Answer
Major Drawback of SOAP
When using SOAP, the firewall security mechanism is the biggest obstacle.
Key Issues
1. Firewall Port Blocking
SOAP works over HTTP port 80 and uses its own port. Firewalls often block all ports leaving only a few like HTTP port 80 open.
The HTTP port used by SOAP can bypass the firewall — this is a security concern that many organizations block by restricting SOAP traffic.
2. Mixed Concerns
The technical complaint against SOAP is that it mixes the specification for message transport with the specification for message structure. This tight coupling makes the protocol more complex.
3. Other SOAP Disadvantages
| Issue | Detail |
|---|---|
| Verbose | XML-based, much larger payload than REST JSON |
| Slow | XML parsing is computationally expensive |
| Complex | Requires WSDL, strict schema, envelope structure |
| Limited browser support | REST is native to browsers; SOAP is not |
| Less flexible | REST supports JSON, XML, HTML; SOAP is XML-only |
SOAP vs REST Summary
| Feature | SOAP | REST |
|---|---|---|
| Format | XML only | JSON, XML, HTML, plain text |
| Speed | Slower | Faster |
| Standards | Strict (WSDL) | Flexible |
| Security built-in | WS-Security | Relies on HTTPS/OAuth |
| Browser-friendly | No | Yes |