An SMS API can be connected via REST or SMPP. SMPP is a more specific protocol to SMS, popular for high throughputs but also possibly taking heavier load in platform resources. REST on the other hand, is more generic and great for triggering real-time and on-demand services. We take a deeper look into each of these protocols and their claim to fame for SMS.

What is REST?

REST refers to Representational State Transfer. It is a software architecture style for designing networked applications, using the HTTP protocol for CRUD (Create/Read/Update/Delete) operations. It is however not a standard.REST protocol characteristics for handling CRUD actions include Client-Server, Stateless, Cacheable, Layered.

REST Principles

The adoption of REST has been largely due to it’s contributions to an API’s cleaner “UI” or library, with the use of RESTful URLs and actions. These RESTful principles are based on Roy Fielding’s dissertation on network based software architectures.

How is REST Used for SMS API?

An overall RESTful API definitely makes things easier for devs by taking away the hassle of synced interconnections with SMS providers. With REST, a simple network connection, handling for Response objects and XML Parsing functionality is required.

HTTP Methods

By using basic HTTP method verbs to specific resource URIs (uniform resource identifier) using request and response headers, interactions with a REST API mirrors the basic principles that the Internet is built on. APIs are usually developed using the following REST style operations.

[GET] — Fetch / Query

[POST] — Create / New / Start

[PUT] — ‘Full’ Update / Alter / Modify

[PATCH] — ‘Partially’ Update / Alter / Modify

[DELETE] — Remove / Stop / Cancel

Devs can use any web development language to access the API, given that REST is lightweight and built on simple and established standards, with no need for additional toolkits.

What is SMPP?

Not to be confused with XMPP, SMPP refers to Short Message Peer to Peer. It is an open, industry standard protocol designed to provide a flexible data communications interface for the transfer of short message data between External Short Message Entities (ESME), Routing Entities (RE) and Message Centres, using a standard internet connection. It is occasionally called the “true SMS” protocol with direct access to network providers, using a level-7 TCP/IP protocol. The most current version is 5.0.

How is REST Used for SMS API?

In order to make use of the SMPP Protocol, a SMPP session must be established between the ESME and Message Centre or SMPP Routing Entity where appropriate. This session is created using a SMPP client that communicates with an SMPP protocol. There is a continuous exchange of SMPP PDU (Protocol Data Units or Packets) to ensure a proper bind/connection is established. The SMPP client takes care of SMS and delivers them to the server. The SMPP server also transmits a delivery report back to the client when there is a change of status for an SMS.

Takeaway

Both are protocols suitable for SMS, with a vast variety of features from 2-way SMS, Mobile Originated SMS, Long & Short Codes, 2FA and Verification in use cases. It is however clear as day — REST is simpler, more scalable and easier for developers with its quick and open implementation. Other key factors to look out for are an SMS API provider with an extensive global coverage of SMS termination and the quality of direct connections to carriers in the market critical to you.

Overall Comparison - REST and SMPP