diff --git a/integration/ocean/AssetOwners.test.ts b/integration/ocean/AssetOwners.test.ts
index cef85a5..01c73be 100644
--- a/integration/ocean/AssetOwners.test.ts
+++ b/integration/ocean/AssetOwners.test.ts
@@ -77,9 +77,11 @@ describe('Asset Owners', () => {
             )
         } catch {}
 
+        const accessService = ddo.findServiceByType('access')
+
         await ocean.assets.order(
             ddo.id,
-            ddo.findServiceByType('access').serviceDefinitionId,
+            accessService.index,
             account2
         )
         // Access granted
diff --git a/integration/ocean/ConsumeAsset.test.ts b/integration/ocean/ConsumeAsset.test.ts
index 105d72b..debfdf5 100644
--- a/integration/ocean/ConsumeAsset.test.ts
+++ b/integration/ocean/ConsumeAsset.test.ts
@@ -68,7 +68,7 @@ describe('Consume Asset', () => {
 
         serviceAgreementSignatureResult = await ocean.agreements.prepare(
             ddo.id,
-            accessService.serviceDefinitionId,
+            accessService.index,
             consumer
         )
 
@@ -91,7 +91,7 @@ describe('Consume Asset', () => {
         const success = await ocean.agreements.create(
             ddo.id,
             serviceAgreementSignatureResult.agreementId,
-            accessService.serviceDefinitionId,
+            accessService.index,
             serviceAgreementSignatureResult.signature,
             consumer,
             publisher
@@ -115,7 +115,7 @@ describe('Consume Asset', () => {
     it('should lock the payment by the consumer', async () => {
         const paid = await ocean.agreements.conditions.lockReward(
             serviceAgreementSignatureResult.agreementId,
-            ddo.findServiceByType('metadata').metadata.main.price,
+            ddo.findServiceByType('metadata').attributes.main.price,
             consumer
         )
 
@@ -162,7 +162,7 @@ describe('Consume Asset', () => {
         const path = await ocean.assets.consume(
             serviceAgreementSignatureResult.agreementId,
             ddo.id,
-            accessService.serviceDefinitionId,
+            accessService.index,
             consumer,
             folder
         )
@@ -189,7 +189,7 @@ describe('Consume Asset', () => {
         const path = await ocean.assets.consume(
             serviceAgreementSignatureResult.agreementId,
             ddo.id,
-            accessService.serviceDefinitionId,
+            accessService.index,
             consumer,
             folder,
             1
diff --git a/integration/ocean/ConsumeAssetBrizo.test.ts b/integration/ocean/ConsumeAssetBrizo.test.ts
index 4d48411..c2beb4f 100644
--- a/integration/ocean/ConsumeAssetBrizo.test.ts
+++ b/integration/ocean/ConsumeAssetBrizo.test.ts
@@ -61,7 +61,7 @@ describe('Consume Asset (Brizo)', () => {
 
         const steps = []
         agreementId = await ocean.assets
-            .order(ddo.id, accessService.serviceDefinitionId, consumer)
+            .order(ddo.id, accessService.index, consumer)
             .next(step => steps.push(step))
 
         assert.isDefined(agreementId)
@@ -75,7 +75,7 @@ describe('Consume Asset (Brizo)', () => {
         const path = await ocean.assets.consume(
             agreementId,
             ddo.id,
-            accessService.serviceDefinitionId,
+            accessService.index,
             consumer,
             folder
         )
diff --git a/integration/ocean/ConsumeBigAsset.test.ts b/integration/ocean/ConsumeBigAsset.test.ts
index 3210409..7522aa0 100644
--- a/integration/ocean/ConsumeBigAsset.test.ts
+++ b/integration/ocean/ConsumeBigAsset.test.ts
@@ -59,7 +59,7 @@ xdescribe('Consume Asset (Large size)', () => {
 
         agreementId = await ocean.assets.order(
             ddo.id,
-            accessService.serviceDefinitionId,
+            accessService.index,
             consumer
         )
 
@@ -73,7 +73,7 @@ xdescribe('Consume Asset (Large size)', () => {
         const path = await ocean.assets.consume(
             agreementId,
             ddo.id,
-            accessService.serviceDefinitionId,
+            accessService.index,
             consumer,
             folder
         )
diff --git a/integration/ocean/Signature.test.ts b/integration/ocean/Signature.test.ts
index 9a46c52..6a66394 100644
--- a/integration/ocean/Signature.test.ts
+++ b/integration/ocean/Signature.test.ts
@@ -46,7 +46,6 @@ describe('Signature', () => {
         const did = `did:op:${'c'.repeat(64)}`
         const templateId = `0x${'f'.repeat(40)}`
         const agreementId = `0x${'e'.repeat(64)}`
-        const serviceDefinitionId = '0'
 
         const serviceAgreementTemplate = await templates.escrowAccessSecretStoreTemplate.getServiceAgreementTemplate()
 
@@ -55,15 +54,16 @@ describe('Signature', () => {
             service: [
                 {
                     type: 'access',
+                    index: 0,
                     purchaseEndpoint: undefined,
                     serviceEndpoint: undefined,
-                    serviceDefinitionId,
                     templateId,
                     serviceAgreementTemplate
                 } as any,
                 {
                     type: 'metadata',
-                    metadata: {
+                    index: 1,
+                    attributes: {
                         main: {
                             price: 10
                         }
@@ -74,7 +74,7 @@ describe('Signature', () => {
 
         const signature = await ocean.utils.agreements.signServiceAgreement(
             ddo,
-            serviceDefinitionId,
+            0,
             agreementId,
             [
                 `0x${'1'.repeat(64)}`,
diff --git a/integration/utils/ddo-metadata-generator.ts b/integration/utils/ddo-metadata-generator.ts
index 57311d2..c1d9af2 100644
--- a/integration/utils/ddo-metadata-generator.ts
+++ b/integration/utils/ddo-metadata-generator.ts
@@ -12,11 +12,13 @@ const metadata: Partial<MetaData> = {
         files: [
             {
                 index: 0,
+                contentType: 'application/json',
                 url:
                     'https://raw.githubusercontent.com/oceanprotocol/squid-js/master/package.json'
             },
             {
                 index: 1,
+                contentType: 'text/plain',
                 url:
                     'https://raw.githubusercontent.com/oceanprotocol/squid-js/master/README.md'
             }
diff --git a/src/brizo/Brizo.ts b/src/brizo/Brizo.ts
index 62628d7..6251e35 100644
--- a/src/brizo/Brizo.ts
+++ b/src/brizo/Brizo.ts
@@ -37,7 +37,7 @@ export class Brizo extends Instantiable {
 
     public getComputeEndpoint(
         pubKey: string,
-        serviceId: string,
+        serviceIndex: number,
         _notUsed: string,
         container: string
     ) {
@@ -47,14 +47,14 @@ export class Brizo extends Instantiable {
     public async initializeServiceAgreement(
         did: string,
         serviceAgreementId: string,
-        serviceDefinitionId: string,
+        serviceIndex: number,
         signature: string,
         consumerAddress: string
     ): Promise<any> {
         const args = {
             did,
             serviceAgreementId,
-            serviceDefinitionId,
+            serviceIndex,
             signature,
             consumerAddress
         }
diff --git a/src/ddo/DDO.ts b/src/ddo/DDO.ts
index 3010933..11d2271 100644
--- a/src/ddo/DDO.ts
+++ b/src/ddo/DDO.ts
@@ -63,19 +63,19 @@ export class DDO {
     }
 
     /**
-     * Finds a service of a DDO by ID.
-     * @param  {string} serviceDefinitionId Service ID.
+     * Finds a service of a DDO by index.
+     * @param  {number} Service index.
      * @return {Service} Service.
      */
     public findServiceById<T extends ServiceType>(
-        serviceDefinitionId: string
+        index: number
     ): Service<T> {
-        if (!serviceDefinitionId) {
-            throw new Error('serviceDefinitionId not set')
+        if (!index) {
+            throw new Error('index is not set')
         }
 
         const service = this.service.find(
-            s => s.serviceDefinitionId === serviceDefinitionId
+            s => s.index === index
         )
 
         return service as Service<T>
@@ -101,8 +101,8 @@ export class DDO {
      * @return {string[]} DDO checksum.
      */
     public getChecksum(): string {
-        const { metadata } = this.findServiceByType('metadata')
-        const { files, name, author, license } = metadata.main
+        const { attributes } = this.findServiceByType('metadata')
+        const { files, name, author, license } = attributes.main
 
         const values = [
             ...(files || []).map(({ checksum }) => checksum).filter(_ => !!_),
@@ -150,11 +150,11 @@ export class DDO {
      */
     public addChecksum(): void {
         const metadataService = this.findServiceByType('metadata')
-        if (metadataService.metadata.main.checksum) {
+        if (metadataService.attributes.main.checksum) {
             LoggerInstance.log('Checksum already exists')
             return
         }
-        metadataService.metadata.main.checksum = this.getChecksum()
+        metadataService.attributes.main.checksum = this.getChecksum()
     }
 
     /**
diff --git a/src/ddo/Service.ts b/src/ddo/Service.ts
index f463464..8d28a5b 100644
--- a/src/ddo/Service.ts
+++ b/src/ddo/Service.ts
@@ -12,7 +12,7 @@ export type ServiceType =
 
 export interface ServiceCommon {
     type: ServiceType
-    serviceDefinitionId?: string
+    index: number
     serviceEndpoint?: string
 }
 
@@ -23,7 +23,7 @@ export interface ServiceAuthorization extends ServiceCommon {
 
 export interface ServiceMetadata extends ServiceCommon {
     type: 'metadata'
-    metadata: MetaData
+    attributes: MetaData
 }
 
 export interface ServiceAccess extends ServiceCommon {
diff --git a/src/keeper/contracts/templates/EscrowAccessSecretStoreTemplate.ts b/src/keeper/contracts/templates/EscrowAccessSecretStoreTemplate.ts
index 1aa7164..c7adcac 100644
--- a/src/keeper/contracts/templates/EscrowAccessSecretStoreTemplate.ts
+++ b/src/keeper/contracts/templates/EscrowAccessSecretStoreTemplate.ts
@@ -59,7 +59,7 @@ export class EscrowAccessSecretStoreTemplate extends AgreementTemplate {
     ) {
         return !!(await this.createFullAgreement(
             ddo.shortId(),
-            ddo.findServiceByType('metadata').metadata.main.price,
+            ddo.findServiceByType('metadata').attributes.main.price,
             consumer,
             from,
             agreementId
@@ -79,7 +79,7 @@ export class EscrowAccessSecretStoreTemplate extends AgreementTemplate {
         } = await this.createFullAgreementData(
             agreementId,
             ddo.shortId(),
-            ddo.findServiceByType('metadata').metadata.main.price,
+            ddo.findServiceByType('metadata').attributes.main.price,
             consumer
         )
         return [
diff --git a/src/ocean/OceanAgreements.ts b/src/ocean/OceanAgreements.ts
index 71b5b42..3fc8dce 100644
--- a/src/ocean/OceanAgreements.ts
+++ b/src/ocean/OceanAgreements.ts
@@ -42,13 +42,13 @@ export class OceanAgreements extends Instantiable {
     /**
      * Creates a consumer signature for the specified asset service.
      * @param  {string} did Decentralized ID.
-     * @param  {string} serviceDefinitionId Service definition ID.
+     * @param  {number} index Service index.
      * @param  {Account} consumer Consumer account.
      * @return {Promise<AgreementPrepareResult>} Agreement ID and signaturee.
      */
     public async prepare(
         did: string,
-        serviceDefinitionId: string,
+        index: number,
         consumer: Account
     ): Promise<AgreementPrepareResult> {
         const d: DID = DID.parse(did as string)
@@ -68,7 +68,7 @@ export class OceanAgreements extends Instantiable {
 
         const signature = await this.ocean.utils.agreements.signServiceAgreement(
             ddo,
-            serviceDefinitionId,
+            index,
             agreementId,
             agreementConditionsIds,
             consumer
@@ -80,21 +80,21 @@ export class OceanAgreements extends Instantiable {
     /**
      * Submit a service agreement to the publisher to create the agreement on-chain.
      * @param  {string} did Decentralized ID.
-     * @param  {string} serviceDefinitionId Service definition ID.
+     * @param  {number} index Service index.
      * @param  {Account} consumer Consumer account.
      * @return {Promise<void>}
      */
     public async send(
         did: string,
         agreementId: string,
-        serviceDefinitionId: string,
+        index: number,
         signature: string,
         consumer: Account
     ): Promise<void> {
         const result = await this.ocean.brizo.initializeServiceAgreement(
             didPrefixed(did),
             zeroX(agreementId),
-            serviceDefinitionId,
+            index,
             zeroX(signature),
             consumer.getId()
         )
@@ -112,7 +112,7 @@ export class OceanAgreements extends Instantiable {
      * in this method before submitting on-chain.
      * @param  {string} did Decentralized ID.
      * @param  {string} agreementId Service agreement ID.
-     * @param  {string} serviceDefinitionId Service definition ID.
+     * @param  {number} index Service index.
      * @param  {string} signature Service agreement signature.
      * @param  {Account} consumer Consumer account.
      * @param  {Account} publisher Publisher account.
@@ -121,7 +121,7 @@ export class OceanAgreements extends Instantiable {
     public async create(
         did: string,
         agreementId: string,
-        serviceDefinitionId: string,
+        index: number,
         signature: string,
         consumer: Account,
         publisher: Account
@@ -129,7 +129,7 @@ export class OceanAgreements extends Instantiable {
         const d: DID = DID.parse(did)
         const ddo = await this.ocean.aquarius.retrieveDDO(d)
 
-        const templateName = ddo.findServiceById<'access'>(serviceDefinitionId)
+        const templateName = ddo.findServiceById<'access'>(index)
             .serviceAgreementTemplate.contractName
         await this.ocean.keeper
             .getTemplateByName(templateName)
@@ -145,9 +145,7 @@ export class OceanAgreements extends Instantiable {
 
     /**
      * Get the status of a service agreement.
-     * @param  {string} did Decentralized ID.
      * @param  {string} agreementId Service agreement ID.
-     * @param  {string} serviceDefinitionId Service definition ID.
      * @param  {boolean} extended Returns a complete status with dependencies.
      * @return {Promise<any>}
      */
diff --git a/src/ocean/OceanAssets.ts b/src/ocean/OceanAssets.ts
index dc0d3e3..fe39dca 100644
--- a/src/ocean/OceanAssets.ts
+++ b/src/ocean/OceanAssets.ts
@@ -91,7 +91,7 @@ export class OceanAssets extends Instantiable {
 
             const serviceEndpoint = this.ocean.aquarius.getServiceEndpoint(did)
 
-            let serviceDefinitionIdCount = 0
+            let indexCount = 0
             // create ddo itself
             const ddo: DDO = new DDO({
                 id: did.getDid(),
@@ -126,7 +126,7 @@ export class OceanAssets extends Instantiable {
                     {
                         type: 'metadata',
                         serviceEndpoint,
-                        metadata: {
+                        attributes: {
                             // Default values
                             curation: {
                                 rating: 0,
@@ -158,10 +158,10 @@ export class OceanAssets extends Instantiable {
                             list.findIndex(({ type: t }) => t === type) === i
                     )
                     .reverse()
-                    // Adding ID
+                    // Adding index
                     .map(_ => ({
                         ..._,
-                        serviceDefinitionId: String(serviceDefinitionIdCount++)
+                        index: indexCount++
                     })) as Service[]
             })
 
@@ -206,7 +206,7 @@ export class OceanAssets extends Instantiable {
     public async consume(
         agreementId: string,
         did: string,
-        serviceDefinitionId: string,
+        serviceIndex: number,
         consumerAccount: Account,
         resultPath: string,
         index?: number,
@@ -216,7 +216,7 @@ export class OceanAssets extends Instantiable {
     public async consume(
         agreementId: string,
         did: string,
-        serviceDefinitionId: string,
+        serviceIndex: number,
         consumerAccount: Account,
         resultPath?: undefined | null,
         index?: number,
@@ -226,18 +226,18 @@ export class OceanAssets extends Instantiable {
     public async consume(
         agreementId: string,
         did: string,
-        serviceDefinitionId: string,
+        serviceIndex: number,
         consumerAccount: Account,
         resultPath?: string,
         index: number = -1,
         useSecretStore?: boolean
     ): Promise<string | true> {
         const ddo = await this.resolve(did)
-        const { metadata } = ddo.findServiceByType('metadata')
+        const { attributes } = ddo.findServiceByType('metadata')
 
-        const accessService = ddo.findServiceById(serviceDefinitionId)
+        const accessService = ddo.findServiceById(serviceIndex)
 
-        const { files } = metadata.main
+        const { files } = attributes.main
 
         const { serviceEndpoint } = accessService
 
@@ -250,7 +250,7 @@ export class OceanAssets extends Instantiable {
         this.logger.log('Consuming files')
 
         resultPath = resultPath
-            ? `${resultPath}/datafile.${ddo.shortId()}.${serviceDefinitionId}/`
+            ? `${resultPath}/datafile.${ddo.shortId()}.${serviceIndex}/`
             : undefined
 
         if (!useSecretStore) {
@@ -265,7 +265,7 @@ export class OceanAssets extends Instantiable {
         } else {
             const files = await this.ocean.secretStore.decrypt(
                 did,
-                ddo.findServiceByType('metadata').metadata.main.encryptedFiles,
+                ddo.findServiceByType('metadata').attributes.main.encryptedFiles,
                 consumerAccount,
                 ddo.findServiceByType('authorization').serviceEndpoint
             )
@@ -288,13 +288,13 @@ export class OceanAssets extends Instantiable {
      * Start the purchase/order of an asset's service. Starts by signing the service agreement
      * then sends the request to the publisher via the service endpoint (Brizo http service).
      * @param  {string} did Decentralized ID.
-     * @param  {string} serviceDefinitionId Service definition ID.
+     * @param  {number} index Service index.
      * @param  {Account} consumer Consumer account.
      * @return {Promise<string>} Returns Agreement ID
      */
     public order(
         did: string,
-        serviceDefinitionId: string,
+        index: number,
         consumer: Account
     ): SubscribablePromise<OrderProgressStep, string> {
         return new SubscribablePromise(async observer => {
@@ -316,7 +316,7 @@ export class OceanAssets extends Instantiable {
                 this.logger.log('Agreement initialized')
                 observer.next(OrderProgressStep.AgreementInitialized)
 
-                const { metadata } = ddo.findServiceByType('metadata')
+                const { attributes } = ddo.findServiceByType('metadata')
 
                 this.logger.log('Locking payment')
 
@@ -327,7 +327,7 @@ export class OceanAssets extends Instantiable {
                 observer.next(OrderProgressStep.LockingPayment)
                 const paid = await oceanAgreements.conditions.lockReward(
                     agreementId,
-                    metadata.main.price,
+                    attributes.main.price,
                     consumer
                 )
                 observer.next(OrderProgressStep.LockedPayment)
@@ -352,7 +352,7 @@ export class OceanAssets extends Instantiable {
             await oceanAgreements.create(
                 did,
                 agreementId,
-                serviceDefinitionId,
+                index,
                 undefined,
                 consumer,
                 consumer
diff --git a/src/ocean/utils/ServiceAgreement.ts b/src/ocean/utils/ServiceAgreement.ts
index b520a34..c634aed 100644
--- a/src/ocean/utils/ServiceAgreement.ts
+++ b/src/ocean/utils/ServiceAgreement.ts
@@ -13,12 +13,12 @@ export class ServiceAgreement extends Instantiable {
 
     public async signServiceAgreement(
         ddo: DDO,
-        serviceDefinitionId: string,
+        index: number,
         serviceAgreementId: string,
         agreementConditionsIds: string[],
         consumer: Account
     ): Promise<string> {
-        const service = ddo.findServiceById<'access'>(serviceDefinitionId)
+        const service = ddo.findServiceById<'access'>(index)
         const timelockValues: number[] = this.getTimeValuesFromService(
             service,
             'timelock'
diff --git a/src/utils/DDOHelpers.ts b/src/utils/DDOHelpers.ts
index 67a2475..a326825 100644
--- a/src/utils/DDOHelpers.ts
+++ b/src/utils/DDOHelpers.ts
@@ -13,7 +13,7 @@ function fillParameterWithDDO(
             case 'amount':
             case 'price':
                 return String(
-                    ddo.findServiceByType('metadata').metadata.main.price
+                    ddo.findServiceByType('metadata').attributes.main.price
                 )
             case 'assetId':
             case 'documentId':
diff --git a/test/ddo/DDO.test.ts b/test/ddo/DDO.test.ts
index bb7e248..ee4a134 100644
--- a/test/ddo/DDO.test.ts
+++ b/test/ddo/DDO.test.ts
@@ -88,9 +88,10 @@ describe('DDO', () => {
             },
             {
                 type: 'metadata',
+                index: 0,
                 serviceEndpoint:
                     'http://myaquarius.org/api/v1/provider/assets/metadata/{did}',
-                metadata: {
+                attributes: {
                     main: {
                         name: 'UK Weather information 2011',
                         type: 'dataset',
@@ -104,16 +105,19 @@ describe('DDO', () => {
                                 index: 0,
                                 checksum: 'efb2c764274b745f5fc37f97c6b0e761',
                                 contentLength: 4535431,
+                                contentType: 'application/json',
                                 resourceId:
                                     'access-log2018-02-13-15-17-29-18386C502CAEA932'
                             },
                             {
                                 index: 1,
                                 checksum: '085340abffh21495345af97c6b0e761',
-                                contentLength: 12324
+                                contentLength: 12324,
+                                contentType: 'application/json'
                             },
                             {
-                                index: 2
+                                index: 2,
+                                contentType: ''
                             }
                         ],
                         checksum: ''
diff --git a/test/mocks/Brizo.mock.ts b/test/mocks/Brizo.mock.ts
index da8f96e..7efe47b 100644
--- a/test/mocks/Brizo.mock.ts
+++ b/test/mocks/Brizo.mock.ts
@@ -4,7 +4,7 @@ export default class BrizoMock extends Brizo {
     public async initializeServiceAgreement(
         did: string,
         serviceAgreementId: string,
-        serviceDefinitionId: string,
+        index: number,
         signature: string,
         consumerPublicKey: string
     ): Promise<any> {
diff --git a/test/testdata/ddo.json b/test/testdata/ddo.json
index fd48c2e..2e75886 100644
--- a/test/testdata/ddo.json
+++ b/test/testdata/ddo.json
@@ -40,7 +40,7 @@
   "service": [
     {
       "type": "access",
-      "serviceDefinitionId": "0",
+      "index": 0,
       "serviceEndpoint": "http://mybrizo.org/api/v1/brizo/services/consume?pubKey=${pubKey}&serviceId={serviceId}&url={url}",
       "purchaseEndpoint": "http://mybrizo.org/api/v1/brizo/services/access/purchase?",
       "templateId": "044852b2a670ade5407e78fb2863c51000000000000000000000000000000000",
@@ -145,16 +145,16 @@
     },
     {
       "type": "compute",
-      "serviceDefinitionId": "1",
+      "index": 1,
       "serviceEndpoint": "http://mybrizo.org/api/v1/brizo/services/compute?pubKey=${pubKey}&serviceId={serviceId}&algo={algo}&container={container}",
       "templateId": "044852b2a670ade5407e78fb2863c51000000000000000000000000000000002"
     },
     {
       "type": "metadata",
-      "serviceDefinitionId": "2",
+      "index": 2,
       "serviceEndpoint": "http://myaquarius.org/api/v1/provider/assets/metadata/{did}",
-      "metadata": {
-        "base": {
+      "attributes": {
+        "main": {
           "name": "UK Weather information 2011",
           "type": "dataset",
           "dateCreated": "2012-10-10T17:00:000Z",