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Compaq Reliable Transaction Router manual 1 The Three Layer Model, ZKO-GS011-99AI

Models: Reliable Transaction Router

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Figure 2–1 The Three Layer Model

The Three-Layer Model

Figure 2–1 The Three Layer Model

Terminals

Frontends (FE)

FE

Client

FE

Client

FE

Client

FE

Client

Routers (TR)	Backends (BE) Database (DB)

	BE
	Server

	BE	DB
	BE
	Server	DB
		DB
TR		DB
	BE	DB
	BE
	Server
TR

ZKO-GS011-99AI

•Allows performance or geographic expansion while protecting the investments made in existing hardware and application software.

The router layer contains no application software unless running callout servers. This layer reduces the number of logical network links required on frontend and backend nodes. It also decouples the backend layer from the frontend layer so that conﬁguration changes in the (frequently changing) user environment have little inﬂuence on the transaction processing and database (backend) environment.

The three layer model can be mapped to any system topology. More than one role may be assigned to any particular node. For example, on a system with few frontends, the router and frontend layers can be combined in the same nodes. During application development and test, all three roles can be combined in one node.

The nodes used by an application and their conﬁguration roles are speciﬁed using RTR conﬁguration commands. RTR lets application code be completely location and conﬁguration independent.

2–2Architectural Concepts

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Compaq Reliable Transaction Router manual 1 The Three Layer Model, ZKO-GS011-99AI

Contents

Revision/Update Information This is a new manual Reliable Transaction Router Getting StartedJanuary Compaq Computer Corporation Houston, TexasThis document was prepared using VAX DOCUMENT, Version 2001 Compaq Computer CorporationUNIX and The Open Group are trademarks of The Open Group Introduction Architectural ConceptsContents 3 Reliability Features 4 RTR Interfaces5 The RTR Environment Glossary Index ExamplesFigures TablesPage Preface Purpose of this DocumentDocument Structure RTR Commands Router InstallationRelated Documentation For all usersReading Path Readers CommentsConventions New termFigure 1 RTR Reading Path System ManagerApplication Programmer If V2 toIntroduction Reliable Transaction RouterRTR Continuous Computing Concepts RTR Terminology Figure 1-1 Client Symbol Figure 1-2 Server Symbol Channel RTR conﬁguration RolesFigure 1-3 Roles Symbols Figure 1-4 Facility SymbolFE TR Figure 1-5 Components in the RTR Environment Nontransactional messaging Transaction ID Transaction Controller 1-8 IntroductionFigure 1-6 Two-Tier Client/Server Environment Figure 1-7 Three-Tier Client/Server EnvironmentFigure 1-8 Browser Applet Conﬁguration Web Server Process RTR Client Application1-10 Introduction Figure 1-9 RTR with Browser, Single Node, and Database Figure 1-10 RTR Deployed on Two NodesFigure 1-11 RTR Deployed on Three Nodes 1-12 IntroductionFigure 1-12 Standby Server Conﬁguration Transactional shadowing RTR JournalFigure 1-13 Transactional Shadowing Conﬁguration RTR Server Types Concurrent servers Callout servers Figure 1-15 Standby Servers Transactional shadow serverFigure 1-16 Shadow Servers Figure 1-17 Concurrent Servers User Accounts Facility Figure 1-18 A Callout ServerFigure 1-19 Bank Partitioning Example TR A partition can also have multiple standby servers RTR Networking Capabilities RouterPage Architectural Concepts The Three-Layer ModelFigure 2-1 The Three Layer Model ZKO-GS011-99AIRTR Facilities Bridge the Gap BroadcastsFlexibility and Growth Transaction Integrity Flexibility and GrowthThe Partitioned Data Model Object-Oriented ProgrammingFigure 2-2 Partitioned Data Model ZKO-GS012-99AIObjects Table 2-1 Functional and Object-Oriented Programming ComparedMessages Class Relationships Example 2-1 Objects-Deﬁned SamplePolymorphism Object Implementation Beneﬁts XA Support Programmers Reference Manual and the RTR Application Design GuideReliability Features ServersFailover and Recovery Recovery ScenariosRecovery Router FailoverBackend Recovery Router Recovery Frontend Recovery Page RTR Interfaces RTR Management Station RTR Management Station $ RTR RTR SHOW JOURNALRTR CREATE FACILITY DESIGN/ALLROLES=NODEA RTR SHOW FACILITYRTR RTRRECEIVEMESSAGE/CHAN=S RTR show transactionRTR RTRRECEIVEMESSAGE/TIME=0 $ RTR RTR START RTRRTR RTRRECEIVEMESSAGE/CHANNEL=C/tim RTR RTRSTARTTX/CHAN=Centers commands at the server RTR show transactionApplication Programming Interfaces BrowserInterface Object-OrientedApplication Programming Interfaces Figure 4-1 RTR Browser InterfaceRTR C Example of object creation in an RTR server programinterface, see the RTR C Application Programmers Reference Manual and the RTR Application Design GuideExample of an open channel call in an RTR client program The RTR Environment The RTR System Management EnvironmentHandles all transactions and recovery Page Monitoring RTR ManagementTransaction RTR Monitor pictures or the RTR Monitor let you view theThe RTR Runtime Environment PartitionManagement Figure 5-2 RTR Runtime Environment RTR Installation Guide Whats Next?RTR Release Notes RTR Migration Guide ifPage Glossary ACIDapplet applicationbranch broadcastcallout server channelcommon classes concurrent serverdata marshalling data objectendian frontend message primary processproperties property classesrollback routerRTR conﬁguration RTR environmentshadow standbytransaction transaction controllertwo-phase commit transactional messagetransactional shadowing Index Index-1Index-2