Chapter 9. Life in a Blockchain Network

Your Fabric network should now be set up and running your application connecting different entities through a smart contract and serving users through a web interface. In addition, to help your developers and system administrators maintain code, push updates, and manage network configuration, you should have instituted a process whereby system testing and maintenance can be done with safeguards in place and no interruption to service.

Yet, this will not be the terminal state of your application. Needs and expectations evolve, and this is especially true for an application that involves multiple collaborating entities, all of whom will have differing requirements at different points in time. In addition, it is expected that software itself will continually change and evolve even if the nature and function of an application is kept intact. Finally, any distributed service-oriented application (a description that can be applied to any Hyperledger Fabric...

Modifying or upgrading a Hyperledger Fabric application

The design of a generic Hyperledger Fabric application presented in Chapter 5, Exposing Network Assets and Transactions, offers hints about the types of upgrades that may be required during its lifetime. Let us examine the various ways in which the requirements of a Fabric network and its users change over time:

• Software updates: Changes and upgrades are an integral part of software maintenance. More frequently, modifications are required to fix bugs, performance inefficiencies, and security flaws (for example, think of the Windows Update Service). Less frequently, though almost equally inevitably, major design changes must be made to software to handle unanticipated challenges. Also, given that most applications depend on other (third-party) software, any upgrades in the latter trigger corresponding changes in the former. Think of Windows Service Packs as an analogy. In the Hyperledger Fabric world, you as an application developer or...

System monitoring and performance

You have now built your application and instituted various processes and mechanisms in anticipation of changes over its lifetime. An additional, but no less essential, process that you must have in place and carry out from time to time is monitoring and performance measurement. Any production application you build for real-world users and institutions must meet certain performance goals to be useful to its users, and by implication, the application's stakeholders. Therefore, understanding how your application performs and trying to improve its performance is a key maintenance task; any dereliction in this task may result in your application having a short shelf life.

The art (and science) of system performance measurement and analytics is a broad and extensive set of topics, and it is not our intention to cover these topics deeply or exhaustively in this book. To obtain such a coverage, the interested reader is encouraged to read other canonical texts on...

Summary

Maintaining and augmenting a blockchain application is possibly even more challenging than creating and bootstrapping it, as one needs to be skilled in monitoring and analytics and also in assessing the impact of changes.

In this chapter, we described the various ways in which a Hyperledger Fabric application can and will inevitably change over its lifetime. We described in detail, using our canonical trade application as an example, how organizations and peers can be added to a running network, how channel configurations can be augmented, how platforms can be upgraded, and how the smart contract (chaincode) itself can be modified without adversely affecting the application state.

In a later part of the chapter, we gave an overview of the tools a developer of system administrator can use to measure, analyze, and improve the performance of a Fabric blockchain application. We also provided guidelines to engineering the system for better performance.

With further research and development...