The service metadata is the off-chain description of a SingularityNET service and is, by default, hosted on the SingularityNET IPFS cluster. In order to use a service, the client needs to know:

• The service metadata
• The address of Multi-Party Escrow (MPE) contract

Fortunately the latter is included in the metadata. The daemon allowing access to the service also needs to know this metadata, in order to configure the necessary payment systems.

There are three ways of providing this metadata to the clients and the daemons:

• as a simple JSON file
• as a IPFS hash that points to the JSON metadata
• as a name of service in the Registry - this can be resolved to an IPFS hash, pointing to the metadata, through the Registry’s getMetadataIPFSHash method.

As a security concern the client shoudn’t use mpe_address from the metadata as a sole source of the MPE contract address. The client should check that this address corresponds to the mpe_address it was expecting. The defaults MPE addresses for various networks are:

• Mainnet - 0x9c9252ec9fa844e2c7bd2e6f54bec2901938479f
• Ropsten - 0x7e6366fbe3bdfce3c906667911fc5237cc96bd08
• Kovan (deprecated) - 0x39f31ac7b393fe2c6660b95b878feb16ea8f3156

A suspicious client should also check that hash of the metadata corresponds to the IPFS hash, otherwise the client can be attacked if the IPFS client is compromised. Fortunately, the snet-cli does this by default.

Metadata Overview

{
    "version": 2,
    "display_name": "Entity Disambiguation",
    "encoding": "proto",
    "service_type": "grpc",
    "model_ipfs_hash": "Qmdxxxhggjkkgk6wAB4GmGBekQfLoiLtXYv",
    "mpe_address": "0x34E2EeE197EfAAbEcC495FdF3B1781a3b894eB5f",
    "groups": [
        {
            "group_name": "default_group",
            "pricing": [
                {
                    "price_model": "fixed_price",
                    "price_in_cogs": 1,
                    "default": true
                }
            ],
            "endpoints": [
                "https://tz-services-1.snet.sh:8005"
            ],
            "group_id": "EoFmN3nvaXpf6ew8jJbIPVghE5NXfYupFF7PkRmVyGQ="
        }
    ],
    "assets": {
        "hero_image": "QmbaewdfafrpZdpug4WhhcmVVCEwUxjLQafq1/hero_named-entity-disambiguation.png"
    },
    "service_description": {
        "url": "https://dummy.io/sadds/users_guide/named-entity-disambiguation-service.html",
        "description": "Provide further clearity regaridng entities named within a piece of text. For example, \"Paris is the capital of France\", we would want to link \"Paris\" to Paris the city not Paris Hilton in this case."
    }
}

This metadata file can be directly edited before publishing to IPFS, or manipulated by snet-cli through service subcommands that have the metadata-* prefix.

The python module for manipulating this metadata directly can be found here.

Last modified on : 11-May-20