI standards (whether internal or international), or to integrate with legacy user-interfaces.

The advantages of a BlueAP System solution can be summarised as follows:

Adherence to International Standards

Regarding networking methodologies, application design methodologies, application development and management tools, code re-usability.

Client/Server Architecture

The performance of a BlueAP System is enhanced by providing the computing resources where needed.

Scalability

The design methodology of BlueAP applications automatically prepares them for future expansion when service demand increases. This permits applications to be functionally partitioned, or to be functionally replicated and subsequently to allow the service they provide to be distributed over several hosts.

Extensibility

Various aspects of the BlueAP methodology automatically prepare them for future changes in functional requirements. For example, the integration of new messages between applications, or changes in the design of messages between application can be incorporated easily without impacting other clients where the new functionality is not required.

In addition, the introductions of new applications into a BlueAP System can be performed incrementally without impacting the currently running system.

Distributed Architecture

The reliability, robustness and scalability of a system is enhanced by spreading the system load over a variety of hosts within a network. In addition, the headroom given by host redundancy, provides the necessary contingency for host failures and network partitioning e.g. where the network is divided into two.

GUI Platform independent

Business Services applications built using the Blue Application Platform run on the Linux operating system, however GUI client applications may run on any platform that suits the requirements.

Open System

The BlueAP System conveniently provides tools for the integration of legacy and external systems. These tools provide for the integration of proprietary codecs, protocols and handlers in a concise and uniform way.

Very High Availability

The BlueAP Kernel processes monitor the running behaviour of a system and ensures that:

• all clients of a failed application are informed at failure and recovery time
• failed applications are quickly and automatically re-started
• applications on failed hosts are quickly and automatically migrated to another host
• clients of applications that have migrated are quickly and automatically re-connected to the re-started application.
• ensures a 24/7 availability of applications

Multi-Tier

The BlueAP solution allows for the development of multi-tiered distributed client/server systems. These tiers, shown in Figure 2, traditionally incorporate;

• the user workstations
• the application servers
• and the database servers

In addition, the BlueAP solution allows for the integration of further layers, for example:

• local servers, for groups of users
• high-level servers for distributing workloads over subsidiary servers

Development Standards

The event/state design methodology of the BlueAP solution dictates a certain amount of discipline into the programming style used for applications. In addition, the clear and concise readability of the BlueAP library APIs encourage this discipline, that may easily be incorporated into a house style of programming standards.

Because the code for all applications looks the same and is similarly structured there are many advantages for software maintenance.

Real-Time Debugging and Diagnostic Tools

The BlueAP System provides many tools to aid the programmer during the development and testing phases. For example:

• event, library and module-level real-time tracing
• precise process control
• memory management tools
• data-structure management tools, including queues and trees
• logical process construction; for example, for building emulators of not-yet-ready system components during the testing cycle
• version control
• event recording and playback

Summary

In practice a solution designed on the Blue Application Platform is a solution that is eminently:

• available
• connectible
• efficient
• extensible
• reliable
• robust
• and scalable

System Designers can concentrate on the business requirements in the knowledge that the Blue Application Platform has all the necessary components to build 24/7, high performance distributed solutions.

Application Developers can concentrate on building and implementing the solution knowing that the Blue Application Platform provides access to the complexities of contemporary distributed services, whilst simultaneously wrapping them in a safe and reliable manner.

Database Managers can concentrate on the design of their data-model in the knowledge that the Blue Application Platform provides a standard interface to the database, and, with the necessary servers can manage real-time updates and data caching, with many clients making many requests, within the required response times.

Communications Engineers can concentrate on integrating the protocols, transports and codecs of external systems knowing that application programmers can access the external services and information in a standard way irrespective of its source.

System Managers can concentrate on the day-to-day running of a BlueAP System in the knowledge that they are provided with all the necessary tools to manage, control and monitor the system.

Business Managers can rely on a BlueAP Systems solution to provide the services required in a cost-effective manner, to provide the scope for future expansions, either in terms of scale or functionality, and to have the strength and durability to provide the backbone of any future business systems solutions. Figure 3, illustrates the cost-effectiveness, in terms of a hugely reduced development effort, of building a business solution with the Blue Application Platform.