Technology Grafting

Created on 2021-12-23 09:48

Published on 2021-12-23 17:01

Wikipedia defines grafting as: "a horticultural technique whereby tissues of plants are joined to continue their growth together". Grafting is often used for producing new varieties of fruits on older trunks that are more resilient or adapted to a climate.

When working with legacy software we can see modernization as grafting. The rootstock is the older technology - proven and battle-tested while the scion is a newer technology that will enhance the rootstock's qualities. The technological grafting needs two things: interfaces/protocols and encapsulation.

The interface layer ensures that the data can be understood by both scion and rootstock. If the rootstock uses some very specific encodings (EBCDIC, various other locale-specific charsets) then the translation between them must be consistent in both directions. Things seem to be easy with textual protocols (although there might be also some issues) than with binary proprietary protocols. If a fast bidirectional translation is not possible (very different protocols) then a middleware might be necessary but in this case, it would be best that this middleware

On the other hand, encapsulation permits the scion to maintain all its properties and continue working as if it would be still attached to its original trunk. When grafting a pear branch on an apple tree the pear branch will continue to function as pear and will not hinder the apple trunk. The same behavior should be present when grafting software components. However, this strong encapsulation requires the open interfaces discussed before.

One of the most interesting technological graftings I have seen lately is in the form of modernizing older web applications using micro frontends packed as web components. The idea is not a novel one, web components are one of the ways of composing micro frontends, but this has massive implications for all the functional and nonfunctional aspects of the application. Imagine old PHP or Struts code bases getting an instant makeup with nice web components that reduce the server load and break monolithic applications into simpler parts. The web components isolate the new developments from the old code base and will permit the evolution of the older code base.

Grafting techniques and patterns might prove very useful in all kinds of modernization scenarios as there are a lot of use cases for this. The use cases can range from, as I wrote above, UI modernization to more interesting ones like adapting 50 years old systems to web or IoT. If the results of grafting are successful then this might help the rootstock also evolve (like Autocad's migration to the web). Grafting permits the progressive evolution of the software without disruptions in base technologies used at a minimal extra cost. The complicated problem is to determine where is the best place to insert the scion and how to make it behave on the same security and functional constraints as the rest of the application.