IBM Z Open Editor Support for Language Server Protocol is a Game Changer

The integrated development environment (IDE) is an indispensable tool for software developers. Before it came along, coding was a laborious, detail ladened undertaking. We’ve become accustomed to the syntax checking and code completion features than even the most basic IDEs provide. These days we tend to forget how hard it was programming with nothing but a rudimentary text editor. Something as simple as finding a missing comma or a misplaced curly bracket that was causing a compilation error could take hours, maybe days should the codebase be big enough. When it came to tracing your way through a seemingly endless chain of functions and classes in order to find the culprit of a runtime error, well…fuggedaboutit! Without the modern IDE, we’d be sunk.

Well, that was then and this is now. A few years back, a new technology emerged on the technical landscape that’s boosting the power of the IDE, and subsequently the scope of work a developer does and the decisions he or she makes by an order of magnitude. This new technology is Language Server Protocol (LSP).

LSP Takes the IDE to a Whole New Level

LSP is a specification developed by Microsoft that standardizes the way certain typical features are implemented within a programming IDE. LSP attempts to consolidate the implementation of IDE commonplace features such as code completion, hover-over tips, jump-to-definition, find-references and syntax checking into a standard format that can be applied to any IDE in an agnostic manner.

LSP is a technology designed to address the following problem. Imagine that a tools vendor has an idea for implementing a new plugin that will automatically do code completion for programs written in the COBOL programming language. Such a feature might be useful to any number of COBOL programmers. However, not every COBOL programmer is programming using the same tool. Some might be using an IDE such as IBM Developer for z/OS. Another might be using a text editor such as Sublime Text, Atom or even something more basic such as vim. In earlier times, in order to get the feature to market the vendor needed to implement different versions of the plugin in a way that was special to the given development environment. There’d be a team working on a Sublime Text version of the plugin, another team working on the vim plugin so forth and so on. Not only did the tool developer need to accommodate different operating systems, but each team might come up with its own, particular way to implement the feature. As team members left the company and new members arrived to replace them, those new developers needed to learn each particular way the feature was realized. As you can see, not only did the variety breed complexity, but things got very expensive very quickly.

LSP does away with the need for such specialized tools development. LSP provides a standard protocol that can be implemented in any tool. The protocol defines a set of standard methods, objects and communication methods that provide a common set of services in any IDE.

Thus, the only work that needs to be done to get the previously described COBOL code complete feature to market is to express it in a way that is compatible with the LSP. The actual work of realizing the feature then involves writing a client that supports the standard. It’s a “one ring to rule them all” process so to speak.

The LSP specification was originally published by Microsoft specific. But the standard has been embraced as an industry-wide. There are implementations in Java, C++, C#, Python, Scala, Swift and PHP, to name a few. Also, there is an implementation of LSP for COBOL under z/OS, which brings us to IBM Z Open Editor.

Bringing the Use of LSP to the Mainframe

IBM Z Open Editor is a free Visual Studio Code extension that provides a state of the art programming experience for COBOL and PL/1 developers. Also, IBM Z Open Editor integrates with Eclipse Che and Eclipse Theia. Integration with Eclipse Che and Theia is particularly interesting because it enables browser-based editing. It’s a powerful tool, even more so given that historically COBOL and PL/1 programmers have lived in the backwaters of modern IDE development. IBM Z Open Editor makes IDE-based software development a general programming experience. Developers can use the same tool to program COBOL as they do in Java or even HTML for that matter.

 Using a single IDE to program in a variety of languages is a trend that’s been evolving for a while. However, adding LSP into the mix allows any IDE to present a consistent set of design time features. For example, one IDE is now able to do code-completion, hover-over reporting and variable tracing regardless of the programming language in play.

For example, Figure 1 below shows the COBOL code completion feature of IBM Z Open Editor plugin for Visual Studio Code. IBM Z Open Editor uses LSP to facilitate code completion.

Figure 2 shows the search and sort features of IBM Z Open Editor, which again implemented according to the LSP.

Finally, Figure 3 shows how the IBM Z Open Editor takes advantage of the extensibility capabilities of LSP to implement a feature that resolves and loads copybooks for preview. A copybook is code that can be copied from a master source and inserted into several different programs or into a variety of places in a single program. A copybook is used to define the physical layout of program data, variables for example, as well as instances of procedural code.

Clearly, LSP brings a lot of power to the mainframe programming experience. Now tools developers can create a unified programming experience using a common methodology. But where things really get interesting is when LSP is used to report data that goes beyond standard programming and code management activities, to a place where the real-time behavior of those using deployed code is being reported. In other words, LSP makes it possible not only to get information about code that is local to the developer’s desktop but also about the code as it is being used at runtime out on the internet.

Beyond the Mainframe: The Long Term Significance of LSP

LSP is extensible by design. As you read above, IBM Z Open Editor extends LSP to allow programmers to preview and load copybooks. This is done by extending the protocol.

The typical IDE to server interaction under LSP is that the LSP client reports to the LSP server when a code document has been opened, changed, saved and closed. Then, once the LSP server is aware that a code document is in play, the server can inspect the document and report back events that are relevant to the programming language (Figure 4).

For example, the LSP server can inspect the document to make sure the code is syntactically correct. If an error is encountered the server reports back the starting and ending location of the error, along with a message. In the case of the copybook review feature, the client reports back the location of the cursor in the code window and the server determines an opportunity for a copybook review and informs the client accordingly.

While the copybook preview feature is powerful, it’s confined in scope to the immediate document. This is good. But, imagine what it would be like if the server had knowledge of all instances of the code deployed and running on computers connected to the internet?

Suppose for example, that your code was powering an API running on the internet and you had the ability to learn about the number of calls to a particular function backing the API or better yet, imagine that you had the ability to learn about function calls that encountered particular problems, such as a pattern of mistyped parameters or high latency calls. Then imagine if that global runtime behavior was reported right in the IDE? Such information would change the very nature of how a programmer approaches his or her work. More importantly, it would change the way an enterprise manages programmers.

What if a programmer could decide what to work on based on global runtime behavior reported into the IDE via an LSP extension? For example, going back to the imagined pattern of mistyped parameters, let’s say that when a developer hovers over the related function in IDE a warning icon appeared informing the developer of 1000 instances of mistyped called were made at the global level. The developer decides that such an error rate is unacceptable. Then, he/she examines the developer documentation and discovers that the parameter type definitions for the function are poorly described and that the document needs to be corrected. The developer then makes updating that developer documentation a critical path, part of the day’s work that needs to be delivered immediately.

Given the power that LSP brings to the programming experience, such a scenario is entirely possible. In fact, there are companies out there such as Apollo Graph Manager that presently allow developers and third parties to register their production APIs in order to collect the sort of global information described above and have it reported in an IDE via LSP. As those of us who have been in the software business for a while have come to learn, once a feature such as global reporting catches on, it’s only a matter of time until it becomes an industry-wide practice. It’s only a matter of time before globally collected runtime metrics delivered to a programmers LSP become commonplace.

Again, the ramifications are significant. Once a programmer has the ability to make fundamental decisions about feature development and deployment schedules, what then becomes the role of the project manager and the product manager?

To take the issue one step further, how much power should a programmer be given? And in terms of general business practices, how much should the programmer know about a company’s products? These questions might seem fantastic, but keep in mind at one time companies guarded their source code as a trade secret. Today, more code than not is shared between companies as part of the open-source movement. As a result, the way code is made and a developers work has changed. The same possibility exists due to the growing trend to extend the capabilities of the LSP. The ramifications of LSP go well beyond simply reporting syntax errors and doing code completion. LSP will change the way the entire industry works, from mainframe programming to developers working in the cloud or on commodity hardware.

Putting it All Together

Given current trends, there’s little doubt that LSP will make even the most rudimentary code editor a powerhouse tool for software development. Standardizing IDE features into a common format allows new features for any development tool to be implemented faster and at a reduced cost. In no time at all we might even figure out a way to use LSP to make is so large bodies of code can be written automatically with just a few guiding keystrokes from the developer’s keyboard no matter the programming language. It’s a real possibility.

Not only will LSP making coding easier and faster, but it’s also going to change the role of the software developer. Once all the code running on the internet becomes LSP aware and accessible, developers will get runtime information about how their code is performing at runtime on a global level. The trend is already in play. As history has shown, the further down a technology goes into a given population, the more powerful that population becomes and the greater the ramifications when the power is exerted. There’s a very real possibility the information that LSP enabled IDEs provides will make the day-to-day programmer more prominent in the product decision-making processes that are presently the responsibilities of program and project managers. Once that shift takes place we’re likely to see another industry-wide transformation take place in the way software is made and delivered. History has shown that such transformations have long term benefit, but in the short term are disruptive and disturbing. We’ll do well to be prepared.

— Bob Reselman