Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
c9831b9680
## Pressing `>` on a TextDefinition did nothing useful
`#1217` moved `TextDefinition` into the Server project for serialization support and added `[PropertyObject]` along the way. `PropsGump` checks that attribute **before** its parsable fallback, so from that commit on the button either drilled into a read-only `Number`/`String` page (both get-only since `#1221`, so no `>` buttons — a dead end) or, when the value was null, re-sent the same page and looked inert.
Worth being clear that `#765` — which replaced the hand-maintained type list with a generic `IsParsable` branch — was **not** the regression. At that commit `TextDefinition` was `[Parsable]` only, fell through to the new branch, and the editor worked. Only the later attribute hijacked the routing.
`TextDefinition` is now caught ahead of the `[PropertyObject]` branch and routed to `SetGump`, which has had `TextDefinition`-specific code at line 35 all along.
## `0` and `"0"` could not be told apart
`Commands.Split` strips quotes before any parser runs, so this was never fixable in `TextDefinition.Parse` alone — the information is gone two layers earlier. The markers now travel inside the value:
| Input | Result |
|---|---|
| `1060847` | cliloc (unchanged) |
| `#1060847` | cliloc, explicit — the form `ToString()` already writes |
| `@"1060847"` | the literal string |
| `hello` | string (unchanged) |
| `(-null-)` | null (unchanged) |
`GetValue()` quotes a string that would not survive the trip back. That check is a real round trip through the parser rather than a pattern match, so it cannot drift from it. `Types.TryParse` decodes the same escape for plain strings — which is what `[get` has always written for the literal `"null"` without `[set` ever reading it back.
**Saved data is untouched.** Serialization reads a discriminated flag plus int/string (`IGenericReader.cs:175`) and the JSON converter switches on token type; neither calls `Parse`, so a stored string `"1060847"` stays a string and spawner JSON is unchanged. The new syntax stays in the text and command layer, where it reaches `[set`, `[add`, spawner props, the props gump and Advanced Search.
## `where` still parsed its constants its own way
`#2625` carried the hand-rolled constant parser across to `PropertyExpressions.Parse` unchanged. It looks for a static `Parse` overload on the property type and gives up if there is none — and `Type` and `IEntity` have neither:
```
where Subject Kind = Static -> Unable to convert string "Static" into type 'System.Type'.
where Subject Owner = 0x1 -> Unable to convert string "0x1" into type 'Server.Mobile'.
```
Both resolve fine for every other command. Routing through `Types.TryParse` picks up type-name lookup, entity resolution by serial, and the `@"..."` literal convention, so a value that works in one place now works everywhere. It also deletes the duplicate parser (−56 lines in `PropertyExpressions`).
Two things are load-bearing and preserved. `where` has always spelled a null constant as a bare `null`, where `[set` uses `(-null-)`; the shared parser reads a bare `null` as the text, so the null case is handled ahead of it and `= null` keeps meaning null. And nullable targets still unwrap first, so `where <int? prop> = 5` is unaffected.
Bare and hex integers, enums, bools, strings, `Map`, and TextDefinition's `#` / `@"..."` markers all resolve exactly as before — 13 of the 15 tests in `WhereConstantParsingTests` pin that and passed before the change as well as after.
## Documentation
The generic command system had no documentation anywhere in the repo: scopes, `where` and its operators, dot notation, `order by` / `distinct` / `limit`, the value and quoting syntax, `[interface` and `[batch` were all learn-by-reading-the-source. `dev-docs/generic-commands.md` covers them, linked from `CLAUDE.md` and `commands-targeting.md`, and points at <https://muo.gg/commands> for the per-command list rather than duplicating it.
Two behaviours it records that were news to me while writing it:
- `Contained` honours conditions on the normal command path but never sets `SupportsConditionals`, and `[batch` is the only place that reads the flag — so the same condition works typed directly and is refused under batch.
- `Multi`, `Single`, `Self` and `Serial` do not parse modifiers at all, so a `where` clause there is passed to the command as ordinary arguments rather than rejected.
Comments in the changed code were trimmed to what is not evident from the code itself; the rationale they carried is either in the doc now or in the commit that introduced it.
## Behavior changes worth a reviewer's attention
Two things go beyond strict bug-fixing, both deliberate:
- **Hex now parses into a TextDefinition.** Consolidating the three `Parse` overloads onto one span codec means `[set Message 0x102CE7` is cliloc 1060847 rather than the string. Previously only the 1-arg `Parse(string)` did hex and nothing called it. This makes the props gump's own `1060847 (0x102CE7)` display typeable.
- **`@"..."` decodes generally for strings**, not only the exact token `@"null"`. So `[set Name @"hello"` sets `hello`. A half-working escape seemed more surprising than a general one, and the `where` path already decoded it — but narrowing it back is a one-line change if preferred.
## Testing
40 tests, each written first and watched fail for the right reason. They cover the props gump routing (populated and null), cliloc/string/quoted parsing and `GetValue` round trips, `where` constant resolution for Type- and entity-valued properties, and the bare-`null` vs `@"null"` distinction that must not drift.
One sort case is added that #2625 left uncovered: ordering a value-typed chain whose intermediate is null, which reads as `default(int)` rather than throwing. Two other tests from the pre-rebase branch were dropped as duplicates of `ConditionalCompilerEdgeTests`.
Rebased onto `
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| .github | ||
| branding | ||
| dev-docs | ||
| Distribution/Data | ||
| Projects | ||
| tools | ||
| .cursorrules | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| AGENTS.md | ||
| azure-pipelines.yml | ||
| CLAUDE.md | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Directory.Build.props | ||
| FAQ.md | ||
| GEMINI.md | ||
| global.json | ||
| LICENSE | ||
| ModernUO.slnx | ||
| publish.cmd | ||
| publish.ps1 | ||
| publish.sh | ||
| README.md | ||
| rider-settings.zip | ||
| Rules.ruleset | ||
| SPONSORS.md | ||
| stylecop.json | ||
| THIRD-PARTY-NOTICES | ||
| version.json | ||
ModernUO 
Ultima Online Server Emulator for the modern era!
Requirements
Supported Operating Systems
Required Frameworks
All Operating Systems
Windows
Hardware
| Use | vCPU | RAM | Storage |
|---|---|---|---|
| Development / test | 2 dedicated | 2 GB | SSD |
| Small live shard (< 50 concurrent) | 4 dedicated | 4 GB | NVMe |
| Medium (50–200) | 4–8 | 8 GB | NVMe |
| Large (200+) | 8+, high clock | 16 GB+ | NVMe |
See dev-docs/server-requirements.md for more information.
Development
Supported IDEs
Getting Started
- Install prerequisite requirements
- Clone this repository (or download the latest):
git clone https://github.com/modernuo/ModernUO.git
- Open
ModernUO.slnto start developing
Building/Publishing
Interactive Mode (Recommended for new users)
Run ./publish.cmd (Windows) or ./publish.sh (Linux/macOS) with no arguments to launch the guided build tool. It will:
- Check prerequisites (.NET SDK, native libraries)
- Walk you through configuration and platform selection
- Build and publish the server to the
Distributiondirectory - Show deployment instructions for cross-compiled builds
Command Line
./publish.cmd [release|debug] [os] [arch]
os- Supported operating systemsarchx64- Intel/AMD 64-bitarm64- ARM 64-bit
Linux Prerequisites
Fedora, CentOS, RHEL, AlmaLinux, Rocky, etc
dnf upgrade --refresh -y
# RHEL-family distributions (CentOS Stream, AlmaLinux, Rocky, RHEL) need CRB and EPEL enabled.
# Fedora skips this block.
dnf install -y dnf-plugins-core
dnf config-manager --set-enabled crb
dnf install -y epel-release
# Prerequisites
dnf install -y findutils libicu libdeflate libargon2 tzdata
Ubuntu, Debian, etc
apt-get update -y
# The ICU runtime package carries the ABI version in its name (libicu74, libicu76, …) and has no
# stable alias, so match it by pattern rather than pinning a release-specific name.
apt-get install -y '^libicu[0-9]+$' libdeflate0 libargon2-1 tzdata
Only the runtime libraries are needed — the -dev/-devel packages are not. Run
./build-tool --check-prereqs to check the current machine and print the exact packages your
release needs.
zstd is not listed because ZstdNet bundles libzstd for every platform, and liburing is not
listed because IORingGroup issues io_uring syscalls directly.
If the shard's configured time zone is a legacy alias such as US/Eastern, Debian 12 and Ubuntu
24.04 also need tzdata-legacy. See Platform Prerequisites
for what each dependency is for and what breaks without it.
OSX Requirements
brew install icu4c libdeflate argon2
Running the Server
- Follow the publish instructions
- The
Distributiondirectory is portable — copy it to your production server for deployment - Run
ModernUO.exeordotnet ModernUO.dllfrom theDistributiondirectory - On first run, the server will prompt you to configure game data file locations
Troubleshooting / FAQ
- See FAQ
Want to sponsor?
Thank you for supporting us! You can find out how by visiting the sponsors page.
Collaborators
Thanks
- RunUO Team & Community
- Voxpire, the ServUO Team & Community
- Karasho, Jaedan and the ClassicUO Community
Development Tools & Plugins provided with ♥ by
Code Signing Policy
Free code signing provided by SignPath.io, certificate by SignPath Foundation.
This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it
Teams & Roles
Approvers & Committers: Development Team