[bigstrat2003]

Java has had shit backwards compatibility for as long as I have had to deal with it. Maybe it's better now, but I have not forgotten the days of "you have to use exactly Java 1.4.15 or this app won't work"... with four different apps that each need their own different version of the JRE or they break. The only thing that finally made Java apps tolerable to support was the rise of app virtualization solutions. Before that, it was a nightmare and Java was justly known as "the devil's software" to everyone who had to support it.

[ivan_gammel]

That was probably 1.4.2_15, because 1.4.15 did not exist. What you describe wasn’t a Java source or binary compatibility problem, it was a shipping problem and it did exist in C++ world too (and still exists - sharing runtime dependencies is hard). I remember those days too. Java 5 was released 20 years ago, so you describe some really ancient stuff.

Today we don’t have those limits on HDD space and can simply ship an embedded copy of JRE with the desktop app. In server environments I doubt anyone is reusing JRE between apps at all.

[simoncion]

While "Well, just bundle in a copy of the whole-ass JRE" makes packaging Java software easier, it's still true that Java's backwards-compatibility is often really bad.

> ...sharing runtime dependencies [in C or C++] is hard...

Is it? The "foo.so foo.1.so foo.1.2.3.so" mechanism works really well, for libraries whose devs that are capable of failing to ship backwards-incompatible changes in patch versions, and ABI-breaking changes in minor versions.

[ivan_gammel]

> Java's backwards-compatibility is often really bad.

“Often” is a huge exaggeration. I always hear about it, but never encountered it myself in 25 years of commercial Java development. It almost feels like some people are doing weird stuff and then blame the technology.

> Is it? The "foo.so foo.1.so foo.1.2.3.so"

Is it “sharing” or having every version of runtime used by at least one app?

[simoncion]

> I always hear about it, but never encountered it myself in 25 years of commercial Java development.

Lucky you, I guess?

> Is it “sharing” or having every version of runtime used by at least one app?

I'm not sure what you're asking here? As I'm sure you're aware, software that links against dependent libraries can choose to not care which version it links against, or link against a major, minor, or patch version, depending on how much it does care, and how careful the maintainers of the dependent software are.

So, the number of SOs you end up with depends on how picky your installed software is, and how reasonable the maintainers of the libraries they use are.

[ivan_gammel]

> So, the number of SOs you end up with depends on how picky your installed software is, and how reasonable the maintainers of the libraries they use are.

And that is the hard problem, because it’s people problem, not technical one, and it’s platform independent. When some Java app was requiring a specific build of JRE, it wasn’t limitation or requirement of the platform, but rather the choice of developers based on their expectations and level of trust. Windows still dominates desktop space and it’s not uncommon for C++ programs to install or require a specific version of runtime, so you eventually have lots of them installed.

[simoncion]

I don't see how Microsoft's and Sun's/Oracle's decision to encourage bundling all dependent software (including what would ordinarily be considered to be system libraries) with your program has to do with long-established practices in the *nix world.

I do agree that the world becomes much easier for a language/runtime maintainer if you get to ignore backwards-compatibility concerns because you've convinced your users to just pack in the entire system they built against with their program.