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gtfs-realtime-php

PHP classes for reading and writing GTFS Realtime feeds — vehicle positions, trip updates, and service alerts. Generated from the official protocol buffer definition, kept current with it, and built on a protobuf runtime that receives security updates.

Install

Requires PHP 8.1 or later. The protobuf runtime dependency is google/protobuf ^4.33.6 || ^5.0 — both currently supported majors — so Composer can settle on whichever version coexists with a project's other dependencies.

Read a feed

Every message type in the spec is here — TripUpdate, VehiclePosition, Alert, and the newer additions like TripModifications — with getters, setters, and has*() presence checks for each field. Field presence follows the spec: a field a producer set to zero is set, and a field the producer omitted is absent, even though a getter returns zero in both cases.

A whole feed converts to JSON in one call, which is how the binary feeds most agencies publish become something a browser can use:

Write a feed

Producers use the same classes in the other direction:

Performance

The pure-PHP protobuf runtime handles typical feeds without trouble. Very large feeds — megabytes of trip updates for a whole network — cost real CPU and memory there. Installing the PECL protobuf extension replaces the runtime internals with the C implementation; no code changes, same classes.

Migrating from lowa/gtfs-realtime-php

lowa/gtfs-realtime-php pins google/protobuf to exactly 3.25.0, which is affected by CVE-2026-6409, a denial of service triggered by malicious protobuf messages — precisely the untrusted input a GTFS Realtime consumer parses. The pin makes the fix uninstallable, composer audit flags it, and Composer 2.8+ refuses to install the package at all. This package is a drop-in replacement:

It also declares itself as a Composer replace for lowa/gtfs-realtime-php 1.0.0, so a project that still requires the old name through some other dependency resolves to this package once it is required anywhere.

Class names match — everything lives in Google\Transit\Realtime — and the legacy underscore names lowa shipped (FeedHeader_Incrementality and friends) exist here as deprecated aliases of the nested classes, so code written against either form runs unchanged. What to check:

• New code should use the nested form, FeedHeader\Incrementality; the underscore aliases exist for compatibility and carry a suppressed deprecation notice that tooling can surface.
• Field presence is tracked for every singular field. Values a producer explicitly sets to a default — direction_id: 0, schedule_relationship: SCHEDULED, delay: 0 — survive parsing and appear in JSON output. lowa's conversion silently dropped them, so JSON from this package can contain keys the old package omitted. The values were always in the feed; nothing that was present before is missing now.
• The spec is current: TripModifications, Stop, Shape, TranslatedImage, and every field and enum value added upstream since early 2024.

Unchanged, for code relying on it: getters on unset fields return zero values (getCause() gives 0, not the spec default UNKNOWN_CAUSE), because proto3 cannot express proto2's custom defaults. Check has*() before trusting a getter, exactly as with lowa.

How the package tracks the spec

The pristine official proto lives at proto/upstream/gtfs-realtime.proto, pinned to the google/transit commit recorded next to it. A scripted, assertion-guarded conversion produces the compiled proto — never edited by hand — and regenerate.sh runs the whole chain with a pinned protoc version. Committed snapshots of the API surface and of golden JSON output turn every regeneration into a reviewable diff.

A weekly job watches upstream: a spec change arrives as a pull request with the regeneration already done, a protoc release as a pull request bumping the toolchain, and a security advisory as an issue. CI tests every release against both runtime majors, at the dependency floor and ceiling, with and without the C extension.

Version numbers follow from that: new spec surface is a minor release, anything removed or any raised floor is a major, tooling and documentation are patches. RELEASING.md has the full procedure.

Changes from the official proto

The official definition uses proto2, which protoc cannot compile to PHP — required fields and closed enums are unsupported, and the PHP generator only accepts the successor "editions" format from protoc 34 on, whose output would confine the package to google/protobuf 5.x. To run on both supported runtime majors, tools/convert.php derives a proto3 file instead:

1. syntax becomes proto3; every singular field keeps an explicit optional label, which in proto3 means tracked presence — preserving proto2's behavior for values explicitly set to a default.
2. required labels (wire-identical to optional, unenforced in the PHP runtime anyway) become optional.
3. option php_namespace / php_metadata_namespace place generated code in Google\Transit\Realtime and GPBMetadata.
4. Custom defaults ([default = UNKNOWN_CAUSE]) are dropped — proto3 forbids them. This affects only what getters return for unset fields, never the wire format or JSON output.
5. Extension range declarations are dropped — proto3 forbids them, and the PHP runtime has no extension API. Extension data in feeds still round-trips as unknown fields (covered by a test).
6. Alert.Cause, Alert.Effect, and Alert.SeverityLevel gain a zero value (PROTO3_DEFAULT_CAUSE, PROTO3_DEFAULT_EFFECT, PROTO3_DEFAULT_SEVERITY) because proto3 enums require one. The names match lowa's. These values never appear in spec-conforming feeds.

The proto package stays transit_realtime, so descriptors and any cross-language tooling see the official names.

Authorship

This package — code, tooling, tests, and documentation — was written by Claude, Anthropic's AI model, supervised by a human maintainer who uses the package professionally in production transit systems. Nothing merges or ships without that person's review: the automation opens pull requests, a human reads the diffs and decides.

License

Apache-2.0, matching the GTFS Realtime protocol definition this package is derived from.