Isopace

A financial transaction framework for Go — ISO-8583 messaging and payment switching, plus the runtime, transaction pipeline, coordination, and security building blocks needed to run a switch.

Get started Architecture GitHub

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Isopace is an independent, clean-room implementation in the spirit of jPOS, redesigned around idiomatic Go: type-safe field access, zero-copy decoding, a pluggable codec catalog, and goroutine-native concurrency. The module is stdlib-only — there is no third-party dependency anywhere in its graph.

v1.0.0-rc.1 — first release candidate (interim, may still change)

A feedback-seeking tag under a "may still change" banner — not the v1.0.0 contract yet (see the roadmap to v1). It narrows what v1 will freeze: the core (iso8583, packager, fieldcodec, lengthcodec, render) is a stability candidate; the higher layers remain experimental until they soak (see the versioning policy). The software Vault backend is for development and testing — production PIN and key handling require a certified HSM, which is not yet shipped.

Why Isopace

• Type-safe field access

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  Get[iso8583.Decimal](m, 4) and tag-bound structs instead of a stringly-typed Map<Integer, ISOComponent>. The type is known at compile time; money is exact fixed-point, never a float.

  The dual field API

• Allocation-free hot path

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  Zero-copy lazy decode: fields are sub-slices of the source buffer. A store-and-forward hop returns the original wire verbatim when nothing is dirty — allocation-free end to end.

  Zero-copy decode

• Composable codec catalog

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  LengthCodec × FieldCodec compose freely — ≈6 length × ≈12 value codecs replace jPOS's combinatorial IF* class zoo. Resolve by name from Go or JSON.

  Codec registry & catalog

• One model, many renderings

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  A single read-only View feeds every renderer: the same *Message projects losslessly to ISO-8583 wire, JSON, protobuf, and ISO 20022.

  Alternate renderings

• Correct by construction

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  The bitmap is always derived from present fields, so desync is impossible. Message is immutable with copy-on-write; Validate() returns every violation in one pass.

  Schema & validation

• stdlib-only, by design

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  No third-party dependency in the module graph. That keeps the dual-license (AGPL-3.0 / commercial) model free of transitive copyleft.

  Licensing

A switch in a few lines

q := teq.New()
isw, _ := q.Switch(connector.Config{Name: "isw", Addr: "isw.example:5000", Keyer: keyer})
up,  _ := q.Switch(connector.Config{Name: "up",  Addr: "up.example:6000",  Keyer: keyer})

q.Start(ctx)                                  // connectors dial in the background
resp, _ := q.To("isw").Request(ctx, frame)    // route by name; auto-reconnects
q.ListenAndServe()                            // or run as a daemon until SIGINT/SIGTERM

Build and read a message with compile-time types — no casting:

s := packager.ISO87A()
c := iso8583.NewCodec(s)

m := iso8583.New(s)
_ = m.Set(0, "0200")
_ = m.Set(11, int64(123456))        // STAN
_ = m.Set(4, int64(2500))           // amount, minor units
wire, _ := c.Marshal(m, nil)

got, _ := c.Unmarshal(wire)
mti,  _ := iso8583.Get[string](got, 0)
stan, _ := iso8583.Get[int64](got, 11)

Full quickstart

The stack

The framework is layered with a strict one-directional dependency rule: the core model knows the wire format only through the *Schema it references, and every renderer consumes one read-only View.

flowchart TD
    subgraph EnterpriseOps["Enterprise & Ops"]
        rbac["rbac · store · ops"]
    end
    subgraph Coord["Coordination & Security"]
        space["space"]
        vault["vault"]
    end
    subgraph Proc["Processing"]
        flow["flow — two-phase pipeline"]
    end
    subgraph Transport["Transport"]
        link["link · listener · mux"]
    end
    subgraph Runtime["Runtime"]
        runtime["runtime — component host"]
    end
    subgraph Render["Rendering"]
        render["render/jsonio · protobuf · iso20022"]
    end
    subgraph Profiles["Profiles"]
        packager["packager"]
    end
    subgraph Codecs["Codecs"]
        codecs["fieldcodec · lengthcodec"]
    end
    subgraph Core["Messaging core"]
        iso["iso8583 — Message · Codec · Schema"]
    end

    render --> iso
    packager --> codecs
    packager --> iso
    codecs --> iso
    flow --> iso
    link --> iso
    runtime --> iso
    space -.-> flow
    vault -.-> flow

    classDef core fill:#0b3d59,stroke:#00b8a9,color:#fff;
    class iso core;

Packages

Layer	Package	Purpose
Messaging	iso8583	Immutable, zero-copy Message; Codec; Schema; typed Get[T] and struct binding; exhaustive validation
Codecs	fieldcodec, lengthcodec	Orthogonal value × length codecs (ASCII/EBCDIC/BCD/binary, BER-TLV) resolvable by name
Profiles	packager	ISO 8583:1987 A/B/C, 1993 A/B, Visa & Mastercard overlays, declarative loader
Rendering	render/*	One message, many formats — from a read-only View
Transport	link, listener, mux	Framed TCP (+TLS), graceful server, connection pool, request/response switch
Runtime	runtime	Component host & lifecycle, deploy descriptors + hot redeploy, config, slog, observability
Processing	flow	Two-phase Flow/Stage/Exchange pipeline: routing, journaling, retry, idempotency
Coordination	space	Keyed tuple space + durable, crash-safe store-and-forward
Security	vault	PIN blocks, MAC/CMAC, DUKPT, TR-31 key blocks, EMV ARQC/ARPC behind a Vault façade
Enterprise/Ops	rbac, store, ops	RBAC + PBKDF2 auth, persistence, health/metrics/admin API, cluster membership

Why not just use jPOS?

jPOS is excellent and battle-tested, but it is Java/AGPL and carries 25 years of design history. Isopace is a from-scratch Go implementation that keeps what makes jPOS great while improving on its data model — compile-time type safety, zero-copy parsing, an always-derived bitmap, first-class validation, and multi-format rendering — and operating naturally in cloud-native, high-throughput Go services. It is not a translation or port of jPOS: it is built clean-room from the ISO-8583 standard and public payments knowledge, with no jPOS source consulted.

How Isopace improves on jPOS

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A product of Teqpace Services Ltd. · Dual-licensed AGPL-3.0-or-later & commercial · Report a vulnerability