Kif tumiġrazzjoni monolith għal microservices billi tuża l-patern strangler-fig?

Question

Accepted Answer

Il-**patern strangler-fig** tumiġrazzjoni gradwalment: inti tillapp il-monolith bi livell ta' routing, toħroġ kapaċità waħda kull darba f'servizz, u tidirixxi t-traffiku lejn dik — sehħ sa sa l-monolith ma jkunx "mħannaq" fuq il-hout. **M'hemm l-ebda rewrite big-bang**.

## Kif jaħdem

```text
Step 1: route all traffic through a facade/proxy to the monolith
Step 2: extract ONE capability → new service
Step 3: route just that path to the new service
Step 4: repeat; delete that code from the monolith

Client ─▶ [ Proxy ] ─┬─▶ /orders  ─▶ NEW Orders service
                       └─▶ everything else ─▶ Monolith
```

## Għażla ta' dak li għandu jitneħħa l-ewwel

```text
✓ A bounded context with clear boundaries
✓ Something that needs independent scaling or deploys
✓ A part with few inbound dependencies (low risk)
✗ Don't start with the tangled core
```

## Immaniġġjar tad-data imkondiviza

Il-parti diffiċli hija d-database. Uħroġ il-tabelli tas-servizz, imbagħad qassam il-coupling tal-DB imkondiviza billi tuża avvenimenti jew saff anti-korruzzjoni, ħafna drabi permezz tat-teknika **branch-by-abstraction** filwaqt li t-tnejn qed jaħdmu.

## It-trassi

```text
✓ Low risk — small, reversible steps, always shippable
✓ Value early, learn the seams as you go
✗ Slow; you run a hybrid system for a long time
✗ Temporary duplication and routing complexity
```

## Għaliex hu importanti

L-irewrites big-bang huma famużi għall-falliment — jiffriżaw ix-xogħol tal-feature għal xhur u jibgħatu qat-over riskjuż kollha tul il-ħin.

Il-patern strangler-fig iżomm is-sistema ħajja u releasable kollu l-ħin, jippermettik li tieqaf jew terreprioritizzaw fi kwalunkwe punt, u jforċak tiskopri l-fruntieri tas-servizz reali mis-sistema li qed taħdem minflok imbagħad jess-spekulazzjoni quddiem.