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 are kept intact. Finally, any distributed service-oriented application (a description that can be applied to any Hyperledger Fabric application) must be prepared for the nature and numbers of end-users to increase or decrease over time, necessitating changes in both hardware and software resource allocation.
Over the lifetime of your blockchain application, you will therefore see many changes that necessitate updates to code and configuration. The kinds of changes listed previously are not unique to Fabric networks, or even blockchains in general, but the mechanisms we will need to use and the considerations in selecting those mechanisms are quite specific to the platform. These, then, will be the main, though not sole, focus of this chapter. We will first examine the different ways in which your Fabric application may need to be modified, with specific scenarios illustrated through sample code and configurations and guidelines to plan for system upgrades. We will then discuss application and network membership changes and the relevant considerations that apply to industry-scale blockchain applications. In the backend of the chapter, we will delve into system maintenance: monitoring the health of your application and system resources and designing or upgrading your system to ensure high performance.
The following topics will be covered in this chapter:
- Modifying or upgrading a Hyperledger Fabric application
- Fabric blockchain and application life cycle
- Adding the new organization to the network
- Modification in chaincode logic
- Dependency upgrades in chaincode
- Endorsement policy update
- System monitoring and performance
- Profiling containers and applications
- Measuring application performance